Let me say this first, Im fuel injected STUPID!! okay heres the problem

Went to the to test and tune with a friend, made a pass on the spray 125hp pulled a couple plugs on passenger side and was running a little rich. So we put a couple degress of timing in it made another pass pulled a couple plugs on passenger side again looked good again. I pulled a plug on driver side ang it was white and very clean. Hmm plulled another on same side same way. It wasnt dangerously lean but def a noticeable difference Put it on the trailer for the day
Question?? What would make on side of the motor be a lot leaner than the other. I checked the connection to the injector harness, vacum leaks and everything look okay. Any ideas?? Thanks

EDIT~~~~
Founds this issue.... Ran the car wiothout the little timing spout in at the track. He set the timing back to run on the motorwhen he got home, shut the car off reinstalled timing spout and car would not start. Like it had no fire. Pull the spout out car will fire right up. Any ideas, Tried different A9L same thing. Module , distributor (pick up) issue?

 

the n20 and fuel distribution through out the runners will cause that. is it a fogger nozzle?

 

Cylinders 7 & 8 (closest to the firewall on driver's side) tend to run leaner than the others because they are at the end of the fuel rail. The best way to cure it is to go w/ aftermarket rails and make sure you have a good high flow, high pressure FP. Most blown head gaskets occur on these two cylinders on a 5.0 because of this. When you're checking plugs, make sure these two are checked.

 

^^ What he said . I've also seen the rubber hose between the two rails get apinhole as well, but I'm sure you'd notice that

 

Cartech plenum and either 24 or 30 lb injectors with a fogger at the TB

 

I could see if it was slight but there is a consiberalbe diffence and its not just 2 cyl. It left side lean and right side rich. All the ones on left are the same and all the ones one the right are the same. The right side was rich enough that we was gonna put some more timing in it. Luckily we pulled one from the other side or I think we would of had problems

 

There are mechanical things that could *possibly, maybe* cause this, that have been discussed, differing fuel pressure, runner distribution, etc.

From an electronic standpoint, there is the possibility of the PCM commanding different fuel volumes for each bank. This is part of the adaptive fuel trim, or 'learning' that the PCM will do. If this is the cause of the fuel difference from bank to bank, it is probably just a symptom of an o2 sensor issue. It is not part of the normal operation of the PCM. You can test this by unplugging the battery for a minute to clear the adaptive memory, and then make a pass.

Hope this helps,

Brian
EFI-Unlimited

 

Hi, Brian. I know there are two different schools of thought on whether or not learned closed loop fuel trims are applied at WOT while you are in open loop. I never thought that it did since at OL, the EEC is supposed to ignore the O2 sensors and run off the oL tables. However, since some people say that the trims are appliedand it sounds like you agree, does the trim supposedly come from that favorite cell at about 180 degrees and 40% load or what?

 

I'm just going to suggest something simple here.

Have you checked to see if the injectors were toggling correctly with a noid light?
The ground from the intake to the firewall in good condition?

The PCM could be having an issue, but I rarely ever see a failed pcm, I would check the simple things first, hell I've seen parts fall out of some of the A9L's and they still work flawlessly .

 

computer was changed same thing, grounds checked everything looked good