No fuel trims in evoscan?

[Twofastoocatch]

Hello everyone,
I have gotten stuck again on this PnP ecu; it has completely stopped logging my fuel trims. When first started playing with it, at the beginning of the summer, I did have the rears to look at, but for about the past 3 weeks, they are all just 0. There's no way they're actually 0. It's about 1300feet elevation here, I don't see 0 fuel trims being remotely logical.

I do have a battery disconnect on the car I usually leave disconnected overnight BUT, for the past 2 weeks I've been driving the car every day (waiting on parts for the DD... Doing the head gasket on a 93 mirage) and have left it on the whole time.

I've searched through the evolutionm forums, and the closest thing I can find is a non responsive O2 sensor, but according to my logs, I do have variance from 0.2v to 0.7v.

I've tried un installing and re installing evoscan, but that didn't make a difference.

I'm also having an issue with a low load misfire (@ 9in/Hg vacuum, and from 2-5psi boost) that's definitely in the tune somewhere that I can't get rid of as well. I know it's in the tune, because when I put the factory computer back in(non flash ecu), it runs absolutely perfect. I have no idea if these issues are related, but I figure they're worth mentioning anyways. Does anyone have any idea why every other aspect of evoscan/ecuflash work, but logging the fuel trims? Any help would be greatly appreciated. Thank you.

[NOMIEZVR4]

bump...my fuel trims are stuck at 0. All of them. everything else seems to be working fine...I disconnected the battery, restarted the laptop, reflashed the car, still stuck on zero. Lo, mid and Hi's.

I did replace the rear o2 sensor, originally I was sent the wrong sensor, didn't work so I replaced it with the right one now. Denso unit. Still no difference.

[Greg E]

The battery disconnect is why the trims reset. Once the ECU loses power, all memory is erased.

[NOMIEZVR4]

I started driving the car and the trims started working...

[Twofastoocatch]

I was driving with the flash ecu for almost 3 weeks every day, (had to do the head gasket on my usual DD, and waited on parts for 2 weeks) not disconnecting the battery, and my trims never did come back. I gave up, put my stock ecu back in, next thing you know, my 700rpm idle came back, and the car ran 300% smoother. No low load misfiring, no issues what so ever. I'll give it another try next year, Hopefully the trims sort themselves out. I'm not sure what to do otherwise. If I can't tune the ECM, I might just sell it and the tactrix cable, and go arc2.

[Greg E]

So let me get this straight because the flash ECU needs some fine tuning to be perfect, it's not worth having and the ARC is the best alternative ?

[Twofastoocatch]

No, because after a whole summer of messing with it, almost $400 in gas to try and get fuel trims, to even BEGIN to start tuning it, I'm almost completely fed up with it.

I understood when I bought this set up it wasn't bolt on. And I do want to stick with it, because it's a far cleaner setup under the hood, but nobody else has had this issue stick, and nobody can help me with it. The walk through says the fuel trims must be done before any further tuning can be done. I can't see fuel trims, so how am I supposed to tune everything else? To top it off, my idle is way off, and won't take, no matter how I do it, with evoscan, or the service manual way. It just goes back to 1100+ rpm when sas mode is disengaged.

Plus I have a low load misfire issue that I can't tune out either with the flash ecu. When I could see the fuel trims, it did start to get better for the misfire, but now I can't see trims and I'm stuck again.

I put my stock ecu back in, the car idles perfect, runs fantastic, and the wideband readings make way more sense to me. What would you do? Can you help me?

[Greg E]

So you have fuel trims with the stock ECU but not the flash?

There is something we are missing here. I don't see how that's possible unless there is an issue with the ECU or the adaptor harness.

[Twofastoocatch]

I don't have access to the fuel trims on my stock ECM. Or rather, I've never looked for them. I hadn't needed to tune the car before when I was using it, as it was still stock.

Since then, I've done a mbc, downpipe, cat delete, and 4" from the car back and conical air filter. I just finished a blow through conversion, but I've never even tried to start it on blow through. (The rest of the clamps just showed up today)

I'm running the PnP flash ecu, so I'm assuming there's nothing wrong with the harness.

At the beginning of the summer I did have fuel trims on the flash ecu, only on the rear, but I did have them. Then I lost the high, later the mid, and finally the low. So now whenever I try and log fuel trims, they all read 0, from the beginning to the end of the log.

[Greg E]

Do you have 2 cycling primary narrowbands?