Stuttering & Missfire, pulling hair out!

[caseyz]

OK, so here it is. Its cold out just like everwhere right now. I'm driving to work and I notice the e30 just doesn't have as much power on the highway as usual, and when I come to a light its stuttering, missfiring, popping. So I find a friend with a heated garage, and park it for a couple days thinking maybe some moisture got into a bad place from all the snow. Didn't fix it. So I start testing replacing things according to the Bentley. Here is the list.

-New vacuum lines
-New distributor (cap and rotor)
-New spark plugs
-Checked resistance in wires
-Check AFM resistance, seemed fine but I've read that that test isn't definitive
-Checked resistance at crank & speed sensor (flywheel type), OK
-It's not trowing a CEL that I can tell

I've also hooked up an inline fuel pressure gauge before the rail. Its only reading 30 PSI at idle. It jumps to 40 when the FPR vacuum is disconnected. Isn't it suppose to be approx 44psi at idle?

I've also tried unplugging the O2 sensor while idle, it doesn't make a difference in the idle, is that good or bad?

For some reason my mind keeps telling me its the AFM, is there a better test I should run, short of buying a new one?

Any help direction would be appreciated.
-Thanks

[redhatpat]

Did the idle smooth out when the fuel pressure went up to 40?

What do the plugs look like? Rich or lean?

If the plug wires are questionable or old you might as well replace them now. They're difficult to test resistance accurately and can cause this problem.

[caseyz]

Thanks for the quick response. A bit of an update. Just checked the fuel flow-rate, seems fine at 30oz/30sec. Also checked the ignition wires with an inline spark light/tester. seemed OK. I was thinking the wires as well. Still might be i guess. Also did a one-by-one test at the plugs disconnecting each to see if there was any noticeable difference when each plug was disconnected. Cylinders 4 and 5 are suspect as there wasn't any noticeable idle change when i pulled the wires.

So I went ahead and pulled #4 and #5 pluggs. They came out squeaky clean, moist, and smelling like petrol. I then -re-tested those cylinders with the in-line light tester. The light was firing, Could there not be enough power for the spark, but enough for the tester-light? Or could this be a timing issue?
Maybe I should just lay down the money and get me some new wires. I just hate putting in the money without results.

[TimR]

Any chance you got some bad gas or water in the tank ??? guy last week had all kinds of trouble after a few rainy days, added Sty Dri ??? for water in the gas,

[caseyz]

Yeah, kinda what I had thought to but forgot to mention it. I put some Heat in there when the problem started, Although I've probably only ran the engine a total of about 40 minutes since putting it in. Not sure how long it takes to correct if thats the problem but the bottle said "fast-acting". I'm in the midwest and I always fill up at Quick-Trip. Although a day before this happened I filled up at a Kroger Grocery station. Needless to say, I'm weary of their gas now.

Anyways, I'm getting ready to pull the injectors and give them a cleaning to kinda cancel that out. It's about the last thing I kan think of that I haven't tested in the "Fuel-delivery" system.

[caseyz]

Arghhhhh! OK, I've been trying to get this fuel rail/injectors off for the good part of 2 hours. It just doesn't want to budge. I've even tried a prybar pushing up to assist. Is there any other way to soften up the seals or get leverage on it?

[caseyz]

OK, got the thing off but one of the injectors is missing the pintle cap. Could it have fallen through the intake manifold. It doesn't look like there is any retaining lip of any sort in the injector hole. Anyone have this happen b4?

[caseyz]

OK, an update if anyone's reading. I decided to go ahead and remove the inatake manifold (not an easy or fun task by any means). And upon removal, as I suspected, the pintel tip was sitting nicely on the intake valve. Sorry but I see this as a kinda dumb design not having a seat for a removable part. Anyways, while I've got all this junk removed, anybody got recommendations on new injectors on the cheap. I've heard mustang injectors work on some models?

[caseyz]

Yep, looks like I'll be needing new injectors. After letting the fuel rail dry out overnight. I tip it over this morning and at least a good tablespoon of rust-power pours out. What a beesh! On the positive side, I think I've found the problem to the misfire and stuttering!

[caseyz]

OK, this thing is driving me crazy. Got it all back together after replacing the injectors, cleaning fuel lines, new fuel filter. I start it up and it runs good. after warming up a bit, the problem returns,

-sputters,
-loss of power on acceleration

I just can't figure this out. I let it cool down again and start it up, runs good for about a min or 2 and then the problems return. I'm thinkin' the o2 sensor now. Any other suggestions would be greatly appreciated.

Another question, can a shop run any diagnostic on an 84?

[caseyz]

OK, just to update myself. After leaving it sit for a day. I came back to it started it up and it runs good. Sputter is gone, power is back. Not sure if letting it sit had anything to do with it. I don't know exactly how these ecm's work but maybe it had to reconfigure for the new injectors etc. Anyways, the problem seems to be gone for now, We'll see how long this last!

[Bene]

if it comes back, I would bet on the o2 sensor.

[bastianshaw]

any update you know what happened?

[Xmedina]

any results?

[jink0619]

Yea i would like to know as well....update pls