tuning question

[tford]

I have the narrow band o2 and am seeing my mv's on the scanmaster dipping into the 740's. I have a slight hesitation under boost and then it goes away. I do not have a fuel pressure gauge in the car. I know the nb o2 isn't very accurate but do you think I should raise the fuel pressure a bit to see if it cures my hesitation problem. To sum up my ?, is the hesitation a common sign of a possible low fuel pressure/lean condition? I see knock but never above 5 degrees. I have the egt hooked up but ATR suggested placing the sensor in the downpipe which was not the correct place for an accurate temp. What do you guys think, should I blindly play with it? I would only raise the fuel pressure in small increments to see if it helps. Thanks, Tim

 

[tford]

anyone out there?

My friend is bringing me a fuel pressure gauge tonight to help.

 

[XLR8]

O2's of 740 seem low to me - especially on pump gas. I would increase the fuel and look for around 800 on pump gas at WOT. I wouldn't think that the low O2's/lean condition would be a cause of hesitation but it may very well be the cause of 5* KR.

 

[tford]

thanks for the response man. anyone else? The hesitation almost feels like an overboost but I'm definetly not overboosting. I might have f-ed up the actuator messing with it one day so that could be the culprit too.

 

[suicide six]

Yes check the fuel pressure,replace fuel filter but also check for vac leaks esp at turbo WYE lines.Whens the last time your car seen new plugs?Wires?These kind of things are sometimes hard to pinpoint but start with the easy things.

 

[boostedturbotom]

Yes check the fuel pressure,replace fuel filter but also check for vac leaks esp at turbo WYE lines.Whens the last time your car seen new plugs?Wires?These kind of things are sometimes hard to pinpoint but start with the easy things.

yea check the plugs its happen to me alot I go crazy and it's the most simplest thing and bust my head !

 

[tford]

plugs and wires are new. motor was replaced last year but the problem just started recently.

 

[JimP]

Do you have a good spare coil pack you can try?

 

[tford]

I checked the fuel pressure over the weekend and it was 41 psi. I raised it to 45 which seemed to lower my knock slightly but I still have the same problem. I'll check the coil pack next. It's been a few years since it's been replaced. I'm pulling the plugs this week to take a look. What are the chances I screwed up the wastegate? I accidently turned the rod and it turned inside the actuator but only a little bit. Can I rule out the actuator by unhooking it and driving around?

 

[XLR8]

You can unhook the WG but I do not see how the WG would cause a hesitation. Make sure you have a good known chip and maybe tape a FP gauge to the windshield so you can see if the FP drops suddenly when the car goes into boost.