SETA misfire when warm... wtf

[rickycricketts]

So i've done some searching and I cant really find any useful info on this issue.
Car: 88 325 (seta) 165k auto

What's happening is the car runs great on cold start until it reaches operating temperature then starts misfiring especially under load. If you hold above 2k with no load it seems to run fine. Misses at idle in neutral and drive (worse). If you shift it manually and slowly creep up the rpms to 3k then punch it, it does not miss. If you floor it in first from 1k to redline the car will misfire>pull>misfire>pull ect. The car runs a lot worse in hot weather.

so far i have performed the following:
changed spark plugs and wires (ran a lot better but got worse again)
new valve cover gasket - (old was leaking and noticed a pool of oil in spark plug holes) - no difference
changed afm - no difference
inspected cap/rotor - looks brand new and better than the used good one i was going to put on there
new coolant temp sensor - no difference
changed ecu - no difference
unplugged O2 censor - no difference

I checked all the boots and connections from the intake manifold forward and everything is sealed there should be no vacuum leaks. vacuum hose on the valve cover is properly sealed.

I'm now lead to believe this is some sort of fuel issue. Is it possible the cold start injector is stuck open? there is no injector on the other side of the manifold like older etas. I'm about to light this one year only bastard child on fire and let it burn! That's one way to fix the problem ;)

[BMWManiac]

Do you have the inline fuel pump and one in your tank? Fuel pressure regulator? It does sound like you have an issue with fuel pressure.

[rickycricketts]

I don't see an inline fuel pump.
But today I changed the fpr, fuel filter and ignition coil. Still misses. Compression is 175-180 accross the board. Kill it with fire?

[rickycricketts]

What spark plugs did you use? I put in some form autozone and my seta couldn't hold a idle.. So I put in NGK and it runs great.

ngk v-power zgr5a. I've heard they're the only recommended plugs besides bosch

[G-Man the Visionary]

Do you have the inline fuel pump and one in your tank? Fuel pressure regulator? It does sound like you have an issue with fuel pressure.

I'm thinking bmwmaniac is on to something... Have you solved the problem yet? My m30 is doing the exact same thing. When messing with fuel lines shortly after the swap, the return line was dry as if the regulator hadn't been working. Also, been wondering about this cold start extra fuel thing I've been reading about.

[G-Man the Visionary]

Ya, try the fpr... Just did mine, way better... Think the plugs are too fouled to be completely solved. In a few days we'll see if they get any better or if they just need replaced... Again...

[BMWManiac]

If the plugs are fouled, they are fouled and should be replaced.....make life easier on yourself. Or you can try cleaning them, but at $2/pop, I'd just replace them

[rickycricketts]

Thanks for the suggestion guys. I swapped the fpr from my bronzit and it did not change the way it ran. I'll pull the plugs this weekend and see if they look fouled or leaned. Also going to test the fuel pressure. It should be around 40 lbs right?

[Mr. Tasty]

Thanks for the suggestion guys. I swapped the fpr from my bronzit and it did not change the way it ran. I'll pull the plugs this weekend and see if they look fouled or leaned. Also going to test the fuel pressure. It should be around 40 lbs right?

3.0 bar, so 43.51 psi

[G-Man the Visionary]

I don't wanna keep throwing random things out there, and it could just be in my head, but when I put dielectric grease on all my temp sensor connections things seemed to get a little better yet. New plugs had to be ordered to the store and should have them today, then we'll see if it goes south again.

[G-Man the Visionary]

Any luck?

[3vilE30]

ngk v-power zgr5a. I've heard they're the only recommended plugs besides bosch

Some plugs don't come gapped properly. The single-four-pack NGK ones come gapped, but the individual single pack ones need to be gapped or else you'll have a nasty miss.

[rickycricketts]

Sorry for not getting back to you guys. It's my girlfriends car and I haven't had the chance to work on it again until yesterday. So I have the hood open while it's running and I'm dousing the engine in brake cleaner looking for vacuum leaks and I hear this tick every time it's missfiring. Turns out the tick was coming from the distributor cap. I checked it before and the points looked as good as new but I took it off again to find a little pin hole on the outside where the spark was jumping to one of the mounting bolts. Changed the cap and it runs like a champ. Looks like I need to pay more attention to detail next time.

[G-Man the Visionary]

Nice! I may have to tackle that soon then... Thanks!

[G-Man the Visionary]

Bosch or Bremi?