TPS dip

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CT9A
Posts: 56
Joined: Thu Mar 07, 2013 11:55 pm

TPS dip

Post by CT9A »

Hope someone can help here with some suggestions. I am battling DBW throttle closing issues for a while now. Engine is a V8 with a supercharger. I upgraded the stock throttle to a unknown brand bigger throttle, then I moved to a LT throttle (SENT type), both would give throttle closing issues. Lastly I changed to a OEM LS9 throttle. This was ok for half a year, now the closing issue is back. I had a new LS9 throttle to test back to back if it would make any difference. New LS9 throttle fixed the issue for now. I attached the logs of the issue on the LS9 throttle and a another log after swapping just the throttle to a another new LS9 throttle, no changes in the calibration.

This issue always occurs around 5000-5500 rpm on all the throttles, maybe vibration at that specific rpm, even on the new throttle you see the disturbance around 5000 rpm.

Anyone went through similar issues, and maybe found a solution, or a throttle in the 90mm range that would work without issues.
Attachments
old throttle log.SD
(419.32 KiB) Downloaded 17 times
new throttle log.SD
(420.86 KiB) Downloaded 17 times
stevieturbo
Posts: 1143
Joined: Sun Dec 07, 2008 2:04 pm

Re: TPS dip

Post by stevieturbo »

log more.

log both tracks for pps/tps, log limp modes, log a/b validation etc etc in case there is a brief error/fault causing the drop.

Run your base duty in that area a little higher ? and give it more overall duty to play with, yours seems to peak around 78%

Although mine are around 63% too with the gold blade.



But certainly in the old log, it's a hell of a drop. Logging pressure on the blower side of the throttle might do no harm too, in case there is some weird huge vacuum in there or something.
stevieturbo
Posts: 1143
Joined: Sun Dec 07, 2008 2:04 pm

Re: TPS dip

Post by stevieturbo »

also, it is a genuine GM throttle, or aftermarket ? I'd include AC Delco as aftermarket as not always sure if they are 100% the same as actual GM parts.
CT9A
Posts: 56
Joined: Thu Mar 07, 2013 11:55 pm

Re: TPS dip

Post by CT9A »

I checked the logs many times when this happens, pps a and b and tps a and b all are good. No limps. OEM GM throttle. On the LT SENT throttle I tried higher duty as well, with still the same issues.
stevieturbo
Posts: 1143
Joined: Sun Dec 07, 2008 2:04 pm

Re: TPS dip

Post by stevieturbo »

You haven't logged those parameters in the log provided ?

The small dip, not a big deal. The large dip is.

Generally the gold blades are very good.

It'd be interesting to scope/record current in use, in case there is a weakness in the power supply to it of some sort from the onboard h bridge.

Plus as said taking a pressure reading just after the throttle in case there is something odd.

Have you established that your ECU 100% is the blade 100% ?
I can't remember if mine can go over fully horizontal, or if fully open is actually less than that.
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