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Weird lean out problem after 4k...

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Old 10-18-05, 12:33 PM
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Weird lean out problem after 4k...

I'm having a really weird problem with my 3rd gen. I bought the car as a shell and installed a new engine. Ever since I've had it running, the car leans out after 3.5k - 4k rpms under boost. I can take it to red line if I stay out of boost. The first thing that I thought could be wrong was my soldered together wiring harness, so I installed a new harness. The problem was still there, so I replaced the fuel fitler. The car has a J&S knock gaurd installed. I thought that maybe it was killing the spark all together, so I disconnected it, but the problem was still there. After that I decided that it had to be the secondary injectors, so I replaced them. It was still doing it, so I wired the fuel pump to get direct 12v... the problem is still there! I'm down to the FPR, fuel pump itself, or the ECU. Also, this car was converted from being an auto by the previous owner, could that have something to do with it?

Ok, so I've:
- replaced the wiring harness
- replaced the fuel filter
- replaced the secondary injectors
- tested the j&s knock gaurd
- wired the fuel pump to 12v

What do you think?

Thanks for any help,
Jesse

Last edited by bladz311; 10-18-05 at 12:37 PM.
Old 10-18-05, 07:42 PM
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bump...

anyone?
Old 10-18-05, 08:21 PM
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get a boost gague and boost controller and get a piggyback or ecu....the boost gague for diagnostics, the boost controller to keep the boost down and the piggyback or ecu will 1: tell you your A/F Ratio and 2: allow you to add more feul.
Old 10-18-05, 10:29 PM
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The car is pretty much all stock, so I don't need the piggy back or standalone. I do have a boost gauge and the boost is at stock levels. I also have the a/f gauge in there which is telling me taht I am going lean.
Thanks for the sugestions though!
Old 10-19-05, 01:08 PM
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bump...
Old 10-19-05, 03:41 PM
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Originally Posted by bladz311
I also have the a/f gauge in there which is telling me taht I am going lean.
Do you have a wideband? Narrowband AF measurements are useless.

Do you lose power in boost? If not, your car is fine and I would dump the gauge.
Old 10-19-05, 03:58 PM
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I think I feel a loss of power in boost, but I try to stay out of boost incase it is going that lean. It is a narrowband. I do have a wideband at my shop, but I haven't tried it out in the car. On the narrow band... It is almost full rich until I hit exactly 4k rpms then it drops off the scale lean. I think that it is reading something happening. The J&S doesn't detect any knock though. Could I maybe have a bad o2 sensor? O man, I didn't even think of that! I'm going to give the wideband a shot tomorrow and see if it happens. Thanks for the help. I'll get back to you.

O, another thing that is happening which shouldn't have any relation to the lean out... If I boost the car in one gear, say I'm in second and take the car into some boost.. I shift.. then I don't have any boost in that next gear. When I let off the gas the car makes a weird sound, like a wmmm (kind of like a baloon being pinched when you let the air out). It won't boost until I let the car go to idle, then I have boost back. I simplified the solenoids hoping to remedy the problem and replaced all the vacume lines and checked all the check valves. The problem is still there. This car is a nightmare, lol.
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