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Discussion Starter #1
For quite a while now I have had this issue.........but never came around to ask. Ever since I installed my Nitrous kit I can not leave the car running for more than 5 minutes at idle because the service engine light will come on. When I took back to dealer they said it was because the computer thinks its running lean due to the nitrous, high flow cats, exhaust, etc.........but its not in reality so if it ever come one I just stop by in five minutes they just reset it for free.

Car runs great though. My question is.......if I can do something something about this and also due you think i'm loosing HP since computer thinks its running lean?

Are there any harmful things due to this or not just the inconvenience!
 

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A'pexi SAFC-2....would be my $200 (used ) solution....or similar remap of fuel curve...

Stock, they run a little lean at higher RPM's....or at least mine did on the dyno...
 

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First, I would not trust what the dealer told you. If they gave you your A/F ratio, I would want to verify it.

Is the intake leaking near the taps for the nitrous jet? Are there any other leaks in the intake tube, plenum? Are you intake gaskets good and new or never tampered with? Is the exhaust leaking before the O2 sensors? Are the exhaust gaskets good?

Let move on to some other stuff. Do you know what your longer term fuel trim is? Have to performed an complete ECU reset since your last modification? Did you ever dyno tune the car for the new nitrous kit?

All of the above are pretty important in answering your question if we assume that the original A/F data is not good. Let us know what you can. Also, if you have the original A/F data, post it up.

Running lean without the nitrous is not that bad. You will loose some HP. Running lean while spraying is a different animal and can blow your engine depending on your jet sizes.
 

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Good point about running lean on the happy gas....My understanding of top ring placement on the VQ's stock pistions is that it's pretty high up there (see the VQ thread from the Supra site), ostensibly for emissions purposes. That would make it really easy to take a chunk out of a piston in a lean situation with the laffgas on.

The dealer will say 'lean due to nitrous'... more likely, it's computer, plenum design, stock fuel sys.
 
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