They cut fuel... cutting spark is for carb'ed cars. And it will cook the crap out of cats and the like when the fuel and air hits the hot exhaust.... Matt
Tim - I don't think larger injectors are the solution... you're spraying WAY less fuel at WOT at 3000 RPM than you are at 6000RPM... and yet our cars run fine at higher RPMs... Also why i doubt it's a fuel pump or fuel filter issue - but I'm going to replace my fuel filter next week, just in case. I'll test my fuel pressure when i get a chance. I'm still thinking it's a fuel map issue with my tune - I'm going to try a retune soon.
I see what you mean. I might just have to follow suit and get a tune, finally. I have RMW's remote tuner, but have yet to get a tune. I'm also fearing I'm having clutch issues now as well. I can't win with this car.
OK, I'm resurrecting this thread. Same crap is happening again off and on. It pretty much stopped for several months, now has come back. While I DID just go from 15% to 17% this weekend, it was doing this intermittantly before I did the pulley swap. I can't correlate anything to this... and it drives me nuts. Behavior is exactly as before - throttle retards to about 50% until it hits about 4000-4200 RPM, then it goes WOT and car takes off like it was shot out of a cannon. Just like the data plot in post #8 shows. Any new ideas? Any specific things, sensors, etc. you'd suggest I log to help diagnose? I can log just about anything now with the new version of AutoEnginuity.
My guess is that this has to do with the kinks in the fuel maps that are required for the bypass valve transition. Try wiretieing the valve open and see what happens. You'll drop a MPG or two during the test, but it will take the valve out of the equation. matt
valve open or valve closed? FWIW, I've done that test previously when having this problem, and there was no change with: bypass valve wired open, bypass valve wired shut, BPV vacuum line connected, BPV vacuum line disconnected, JCW intake connected or disconnected, JCW intake vaccum like connected or plugged, JCW intake flap blocked open, TMAP sensor swapped....
Valve closed... but if you did the test already, there will be little to learn. FWIW, the throttle body position is set by the ECU based on driver demand (eGas pedal) and intake pressures. So if you log the MAP, T-MAP, Driver Demand and TB position, you might learn something. BTW, the Driver Deamand and TB position each have two raw signals. Matt
My thoughts ....maybe it is time for a re-tune...when Jan did mine (late spring) he did mention that the "transition" between full throttle, and the o2 regulated enrichment...or something to that effect was not so good on some of the earlier tunes....he said now the r53 tunes are more advanced than ever (he said some tunes had a bit of a flat spot, but it does sound like yours is huge...)....maybe you could use a flash tool, save your tune, and flash it with an OEM tune...and see how it runs...he used terms that were a bit different...but the above was the jest of it. Is it safe to assume that you have clean every sensor you can get too? My gut intinct is that a sensor might be sending some info that is not quite right...and a simple voltmeter will not show you...I have always been told you need to put sensors on a scope to see what the response actually is....since they can sometimes be OK on a voltmeter...but that stuff is a bit beyond my expertise...and electrically a bit beyond my comfort range.
Thanks Zippy. Was just halfway retuned by Jan with a new map several weeks back - wasn't doing this before or after the tune, but the symptom has come back now. I still need to fix a couple little exhaust leaks (way downstream, not impacting O2 readings) and then get Jan to do a new remote tune anyway. But this behavior has persisted across a couple of Jan tunes and is intermittant. Dr. O - I'll log that combo and see what I can learn.
it's either a wiring issue on the throttle body or a throttle body that is causing this, as nothing in the tune will cause it to close the TB
Just had a similar problem on the wife's BMW, the throttle body was hanging up either mechanically or electrically and ultimately it got worse until we replaced the throttle body. All's good now and running fine. It is funny that your problem comes and goes....of course so did the beemer's.... We tried everything to find a resolution before the replacement.... Paul maybe one weekend we could take mine off and put it on yours for a test.
Thanks Jan I'm definitely not blaming the tune. I've considered TB as a possibility and have definitely thought about swapping the TB. The thing that seems weird to me is (a) that the symptom is intermittant over the past year and a half and (b) that, when it's doing it, it's 100% consistent in behavior, and 100% linked to RPM (retards throttle until ~4000RPM, then goes WOT just fine). I don't see how a bad TB or TB wiring would produce that kind of behavior. Seems like it's doing exactly what it's being told to do by the ECU... and no codes. But I'm close to swapping the TB just to eliminate that as the cause....
I've got a TB around here somewhere I think... I can go check. The swap is a good idea. But I'd be surprised that a TB wouldn't go where told without a code. That's a pretty critical engine performance and safety issue. Matt
Yep, I got one... it's an M7 60mm unit, I think, or a stocker, I can't remember which is on my car. Anyway, if you want to use it for testing, you cover postage and I'll send it out. e-mail me at [email protected] Matt
Paul, you're in luck. My car's gonna be up on jack stands for another week and a half while I finish up. You want to borrow my throttle body?
This is really maddening. I replaced the SC pulley, tensioner and belt over the weekend. Car was consistently exhibiting the throttle retard described above when I test drove. Car sat until Tuesday. Drove on Tuesday, car was consistently exhibiting the symptom. 100% of the time. I couldn't make it NOT do it. Car sits until today. I pull the car out of the garage today and NO PROBLEM. Car runs PERFECTLY. I try to produce the symptoms via approximately 100 WOT cycles... it never does it. Absolutely nothing has changed since Tuesday. Same fuel, same weather, never even popped the bonnet. So I have Ben's TB now... but no reason to test it until the symptom recurs.