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Still coping with my check engine light. New injection temp sensor and fuel pump relay no help. Now have a new problem. Very hard start after car has been sitting more than 5 hours. It will start after much cranking. Replaced fuel check valve no help. It runs perfectly after delayed start.Idle normal. An experienced Volvo retired guy took the plug off the AMM and it started in the "limp home" mode. I replaced the AMM about 35K miles ago. Do I need another one?
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https://www.brickboard.com/RWD/volvo/1688566/220/240/260/280/87_244_rough_running_start_runnung.html
Experienced Volvo mechanic but no mention of Volvo manuals with diagnostic procedures.
Difficult/no start when cold but starter fluid helps sounds like no cold start enrichment. See above link for possible solution.
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You really need to read out the Check Engine OBD code(s).
Unplugging the AMM in order to force the ECU into limp home mode and it now starting is very suggestive of a second AMM failure. As Kitty suggests, a failed airbox thermostat (a piston device) is often associated with a "cooked" AMM, especially multiple failures. Almost always when the AMM fails that way it's game over and you should no longer be able start or run. That with enough cranking you can start with the AMM connected means there's hope it hasn't failed. Most would recommend as suggested, disabling the preheat function permanently so as not to have to worry and repeatedly check thermostat function. There will be no noticeable difference in warmup or mileage unless you're in an extremely cold region. Fastest way is as mentioned, just pull the preheat hose off the manifold shroud. If you are subject to inspection, you can quickly push it back on, or as many of us do, leave the hose in place and instead open up the airbox and permanently screw the flap shut from inside such that the thread sticking out can't be noticed.
Have you checked the main system 25 amp fuse under the hood? When it starts to corrode you might get this kind of behaviour.
Definitely have the CPS sensor on your suspect list, as Phil noted (he meant to say '89 was first year for LH2.4, not EKZ). When they first start to become a problem it often affects cold start first and once you get going things can be normal. Carefully check the cable for split/damaged insulation along its length, especially at the standoff clips and most especially any tiny little split at the very bottom where the cable joins the sensor on the bell housing, a difficult area to access (good light and a mirror helps). Any little split can allow moisture in, ultimately getting to and rotting out the sensor coil. Damaged foil shield can also allow signal interference. Although there is an OBD code for a missing CPS rpm signal, you won't get that code for a no start (the ECU can't know the crank is turning without that signal so doesn't know it's even trying to start). That code will typically only be set if it abruptly loses the rpm signal while running above idle.
Please get back to us with the OBD code if you need further help.
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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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Dave, thanks for your input(others as well). My problem still persists. I am a retired aircraft mechanic, but also have a very well qualified retired Volvo guy involved in this. So far we have replaced the airbox thermo, FPR, CHECK VALVE,CRANK POS. SENSOR,FUEL PUMP RELAY, AMM,FUEL FILTER, and cleaned the 25 amp fuse. I get a normal start by injecting starter fluid into the throttle body by removing the large vacuum hose that goes to the cannister. Takes about 30 seconds of intermittent spraying for a good start. After about 2 minutes of running at 1K rpm it will idle normally. After a short warmup, a normal restart will occur. Yesterday I drove it running errands without incident.Forgot to mention, we also replaced the fuel injector sensor and the fuel temp sensor. We are in 60 degree weather here, so the cold start valve should not come into play?? Engine light still on. Would disabling the EGR system do any good. This is a Calif. car with a mint body. Don't have a fuel pressur gauge. Could a running main fuel pump not producing enough pressure cause this? I have a new pump on the way. Thanks so much for the Brickboard help. Bob
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Still like to know the OBD code(s). The ECU is not happy with something. They can provide valuable clues. Be sure to clear the codes and note how quickly they come back, either immediately or after a bit of running. Your Volvo guru having touched a 1989 or later should know how to do this for you if you can't figure it out from the mentioned section in the FAQ.
