m almost to the point where I want to light the car on fire. The car starts ok, idle goes to 1500rpms for a few seconds then drops and surges between 1000-1500, I can watch the pfc and the injector duty goes from 9% to 0% as it surges as well. I am pulling a -500 vacuum according to the pfc, Ive checked for leaks over and over, pulled the turbos and checked for the leaks, nothing. Checked TPS ists within range, o2 sensors working right, fuel pressure is perfect and steady. Any ideas? Its a new streetported motor built with all new housings etc, by demetrios at reactive racing. Im running off a map from another car that is a stock port as well. Any help Id appreciate. Also when I drive the car down the road it bogs and doesnt go anywhere hardly. I used a block off plate on the back of the TB for the white connector, so the only electrical connectors left are the two black under the manifold and the tps

 

Since you don't have the ISC, have you tried adjusting your bleed (under the TB) screw. Keep tightening (allowing less air) until it's all the way in to see if that helps. If it's all the way closed and still surging, then your looking at a vacuum leak after the TB. Have you sprayed carb/brake cleaner around the gasket between the UIM & LIM? From there I guess I'd try replacing vacuum hoses after the TB?

Outside of that I'm not sure what else to look for per your message. Good luck, I know that can be frustrating.

Grant

 

Anyone else?

 

Ive adjusted that screw, tightened it all the way, still suges. Ive checked the vaccum lines and replaced every one of them. Ive been told it might just need to be tuned out because its running lean at idle, or because its a ported motor the map needs to be adjusted.

 

Still havent resolved the issue, I went out last night and replaced all vacuum lines, tested both the lower and upper intake manifold for leaks and couldnt find any at all. I have only the air temp sensor left under the UIM so I know its not a sensor on that, and the TPS is within range. The idle scew under the manifold is almost all the way tight. I have no idea. Also when I went to move the car it bogged bad, so I figure with the map I have not being A:for a streetport B:not for my turbos that it needs to be tuned out.

 

This may sound really obvious and/or stupid(especially since you are far more knowledgable than I), but are you bogging from too much fuel? Do you smell it?
You've been so through everything mechanically, that I think it's a good possibility that you need a tune.
What about a bad injector?

 

I dont think its too much fuel, I have someone that will be coming down within a week to try and tune it out and we can see what happens from there.

 

Ive come to the conclusion after Ive blocked everything off excep the air temp sensor under the UIM, blocked off everything including the vac ports on the LIM, blocked off all but (2) vacuum lines on the UIM and replaced those (2) vaccum hoses, changed the gaskets on both upper and lower manifolds, checked the injectors, checked the TPS, that it must just need to be tuned. I cant see anything else causing it. I start it and it idles at like 1200rpms for a few minutes, then goes to 1400rpms for a minute or two, then starts surging after that.

 

I dont have this problem at idle, but my car does this when its in motion in the lower gears. Mine does this in the 1500-2000 rpm range. It bogs & the rpms drop by maybe 500. Then when I push the throttle past a certain point, all of a sudden it starts accelerating fast. 0-1/4 throttle bogs & loses rpms, 1/4-full throttle its fine.

I tried changing the various things including ait, thermo, plugs, tps adjustment. My car is mostly stock on stock ecu. In response to Vader's comment about bogging from too much fuel, if the car doesnt backfire or smoke, it's probably not from running too rich. It feels a lot more like fuel cut. I was thinking it might have something to do with the fuel system, maybe the fuel pump, rails, fpd (??) or injectors. I dont think its vac related.

Let us know if you solve this problem. I believe theres a lot of us with the same problem

 

turn off the o2 feedback controll on the pfc to start with

 

quick update. I have a local tuner coming to my home tommorrow (wed) at 130. I guess I will find out if its the map, or something else is wrong....I will update once I have the results

 

try adjusting your fuel recovery rpm on the pfc.

 

tuning was the issue, its idling fine now, all I need now is to figure out why the speedo isnt working

 

speedo most likely the wire at the transmission has been knocked around during engine/trans install-remove and has broken. you can check it from under the car. it is on the pass side near the rear of the trans and the sensor is secured w a 10 mm bolt.

howard coleman