Long term fuel trims issues

[Kurtomac]

did my first few logs and the Ltrims are through the roof...so from what i hear theres probably a leak inbetween the maf and tbody or around an injector...well anywhere past the maf basically...discovered my air bridge on my vette was crushed slightly so i RTV'd it a few days ago and it doesnt leak at all now...i was told to spray brake cleaner all around there and around the maf and all connections after the maf and if the idle change or better yet if i logged watch fuel trims. soooo....sprayed it all around the maf...the air bridge to bellow...bellow to tbody and at each injector and where the intake meets the head....no change in idle...and i was logging this...no change at all in LTrims.....now heres a question for you guys....I did long tubes and no cats a month or so ago....left the air pump and tubes connnected so i didnt have to take off the intake manifold to get the air tubes out....now the car was in closed loop...does the air pump run at all in closed loop?....if the air pump keeps running due to the fact that i have no cats and it never senses the cats are lit off so it remains on and pumps air into the exhaust...maybe my 02s are seeing this extra air and pumping in more fuel via the LTrims....also i reset my fuel trims before doing this....on up they went....BUMP guys thanks for your help looking to fix soon....Need be ill take out the AIR system and put block off plates on the headers

[joecar]

The AIR pump should run shortly after cold startup and runs for a specified time, and then shuts off.

You could pull the fuse and the relay for the AIR pump motor... and/or you could disable it in the tune.

But, when the AIR pump does not run, it's plumbing accumulates condensation, so you either have to pull the hose and tape off the pump, or remove the pump...

(the condensation flows down the hose into the pump and shorts the pump motor if you ever reactivate it -> dead pump motor plus blown fuse).

Cheers,
Joe

[Kurtomac]

any idea about the Ltrims issues?

[dfe1]

any idea about the Ltrims issues?

Not knowing what you changed when installing the headers, the air pump system could well be the problem. Although the pump only runs after start-up, prior to the system going into closed loop, (it doesn't know or care that you've removed the converters) it could be providing a path for air to enter the headers. If your long term trims are way off, you either have a serious calibration problem (bad data in any number of tables) or an air leak, somewhere in front of the oxygen sensors. The air pump on a C5 is electric, so all you have to do is disable it in the tune. However, I would disconnect the lines connected to the headers and block-off the openings with a plate. What air tubes are you referencing taking out of the intake manifold?

[Kurtomac]

the only change i made was LT's and Offroad x pipe....the pass side air tube runs behind the intake....dont see how it could be a path for air since they are hooked up like stock....since i added headers and theres increased exhaust flow....no keep in mind i havnt tuned it yet, just deleted rear 02s and cat protection crap and whatnot...now if i did the auto ve and tuned the maf accordingly would that possibly help my ltrims?....also keep in mind i got my tuning stuff around the same time that i got my headers on so i dont have any pre header logs so this could have already been a problem

[dfe1]

The first thing you have to do is determine whether you have a tuning or mechanical issue. Every time I've gotten involved with a car that has a really strange problem, the cause turns out to be something undocumented or a component that wasn't supposed to be what it actually was. In the case of fuel trims being out of whack, if the PCM had never been reflashed, (you know it hasn't?) I'd check fuel pressure and injector size-- actual versus claimed flow rate. Are you sure the injectors are the original ones? If you know they're not, what flow rate are they supposed to have and does that match the data in the IFR table? Is the MAF stock, or has it been modified? Make sure all the mechanical part are operating properly before you alter the tune.

[redhardsupra]

The first thing you have to do is determine whether you have a tuning or mechanical issue. Every time I've gotten involved with a car that has a really strange problem, the cause turns out to be something undocumented or a component that wasn't supposed to be what it actually was.

AMEN! i couldn't agree more

[Kurtomac]

The first thing you have to do is determine whether you have a tuning or mechanical issue. Every time I've gotten involved with a car that has a really strange problem, the cause turns out to be something undocumented or a component that wasn't supposed to be what it actually was. In the case of fuel trims being out of whack, if the PCM had never been reflashed, (you know it hasn't?) I'd check fuel pressure and injector size-- actual versus claimed flow rate. Are you sure the injectors are the original ones? If you know they're not, what flow rate are they supposed to have and does that match the data in the IFR table? Is the MAF stock, or has it been modified? Make sure all the mechanical part are operating properly before you alter the tune.

cars been tuned before (ie spark table adjustments(both low and high tables are identical...im going to change) fans and skip shift have been change)......checked the ve table with stock...same...check IFR table...its stock....per the previous owner he just did vararam....he didnt know it had been tuned until i downloaded the tune...ive flashed it with fan changes and turning off a few codes...the car only has 12k mils and appears to be stock....everything in the engine bay looks like it hasnt been touched...usually you can tell (i had a HC TA before this).....had the intake tract off the other day trying to see if i had an intake leak....it appear stock 85mm maf...no screen...

[joecar]

The first thing you have to do is determine whether you have a tuning or mechanical issue. Every time I've gotten involved with a car that has a really strange problem, the cause turns out to be something undocumented or a component that wasn't supposed to be what it actually was. In the case of fuel trims being out of whack, if the PCM had never been reflashed, (you know it hasn't?) I'd check fuel pressure and injector size-- actual versus claimed flow rate. Are you sure the injectors are the original ones? If you know they're not, what flow rate are they supposed to have and does that match the data in the IFR table? Is the MAF stock, or has it been modified? Make sure all the mechanical part are operating properly before you alter the tune.

Ditto.

[Kurtomac]

ok well i got a new stock air bridge....so if there was any leak in my rigged slightly crushed at the clamping point stock one...it will be gone...im throwing a bank 2 sensor 1 slow response...going to try new 02 sensors....after this is done and Im still logging high LTRIMS....would i be safe to start tuning? Will be using a LC1 still yet to intall
stock injectors so i dont need to change the IFR table
stock cam so no idle tuning will be needed
might tweek my timing tables
so i should start by tuning my Main VE table in SD
Reenable my MAF and tune the MAF strictly in MAF Mode....
then hit a dyno and spark tune?