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1993 240 wagon. Runs fine when cool or when i start my daily trip...within 15 or 20 minutes...starts to ping quite a bit...especially loud when going uphill.
There is no spluttering or hesitation. Temp guage is steady and even. Plugs look slightly rich, but not badly so.
i checked the OBD1 and it reported No fault codes.
Any and all suggestions are welcome.
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posted by
someone claiming to be LV 240
on
Thu Feb 20 10:11 CST 2014 [ RELATED]
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My 4Runner had the same problem 10 years ago: engine pinged, especially going uphill.
After using one bottle of Techron Fuel System Cleaner (20oz) and driving on freeway at 65 for an hour, the problem was getting better. A week later, I poured another bottle of Techron and filled up the gas tank. The problem was completely gone and never came back.
For my Volvo 88 244, I always use Techron (12oz) and Seafoam (through the vacuum system) to keep my engine clean.
To enjoy driving my Volvo, I also keep the Mass Air Flow Sensor clean (CRC Mass air Flow sensor Cleaner) and the Transmission Mount in a good shape (it gives a smooth sift).
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"within 15 or 20 minutes...starts to ping quite a bit...especially loud when going uphill. There is no spluttering or hesitation. Temp guage is steady and even."
I realize that the temp gauge is steady, but the symptoms are a lot like an overheated engine. Is the upper radiator hose hot when this is happening? If not it could be a stuck thermostat.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.
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hmmm...i checked the rad hoses after 30 minute run this evening...with the laser temp gun: upper hose was about 163 and lower was about 95 in the middle of the hose...(about 130 close to the engine block)
I replaced water pump and thermostat about 2 months ago.
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The 163 degrees of temperature is way too cold, if you are fully warmed up.
You should see at least 190 degrees on the outlet pipe to the top hose.
You may have been running richer than you should have and now have excess carbon in the cylinders which could cause some pinging.
I like a Wahler thermostat because they stay accurate longer. They are complexly made of brass all around the filled wax copper casing. I think it senses or expands more evenly against/with the diaphragm disk.
I boil my stats in vegetable oil, even those from right out of any box, nowadays. If it cracks open any sooner, at all, you need to know that!
For me it’s a more even temperature testing method. The oil heats upwards from the bottom of the pot in a more controlled manner while at the same time you can see the disk as it just starts to open without all the bubbles.
In cars with pressurized systems there will not be any bubbles if the recovery bottle and cap are doing their job.
If you have a Stant or Caloric thermostat one in there, toss it!
Phil
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The owners manual calls for at least 91 a.k.i. optimally, and I wouldn't use less than 89. The engine is really not designed for "regular" which, in this country, usually means 87 to most people, although in forgivable circumstances 87 is tolerable, but a lot depends on the terrain where you drive, and the ambient temperature -- hot weather and hills both suggest using higher octane.
In any case, in our '93 cars (I have two '93s) there is no way to adjust timing or the advance curve. In older cars, you used to be able to do that by turning the distributor, and proper advance or retardation was enabled by springs and weights, and a vacuum diaphragm, in and on the distributor. But in our cars, the distributor is fixed (cannot be rotated) and empty, devoid of all the aforementioned mechanical gadgets -- it's even devoid of a crankshaft position sensor (hall effect pickup), which is replaced by a CPS on the bell housing. All of the timing and advance/retardation is calculated by an algorhythm programmed into the ECU, and therefore isn't adjustable.
Your only recourse is to consider the gasoline you buy (is it good quality), and perhaps whether your injectors are good (too lean a mixture, because the injectors can't deliver enough fuel, can cause knock).
Also, check the AMM, your O2 sensor, and even your coolant sensor (not the one to the gauge, but the other one to your ECU) -- they all feed information to the ECU with which it makes your timing decisions.
Good luck.
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Pinging may be related to the quality of the fuel you are using, try a different brand or higher octane.
Dan
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tank 91 octane didnt do much....on acceleration there is a loud clattering and loss of power
At idle, vacuum gage reads dead even 20 psi, without any hiccups or dancing of the needle....engine is very quiet and even. Under load it sounds like a diesel.
