M20 Misfire (Please help....)

[iamsam]

well, keep the thread updated.....

[quikveedb2]

You need to short pin 36 to ground for the main relay to "click." With that still in there short the other pins to ground to get the other things to work. I actually was just doing this today.

I actually have the same problem. Cold the engine runs great. The car becomes almost undriveable when warm and will take a while to start when warm. The car idles perfectly fine when warm though. When driving along for no rhyme or reason the entire engine will misfire and I have to baby it along. I am talking in 5th gear going 35mph barely touching the throttle or else the engine misfires. I have checked almost all the electrical things in the bentley but no dice. Everything reads fine at the harness.

i did have pin 36 shorted for all the tests the bentley called for it, still no luck. lmk what happens with your WOT experiments, your issue sounds very similar to the problems i'm having, and i'm pretty sure my WOT switch is not working right, i'm getting a code even after adjusting it. i can make the engine run right if i feather the throttle just right, but it's dicey at best, especially when warm or if it's raining/humid. the car is off the road at this point because of the poor drivability.:letitout:

[Quailane]

The problem seems to be getting worse and is now present when the engine is cold. It still persists at WOT. My main guess right now is the fuel pump and I'm going to test out its flow rate this evening.

[Quailane]

The fuel pump is fine and I replaced the filter. Now I'm thinking spark issues. I'll check the distributor tomorrow. The coil's resistances are both nearly exactly spec. I'll also replace the spark plugs for the hell of it.

[nando]

what have you tested?

makes it even harder when there are 3 people in the same thread :p

[nickpdx]

I have no constructive input, but this problem sounds like a major pain in the ass. Good luck solving it.

[quikveedb2]

makes it even harder when there are 3 people in the same thread :p

true, true, but at least we all seem to be having the same problem so hopefully 3 heads is better than one...

[Quailane]

what have you tested?

makes it even harder when there are 3 people in the same thread :p

Let's just say I've definitively tested the fuel system and all the sensors feeding the motronic unit. Right now I'm really leaning towards the distributor not functioning properly.

[quikveedb2]

i'll be replacing my cap & rotor after the weekend, but i don't understand how it would make the car cut out completely, unless something is wrong with the coil. weird...

[Quailane]

Bad news.........

I replaced the spark plugs and tested it around the neighborhood. It seemed a little better and then it died. I started it back up and there was intermittent grinding coming from the engine. I don't know what to do. I guess I'm going to take off the valve cover and look for the damage. If I still don't see what's wrong I'm going to really piss myself. I guess I'm going to be traveling on two feet for the foreseeable future.

[e30slut]

sounds like you have no oil pressure buddy...

on one of the m20's I had It would seem like I was losing fuel or "missing" as I drove 70mph down the hwy. I checked all my guages and the check panel said I was good so I kept on keepin on. then the car cut off so I pulled to the side of the road and tried to start her back up... started up and made it to my street. then she went BOOM. blew a hole the size of a tennis ball out the block.

check you oil pressure and fuel pressure...

when you open the valve cover and see no oil... get a new engine

[Quailane]

sounds like you have no oil pressure buddy...

on one of the m20's I had It would seem like I was losing fuel or "missing" as I drove 70mph down the hwy. I checked all my guages and the check panel said I was good so I kept on keepin on. then the car cut off so I pulled to the side of the road and tried to start her back up... started up and made it to my street. then she went BOOM. blew a hole the size of a tennis ball out the block.

check you oil pressure and fuel pressure...

when you open the valve cover and see no oil... get a new engine

From what I could see with the valve cover off and a flashlight, everything looked like it was being lubricated. I removed the distributor and the contacts on the rotor and casing were completely black and pitted. I'm hoping that was the issue. I will test for spark on sunday or something like that. Also the oil pump should squirt up oil with the starter motor spinning it, right? I could check that at the same time.

[quikveedb2]

yeah i doubt if oil pressure is the issue, though the grinding you mentioned does not sound good. oil starvation would be a possibility at high rpms, but the misfire it seems like we're all experiencing occurs at all rev ranges. fuck if i know...

[Quailane]

yeah i doubt if oil pressure is the issue, though the grinding you mentioned does not sound good. oil starvation would be a possibility at high rpms, but the misfire it seems like we're all experiencing occurs at all rev ranges. fuck if i know...

I checked the coil and it sparks for sure. Also I noticed oil coming up into the head so that seems fine. Also the grinding might have been the distributor or possibly something to do with the starter motor. When I noticed the grinding, it was the kind that lasted for just a second, and I was having to floor the throttle, juggle the clutch, and operate the starter about 20 times. It also happened when I was able to get it to idle in the garage. With the distributor off, I can't get the grinding noise by using the starter, so it probably was that gone bad. I ordered a new cap and rotor. I'm going to adjust the valves, replace the oil, replace the distributor cap and rotor, and use another AFM. I was thinking maybe the temperature sensor in the AFM is bad. Anyway, the car is going to sit undisturbed for a week or two.

If none of this works, I'm going to replace the control unit, check for continuity from both ends of each and every wire, and replace all the little switches and sensors.

[quikveedb2]

If none of this works, I'm going to replace the control unit, check for continuity from both ends of each and every wire, and replace all the little switches and sensors.

i'm leaning this way too. iirc, iamcreepingdeath swapped for a good ecu with no change to the misfire issue though...

i still haven't done the cps, if i get a chance i'm gonna do it this afternoon. i don't think anyone else in this thread has done it, so i'm praying this fixes the problem as i can't even drive the car more than 1/2 mile as it becomes totally undrivable at operating temp.