M20 wont start all of a sudden

[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]

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.

[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?...

[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]

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?...

[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.

[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]

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

[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]

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?

[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.

[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]

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?

[ezlnh8u]

You are on the right track. Confirm plug wires are correct. I doubt that there is anything else wrong with the car. If it ran before you messed with it, and the only thing that has changed in the main relay to get it running again, it is something that you touched.

Generally the O2 sensor won't have enough authority to modify fueling so much that it will cause the car to run poorly. If you have so much extra fuel that you smell it, likely some cylinders aren't firing.

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

[george graves]

air, fuel , spark.

90% of the time it's spark. Pull a plug and see if you can see it spark.

Jaxx_ has a good point, if you smell fuel, it's not firing.