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After driving 20 minutes and the car sounds like a diesel, i attached the timing light: at idle the notch on pulley lines up exactly with the rightmost timing mark...then when i open the throttle and raise rpms, the notch quickly moves to the right in the RETARD direction(at least a few degrees), then doubles back and crosses over the timing mark and heads in the ADV direction.
This is with Knock sensor attached. Ill try later without the KS
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Geez, I am not sure if you are lost or if I am the one lost here?
What you describe is what the knock sensor is suppose to be doing.
When you say it lines up with the right most timing mark at idle is what blows my mind because that would be the zero timing mark. I hope you are miss stating, what is, the most far right mark?
That should not ever happen unless there was a severe knock all the time! That would not be right since you have the CPS timing system. It should be settled in the 12 degree BTC area which is a blank space between 10 and 15 going to the left. The engine spins to the right so the marks are going to be spotted to the left (in advance = before) of TDC which is the zero.
What you describe is the spark is on the zero, which is in essence at idle, is AT or after ATDC ! Way retarded!
If you were starting a hand crank engine like an model A or an old motorcycle you would retard the spark to fire AfterTC as to not break your arm or throw you over the handle bars to kiss the front wheel!
In those days all you had was a "static" method to time those old engines with a light bulb hooked over the points. All in the days before neon timing lights and even newer transistorized xenon tubes came on the scene.
It takes a certain amount of time to generate and move the spark of electricity down the wires.
The pistons DO move faster than that amount of time and they get many times faster. As that happens the spark is sped up faster by starting it even sooner to keep up to give more burning time of the fuel.
I have often wondered just how fast that can occur, but anyways, this knock is happen to soon which can happen for SEVERAL reasons that should not be happening on these modern engines.
If you are seeing what I understand is a actually zero, then something is in fact, of that infamous term again, "whack." I want to say mechanically too!
The distributor might be off one tooth on the timing belt, could have been install off a tooth in relation to the intermediate gear. The flywheel or the crank pulley is not located properly and lying under the light. Trick is, its knocking? The knock sensor is working overtime! Things are WHACKING in there which is very unusual!
What's the history of past work done on the engine before this started? Clutch, transmission, cylinder head or timing belt change?
Any coolant loss going on?
Are you using the standard heat range sparks plugs recommended?
I am also curious of what type/brand oil you are using and how much between changes?
The type of driving speeds and lengths of drive do you do on a regular basis?
There has to be something to explain this, even if its possible to be some electronic anomaly.
You may have post a video and we will have a show and tell party!
Ooh boy, I have been there, since face time thoughts have occurred, by my relatives and I got this handed down, iPad, from my wife's long time electronic arsenal! (/-) blind sided I was!
Phil
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Phil,
Have a long look at volvo's design and construction information in TP31397/1 posted on line under "ignition systems" at http://volvowiringdiagrams.com. If you can sort out the stuff particular to EZ116K from the rest, I think you'll enjoy reading it.
--
Art Benstein near Baltimore
Duct tape is like 'The Force'. It has a light side and a dark side, and it holds the universe together.
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Thanks Art for this information.
I did take a LONG look at reading material. You are right there is a lot of sorting to do in that article.
I notice you said he could rest the retard memory of the adaptive driving feature on the 93. That could be what's happening but figuring out what has pushed it into that memory zone is still the puzzle. Like you said it could be carbon or the timing belt is off.
I even read that the throttle switch not closing to idle mode will make the ICU keep retarding as if it was under the driving mode all the time.
That's a new twist for me to learn but then I do not have a 93 to sense an engine doing that even if my 91 could do it.
The diagrams have helped me spot the number two terminal as the one the ECT is communicating to the ECU on! That will help on some other posts too. I could not remember that, the other day.
It was really entertaining to see the described layout of flywheels. All using the CPS with holes and tooth variations for timing even numbered cylindered engines.