A whole lot of parts being replaced here with minimal diagnosis in my opinion. Are you replacing all with new, or proven working, or unknown used? With untested used parts, even rebuilds, you can't eliminate a suspect device unless the problem goes away.
The cold start injector malfunctioning is a distinct possibility as is a bad temp sensor that the ECU uses to control it. There is an OBD diagnostic test mode (DTM 3, described in the FAQ) that can be used to confirm cold start injector operation (by sound/feel, you can do this warm or cold). You can additionally remove the injector when stone cold in the morning and pointing it into a jar to confirm that fuel is flowing during cranking (pull coil wire to prevent starting). You said you replaced a temp sensor, presumably the correct one, the rearmost of the two under the intake manifold. I'm not sure what you mean by replacing a fuel injector sensor, no such animal called that in an LH system.
Misbehaving fuel pumps are another possibility, although perhaps less likely if you can blip the throttle up to high rpm without stumbling immediately after starting. A dead in-tank pump is a distinct possibility, even more likely if the tank is low. Do the fuel pumps buzz for a second or so when you switch the ignition to ON (KP-II) which initially pressurizes the system? Do this 3 or 4 times prior to starting to see if this makes a difference. Listen separately for both the main pump and the in-tank pump. Check the in-tank pump with the engine running, open the filler cap and listen in, insert a hose or tube as a listening device in a noisy environment. Pull the in-tank pump fuse (#6 as I recall) to listen only for the main pump underneath (also check the ends of both fuel pump fuses for wear or corrosion). After a good run, check how warm the main fuel pump casing is. Warm is good, hot is okay, but scorchingly hot can be signs of a badly worn pump. Be very careful not to burn your hand, start with a glove.
You can do a crude test for approximate fuel pressure at the Shrader valve on the fuel rail using a stick tire gauge if needed. Use a shop towel underneath to catch gas. Gauge will load with fuel, so may not be happy until it thoroughly dries. Given your symptoms, what you're interested in knowing first is if there is significant residual fuel pressure first thing in the morning, then again after switching the key on and priming the system, compared to soon after having stopped a warm engine.
Again, please give us the codes.
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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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Problem solved. Thanks to all of you who responded. The OBD code was 1-2-3. Previous mechanic installed wrong coolant sensor.(injector) It had a blue top sensor for 83-88 240s. Installed correct sensor(black top) Engine light now out and hard start problem no longer an issue.Many thanks to Brickboarders. Bob
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An initial check for that 1-2-3 OBD code as some of us recommended here before going further, could have saved you a lot of time, trouble and expense isolating the ECT as the problem. I hope your mechanic putting an LH 2.2 ECT into your LH 2.4 engine was an oops, rather than not knowing better. I'm glad you finally figured it out. You've at least gained some new parts and a number of good spares. This serves as a lesson to others to check for OBD codes whenever the Check Engine light comes on. I wish more people here knew more about being able to use the OBD connector for both diagnosis and testing, even though it's the relatively primitive OBD-I system. It's all in the FAQ and well worth a few practices when you have a spare moment under the hood.
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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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Hi,
I just got back home tonight and read some of the thread.
Dave Stevens seems to have me thinking twice or more …🧏
I realized that the EKZ lettering is transposed or backwards as I find it written EZK elsewhere.
I think I will have to remember the system that it should be “Easy” K- Jet
The K jet used a reluctor/Hall effect distributor on through to all the LH series until the LH 2.4
Now can I associate that the 1989 has the CPS and that only works with the EZK ignition system?
Can I relate that the LH 2.4 system are the one in the same animals or am I messed up on the model years?
My first sample or example of the change over for me is my 1991 running with the CPS.
The First car with a check engine light too.
The 1,000 rpm speed is not supposed to be happening at all unless you have unwanted air entering behind
the AMM.
The IAC works within a narrow range just above a predetermined “basic idle” speed of 500.
