So who wants their ECU's "Chromed"?

[Greg E]

It should at least cycle around 14.7 though. 10.5-11.5 sounds wrong but then again, 14.1 before is off too. Since you didn't list WB02s I assume only one in the mixed stream. You could have had banks running different screwing things up.

Depends... If he's got bit2 disabled, the ecu is only using the rear o2 for trimming. If the front bank is rich, that'll never be compensated for.

I'd be willing to bet the issue is something simple like the pin wires switched around in the adaptor harness for the front/rear o2s or maybe even just one of the intake tubes is popped off (but doesn't look like it).

Easy test (since the car is stock) would be to swap the stock ECU back in. If the car runs normal, I'd suspect the adapter harness is setup wrong. If it motor still runs poor, I'd suspect something mechanical with the motor.

[Greg E]

The flash ecu with the chrome ROM should still run exactly like stock. Chrome V1 is a stock ROM!

[Chris@Rvengeperformance]

The flash ecu with the chrome ROM should still run exactly like stock. Chrome V1 is a stock ROM!

it does

I just got my 95 TT back from the body man and checked the trims. I didn't alter the rom at all and put this ecu in my 1995 from my 1992. The big differences being that the stock turbos, FUEL PUMP, heads, and cams gears are still on the 95.

The idle trim was + 9% and the cruise is +6. Not bad considering the stock fuel pump. I am sure with the aeromotive pump, a hotwire, and the stock FPR those numbers would come down.

I only had to add 5% to get those numbers down (I reduced the injector scaling from 565 to 535), but the car drove perfectly with no changes. I'm sure it was a tad lean, but the stock map is so rich up top it still was safe.

[Greg E]

Even on my completely 100% stock car, the trims vary +/- 5 to 8%....

[Vishnu]

Easy test (since the car is stock) would be to swap the stock ECU back in. If the car runs normal, I'd suspect the adapter harness is setup wrong. If it motor still runs poor, I'd suspect something mechanical with the motor.

Lucky me, I have both of them in the vehicle, just a matter of swapping wires around.

[Toni]

Depends... If he's got bit2 disabled, the ecu is only using the rear o2 for trimming. If the front bank is rich, that'll never be compensated for.

I'd be willing to bet the issue is something simple like the pin wires switched around in the adaptor harness for the front/rear o2s or maybe even just one of the intake tubes is popped off (but doesn't look like it).

Easy test (since the car is stock) would be to swap the stock ECU back in. If the car runs normal, I'd suspect the adapter harness is setup wrong. If it motor still runs poor, I'd suspect something mechanical with the motor.

Well I guess what I am saying is that even before things weren't running right. I can't keep the ecus(1st gen vs 2nd vs flashable) and o2 stuff straight but a perfectly running car should have both banks cycling around 14.7 no matter which o2 it's reading. Obviously with both o2s reading separately then both banks should be good. But if you have one back running wrong for mechanical reasons or exhaust leak throwing off the sensor then it will effect things, either on one bank or both depending on the ecu and the bits.

For example, when I got my car my rear o2 bung was welded onto a jdm housing. There were a ton of pin holes around it that were throwing off my rear sensor and thus making my car run super rich but the mix of the rear and front with a single o2 made it show cycling around 14.5 which seemed ok but it was far from what was going on.

edit- I guess I was making more of a general statement, as we all know throwing more complexity at a problem (flashable ecu) makes things difficult.

[Greg E]

Well I guess what I am saying is that even before things weren't running right. I can't keep the ecus(1st gen vs 2nd vs flashable) and o2 stuff straight but a perfectly running car should have both banks cycling around 14.7 no matter which o2 it's reading. Obviously with both o2s reading separately then both banks should be good. But if you have one back running wrong for mechanical reasons or exhaust leak throwing off the sensor then it will effect things, either on one bank or both depending on the ecu and the bits.

You are over complicating it.

I'm not aware of the history of Vishnu car. My memory isn't that good... If this was an issue with the stock ECU, then yes obviously the issue would still be present with the flash ecu. That's why I was saying to first eliminate the cause being the ECU/adaptor harness.

Couple things:
*Narrowband are not accurate nor are they consistant
*Front bank trims NEVER match the rear. One is always much richer than the other. There have been speculations into this for a while.

Because of O2 sensor location, going by one bank will never get an accurate AFR because it's trimming for both banks using only the rear as a guide. You're right in saying that it "shouldn't be" reading THAT far off but I've seen it happen before. It's quite common for a motor to run rich when disabling the front NB.

In either case, the car should still start and idle like stock because the 02s aren't used for at least the first 10 seconds after the motor is started. Bad, mix-matched or even leaky o2s won't cause ruff starts.

[dferguson]

Hey Greg or maybe someone can answer a fuel trim question for me?I have my 91 flashed with the 1.01 version and was having trim problems when i was using my wideband in the rear pipe (bank one sensor one)and using the narrow band simulation feature on it,anyway some part of that was not working correctly and everything was out of wack,so i removed it and installed my factory o2 sensor and it cleared up and looked good,my question is i have a OBD 2 scan tool i use at work so i hooked it up and by what it shows, its using the rear bank (bank one sensor one) for the fuel trim settings,it doesnt look like its using the front bank (bank two sensor one) for trims,correct?If so i was going to run my wideband in it and run it to my gauge,I cant run it thru the ECU because its not an AEM or LC1,oh and my perpherys are set up like aaronatstate. Thanks alot

[Greg E]

Turn bit 2 of peripheral 0 back on.

[Vishnu]

Here's a video of my car attempting to start which I took real quick on the way to work. Vr4 choking - YouTube

Note, there's a chance that front and rear are miswired Fed spec adapter harness in a cali car. Need to confirm under the dash, will be doing it over the long weekend.