posted by
someone claiming to be Ivo
on
Fri Jul 24 20:02 CST 2020 [ RELATED]
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My trusty 1993 Volvo 240 refuses to start. It cranks well, I can hear the fuel pump buzzing, and fuel relay clicking. However there is no spark...no high voltage coming to the distributor. I swapped the high voltage coil with another one. That didn't change anything. Fuses look good too.
Not sure what to do next. Perhaps check OBD codes.
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I thought if the computer doesn't see spark, the fuel pumps won't run?
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Post Back. That's whats makes this forum work.
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Hi aleecat,
I think the Op may be interpreting the momentary operation of the fuel pumps at KP-2 as an indicator of fuel. Someone correct me if I'm wrong, but I don't think that's any guarantee that the pumps will be on when the engine is cranking.
regards, Peter
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You are correct, Peter.
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Art Benstein near Baltimore
"To make anything interesting you simply have to look at it long enough." -Gustave Flauber
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Hi,
Good statement!
Yes, but not exactly, because there is no feedback from anything, to know there was no spark.
Now if the timing belt breaks, it doesn’t know that either!
Same issue but the CPS says the engine is turning.
The cam belt has no output like the older distributor hall sensors (LH 2.2) gave out its other chain of systems.
The ICU, that is in the cabin with the ECU, needs to see a signal from the CRANK Position Sensor to know when to fire the spark.
It tells the Electronic Relay to open the ground on the coil to fire it’s power into the secondary coil that has a spark plug on its far end.
The ICU, in turn sends a signal to the ECU or computer to turn on the system relay for fuel pumping and open the injectors by grounding the injectors opposite side.
The ECU does this all the while getting that signal from the ICU. The ICU moves the timing around per feedback a program from inside the ECU.
The ECU works with relays and the AMM to set mixture variations with an overall “eye of combustion” response from the oxygen sensor.
This is why I chose to pick on the middle man out there by the battery that is always neglected in maintenance schedules. Just because it’s not mechanical it doesn’t mean it cannot be without “his own” faults!
(:-). We all know they exist, if it was made by man!
Phil
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If the crank or cam position sensors fail, there will be no spark. There will be a code. Most times it is just corroded wiring plugs, easily cleaned.
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Keeping it running is better than buying new
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Not totally true for LH 2.4/EZK about a code always being set for a missing rpm signal (as seen through the CPS). You can easily have a nostart from a bad CPS without a code, hence why we have so much trouble figuring it out some days. The control units basically don't know the engine is turning over without the signal so have no reason to set a code if the CPS has outright failed. Once the engine is running, it's a different story for a failing CPS. EZK ICU will set a 2-1-4 code on port 6 for an intermittent rpm signal, but only after the engine has been seen turning over. The ECU will set a 1-3-1 code on port 2 if it's not seeing any kind of reliable rpm signal (either a pulsed or stationary ground) being passed to it by the ICU, basically a wiring issue or a very flaky pulse. Only if you're lucky and the CPS doesn't outright fail, but is providing a weak or intermittent signal will you tend to get a code, most often the 1-3-1 code in my experience. Leastwise that's how I understand it.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be Ivo
on
Sun Jul 26 20:19 CST 2020 [ RELATED]
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Last year the CPS on this car died, slowly, over few days. Long enough to register OBD code. This time no such luck. Car worked one day, and refuses to start the next. No OBD codes. So far I eliminated following components. They have been bench tested and also swapped with parts from my other working cars:
Coil, ignition module (power stage), in tank fuel pump, main fuel pump, fuel pump relay, all the fuses and all the wiring feeding the fuses. There is still no spark coming from the coil.I also checked the timing, no problem there.
(Yes, I have lots of gas in the tank...)
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Ok? ... Doctor of R&R!
Since you didn’t answer a question about your testing methods I will assume you have no idea if you have any good electric’s are working between components.
The discussion about the CPS is fine and dandy, as it is a starting place for things to start happening first, but you and we don’t know if they are?
