Help with tune, fuel trim/o2 reading

[chevy42083]

Can anyone tell me if these numbers are normal or not? My brother and I are trying to figure out why the truck doesn't run right.

B-body pcm has an unknown tune... may be changed for the cc503 cam, lifters, no emissions etc. The F-body PCM is bone stock.

B-body...
DTC 29 - Air injection pump
Both o2 sensors are reading about the same .75-.08 Millivolts. ( I DO have leaky collectors that need to be fixed, not sure how that effects it)

Fuel Trim = 160 at idle, and drops to about 130 with foot on the floor revving.


F-body...
Barely idles still and had a fuel trim of ~200. It did throw a knock sensor code and reverse inhibit code.

[MEAN LT1]

What you need to first is fix your exaust leaks. This will cuase the pcm to make corrections when there doesnt need to be. Once you got that fixed then you can go and start messing with the pcm. The b-bodty pcm needs to have th air function turned off. Thats the easy part. Once you get the exaust leaks fixed your o2 fuel trims should start reading different there for your your o2's should look different as well. One will affect the other. The F-body pcm thinks your running a m6 and basically nees to be flashed for your a4 and it wont look for that. The fuel trims go back to your exaust leaks. Take care of that stuff and go from there. BTW when the ocm goes into closed loop your o2's should be cycling irratically. If its not then you need to replace the o2 sensors.

[Fastbird]

Which fuel trim are you talking about? STerm or LTerm??? It's the LTerm you need to be most concerned with. If those are 160/200.....that's WAY lean. The 200 though makes me thing you're talking about the STerm because the limitations of the LTerms is 160.

[chevy42083]

huh... not sure if it's short term or long term... I'm just relaying the numbers that he read from the scanner. The truck hasn't had a battery hooked up to it for years... it's only been ran a few times around the block, and lots of idling, not sure how that would effect short v long term fuel trims.

I tightened up the exhaust, and the leaks are pretty much gone... but still leak just a little. I HATE Hedman's thin flanges. This is the best it's going to get till I get new headers. They were already on the list... these SUCK, and that's why I hadn't messed with the tune in the past. Was waiting for headers... but I really don't know when I can afford them.

As for auto vs manual... the truck is an A4... but it's not computer controlled. That was the reason for getting the manual computer. Technically both computers would need all tranny functions turned off.

I ordered a new battery and power cord for my laptop... so HOPEFULLY I can get datamaster and tunercat up and running to make the changes needed.

I was also told that the tune would need to reflect the injectors and fuel pressure... I THINK it's a stock regulator, but i have no idea what the injectors are rated at. Is that normally marked on them (either rating or a P/N)?


Thanks for the replies guys.

[chevy42083]

Well, finally got a laptop and datamaster to play nicely with my truck, so I have a datalog, and a copy of the .bin file. Now I get to dive into research :detective:

During this datalog I remember short term as right at 128-130, but longterm was 160 :confused: I'll have to start digging into this when I'm not at work and can look through the file.

At the very least, I can calibrate the speedo :laugh:

[Fastbird]

Well, finally got a laptop and datamaster to play nicely with my truck, so I have a datalog, and a copy of the .bin file. Now I get to dive into research :detective:

During this datalog I remember short term as right at 128-130, but longterm was 160 :confused: I'll have to start digging into this when I'm not at work and can look through the file.

At the very least, I can calibrate the speedo :laugh:

Shoot me a copy of the datalog and Let me have a look at it. I'll see if I can't help some.

[chevy42083]

That would be helpful
Address? I didn't see one in profile, or your website.

<well, saw the Fastbird @ fastbirdPerf.com, but didn't know if you wanted this type of stuff to that e-mail. >

EDIT: Went ahead and sent it to that address.

EDIT again:
This just in...
http://ltxtech.com/forums/showthread.php?p=53165#post53165
Apparently I have 20lb injectors. I know the .bin file was set at 24lb