:::RHMT::: Real Home Made Turbo
General Category => Engine Management => Topic started by: marcj on May 15, 2009, 06:13:46 PM
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Okay. I've had enough of toying with my tune with my new setup. The entire map runs good aside from the part throttle 2-4k rpm acceleration. The AFR have went from low-14's to high 11's and back to low-14's during adjustments in that region and I still have the same problem each time. I'm starting to think it's something else.
JD said it was a lean pop, but I don't see how if it still happens when it's pig rich. I've went back to the standard timing to rule out that idea, retarding .75 per psi.
Can anyone else speculate what the issue may be. It runs great at low rpm shifts and full throttle. mid 14's at cruise and high 11's at full throttle.
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If you missfire it will read lean.
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If you missfire it will read lean.
U sure about that?
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If you missfire it will read lean.
U sure about that?
no.....lol
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this backfire ONLY happens when I shift between 2500-4000 rpm around 30% throttle. it's the strangest thing because I've went from 15:1 to 10:1 in increments and it continuously happens. I don't know what else to try at this point. someone said it could be a valve but I doubt that
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are you in boost most likly unburnt fuel in turbine
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I've had this issue with serveral cars as well. It's nothing too major, just annoying. I've been doing some reading around pfmgi and it seems like it could be a load/vac issue. Either the injectors leak a little bit, or the fuel cut off doesn't react fast enough because the motor doesn't go into the highest vac column, but stays in the 20-18 section.
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You have ectune right? I'd have to guess its the fuel cut issue. As stated above, the older rom wraps around to read the last fuel column. Basicly it dumps a ton of fuel, blows out the spark, then that fuel gets re-ignited in the exhaust due to the momentarily retarded timing.
Try to watch which column it reads from during those points, then look at your datalog very closely. I think you can display fuel cut, so watch that along with AFR's and vacuum.
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Just for future reference, I spoke to Fred this morning, and he said it sounds like an exhaust leak before the turbo.. turns out he was right. No backfire between part throttle shifts any more.. builds boost much faster! spools the HX35 between 3500 and 4000 depending on which gear, full boost not sure yet.
I plan on making my own flapper valve for the turbine soon, many know it as the quick spool valve. I was the one that started the thread over at the ohmt. I see chronic came over and started his diy quick spool valve thread here finally. Some of the V8 guys running big turbos have seen 140 wheel torque increase. I'll start a thread once I'm done with mine :noel: