Is fuel over-run cutoff broken in 1.2.2.2?

Razathorn · Post by **Razathorn** » Tue Jan 30, 2007 12:08 am

I have recently helped someone get their CTSC @ 9psi on a k20a2 tuned based off of a JRSC base cal. After boost tuning, I was reviewing the part throttle closed loop trends to see if some changes were desirable -- which they were, since I had dialed in the part throttle curves by basically modifying the whole map by a percentage and there were definite differences in the way the 520cc modified honda injectors operated vs the 650cc injectors. After reviewing the logs, we both noticed cases where the S.TRIM would climb as far north as it could. What it looked like to me is that the engine was decelerating under high vacuum, and the fuel should have been cut (like 18 - 25 kpa), but instead, the engine just flamed out and then the ecu just started dumping fuel because it showed up as a lean condition. Normal operation resumes right after the pedal is pressed again and things pickup right where you would expect them.

Calibration:
http://caramello.chewies.net/~raz/tunes ... psi-10.kal

Datalogs:
http://caramello.chewies.net/~raz/tunes ... 7-1-29.zip

The easiest way to find the instances I'm talking about is to graph S.TRIM and wait for it to peg north real quick and then return back to normal. You can see this happens when the throttle is lifted and one would think the fuel would cut. At first I thought it was TPS, since it was at 1 at it's lowest value, but my car as well sticks at 1 and it cuts fuel just fine -- of course, it's running a load from a few months ago.

Wayne

Post by **Hondata** » Tue Jan 30, 2007 10:58 am

Adjust the TPS so that it reads 0% with the throttle closed.

Razathorn · Post by **Razathorn** » Tue Jan 30, 2007 11:08 am

Hondata wrote:Adjust the TPS so that it reads 0% with the throttle closed.

Did this behavior change in recent versions? My car cuts fuel just fine and never dips below 1 tps -- of course, it hasn't been loaded with any recent kmanager in a long time.

Wayne

Razathorn · Post by **Razathorn** » Wed Jan 31, 2007 2:32 pm

I suggested he trim the tps as suggested, but I'm still interested in knowing if and when this behavior changed? TPS didn't previously need to be 0 for cutoff to happen, and in some cases, cutoff did happen in those logs with tps at 1.

Wayne

Post by **Hondata** » Thu Feb 01, 2007 10:05 am

It should always be 0%. What if it works at 1.1% but not at 1.4%? Datalogging will look the same but the ECU may not cut on overrun.

TransformedBG · Post by **TransformedBG** » Thu Feb 01, 2007 9:28 pm

Hondata wrote:Adjust the TPS so that it reads 0% with the throttle closed.

is there a correct way to do this? Im getting ready to install a BDL 70mm TB on my car, and i was wondering if theres a DYI guide?

Post by **Hondata** » Fri Feb 02, 2007 9:37 am

Either rotate the tps sensor until datalogging shows 0%, or, use the TPS parameters to set the open and closed points of the throttle.

TransformedBG · Post by **TransformedBG** » Wed Feb 07, 2007 7:49 am

Hondata wrote:Either rotate the tps sensor until datalogging shows 0%, or, use the TPS parameters to set the open and closed points of the throttle.

Do this while the car is running?

Post by **Hondata** » Wed Feb 07, 2007 1:05 pm

No, do this with the key on and engine off. Otherwise your neightbours will complain.

TransformedBG · Post by **TransformedBG** » Wed Feb 07, 2007 8:55 pm

Hondata wrote:No, do this with the key on and engine off. Otherwise your neightbours will complain.

They already complain.. open headers lol. Thanks though!