Nothing showing after 3 drive cycles…I’m going to drive to work and check it again when I get there. I’ll let you know if anything pops up.
:rofl Jesus. Hope you can figure it out man!
It threw the P0170 code, but cleared on its own, on my ride home from work. I wonder if the new MAF is a cheap ebay one, is there a way to tell for sure? I know its not OEM. I’ll also check again for vacuum leaks. I’ve noticed that the vacuum line under the fuse box is plugged.
UPDATE:
Since nothing has been replaced on the vehicle since 1998, I swapped out the elbow after the TB, the hose that connects to it, the MAF, the IAC, the CCV, new air filter, and replaced all of the vacuum lines with new ones, as preventive maintenance. The butterfly on the traction control is staying open. I took it to a garage, who had a BMW diagnostic tool, and it showed no codes or issues, from what I was told. It will not rev past 4k. The vehicle is stuck in limp mode. I was able to get it to show random misfires with my generic OBD scan tool. P0300, P0301, P0302, P0305. As soon as I let the rpms ease back down and drive a bit, the codes disappear and the OBD scanner shows every things ok, but the CEL will stay on, but shut off upon the next start. I literally, just checked the plugs. Everyone of them was hand tight. They are Bosche 4301 Platinum +2. They still look new. Could this cause the issue? Should I replace them with the NGK BKR6E plugs? Thanks for your help everyone!
Is it auto or manual? If its auto isn’t there another computer linked with the tranny that can be scanned? Would something wrong there throw it in limp mode?
These motors generally dislike those multi-tip plugs from what I’ve heard, all I use is NGK Coppers…bkr6e.
Serious question though, do you have a speedo signal/has the diff ever been out/any erratic speedo behavior?
It’s a manual.
I’m going to pick up those plugs right now and get the NGK(s). The speed works fine. I can ask the previous owner about the diff, but from when I was under the car, it looks like it was never monkeyed with.
I just put the new plugs in and it misses, stalls, hesitates, but won’t throw a code.
Have you tried swapping ignition coils around? These generally don’t fail int he same way coils from other manufacturers do in my experience, they’ll get super weak but not necessarily fail. Can cause those exact symptoms. Have you verified fuel pressure?
Pull each coil out, stick a plug in the end of it, and arc it to a bolt or screwdriver or something while turning the motor over, verify that you get a nice strong blue arc with a regular frequency and not a sporadic orangeish yellow arc.
when you say will not go past 4K rpms do you mean it doesn’t have the balls to pull it beyond that or is it hitting a hard rev limit?
check out the crank sensor.
Sorry I haven’t got back to you, I work late nights and sleep my day away…then repeat…
All of the cylinders check out for spark.
I’m going to test the fuel pressure tomorrow. Under a load the car loses power, then if I continue to increase rpm levels, it misfires. Slow acceleration in 1’st and low rpms of second, are fine, once a load is added the problems begin.
I disconnected the vacuum to the FPR. The engine ran exactly the same, only difference was I got the P0170 generic code, to throw the CEL. This was the code that would show pending condition, but not throw the CEL. I’m going to rent the FPR tester from autozone tomorrow, I got to work the graveyard shift again tonight. The only visual clue is that, the fuel consumption gauge, doesn’t drop under load, it hovers around 10mpg. What PSI should I have? I do have a Bently manual also.
I swapped that out with a new one, I had laying around, when I took off the intake to redo the vacuum lines and gaskets.
did you check the wires/engine harness or clips when you changed the cps?
it sounds like a problem mentioned in this thread
Yes, when I had my M3 they were all dry rotted from road salt, so I made sure they were in good condition.
Fuel pressure, system primed but engine off will be ~3.5bar or ~50psi. With the engine running at idle, it should be around 43-45psi with a functioning regulator. Normal engine vacuum at the regulator will drop the pressure from the normal base pressure to the rough 43psi at idle.
Low fuel pressure can cause the issues at hand.
Do you have access to an exhaust back pressure gauge? It almost sounds like a plugged cat
Yeah that doesn’t really happen with these cars, the cats are awesome, set well away from the motor, and there’s not much that can plug them upstream.
does it sound like its straining or does it just hit a hard wall at a specific rpm (like a limiter)
I know its not a common problem but with the state he got the car in catalyst materials inside the converter could have been damaged. If all other options are exhausted pulling the upstream O2 and checking backpressure might not be a bad idea
The fuel pressure checked out. IN 1st gear the car revs up, but then it strains to build rpms, once it hits 4k, its like hitting a brick wall in any gear. I checked the new MAF, and its a cheap ebay one, so I’m going to go see BMW Joe tomorrow and swap one out and see if thats the issue. I replaced every vacuum line, to include the small on on the FPR, IAC hose, the elbow, CCV, and the IAC. I also reconnected the vacuum, under the fuse box, to the T fitting and replaced the canister just to be on the safe side for now. If I disconnect the MAF the idle will stumble a bit, but then no difference. If this is not the issue, I’ll probably take it and get the cat checked. I’ve only sunk $150 in misc parts so far, most of which is stuff which should be replaced reguardless of this issue.
Adam-- thanks for the info on the fuel pressure!
A low tech way to see if the cat is your problem would be to pull the upstream O2 sensor and see if it makes any difference.