M20 wont start all of a sudden

[bankrupt]

My 1991 325Ix won’t start. Last few months it had a hard time starting sometimes about 10% of the time. Replaced fuel pump but only ran for a day. Switched fuel relay. Check no spark at the plugs. Replaced Ignition coil. No luck. Any ideas?

[Jaxx_]

Thanks for the info, if there is no spark, that indicates to check, cap and r? Any.other relays?

you have spark if the car runs. The question is whether all plugs are firing or if they are just not in time(incorrect spark plug wire order).

As mentioned, check your spark plug wire order before anything else.

[bankrupt]

Cranks but It will not start. No spark. I will check other spark plugs. Also will check if coil is firing at all tomorrow. And current to the coil. P.S. it ran great for 6 years till last Tuesday. Wednesday it ran w new fuel pump. I noticed misfired and higher idling speed. Thursday. No start.

[ezlnh8u]

Swapped the 02sensor, checked the AFM and the ICP, Tried 3 different ECU's, checked the spark plugs and they are black, I believe because the car is running rich. Cap and rotors were cleaned. Next up is a compression test, than injectors. Any other suggestions?

[ezlnh8u]

Cranks but It will not start. No spark. I will check other spark plugs. Also will check if coil is firing at all tomorrow. And current to the coil. P.S. it ran great for 6 years till last Tuesday. Wednesday it ran w new fuel pump. I noticed misfired and higher idling speed. Thursday. No start.

There is spark to all cylinders, fuel pump primes well. Doing a compression test as we speak.

[ezlnh8u]

Compression test done, they all check out above 120, next up will be the injectors, any suggestions on how to check them?

[Jaxx_]

There is spark to all cylinders, fuel pump primes well. Doing a compression test as we speak.

You're moving way too fast down the diagnosis tree. I feel like you're gonna check to see if the gas in the tank is good next--do yourself a favor and step back for a second... I HIGHLY doubt anything else failed with the car beyond the main relay you replaced. Changing ECUs, for example, is likely a fool's errand.

Confirm the plug wires are attached in the correct order. You still haven't posted that you've done this. Just because you have spark to all cyls doesn't mean you have them in time. It is very easy to mess this up with 7 wires at the dizzy cap. 1 out of order will cause 2 cyls not to fire. Confirm again by taking them out of the organizing plastic if they are in it. Seriously.


Once you have confirmed the wire order, move on:

When you inspected the plugs and they were black, did you clean them? It could simply be spark plugs are too fouled from lack of firing. If you didn't clean them, clean them. Or buy new single electrode copper plugs to throw in.


Once you have confirmed plugs OK, move on:

You are probably getting too much gas(rich), as you assume. It likely means that some of your injectors are stuck open. You can test them by running the car and listening to the injectors. They should be clicking/ticking clearly at idle. Do not mistake the valvetrain noise for this clicking. You can use a vacuum hose or a screwdriver on the injector to listen to it.


If some are NOT ticking, post back with which ones are not ticking.



If they are all clicking away no problem, you then should consider redoing your tests around sensors that give the ECU information about the fuel mix: AFM, CLT sensor, TPS, etc. As I mentioned before, your something like your o2 sensor is not going to cause your car to run like this. Each time you replace a part you could be introducing more issues to the car because of changes you've made.

[ezlnh8u]

You're moving way too fast down the diagnosis tree. I feel like you're gonna check to see if the gas in the tank is good next--do yourself a favor and step back for a second... I HIGHLY doubt anything else failed with the car beyond the main relay you replaced. Changing ECUs, for example, is likely a fool's errand.

Confirm the plug wires are attached in the correct order. You still haven't posted that you've done this. Just because you have spark to all cyls doesn't mean you have them in time. It is very easy to mess this up with 7 wires at the dizzy cap. 1 out of order will cause 2 cyls not to fire. Confirm again by taking them out of the organizing plastic if they are in it. Seriously.


Once you have confirmed the wire order, move on:

When you inspected the plugs and they were black, did you clean them? It could simply be spark plugs are too fouled from lack of firing. If you didn't clean them, clean them. Or buy new single electrode copper plugs to throw in.


Once you have confirmed plugs OK, move on:

You are probably getting too much gas(rich), as you assume. It likely means that some of your injectors are stuck open. You can test them by running the car and listening to the injectors. They should be clicking/ticking clearly at idle. Do not mistake the valvetrain noise for this clicking. You can use a vacuum hose or a screwdriver on the injector to listen to it.


If some are NOT ticking, post back with which ones are not ticking.






If they are all clicking away no problem, you then should consider redoing your tests around sensors that give the ECU information about the fuel mix: AFM, CLT sensor, TPS, etc. As I mentioned before, your something like your o2 sensor is not going to cause your car to run like this. Each time you replace a part you could be introducing more issues to the car because of changes you've made.

We tried a new plug set,new cap and rotor, plug wires are in the correct order.

[ezlnh8u]

Checked all the injectors. Took them out, all of them read 16 OHM, did a thermal cleaning on them, started the car, same symptoms. Left it running for about 2 minutes. And the car started idleling smooth. Took the car out around the block, it pulled strong and smooth, on the way back to the house. It reverted back to the surging symptoms. At this point I think I Should dive into the timing?...

[Cayoncrusier93]

Checked all the injectors. Took them out, all of them read 16 OHM, did a thermal cleaning on them, started the car, same symptoms. Left it running for about 2 minutes. And the car started idleling smooth. Took the car out around the block, it pulled strong and smooth, on the way back to the house. It reverted back to the surging symptoms. At this point I think I Should dive into the timing?...

I personally find it very hard to believe that timing somehow jumped after having a dead/swap battery. Timing is set manually, so if the timing was OK before, timing should be OK now, unless somehow you changed it. Thought you said that it was so bad that driving it was impossible to drive?

[ezlnh8u]

it feels like there is no gas, and extreme hesitation. I can drive it if I drive the heck out of the clutch. after putting the injectors back and the rail. It settled it's idle down and ran fine around the block. But than back to that hesitation stop and go feeling. Could I have jumped a tooth?...

[ezlnh8u]

I personally find it very hard to believe that timing somehow jumped after having a dead/swap battery. Timing is set manually, so if the timing was OK before, timing should be OK now, unless somehow you changed it. Thought you said that it was so bad that driving it was impossible to drive?

The issue never was a dead battery. The car would crank but wouldn't turn over. That's how it all started.

[george graves]

Wait - so it runs but drives like crap? This thread is so confusing. Kill it and start a new one. Thread or car. :)

[ezlnh8u]

Wait - so it runs but drives like crap? This thread is so confusing. Kill it and start a new one. Thread or car. :)

I have been reporting everything that has happened since the issue started.

How it all started.

From one day to another the car would crank but not turn over, it ended.up being the main relay, the car then started but with surging and and rough idle, and rich.
replaced the following.

1: 02 sensor.
2: coolant temp sensor.
3: ICV
4: AFM
5: plugs and wires.
5: cap & rotor
6: FPR
6: cleaned injectors.

After doing all this, the car still ran with the same.sirging issies, I let it warm up for 2-3 minutes, the idle went back to normal, drove it for 2 blocks, it ran good, on the way back to the house it reverted back to the same symptoms. (Surging, rough idle and rich). The thread explains it all from start to present. I don't see how starting a new thread will help?

[ezlnh8u]

https://youtu.be/pOgXzB3bMLo

Link to a small video of my car shot by cars on board.