L, M, and H fuel trims at 140%

[90 GSX]

I need help figuring out exactly what this problem is. Engine compression is okay but could be better (ranging from 140-150). It has many new parts, knock sensor, isc, crank pulley, all belts to name a few. Basically when I got this car it wasn't running too well but it was in good condition, I fixed a whole buttload of things. I set the base timing back to 5*, I swapped to a 91 eprom ecu with new caps.

Okay anyway, that was just so you have an idea of the car. Now for how it actually runs and the problems i needed help with. The car is bone stock except for the K&N air filter, joe p mbc set to 10psi, and the ecu and some other little stuff that has no effect on the motor. It will get anywhere from 5-15 (maybe more I can't remember) knocks on my datalogger under boost usually past 5000 rpm or so. The amount of knock and the point at which it comes on varies, but basically when i get on it there is some sort of knock going on. Would a bad injector cause any of those problems? What about a boost leak. Like I said in the subject, all my fuel trims are at 140% like the comp. is trying to compensate for something. At full boost my timing will drop down to around 18* give or take one or two degrees but I have seen it go as low as 12 or 13 once that knock starts kicking in and the power just drops off the face of the earth.

I also have a problem with the car dying at idle with the a/c on or when it's still really cold and I come to a fast stop and I'm pretty sure it's all related. Overall it runs okay that's why I have lived with it but I need to get it running really good so I can start modding and having real fun, I run just about even with my buddy's 1.8 acura ls so I know it has a lot more power once I solve these fuel issues, I just don't want to get on it too much like this...

Here's a really important tidbit. I don't know what kind of vacumn dsm's are supposed to make, but mine makes anywhere from 13-16 in hg. So can anybody help me out or give me advice on things I should do to solve these problems I'm having. Is it a boost leak? I have made a boost leak tester per vfaq but I didn't have a boost gauge. I still connected i t up and used my judgement so I didn't go too far with the air and I couldn't get it to pressurize. The motor was at #1 tdc (piston on the far left standing infront of the car)... anyway, did I do it correctly by attaching the tester to the turbo inlet??? Or do I need to attach it to the LICP??? Is there anything I need to block off to make it work? I have a boost gauge now, whats an appropriate pressure to test with.

Englighten me.

 

[Blue92]

Basically what causes knock is too much timing or too much heat. If you are running <20 degrees of timing, that is not the cause. Sounds to me like you got a boost leak. The boost leak must be relatively small if you are still making 10lbs, although that isn't a lot of boost. Why do you have a boost controller to run 10lbs anyway? So if you have a boost leak, then the turbo is working like hell to make that 10lbs, so there is tons of heat being output by that charge air from that little stock turbo. Check for a boost leak again.

 

[90 GSX]

I'll try checking for boost leaks again. The MBC is backed out quite far, it actually hit 10 psi on my first time out to adjust it. I see what you could mean about heating the air up... what about the intercooler? Is there anything I can do to make it work better?

 

[leakyfaucet]

what about the intercooler? Is there anything I can do to make it work better?

Clean it out with the VFAQ instructions. It's very possible that it's half full of oil.