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Thread: Boost + lean problems

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Posts: 1-10 of 16
2010-09-01 01:02:39
Boost + lean problems
Ok Having some issues need some imput ... Have a w11 det swap with a gt25 turbo on a stock w11 det ecu ,370's and a s13 det Maf . Running bkr7's with gap set a .39 and timing set @ 15 . Fuel pressure is at 45psi . I had it on the dyno two weeks ago and hit 10psi no problems But had a lean spot from 4-5k ! Now it only hits 6-7 psi and the boost gauge needle is going nuts flickering ! Now my a/f hit 15.9 between 4-5k rpm at WOT ! Very lean ! And after 5k it goes back to 11.9 witch is good . Today I changed over the intake manifold to a jdm highport as i had the stock de manifold on it because the det manifold was damaged when i got the motor . Now I suspect the stock wastegate to be the cause of my boost isues but I'm not positive on this . I also have a manual boost controller ordered to keep things in check . Any feedback would be great ! Also wondering if the stock w11maf and the s13 Maf have the same values ?Oh and I have not swap the built motor in yet so ignore my sig .
2010-09-01 01:06:29
i would gap those plugs down a little .29ish.

are you getting any spike on the boost gauge or is it holding consistantly on 10lbs?
2010-09-01 01:17:29
It was hitting 10 and holding but now bearly hits 7 ! And like I said the needle is flickering at 6-7 wot . Could be bad wastegate ? It is the stock gt25 w/g. I'll regap plugs to 29 . What about my timing at 15 ? I'm running 93 in it .
2010-09-01 01:25:36
well i was thinking if it was a wastegate issue that you might be getting spike as when the wastegate doesnt open the turbo keeps spooling causing a spike issue. can you manually open and close the flap, i assume its a internal wastegate? i know that its not really easy to do just wondered if it might be stuck open slightly....just throwin some stuff out
2010-09-01 01:41:29
Yea it's a pain to get at but I'll check to see if it's opening and closing freely . Maybee its a sticking open witch would be why it's only hitting 7 .
2010-09-01 02:27:00
one way to test, is if u have a air compressor, regulate it to the boost u want like 10psi and blow it in the tube that goes to gauge + waste-gate, T them off if u have to and this will show u if u are opening at 10psi.
2010-09-01 02:38:30
Thanks rob I have all that good stuff at my shop I'll give it a shot . As far as the lean issues I need to fix the boost problems first and then focus on that .
2010-09-01 04:03:11
Probably an issue with the maf. Normally you need the maf to match the ecu. Also have you checked for boost/exhaust leaks? I had issues with boost spikes then drop-offs, bought t-bolt clamps and it fixed everything.
2010-09-01 04:54:11
Are you on a stock Fuel Pump?
2010-09-01 05:21:26
Originally Posted by Vadim
Are you on a stock Fuel Pump?


I have known some SR20s doing that crap around 4-5K because of the fuel pump, even N/A. Before you change it, just put some dedicated 12V direct battery power via a relay first, it may be the wiring (use the stock power wire just to trigger the relay, then batt power for the pump instead). Even if you change the pump this is a good idea.

But you also have that wastegate to check.
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