Overnight misfire

[strang3majik]

Hi everyone, I'll make a intro thread in a little, right now this is important...haha.


Friday night I was driving my 87 325e around and it was running great. Its been down on power since I've owned it, but always ran smooth.


Well, I parked it Friday night and Saturday morning went out to drive it, started it up and it sounded like it had a miss. Drove it down the road to the store and it sounded like a v-twin motorcycle and was down on power a lot.


Drove it home and pulled each plug wire one at a time, and every one made it run rough(er) than it was. So its firing on all 6. Pulled each plug, all looked fine but all were wet with gas.


Unplugged the oxygen sensor, no change. Replaced the cold start injector with a known good one with no change either.


I can't think of anything that, overnight, would've happened to cause this. My only guess is a sensor failure or something. But, it does smell rich, and as I said, it sounds like a miss, even at idle, but, every cylinder is firing.



Any thoughts or ideas? Anything to check?

And I think it'd have to be a large vacuum leak to cause this, and for that to form overnight? And it hasn't cleared up or gotten worse since it started.

[TurboJake]

Vacuum leaks can form overnight.
But so can leaky injectors... Or faulty ICMs. Or herpes. Not that herpes is the issue.

























Unless your car is a slut and lets everyone in.

[strang3majik]

Vacuum leaks can form overnight.
But so can leaky injectors... Or faulty ICMs. Or herpes. Not that herpes is the issue.


Unless your car is a slut and lets everyone in.

And I don't believe theres any vacuum leaks, especially one large enough to do that...I will spray some brake clean around it though.

But for every injector to leak??? And ICM? Sorry, I'm still new to the Bimmer terminology...haha Idle Control Motor? If thats what you're saying, I did change that out with one that looked brand new.



And theres is a good chance its herpes. It does get raped by everything on the road.

[FLG]

If your sure its not ignition related check your coolant temp sensor. There's a writeup somewhere for testing resistance to make sure its still good.



Sent from my Galaxy Nexus using Tapatalk 2

[jefrolison]

Overnight Misfire

My moneys on compression.

[TurboJake]

And I don't believe theres any vacuum leaks, especially one large enough to do that...I will spray some brake clean around it though.

But for every injector to leak??? And ICM? Sorry, I'm still new to the Bimmer terminology...haha Idle Control Motor? If thats what you're saying, I did change that out with one that looked brand new.



And theres is a good chance its herpes. It does get raped by everything on the road.

Engine/body/battery ground good?

It doesn't take every injector to leak to cause it to run retarded. I've seen an M20 sound like it's cammed to shit from one leaky injector flooding the cylinder. Drove for poop.
ICM = Idle control module. If you tried a second one, chances are you can rule it out (as you have)

[strang3majik]

I just doused all the vac lines/throttle body/intake boot/injectors/intake with carb cleaner and only one place sucked it in and changed the idle and thats where the hose connects to the valve cover, and its been leaking some since I got the car, just haven't found a replacement hose yet.

So I'm ruling vac leaks out.


And yes, the ICM has been replaced then, both with no change, one is original one looks brand new.


As far as the grounds, I can tell someone has added grounds at some point because there's one going to the firewall thats a 14gauge wire with yellow terminal ends...so...I could put another on it just to try.


Also, i unplugged every coolant sensor on the thermo housing while it was running and the idle got higher, but still had a dead miss...that wasn't really a miss. If my logic is flawed, please correct me...but in the 80s Mitsu world, you unplug crap until it runs right...hahaha.




And with the injectors....every plug is dripping fuel, thats why I wouldn't think just one would cause it to be rich acrossed the board? If anything lean, I would think?

[strang3majik]

Just went out and did a little more testing...

If I spray the TPS with carb cleaner it damn near stalls out. Not sure whats going on there.

Also, if I pull one plug wire, any of them, the idle change is hardly noticeable. Maybe its just these engine, but, I'm not sure why. I'll pulled two, then it got noticeable.

