EPS with no Long or Short Fuel Trims

[DDozier]

Thanks for chiming in here. I'm not sure that would be it. Even if I did have them swapped on the rear O2's, running the mini-cats would not give enough of a reading to throw the banks + and then - with that much of a swing. And by pulling the F/IC out of the equation, the stock ECU had everything perfect. I'm still leaning toward the F/IC and it could be the board or software. I'll know more tomorrow.

JC, there are four O2 sensors two on each bank, the secondary O2's will have no effect on this issue. They are there to measure the efficiency of the CAT. They make no change to fuel in the OEM ECU. What you need to check and double check are that the correct primary O2's are installed in the correct banks. The front bank primary O2 connections are on the passenger side of the car and are mounted to the front of the valve cover. If you have headers you should have O2 extensions follow the wires from the connections to the O2 and make sure it is pluged in and installed in the same exhaust path. The rear bank primary O2 connector is on the passenger side rear valve cover, but there are two connectors there and this is a possibility that the wrong sensor is plugged into the wrong plug or the primary O2's are reading from the same exhaust path if they are not installed correctly. I hope that makes since it is hard to describe this but you have to make sure they are correct. You could also setup your scan tool to look at O2 voltage instead of trims fire the car up and make sure the O2's are working by reading the voltages of the sensor. Unplug the front Primary O2 at the connector on the valve cover and see if the correct O2 voltage stops showing in the scanner, then move on to the rear O2 and run the same test.

If the two primary O2's are connected and seeing the correct exhaust paths the problem you are having should not happen and it could be the ECU or F/IC but not likely. If I were betting I would bet on either the primary O2's seeing the wrong exhaust path or somehow in the process of setting up your new exhaust the primary O2's are reading the same exhaust path (most likely the rear bank primary sensor is seeing the front bank exhaust path). Everything winds around back there so take your time and check everything out it almost has to be something like this to have the problem you are having.

Just to clarify with the F/IC out of the car, what did your trims do? The car should have been PIG rich on the wide band and then after the car started trimming the long terms should have moved to -30 to -40. If the trims stayed at zero then you never got to closed loop, no car will ever be at zero on the short term trims, and it is rare that the long term trims would be at zero as well, but the long term trims should be between +/- 5 and the short terms will move around alot but should be +/- 10 after the long terms settle in. Keep in mind that with the larger injectors you are dumping in a lot more fuel than the OEM injectors so the car will be running really rich it is not a good idea to run the car like this for more than a few minutes and if the car is cold the engine coolant temps may not be warm enough to let the ECU go closed loop.


Good luck and let us know what you find.

Dave

[Valhalla]

Thanks Dave. I only unplugged one front O2 sensor when I had the EGT bung installed so there is no way they would have been swapped.

When we (Bisi and myself) disconnected the F/IC, all trims went to zero and in open loop. Hooked the F/IC back in figuring we had eliminated one variable and the trims went in opposite directions like before.

So last night I populated the F/IC with the latest calibration AEM software and patch. Started the car this morning and both fuels systems read open with zero trims long and short. Didn't take long but they both went to closed loop. Long and short trims were nearly identical front to rear bank this time. The long trims were arouind -30 and the short -5. But at least both banks were reading negative and their numbers were almost identical. I feel I'm making a little progress. I've reset the ECU again and when I leave work tonight we'll see where it sits. Still waiting on a call from AEM.

[Valhalla]

Well I could install this for less than 1K.

http://nitrousexpress.com/product-details.php?id=1208

When you hit boost I'll hit this and we'll see who's looking at who in their rear view mirror. And I would still have a totally reliable, headache free daily driven CTSC.

JC, not trying to rain on your parade, just Jason's as I know what you've been going through my friend.
__________________

Oh I know you mean nothing to my current woes. It certainly is entertaining watching you two go at it.

Once the F/IC is fixed, I will have a relaible daily too. Especially since I have replaced half of the car with new parts!

[Valhalla]

This should be the next to last update. The ordeal of the missing and sometimes going in the wrong direction fuel trims is coming to a close. We have stability. The shorts and longs are now both in the minus column and very close if not the same numbers. I guess reloading the calibration file and the patch were all that were needed all along. So now that we can actually tune the car I'll go with the base map that gets me the best/safest numbers for now and wait for my tune on May 10th. My God what an ordeal.

Many thanks go out to Dave Dozier who built my Zeitronix package and has answered my every question. Also thanks for the patience of Bisi who must rue the day he gazed at Layla. To SuperSonic who was always there (doesn't he have a home or something?) to assist and lend support. RYU who was going to lend me his new F/IC knowing my well deserved reputation for all things NSX electrical. To all the Primer's who have chipped in their thoughts and suggestions. I couldn't live without you guys. And most of all to my poor deserted wife who I'm surprised has not taken an axe to my Mistress in the middle of the night! Thank you all.

[LMR]

This should be the next to last update. The ordeal of the missing and sometimes going in the wrong direction fuel trims is coming to a close. We have stability. The shorts and longs are now both in the minus column and very close if not the same numbers. I guess reloading the calibration file and the patch were all that were needed all along. So now that we can actually tune the car I'll go with the base map that gets me the best/safest numbers for now and wait for my tune on May 10th. My God what an ordeal.

Many thanks go out to Dave Dozier who built my Zeitronix package and has answered my every question. Also thanks for the patience of Bisi who must rue the day he gazed at Layla. To SuperSonic who was always there (doesn't he have a home or something?) to assist and lend support. RYU who was going to lend me his new F/IC knowing my well deserved reputation for all things NSX electrical. To all the Primer's who have chipped in their thoughts and suggestions. I couldn't live without you guys. And most of all to my poor deserted wife who I'm surprised has not taken an axe to my Mistress in the middle of the night! Thank you all.

This is very good news. See you soon.

[Valhalla]

^^^^^^
Yes you will, but only for a short period of time, I'll be gone.

[LMR]

^^^^^^
Yes you will, but only for a short period of time, I'll be gone.

Okay Jason

[Valhalla]

Okay Jason

Sorry, wrong Primer

[LMR]

Sorry, wrong Primer

No, I have the correct primer as you are now talkin like Jason.

[Valhalla]

Are we a little testy this morning? My goodness. The bench racing battle that you and Jason have been waging, for what seems an eternity, has been epic. I want no part of it and have told Jason so. You guys just go have fun.

I was simply stating that you won't be able to run and hide. There are several other SoCal Primer's who are now at your horsepower levels or higher. We're all good.