Makes sense that the French had their own ways of making it the hard way. 18.8 degrees throughout, all the way into the electronic factoring process.
There is not that much difference in the resolution at the bottom line. One-third degree versus three-eighths degree.
One might need a degree in electronics to build the circuit though.
Bendix of France, who else would have thunk that one up and got away with it? It's no wonder to why obsolete items and crap in up in round piles!
Still got to thank them for the fragrances that our ladies wear!
I will store that book in my favorites listing.
Thank Phil
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Lotta questions..but first things first. The timing light shows the notch (at idle) to on or just to the left of the right-most timing mark...depending on where you hold your head.
Very hard to tell from the retarded picture in my Bentleys manual (pun intended)
but it appears the marks are 20, 10 and 0. If thats the case then the notch appears at between 3 BTDC and 0. (after 20 minute warm up run)
Just realized that was read with KS connected. Shouldve done it with KS disconnected as ell. Do that tommorow.
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same with KS connected or not: idles at 0 deg or maybe 2 BTD if you close one eye....still thats a long way from 12 BTD
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Yes it is!
What concerns me from here is what else could be off?
The timing light and its spark are being fired off the flywheel by the CPS. For the moment we have to agree that the flywheel and its notch are doing things correctly mainly because it's all working.
The most common thing to throw things off would be the timing belt. But! of course, someone may have "tried" to correct it by rotating the distributors housing.
The bolt that holds down the distributor should be just to the left of being centered in the bracket. On my 91, there is an elongated plate under that bolts head. To the left of that I can see about 3/32 of an inch of the slot showing.
You may want to take a quick look to if you are in the "ball park" there.
Meaning, not so much anything to do with ignition timing but having the post terminals of the distributor aligning or centered up with the width of contact face, that's made into rotor button, when the pistons are at their TDC. The spark needs a duration path for that much distance giving up by the rotor button. Its a process, for about 80 years, to deal with the plus and minus thing and not just electricity! (:-)
The timing of the distributor is set first by locating its drive gear orientation along the path of the timing belt.
There is a dot on the face of the gear that has to be lined up with a mark at the three O' clock position on the plastic timing cover when the crankshaft and camshaft marks are properly aligned on the engine block.
Most of the time a mirror has to be used to reflect that gear face upwards into ones eyes to see the alignment alongside the raised groove. I understand your winking issue and thought I could throw that at you. (;-)
You can remove only the top portion of the timing cover and with a brightly directed light and spot all the of the most accurate "blocks marks inside" there.
The number one cylinder at TDC "O" ( the outside "reference only" scale to the pulley) on the compression stroke to check it out. Damper marks can move on these cars, unfortunately.
If needed, you loosen the tensioner and reset the distributor or camshaft if needed.
The lobes of the camshaft will be pointing upwards at you on TDC and the mark should line up with notch on the covers back plate.
Until you can confirm the engine is in a "timed mechanical state" with the CPS, the knock sensor electronics will have to be left out of the picture.
Time to lean over the radiator and see if some hugs will help you find something! (-:)
Phil
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The bolt holding the dizz down is recessed inside a black metal plate, which itself sits atop some ridge that is part of the block, or colored that way. I dont really see any slot...perhaps just a tiny slivver on the pass side.
hopefully this pic shows
Also i asked local Volvo shop in the city about my sypmtoms..he suggested that the crankshaft pulley rubber has separated and that i should replace the pulley...Im not quite sure how that would affect ignition or valve timing, but im all ears
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The distributor is not supposed to be turned, and that's the reason for the black plastic insert into the slot - the slot being just a casting design remnant from the days when the distributor was the source of the timing. Now that, in your car, the timing source is from the crankshaft, the distributor clocking is only important from the standpoint of delivering the spark to the correct plug over the range of timing adjustment provided by the ignition controller. The wide contact assures that range can be accommodated.
