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50% equal to WOT Fuel maps

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architechnik

15+ Year Contributor
690
10
Jun 21, 2007
Glad, Oregon
Fuel trims have been reading at 82% for some time, but I think it is a failing O2 sensor. I recently installed a WBO2 to completely track the problem. I noticed that once the throttle reaches about 55% the Wideband goes to straight rich (10:1 maxed on display).

According to MMCd the tps seems to move fairly constant with small jumps, but I think it is just the palm.

Has anyone documented something similar? Is there something that would confuse the high fuel trims or is there something wrong with one of my maps? I will double check the voltage stream from the TPS tomorrow and provide an update.
 
Sorry for the delay - my assistant (15yo sister) has been sick and I've been the one to take care of her.

Ok, double checked the actual voltage from the TPS and it looks good. I'm noticing there is intermittent failure in the purge system. It's a CA and occasionally code 43 arises. I have rerouted the AEM Uego wideband into the ECU and noticed immediate responsiveness. (As a note: this device has a standard 0-5v output with a setting adjustment to restrict to 0-1V reversed. I hope this is right and only took it for a quick drive and heavily monitored the true wideband output.)

It still went to flat out rich at 50% throttle. If anyone has any ideas about what could cause this, feel free to chime in.
 
Well the DSM factory computer switches from sequential to batch fire at 4k PRM's for "cooling aid" so i could see it at a range 50% or more going directly to the open loop mapping. Most closed loop systems cut out at more than 30% throttle anyway(not sure on the DSM factory ECU)

So it's probably just using the maps that are for that load range, and those are what needs tuned if it's too rich for you. On a side note. i've been able to build 15+psi of boost at less than 30% TPS so if the closed loop didn't kick out at that point it would do some serious heating up of components.

I think you're just seeing part of how the programming works
 
You really have to ensure timing accuracy. Sounds like it's retarted right now. Did Jeff put the stock fuel maps on your chip? You almost could have a boost leak. With the ECU pulling fuel in a vacuum (cruise) and the car running richer than a W/B can read sounds like a boost leak.
 
The factory ECU is programmed for a safe 9.8:1 in open loop mode. On an untuned/stock car, once you reach open loop (certainly at 50% throttle) your wideband will shoot rich.

When you log o2-R, does the o2v cycle up and down or stay at 0.00v?

Vacuum/boost leaks make you run lean at idle/cruise, so it could quite possibly be the o2 sensor. Then again, I am still yet to see a bone-stock DSM get a perfect 100% across the board for low/mid/high fuel trims.
 
The ECU has the stock maps copied over onto a new chip from my original (removed for safe keeping while messing with tuning). I haven't messed with the new settings until I get everything in place and make sure it is working properly as a stock setup.

This all makes sense in terms of switching to a single map at a set throttle position. I was thinking there were two maps while not in closed loop - one for lower throttle and one for WOT that would kick in around 80% TP.

As far as vac/boost leaks - I'll have to get back to you on that one. The hoses are original and they show cracks; I have tested the vac/boost with no leaks while stationary, but I think there are cracks that open with the engine vibrations.
 
Only one map. The STI has several maps as do some GM OBD I ecu's to name a few. TPS really doesn't do anything for the car other than a O/L C/L set switch of sorts.

And I was backwards earlier. It wouldn't be a boost leak. I was thinking backwards. You have a fuel pressure regulator? You might be running to much fuel pressure. If you have a non standard set of fuel injectors and your trims are all different by a decent amount progressively going in one direction it's a good sign of to much or little injector deadtime.

Anyways get a timing light and set your timing correctly. Then go from their.
 
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