Tried unplugging then replugging everything. Cleaned the terminals on all the corroded stuff.

Ran an 8 gauge and a 14 gauge wire from the valve cover (where the bracket that goes to the intake bolts on) to the strut tower.

All that, and no difference noticed.



I'm seriously puzzled.

[jlevie]

I just doused all the vac lines/throttle body/intake boot/injectors/intake with carb cleaner and only one place sucked it in and changed the idle and thats where the hose connects to the valve cover, and its been leaking some since I got the car, just haven't found a replacement hose yet.

So I'm ruling vac leaks out.

That is an intake leak and it is probably pretty bad if carb cleaner worked. Carb cleaner only works on large leaks close to the head that can be saturated by fluid. There are plenty of places to have leaks that carb cleaner won't work on. But a smoke test of the intake works anywhere and every time. That should be the first thing you do.

That hose is not problem to find. Go to your dealer and order it.

[strang3majik]

I'm going to pull the throttle body off today and look at it and see whats going on there. That's the only vacuum leak I found with carb cleaner.

I will worry about the smoke test and all once I get it back to where it was, but, my thing is, a little vacuum leak can't be causing this...if the large one in the throttle body is new, which I have a feeling its been there, then maybe that could cause it...but, I'm just looking to getting the horrible miss and overly rich condition taken care of first. I know its a good thing to do, but, I'm trying to address one issue at a time. This may be the cause of the surging that was happening before, but I'll get to that next.



The one thing I'm going to try today for sure, is a fuel filter. I put a bottle of that startron stuff in there about 3 weeks ago and I went to florida for a 2 week trip and left the car sit. What I'm thinking is it broke down all the crap in the tank, and after driving it, it shuffled everything around.....next day i started did, sucked all the crap into the filter and plugged it up. Low fuel pressure, fuel dribbles in instead of spraying in a pattern, which could cause it to actually run rich.


Seems a good theory to me...guess we'll find out :/ I've never changed the filter anyway, so, definitely won't hurt.

[jlevie]

Before you pull the throttle body check to see if side fittings on the throttle body are loose and also check where the evap control valve attaches under the throttle body.

[dnguyen1963]

Also, make sure that your FPR is still in good working condition.

[strang3majik]

Fuel filter did nothing :/

Before you pull the throttle body check to see if side fittings on the throttle body are loose and also check where the evap control valve attaches under the throttle body.

Will do.

Also, make sure that your FPR is still in good working condition.

How exactly can I check that?




Also, how long should the system remain pressurized?

Its been sitting since last night, and when I pulled the filter off, the only gas that came out is what was trapped in the filter. If I take the fuel lines off up by the engine after it sat for a little while, fuel only dribbles out.


The one at the junkyard that I got the cold start injector out of had been sitting there at least a month that I know of and fuel poured out when I undid the fuel line by the intake.


But idk. A local supposed "BMW guy" told me that a piece of carbon probably got trapped and is holding one of the valves open and to do a compression test, but, that still doesn't explain to me why its running way rich.


I really don't know :/

[strang3majik]

Ok....what should my fuel pressure be reading?

At idle it reads at 30psi solid. When I rev it, it dips down to 25 for a slplit second and shoots up to 35. When I let off it dips to 25 then recovers to 30.

I drove it up the steep hill that is my driveway, 35psi up the hill, running rough and rich as can be.



Does that pressure seem low? Or high? I know most modern systems are around 45psi, but not sure, as I know the 80s was the start of it all.

[jlevie]

About 30psi at idle and 35-37psi would be correct for an ETA as it has a 2.5bar FPR. But you should not see a drop below 30 as you open the throttle.

The lack of residual pressure could be from a leaking FPR or a bad check valve in the pump. The drop in pressure could be the FPR or a from a worn pump. You can find out if the FPR is leaking by replacing the return hose with a hose you run into a container. The briefly start the engine or jumper the fuel relay socket and watch to see if fuel flows from the FPR after the pump shuts off. It shouldn't.