Tuning #s

[imjoesnuffy]

Need a lil help with this. Well I have recently developed a sputter/backfire.

New NGK5s gapped at 35
New Taylor made Thundervolt 50s
87 Coil conversion coming this weekend.

Scan numbers:
TPS .46 at idle, 4.7 at WOT
IAC 28 at idle
BLM = 150???
INT = 128
O2 volts at idle .10 ish, WOT .93

Can't get it to idle less than 975/1000. No matter how I mess with the IAC screw.

Any suggestions? TIA
Sputter/Backfire usually occurs at part throttle.

One more question, what size is the stock DP? Think I found a set, want to make sure they will be an improvement

 

[imjoesnuffy]

fp

Forgot to mention FP is at 38 line on. 42 line off.

 

[BRAD_PADGETT]

I do not think the plugs are the problem-I run NGK-UR6. The high idle maybe a bad idle air control valve. The cheapest I found was Postons. I made the mistake of going to my local auto parts store. The high BLM is most likely a exhaust leak or a vacuum leak. I would zip tie every vacuum line and the go hunting for the leak. Hunting for the leak requires buying carb cleaner. Spray every vacuum hose, exhaust connection, and around the turbo. Any leak that has carb cleaner sprayed on it (while the engine is at idle) will change the idle speed as the computer changes it. Good Luck Brad

 

[1QUICK85]

What boost levels you running? What chip are you running(idle)? You should be setting the TPS with the ignition on, engine off. IAC isn't bad. Your WOT values are high at WOT. Should be between .76 to .80 @ WOT. So, take a little fuel out OR put a little boost in and watch your knock. Your running rich on the top end, causing backfire? I would check that TPS setting first with ign. on and engine off, then see how she runs. -Nick.
http://www.gnttype.org/maint/quickref.html
http://www.gnttype.org/techarea/maintenance/TPS.html
http://www.gnttype.org/techarea/maintenance/TPS.html

 

[imjoesnuffy]

tps

TPS is unchanged at idle and key on engine off. Both read at .46

Stock turbo, can only get about 10lbs boost.

Im thinking its running rich leaving excess fuel in the cylinder. Getting back in the throttle even a little bit, usually causes the backfire. At WOT it never backfires.