The suggestion to check the harmonic balancer had shifted is probably based on your description of the timing you see. Myself, I doubt it is off just a few degrees, but rather you are seeing the correct timing which is of course retarded by the ICU which defaults retarded when it senses a problem with the KS or an out-of-range condition. Still, if the ICU is OK, and you reset its adapting memory by momentarily removing power (fuse 6 or the pal fuse if you've a late version 93), running cold you should see it attempt to advance again until it repeats the limp-home retarded default. Still doesn't hurt to check your pulley. Easiest way is rather simple -- just pull spark plug #1 and stick a popsicle stick in there and see that you get tdc when it is tdc. Very accurate - easily within one tb tooth.
Did I miss somewhere you answered the several questions about the history of the car and its pinging problem?
--
Art Benstein near Baltimore
Expert: An "ex" is a has-been and a "spurt" is a little drip under pressure.
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Hi Art.
I read your post where you mention a "pal fuse":
"...reset its adapting memory by momentarily removing power (fuse 6 or the pal fuse if you've a late version 93)...."
One of my two 93s is the later version with the set of fuses on the positive battery cable clamp. But I don't understand your reference to a "pal fuse" as if to infer that you mean a fuse other than the usual fuses (i.e., the ones on the panel by my left foot or else the set on the positive clamp) -- could you elaborate as to what "pal" means? Or, does it mean one of the fuses on the clamp? Is "pal" actually initials for something?
Thanks very much.
Ken
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I did as was suggested and I came up with two conclusions. Besides it just being a blade type fuse.
The fuse could be connected in-line with an input or output circuit to a Programable Array Logic device.
The next one was, if its not located like those inside the car interior with the floorboard but out under the hood.
It then can be called Pull And Lose fuse! (:-)
Phil
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Hi Art.
I read your post where you mention a "pal fuse":
"...reset its adapting memory by momentarily removing power (fuse 6 or the pal fuse if you've a late version 93)...."
One of my two 93s is the later version with the set of fuses on the positive battery cable clamp. But I don't understand your reference to a "pal fuse" as if to infer that you mean a fuse other than the usual fuses (i.e., the ones on the panel by my left foot or else the set on the positive clamp) -- could you elaborate as to what "pal" means? Or, does it mean one of the fuses on the clamp? Is "pal" actually initials for something?
Thanks very much.
Ken
Hi Ken,
Rather than taking it from me, try typing "pal fuse" into a google search window. You'll catch my drift (nautical idiom, professor? ;)
--
Art Benstein near Baltimore
A woman came home, screeching her car into the driveway, and ran into the house. She slammed the door and shouted at the top of her lungs, 'Honey, pack your bags. I won the lottery!'
The husband said, 'Oh my God! What should I pack, beach stuff or mountain stuff?' 'Doesn't matter,' she said. 'Just get out.'
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Piston TDC, crank pulley lined up at 0, dizz rotor points to the notch..actually about 2-3 mm past it...but it seems close enough ?
The wagon ran well this evening....after about 15 minutes the valve clattering appears
History ? er...i have not changed the timing belt since inheriting the wagon from my dad a few years ago...i have driven it across country and over the Sierras and various long distance trips thru mountains, deserts etc...this wagon is road warrior !. Its not great in the steep mountains, but fine otherwise..lately just daily in the city about 10 miles a day. The valve noise appeared only a couple months ago..getting progressively louder under load.
Cleaning the MAF wire definately helped diminish the noise, but it is still quite noticeable.
One major issue i had in the heat of the deserts was charging system failure. I replaced with rebuilt alt(s) and regulators and rewired bla bla..it is okay in temperate climes but fails in extreme heat..only now do i suspect the harmonic balancer....its not an issue here at the coast, but still i would like to resolve
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What you've said of the history is enlightening to me. Now we (I) know this isn't a car you've just acquired from a young enthusiast who was into spirited driving and engine mods. As our favorite cars get older, the probability they are not serviced by skilled people increases, but yours is just the opposite -- a family car. You are truly fighting a symptom not caused by someone's tinkering.
However, with regard to your own tinkering, why, after stating the TDC agrees with the mark on the pulley would you "suspect the harmonic balancer" and whatever is the relation of that suspicion to your coastal dwelling? One minute I'm clear, and the next I'm confused.
