Streetk14

Fuel pumps tend to dislike when you run them low and allow the fuel to get hot. Their performance tends to drop off when you do that anyway. I've had issues with fuel cavitation and performance (pressure) loss on two different cars due to this. Never got any lean codes, but I also know my car is well tuned with fuel trims near 0%. Not saying that is or was your issue -- honestly you didn't give us enough hard data to determine anything. I figure these kinds of things out for a living, so I'm pretty good at it. Just need data to do so.

The BAP shouldn't do anything at idle or cruise, and even at WOT, I'm not totally sure how you determined it was coming on. That's something that needs to be tested with a vacuum pump with the car stationary. I can audibly hear mine get louder when I activate my Hobb's switch.

But either way, the BAP should have no effect on idle fuel trims. Like schpenxel said, the PCM (i.e. computer) has no idea what the AFR is when you drop the hammer. It won't throw any mixture related codes at WOT for this reason. So you need to be very careful until you're sure it's fixed. Issues like this don't normally fix themselves.

You should also really look into a wideband and way to monitor critical OBD2 data. Something like the DashLogic is great for keeping an eye on fuel trims and such. Can also display your AFR if you don't want to mount an actual gauge.

nightster

My car was tuned last week and my fuel trims were perfect per Pat G. I don't see how the trims would have changed.

nightster

I have a bluetooth obd ii and the torque app on my phone. I can get some info, don't know how accurate that app is though.

Streetk14

If it's ODB info, then it should be exactly what the PCM is seeing. I'd at least be watching the fuel trims. Both short and long term. Some tuners turn off the long term fuel trims and just run with the short term to control part-throttle fueling.

I didn't realize you just got this thing installed and tuned. Definitely want to be cautious. Fuel trims don't change on their own, but sudden and noticeable swings are a sign something may be off (air leak, fuel issue, etc.). If it's running lean at idle, it's probably running leaner than it should at WOT. Fuel trims are an easy thing to monitor, and are what your code was related to. So start there.

nightster

Ok so stupid question time. Before the cel came on, nothing wrong with the car. Dynoed 577rwhp/507rwtq with just the base ecs kit on 9psi and a catback. Car running great. I have 100r faith in Pat G when he tells me my afr is perfect across the board to redline. Belt issues then shortly after, cel for lean conditions comes on. I can't find anything wrong with the car. After starting the car a few times while checking for vacuum leak and a full tank of gas the cel goes away. Codes still present when I checked on the obd ii, cleared the codes. Take the car for a drive and no cel comes back on. Why would anything be different with my tune/trims now? Cars runs the exact same as before the initial cel. I'm not saying your wrong just wondering why it has apparently changed, and if something is wrong and has changed, why the cel hasn't come back on? I probably sound like an idiot...

nightster

Well I had a check valve in the wrong place. Put it in the correct spot and everything works fine now. Sent a log to my tuner and he made a few small changes and the car runs like a top now. Stoked!

DEE_Vette

nightster

Funny story, shortly there after changing the check valve my fuel pump went out. Car sat for a while. Finally I mustered up the courage and funds to change the pump. About two weeks ago I completed the pump swap and everything has been hunky dory, that is until today. Same cel as before. I wrote it off on a failing fuel pump but with a new fuel pump idk what could be the issue. Sorry to bring this thread back from the dead but the issue is apparently still there. Contemplating on getting a new MAF sensor and swapping my 02 sensors back to the ones I had before getting it tuned. Doesn't make sense for both o2s to start having issue. Problem has to be somewhere up stream. Will be looking into getting DashLogic soon as well...

schpenxel

You need more information that you aren't going to get without getting it connected to HP Tuners or EFI Live or whatever GM's scanner is called. Otherwise you're guessing

O2 sensors won't make enough of a difference to matter, but it won't hurt to try

MAF sensor shouldn't be a huge difference either ASSUMING you're using the same model before/after.

Can't hurt to swap everything back though..

nightster

I haven't changed the MAF, its the stock one. I was watching my long term fuel trims today and they seem to go lean when the car is idling. Cruising down the freeway they stay between 0 and -7 but at idle they are around 18 to 22.

schpenxel

That's an easy tune fix (assuming nothing mechanical).

Sure there isn't a vacuum leak?

nightster

I've checked and double checked but I'm not perfect. I'll triple check and hope that I can embarrass myself by coming back here and say I found a vacuum leak. New MAF will be here Saturday.

schpenxel

They can be tough.. smoke machine helps but not exactly like most people (including me) have those laying around

nightster

Interesting update. Car just died on me again. Same as before seemed to be starving for fuel.

DOUG @ ECS

I have seen some issues with the fuse panel too so make sure you are getting power to the pump.

Also a lean condition at idle only, when it was once ok is usually a vacuum leak. Do you have a FSAT intake or stock?

nightster

Stock intake

nightster

Got to the car today and found a blown 20a fuse in the racetronix bap wire harness. Replaced it and the car fired up, started on my way home only to be left stranded again. This time the fuel rail was empty. So I think the fuel pump I just replaced went out. Hey at least I know how to change it now right. Probably going to take the bap off and replacing it with a fuel system.

Streetk14

I'm not sure if you have other issues going on, but I'd try a 30 amp fuse in the Racetronix harness before you do anything else. Pretty common to pop the stock one if running a BAP. As a matter of fact, mine popped when testing it with a hand pump in the shop right after install. This was on a ~1000 mile car that was about 6 months old. I do run the 20 volt BAP (which will pull more amps), but still. I'd recommend everyone upsize the fuse.

You might want to also go over the Racetronix harness install and all connections to the BAP. A poor contact can cause the type of issues you've been having.

nightster

Thanks! The other day when I got INVOs put on at discount I noticed they jacked the car up behind the proper lifting spot and wonder if they smushed my wire harness. Needless to say, I've learned my lesson and from now on will be taking my rims off at home. Anyways, I checked the 20a fuse again and it had not blown a second time. Tonight when I get home from work I'm going to inspect the wire harness and test to see if the fuel pump is actually gone bad or if the bap is the malfunction. I'm beginning to wonder if I'm chasing two separate issues as well. Would a failing fuel pump cause the lean codes to be thrown? In my mind it seems as if though not having adequate fuel pressure would cause it to run lean.

schpenxel

It could