750 +/- 50 rpm is idle speed according to an emissions sticker on the strut tower.
There are three lines involved.
Inputs of Tank vapor, a vacuum control line and finally vapors line into the manifold.
Check the entire length of the fuel vapors line. Gasoline and road grime damage it.
You should not be able to suck air or vapors from the canister’s top check valve with engine off.
There has to be a vacuum to open it.
It opens only at idle or if and when the throttle is shut to coast creating a high vacuum.
There is no code issued from this. Newer cars can throw a code for a loose gas tank cap.
So the plastic valve down onto top the canister could be stuck open and it needs to be cleaned with a light solvent.
I use denatured alcohol or doesn’t soften plastics.
This place is a commonly overlooked air leak.
That makes me think that the CEL is an emission code problem and my 1991 has the EGR.
I got my car for that reason as her independent mechanic couldn’t fix it without charging for more wrong parts. His payments could make her new car payments.
There is a vacuum valve on the left strut tower that controls the EGR.
A stuck closed EGR doesn’t affect much but a CEL light.
But a valve stuck open, then, the engine gets in to rough running all the time.
Im not reading that so not the case here?
As I remember there is a yellow dot underneath.
The vacuum line goes on that port.
Under a small flat cap there a foam filter that rots.
Beneath it is a vent hole used to equalize or remove vacuum during off cycles.
Remove the aluminum cap and discard the foam.
I replaced the foam with a pinch of polyester pillow fill as It doesn’t rot. Goes for years in between getting plugged again.
The EGR has a temperature sensor that changes value when heated.
A resistance change of any value needs to be seen by the computer.within a time frame
It may be a “rich or lean” code as it’s a catch-all for just about anything.
Did you order or investigate a “in-the-tank” fuel feeding pump?
111 K miles is not much for a Bosch main pressure pump as they can go twice that far.
If you are hearing the main pump hum easily then it could having cavitations?
Got to go to bed getting winking eyes.
I will keep thinking on it along with the others.
Phil
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Hi
So you have thought a fuel issue to change the fuel pump check valve? It could have been but it’s rare.
The coolant sensor for the computer can cause a starting problems that is more of a temperature related than a time related symptom.
From past experiences a wait time allows the fuel lines to lose rest pressure. In actuality a less volume of fuel to be available.
That amount has to be replenished by a couple tries of cranking. This is usually after an overnight length of time.
You make no mention of the fuel pressure regulator (FPR) that sends excess fuel back to the fuel tank.
They fail in two ways.
First question, If and when it does start, does run smoothly after starting?
This means no excess fuel is in the cylinders so it’s not flooding.
The rest volume of fuel probably leaked back to the fuel tank return line in that time frame.
If it’s happen regularly at five hour intervals that is a very close symptom.
The second way is the rubber diaphragm leaks off fuel into the vacuum line to it.
The fuel lies there and back up towards the manifold. The fuel gets sucked right into the intake manifold upon cranking but it runs rougher.
This can happen hot but means it was really bad before your five hour off time period.
The 1989 was the first year of the EKZ fuel injection system and a crank position sensor being used.
They become suspect at anytime if they are aged or if the cable to the sensor becomes chafed or split.
This can create a hard start problem at anytime hot or cold engine.
It can keep the fuel pumps from running or firing up very quickly by not sending a signal to the computer that turns on a system relay that you mentioned.
Unplugging the AMM shouldn’t make the CPS or fuel relay to suddenly work!
So fooling around with that doesn’t mean much IMO.
Back to the FPR, some people plug the vacuum nipple OR clamp off the FPR return line line right after shut down and wait out the time frame.
You can do one at a time
Just remember to replace them back to normal before starting.
If it changes the symptoms then you are close to finding out it’s a bad FPR.
If you buy one it’s not a wasted investment as in some day it will eventually fail.
So how old is it by chance?
111K but it’s the years that make FPRs to fail.
Phil
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