Anyhow, I can see you have tools (i.e. vacuum gauge, fuel pressure gauge) so do a compression test.
--
Art Benstein near Baltimore
A wife was making a breakfast of fried eggs for her husband.Suddenly, her husband burst into the kitchen. 'Careful,' he said, 'CAREFUL! Put in some more butter! Oh my gosh! You're cooking too many at once. TOO MANY! Turn them! TURN THEM NOW! We need more butter. Oh my gosh! WHERE are we going to get MORE BUTTER? They're going to STICK! Careful. CAREFUL! I said be CAREFUL! You NEVER listen to me when you're cooking! Never! Turn them! Hurry up! Are you CRAZY? Have you LOST your mind? Don't forget to salt them. You know you always forget to salt them. Use the! salt. USE THE SALT! THE SALT!' The wife stared at him. 'What in the world is wrong with you? You think I don't know how to fry a couple of eggs?' The husband calmly replied, 'I just wanted to show you what it feels like when I'm driving.'
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"The valve noise appeared only a couple months ago..getting progressively louder under load."
It's my understanding that the valves are quite noisy on these engines. Maybe everything is fine timing-wise. That you just need new valve hushers. (I Googled "valve hushers" and volvo 240's head the list.)
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.
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I have been wondering for awhile if we aren't just talking about noisy valves? The engine is not known for being real quiet.
Dan
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Good point. That would explain everything. Piston slap goes away (or not even present in "L" squirter engine) and valve lash noise appears as things heat up?
The problem I have with that theory is I expect someone who is savvy enough to do what many of us can't seem to accomplish -- use a vacuum gauge and measure fuel pressure -- knows the difference between the sound of pinging under load and excess valve clearance.
--
Art Benstein near Baltimore
Marriage is a relationship in which one person is always right, and the other is a husband.
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Before you touch the distributor, line up the marks on the pulleys as instructed elsewhere.
Now that you know that the shafts are all in sync, pop open the distributor and observe where the rotor is pointing. Where it is pointing is Top Dead Center.
Look for a scribe mark on the distributor rim. It marks where the ignition wire for cylinder 1 sits. If it is not lined up with the rotor, loosen the distributor and rotate it so that the rotor points at it. (You may have to remove a plate under the lockdown bolt that prevents distributor adjustment.)
With the rotor pointed at the scribe, cylinder 1 is set to fire at TDC without ECU input.
So any timing drift arising thereafter will likely be caused by the ECU.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.
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Your 93 might be slightly different than my 91. The silvery part should be part of the distributor housing and rides on the surface of the red block. I just wanted to know how centered do you think the bolt is. I did not want you say it was all at one end or the other for sure.
I could not see any picture. It might be my iPad, sorry!
That pulley could have slipped but that would not make the engine ping unless a person used it to set the timing belt instead of the solid engine marks that are made on the engine for use with the belt.
Like I said, the pulley mark is only a reference and means nothing to the CPS. If it has not slipped or was installed wrong though, then it does mean something like.....this?
You are at the IMAX movie theater but you are sitting in the wrong seat to see the movie centered up evenly! The spark is there, but you might not be getting the benefits of its full effect? If that helps any?
I am north of you up by the Oregon border. I also have a house on the Central Coast area. My wife has a widow sister there, so we bounce between them together or separately. It keeps me busy doing maintenance on three houses and all their mechanical stuff connected, let alone any of my hobbies. I am retired also.
I use to do business with RPR, there in the Bay Area, until I helped buy Rusty out of stuff he had to sell to clear his building. Two wagon loads worth is why you may have thought I lived in that area.
He retired and went to the Napa Valley area. I do not know if he still dabbles in Volvo's parts out of his house. He was undecided if he would. He sure knew his parts business and sold other weird things on the side. If you had ever been in there you would know what I mean. I bought so much stuff he gave me stuff to help him move!
Us boomers are bombing out anymore! (:-)
Phil
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It wouldn't but you can test it by drawing a line across both metal pieces, run the engine and see if the line separates.