When cranking do you have voltage on the orange wire of the AMM?
Art Benstein uses visual confirmation technique called a test light.
He works logically and he can be fast and dirty just like you want this affair to be!
You can go to cleanflametrap.com and study his explanation of why to check there.
This is especially true if the starting fluid spray works and it runs a little bit!
Have you tried that, it’s fast and dirty!
His advise will take you to the place of knowing if the “system relay” is powering up the fuel pumps, the injectors and the AMM.
A relay can fail only on one side of its two circuits! It can be an intermittent animal too!
That orange wire travel the circuits if you read electrical schematics of a Bentley manual.
IF you are getting zero codes from the OBD, we can assume, there are reason why you’re not getting them like Dave Stevens says!
Heck with the way the 1993’s are about being built with on-going production revisions and close outs, you might have a LH 3.1
I have a 1993 and I’m finding all kinds of subtleties. Items moved in the engine bay or the rounded tooth timing belt for instance.
But I will tell you right now, don’t deposit any money in the bank on the references of that OBD system, as it’s too vague most of the time, IMHO!
For MY TWO COINS worth, rubbed together (:-), says,
Your best friend is the voltmeter or tests lights as it’s the only way you’re going to see deeper into your sickly patient.
Keep us updated as I’m intrigued!
Phil
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Hi,
Look behind the battery for the ignition electronic relay.
Attached to the inner fender.
Most of the time it’s corroded terminals inside the connector where some tiny pins and clips are located. We are talking about low voltage signals in operation here.
Get them clean and and lubed up with corrosion inhibitors. Check for clean grounding screws and if the unit has never been service some heat sink paste may need to be replenished.
This thing may not like hot days either, so it can just turn off at anytime, but its really about clean connections.
It’s a “middle man” that fires the ignition coil when the ICU’s commands it.
The CPS and the ICU are doing their jobs, to run the pumps and the injectors, so it should flooding with gas, if there’s no spark.
Do you smell gas at all?
With relay clicking I will assume that you are referring to the system relay under the glove box?
Good ears, if you hear it and sensitive fingers, to feel it!
There is a no code for the above symptoms.
If there is the description it would be hidden in wording under a related failure combination, of which, I refer to as a “Shot Gun Blast” at one side of a barn wall. Yep, the barn shook enough on a code to be noticed but in turn, it means, your close but you missing a whole lot of that wall!
If you find more symptoms get back to us on the board!
Phil
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posted by
someone claiming to be Ivo
on
Sat Jul 25 15:26 CST 2020 [ RELATED]
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I swapped the power stage with a good one. It did not change things. Still no start. No high voltage coming from the coil. I also swapped the coil with good working one. No change...
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Hi again.
What you are stating leaves more questions than answers.
You need to explain how you are checking for spark.
Where are you looking for it to be sparking and where is your grounding point for the coil wire?
If you are using a plug wire, you might have a bad rotor button under the distributor cap or even the cap could be bad?
Are you using a test light or voltmeter to check the operation of 12 volt power on the primary side to the coil?
We do not have a way of knowing what shape the car is in or the experience of the owner/mechanic?
What does happen is you will keep doing the same wrong things over and over!
Like one wire going back to the same place because you thought you remembered it that way!
Many of us start our early days or shade treeing 🧰 that way! (:-) “Live to learn or learn to live is a work in progress!” (:-)
Changing out working components is applying a technique called “Luck or by Golly!” With good chances of a low return on investment of time and money lurking in the shadows.
Are the plugs getting wet with gasoline? They should be if things are doing as you said.
Have you tried using the starting fluid trick into a vacuum port with everything connected ready to run? Give it a good shot of spray and roll it over!
This confirms spark and or the lack of fuel in one fell swoop, because you know fuel is there now!
If nothing happens, check for turning of the timing belt by looking for the cam lobes to move through the oil fill cap!
Or did you do it first?
Feedback please! Teach us what you know, as it helps us know, what we don’t!
Phil
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