hesitation and sputtering

[ponyetr]

I got the fuel set at 42, and the boost at 18. The engine is broke in, though about 2500 miles on it. I just got the new pump and regulator recently. However, I do notice when I'm at a dead stop and hit it, there's a little hesitation. I have the stock air kit ( I know, get rid of it!) And stock plenum and tb. I'm just wondering if this might have something to do with it? Also, would too much boost cause it to spit and sputter and sound like it's backfiring?

 

[Cale22]

I had a similar problem, and people on the board suggested adjusting the Cam Sensor.

 

[ponyetr]

really? hmmm...did it help you?

 

[John Larkin]

Usually a hesitation or tip-in stumble is the result of a needed IAC adjustment. Try for IAC readings of 10-20 on Scanmaster, car idling hot in park with TPS also properly adjusted. If you don't have a scan tool, set the IAC screw with about 1.5 - 3 threads showing and test it.

 

[Haynesie]

where is the IAC generally located, i have a similar problem as well,

 

[ponyetr]

I'm new to this, so...IAC is???

 

[ponyetr]

oh, duh, idle air control...yeah, where's it located?

 

[WarpSpeed]

It's under the throttle body, and controlled by the ECM. You adjust it by what looks like a idle control screw on the side of the throttle body.

 

[TurboBuckeye]

Hopefully this works....



http://www.geocities.com/mdpar3/IACresetscan.html

 

[ponyetr]

I don't have a scan tool, so I'm doing what I can here. I adjusted the IAC so about 2 threads were showing, and then adjusted the tps according to what was on gnttype. Took it out, and same problem. Only this time my boost shot up over 20. Also, I have a vaccum pod with 5 on the one side, and one on the other, which was capped off. Well, evidently it shot it right off the pod. ?????? Am I get closer or farther. I feel it would probably be a good idea to get the other pod. HELP!

 

[ponyetr]

any ideas?

 

[Paul Clark]

What injectors do you have?
009s will sometimes stumble unless the chip is right on.
You're pretty much "dead in the water" if you don't have a scan tool.
Hope the Turbo Regal web site comes back soon. There's a write-up on setting the IAC there. I'll look and see if I can find a copy of it.

 

[ponyetr]

thanks...somebody left a link for me for the iac reset and for setting the tps. But yeah, I figured it was tough to do it without the scan tool. I have 42.5 lb injectors with the chip.

 

[Robes87GN]

I have the same problem. I put my pitbull chip in and dropped the FP to 42psi from 47psi. Helped some, but still does it.

 

[2 SLOW]

I don't know about the hesitation, but 18 lbs of boost is too much to start with. Most cars on pump gas don't go more that 15 or 16 lbs before detonation. And 20 lbs is asking for trouble. Turn the boost down to 14lbs and work your way up. If it sounds like crackling or popcorn popping you are detonating and asking for head gasket problems.

The best thing you can buy is a Scanmaster that you can read in the car all the time. They cost about $250 but are worth it. You can adjust TPS and IAC. It shows you o2 volts and retard in degrees. You can read Battery volts, air flow, Integrator, Block learn, RPM, cross counts, trouble codes and a few others. It also tells you the lowest o2 (leanest) and most knock retard at WOT and what MPH it occured at. I don't know anyone I race with that doesn't have one.

The hesitation could be a number of things. IAC like was said. TPS adjustment, bad MAF, bad o2, bad coilpack and/or Module, bad plug wires or plugs, vacuum leak. Thats probably enough to start with. Maybe even a bad chip.

HTH

 

[ponyetr]

ok, thanks...I'll pick up a scanmaster. And lower my boost, too...I have the original wastegate, and don't think it's any good anymore, so I'm gonna pick up a new one of those too. Thanks for all your guys input, I really appreciate it.