Dan
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Phil, Thanks for the very clear explanation...makes sense. Im working thru some intermittant rain here in Bay Area. By the way, what part of CA are you located ?
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with the KS dis-connected..the timing notch does not go in the Retarded direction...it Advances as expected...the engine clattering noise dissappears BUT the pinging of marbles is quite clearly heard
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Do your fuel pump readings lead to a suspected clogged fuel filter?
The in-tank pump is loafing and the main pump is grunting.
Do you maintain your car according to Volvo's timetable?
Is it a turbo?
With today's fuel prices, using low octane fuel can be a fool's game, for the price difference, 1 more MPG may actually be worth the extra cost - and your engine will love you!
I am using Sunoco 260 now, it is only 4 cents a gallon more!
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No factory turbo available on 93 240's. The last factory 240 turbo available was in 1985.
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swapped out the knock sensor and there is no change in situation.
During last few days of rain, the pinging was minimal and car ran fine.
Today, a chilly dry day, but pinging resumed with worst at low rpm + uphill....loss of power is noticeable at these times
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How old is the fuel pressure regulator and what are the numbers on it? You said the plugs showed rich.
Does the car start up when cold, quickly on it first try of the day? What I mean is no long cranking moments. I am thinking its rich enough to start ok but the engine is a lot leaner after it warms up.
When was the last timing belt change or the last time you loosened the tensioner bolt and retightened it? I wonder it the timing is off (a smidgen) almost a tooth.
The combination of it with a lsticky spring onto the diaphragm in the FPR just might get its act together on the hills and pulling.
The spring has to close down on the return line going back to the tank while accelerating or pulling a grade when there is less vacuum to hold the line open.
The rich plugs are saying something is not right or the O2 sensor should be yelling at the ECU.
I cannot get it to add together without more symptoms.
What's your gas mileage? Stick or automatic transmission?
Give us a few more quirks or past history.
Phil
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Ok a few tests today.
In-tank fuel pump: 2.6 Amps (bentleys says 3-4 A)
Main fuel pump ( about 8 amps) (Bentleys says 6.5 A max)
Fuel pressure: at idle, and at rpm about 36 psi (Bentleys: 43.5 for LH2.4)
oddly, after 20 mins residual pressure was still up around 30 psi
This is a 93 wagon, so i assume it is LH2.4
next up : test fuel press reg, and remove fuel filter and check for blockage
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Most 93's are LH 3.1
As already suggested, I would check the engine coolant sensor, knock sensor, O2 sensor and ICU. Sounds more like a sensor (or electrical) issue to me than a fuel issue.
Clogged fuel filter results in engine fuel starvation and most likely sputtering. Bad fuel pressure regulator can cause poor idle and running. Don't remember hearing/reading anything about pinging.
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Most '93s are not LH3.1. Everything I have seen and heard indicates that only cars with manual transmissions in the '90s got the LH 3.1 system - there are very few and conflicting reports as to whether ANY automatic was outfitted with the LH 3.1 fuel system from the factory.
Further, I have read several reports of '93s with manual transmissions that had the LH 2.4 system from the factory.
The general consensus seems to be that LH 3.1 was used in manual cars only, from '90 to '92, and perhaps inconsistently in '93. The original poster is most likely to have the (in my experience) more stable LH 2.4 system.
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Your information is in concert with mine. For some reason, some folk think LH3.1 must be the more advanced direction LH2.4 took and with all the 1993 year anomalies figure they must have LH3.1. Not so.
Just this month saw a myth concerning LH2.4's behavior at WOT cranking. Already people are quoting it as fact.
As for the pinging, depending on the history (like did I just buy this car from a short-trip owner) I'd take a look with the timing light to see if the ICU was advancing at all under load. Probably need some help there to get someone to stand on the brake while I moved the throttle spool and not trust the parking brake. I'd be sure the belt wasn't put on wrong if the car was new to me. And if it was clear the knock sensor was working at all, I'd look at compression and imagine the carbon built up inside and anticipate doing a little water torture and Italian tune-up (all while running 93 gas of course).
