Weird 2000-2500rpm missfire? (not 3800rpm related) Need help
 

Info about the car:

6 port turbo, port s5 lim to 6 port block, stock s5 turbo/manifold, 550cc/680cc injectors, n/a ecu + safc II, Fd fuel pump.

The car was running fine a couple days ago.

Problem: Sounds like the car is miss firing whenever I'm going from 1000rpm to 3000 rpm. But anything after 3000rpm the car will run fine. I car pulls fine, and boost holds. But when I am applying very light throttle, the car drives some what ok, between 1000-3000rpm. Anything with 1/4 or more throttle you can hear it missing.

I am assuming it's the primary injectors, but i'm not too sure. I have a new fuel pump strainer, fuel filter was replaced not to long ago. But I did run the tank low a couple times. I don't have any high end lose, but I am baffled.

Also the car smokes at idle every now and then. It will happen randomly, but I don't have any leaks. The smoke is whiteish. The car will smoke for probably 3 minutes then stop. As I said it happens randomly.

I'm getting stumped, it's a rebuilt engine. The compression wasn't off from each other, I'm having a little hard start.

Any input would help.

I have the fuel pump resistor relay removed as well. I'm getting stumped.

Update: I hooked up my air compressor to the throttle body elbow, and I have a leak between the throttle body and elbow plate. Working on fixing it now.

Im sure the descriptions are pretty vague, sorry. But i'll try cleaning the injectors first.

Can timing change out of no where?

Seriously? Not even a guess? Where's the love at?

Update: I took off the uim and primary injectors, and spun the cas gear. The spray pattern is good. But I did noticed that my cas was 180 degrees off timing. I re-timed it and it ran better. But I still hear kind of a missing at idle still but I can accelerate smooth from 1000rpm+ now.

But I am still confused to the smoking. This is unrelated to the previous thread before this. I rebuilt the engine, and it's still smoking. I used all good parts and rebroke in the engine until 400miles. The smoke will stop after awhile. The smoke isn't consistent at all.

Any help?

Nevermind still misses. But drives a lot smoother.

I noticed it sounds like "knocking" at the rear rotor housing. I'm not sure what it means, since if the rotor were really hitting the housing I wouldn't be running correct?

Ok, So i'm going to bite the bullet and pull the engine and figure out what's going on with it. I'm assuming it's a chipped apex seal. But can someone tell me what the symptoms would be?

Would a chipped apex seal smoke at idle, or is it the oil control rings?

Im sure the descriptions are pretty vague, sorry. But i'll try cleaning the injectors first.

Can timing change out of no where?

For injectors, you can check to see if there spraying by taking off the primary's and spin the cas gear to have the injector fire. Mine seemed fine, so I didn't clean them.

My timing was 180 degrees off, because when I lined up the crank pulley to the yellow leading mark and pulled the cas, the dot was on the other side of the alignment.

Also are you asking or saying?

Took the turbo manifold off, and no wetness in either exhaust ports. So I'm kinda stumped on why it smokes now... Hmmm Would a bad turbo charger cause a miss fire? I've never had that happen to me before, so i'm asking.

Also any input would be nice.

Ok, so I cannot figure out the smoking. But good news is my exhaust ports are dry. How can I tell an apex seal has chipped? I did the compression test and the numbers are all around the same. 90psi total compression for all 6 faces.

Does someone have a video of good apex seals and how they sound when you crank them by hand? I think my hearing is tricking me, so I want to hear what a good rebuilt engine sounds like when you turn it over by hand.

I would think that if it was an apex seal that had broken then the compression would show a drop on one or two of the faces. What about checking grounds. What about checking plugs. The white smoke sounds like a bad coolant seal from what I know. Does the exhaust smell sweet? Do yourself a favor and buy an Rtek as well.