I will try to make this as short as possible. Car sat for 2 weeks while I was redoing some bushings. Put fresh 110 in it and drove to get an alignment. On the way there the car had a bad hesitation going from 3rd to 4th. It would clear up then drive like normal. On the way home the car started doing the same thing, but it got worse and worse. Fully tuned on s300, the car used to idle at 13.7-14.00 with 1000cc injectors and a intank walbro. Now it idles fine, but its in the 10's. Partial throttle now is in the 12's.

You know a car drives with a bad plug wire, well thats what the car feal like, but multiplied by ten. By the time I got home the car would shut off at every light. Hesitate and stumble at every throttle input. Looking at the wide band, everytime the car would stumble...the AFR's would shoot to lean. Sometimes it would be hard to start.

S300 is saying that every sensor is reading right, so I just started swapping parts to find the culprit. I have changed the dizzy, FPR, plugs, injector box, and map sensor. The fuel pressure is reading the same as always. Anyone have any ideas to point me in a direction?

Damn-it, I ment to post this in the forced induction forums. My appologies.

 

Plug wires all good?

 

fuel pump going bad?

 

Kinda sounds like you have a corrupted calibration. Try taking the original calibration from your tuner and reuploading it to the ecu. Do not download the calibration from the ecu then reupload it to the ecu. I had the same problem you are having on a previous car. The file became corrupted when i tried uploading it from the ecu. Good luck

 

I had a similar issue with my injectors try a diff set if you have access to a set

 

Check your tps wires. One or more might be broke or frayed

 

Try what JDMHead said, I got in a bind and downloaded it from the ecu and it cost me a motor....
Get the file and save it as DO NOT MODIFY!

 

yes plug wires are good. Whats wierd is, before the car sat for 2weeks, I was at the track and the car ran great. All that changed was the car was on jack stands for a couple weeks. My tuner also already tried to reset my ecu and tune and that made no difference either. Also sometimes, I can rev the car out if I slowly give it throttle sitting in neutral...but it I quickly stab the throttle it goes lean and hesitates.

 

Sounds like the Idle air control is either clogged, stuck open, or no voltage.

 

the idle air control wouldnt effect the car under load/throttle. I would assume by the OP last post its def. fuel delivery.

 

Ive had an intank walboro do that exact thing on an allmotor setup years ago, it progressivly ran worse but idled, then stopped idling.

I dont really know how to check pump volume output, especailly when its in the car, so i cant help u there.

 

Man it could be some many different things at this point. Something that I always try to do and tell other to do is always start with the least expensive thing first and start troubleshooting from there. Lets put it this way...the most obvious but least expensive part. lol. Not just the least expensive. I would start out with the calibration file since it wouldn't cost you anything...if you tuned it then just upload it or get it from you tuner if you had it tuned.

Well keep us posted! Let us know what you find out!

 

Last if you cant figure it out Iv seen where cars sit with race gas in them and they get build up on the valves, do a leak down and see if there leak n , if so pull the manifold off and see if u see the lead build up on the valves, if there is buy eagle one alloy wheel cleaner(on the back in the ingredient it has a lot of acids) and spray it in the ports it will eat away the corrosion, sounds off the wall but we have had to do it before on cars that sit with race gas in them

 

check the hose coming off the pump its self. i had one split one time and it did the same thing.

 

What brand injectors and what brand fuel?

 

I think I'm going to look into the pump next, since that is the cheapest thing left to look at, then maybe send out my injectors to get tested. The gauge on the fuel filter is reading normal though, at idle and reving. Injectors are 1000cc Precisions and the fuel is Sunoco 110.

 

Have you checked exhaust temps on the manifold to see what cylinders are misfiring?
If all cylinders seem to misfire the same, id look at the fuel.
If its just one cylinder, try swapping injectors with another cylinder and see if the misfire follows..But it kinda sounds like a case of bad gas to me...

 

swap with a known or new distributor

 

Bad gas. 2 weeks sitting I enough time to go bad.

 

bad tps?

 

exactly wut i was gonna say had the same problem with rc injectors and my friend went through the same thing last week..

 

Thats what I was thinking to.

 

Tried a working dizzy, no go. I just emptied out the gas tank and put fresh fuel in...no go.

 

Compression test?

Too rich makes me think that there is an internal or ignition issue. If it was lean I would lean more toward the fuel system.

 

I had this problem sometime ago and it turned out to be two raw wires touching on my ecu harness.