According to my understanding of EZ-116K, the knock sensor deals with each cylinder separately unlike the Chrysler system used with LH2.0 and LH2.2 where we were told to test it with a hammer tap and timing light. That test is not supposed to be effective with EZK.
--
Art Benstein near Baltimore
If you tell the truth, you don't have to remember anything.
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Do you use regular gas? If the knock sensor is bad this won't work, but try a tank of the highest octane premium you can find with a bottle of Techron Concentrated fuel system cleaner. My 90 always ran better and quieter after giving it "the treatment".
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Try socket six, it might cover (test) the knock sensor and the throttle switch.
The knock sensor could have become disconnected or gone bad.
The ignition timing should be dead on since it uses a CPS but the computer may not be getting proper information to adjust for the Ping of lower octane or the load ratio. The load ratio is part of the throttle position duty IF you have the variable type switch that is in the LH 3.1 for 93's.
The resistance type switches can wear in a "dead spot" as they get older.
I do not own a 3.1 but they are good old problem child's on Chrysler products. Anybody with the mid 80's cars know about their shenanigans they left us with in the ICU connector.
This Ping thing has not been batted around much on the BB. This will be a good post to hear what others have to say!
Phil
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Thanks.
I did try the socket 6 on the OBD and got 1-1-1 (No fault codes)
Is there a way to test functionality of Knock Sensor using multimeter ? or timing-lioght ?
I think my TPS is simple microswitch on/off type..ill look into that
Car starts and runs very well until fully warmed. Use 87, never had an issue with that until few days ago when pinging became noticeable...octane booster additives nave not helped
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With respect to testing the knock sensor, the Green Book manual for my 83 (first year for the knock sensor) says:
"Read ignition timing. Then use a hammer to tap on the cast iron boss on the engine right side, above the oil filter. Read ignition timing. It should be retarded by max. 6 degrees. It will return to normal automatically."
According to another section in the book, the retardation and return happens very rapidly.
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Bob: Son's XC70, my 83 240, 89 745 (V8) and S90. Also '77 MGB and some old motorcycles
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I cannot answer that question about the knock sensor.
I think its more like a microphone and it sends out a frequency or signal that the electronics read and shift the timing to compensate for it. I suppose its powered and the sound changes something in or out?
I truly do not know how it works, just know its suppose too!
All I can say about the now clicking switch is to make sure works and most surely be plugged in!
You should be able to run any fuel at or higher octane than the one recommended in a owners manual for that year. This fuel management system self tunes all the time!
I am going with a lean mixture theory and thinking more, even though it hurts sometimes! (:)
I am wondering now if you may not have a Engine Coolant Sensor gone bad as it might throw the engine lean and off its program in the ECU? It's the one smaller than the knock sensor and farther back under the manifold. Never knew one to cause pinging....but?
Does it run with the same power as when it's not warmed up, on the flats?
Going up hills draws on the fuel pressure regulator to provide more fuel, which is vacuum controlled. It enriches the mixture by closing off the bypass back to the tank and raises up pressure in the fuel rail.
Improves power and helps keep it from going too lean.
The pinging sound is a one sized wrench, laying in a pile nuts here!
Timing change usually corrects that. The load scenario is telling us something. In old engines it was carbon but that was another era of big engines and short trips!
Check from the throttle body for a vacuum hose to a sliver can mounted to the fuel rail. Check for vacuum with the engine running. Check for cracks that might leak air in and any gasoline or smell from inside of the can or hose.
Did this come on all of a sudden? Could it be a bad tank of gas?
Again, its a empty wrench on my end.
Keep sorting!
Phil
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dingowagon wrotee--"Is there a way to test functionality of Knock Sensor using multimeter ? or timing-lioght"
I don't know if there's an official way to test a knock sensor but once, for the heck of it, I set a knock sensor in a vise--tapped the vise with a hammer and my digital multi-meter showed about 1 volt. -- Dave
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