Finally didn't get rained out.

The track is 112 miles form me. While driving the Vette to the track i could feel some surging and a bog at low rpm in higher gear when stepping on the gas. It has done this for some time and i was beginning to think it was normal. I matted the gas a couple of times and it pulled hard. I thought it might actually run good at the track today.

I let the Vette sit for about an hour waiting for the track to get their act together. My first run was ok but I felt the acceleration come up in spirts and gradually increasing. It felt like the knock sensor pulled timing and then in increments settle back to zero. When I finished the run I could tell it was not running good at all while returning to the starting line.

I made a second pass without letting it cool down. It was a terrible run. When I matted the gas there was practally no power and the car accelerated poorly in a jerky manor. At the very end of the 1/8 mile the car all of a sudden slammed me into the back of the seat and I got to feel the potential of all the power that is so reluctant to come out.

I made a third run and it was the worst of all. I matted the gas at the same time as the first run which netted a .640 reaction time but the car started moving so slowly all I got was a 1.04 reaction on a .500 tree. The power was terrible and when passing through the traps it set a code so severe that the engine shut off and would not start until I cleared the code. I did not have time the find out what the code was because i was blocking the track and had to get the car moved. Very embarrasing.

I was able to log the data on the last run. The weird data I saw was the timing. It was all over the place. I didn't get any spark knock so I am wondering what can change the timing map besides the knock sensors.

The thought of a bad injector has crossed my mind but I'm out of guesses!

Below are the ET slips and the timing vs RPM data. I have a ton more data. If anybody has an idea what might be wrong I can produce more data.

Also, driving the car back home was awful. It was down on power for several miles and then improved slightly.

1/8 miles runs

 

Who did your installation? Can you take it back to them?

I have the E-Force on my GS and I haven't ever experienced the symptoms that you are describing.

 

IAT, ECTs, and many other tables affect timing.

Could be a bad plug/wire too.

 

I installed it myself. Perhaps my biggest mistake but I needed a project to keep my mind busy.

Orginally we thought I rolled an O-ring during installation so I removed and replaced the SC being careful not to disturb the O-rings. It was suggested that I replace the sparkplugs and I replaced them with NGK's. The car acted a bit better but now I realize it isn't fixed. The installation of the SC really is easy and about the only places you can mess up is chaffing a wire or creating a vacuum leak. Any other mistakes will become very obvious - I think.

Fuel pressure / volume might be a problem but I kind of doubt it as it doesn't fit in with all the problems I have been having. A vacuum leak still fits the scenario.

Thanks very much! Two heads better than one.

 

Take it to a real tuner. The tune that is sent with the supercharger is JUNK!

 

Engine coolent temps never exceded 216* and stay around 190 most of the time. IAT climb slowy and tops at 150* at the end of the run. The canned tune doesn't pull timing until 160* if I reading it right. Also, the timing is very eratic and I'm not seeing an eratic sensor that could be causing it.

Plug wires, could be a problem. I will ohm them tomorrow or maybe just replace them. Good thought!

Things to check so far:
Plugs wires
Check for more vacuum leaks
Fuel pressure
Flakey Injector

Thanks!!!

 

Anybody rig a home made fuel injector test stand? I would prefer to volume / pattern test them with a non-flammable liquid.

 

I might have to do that but there are many people using the canned tune with very good results. You got me thinking though. Maybe when I installed the canned tune it got corrupted some how. Usually CRC checks prevent that from happening but I will reinstall it anyway just to be safe.

Thanks a bunch!

 

Traction control/torque management is another big thing that can make timing look like that.

 

I promise you, I have retuned a few and I was very concerned. Just take your car to someone with a good reputation and you will be fine.

 

Ok, now you are getting a bit over my head. I turned off everything I could at the console ie traction control and active handling. Can you elaborate on this a bit more?

 

That's probably not a bad idea but I don't know of any "good" tuners around here for several hundred miles. I have had a couple of offers. One of the closer ones was 400 miles. Also, mail order tuning is out right off the bat. Not a fan of it. I would probably drive 400 miles if I knew I wouldn't damage the car driving it and be absolutely sure they could fix it without costing me an arm and a leg.

 

I should have asked you this before but have seen this kind of problem on another E-force tune that was fixed by retuning it?

Thanks, if so it might save me a bunch of work.

 

I think if you had logged A/F ratio it would give more of a clue. The drivability issues you describing could be tune related. Try and get it sorted before doing more full throttle runs or you may end up spending much more than what a tune costs.

 

I would check fuel pressure next

 

something is def wrong,

The spark pulling could be realated to Torque Managment Still left on IN the tune.

But thats not the only issue, because my cam A6 runs 7.1 @ 98 in the 1/8.

Im assuming that i did some knocking and is now running off the low octane table.

need some a/f data, what tuning software are you using?

 

I will not do anymore full throttle runs.

Unfortunately I don't have a wide band O2 sensor or anyway to connect it. When I first put this system on my gut instinct was that it was lean.

Does lean mean certain spark knock because I'm not getting any spark knock.

 

Fuel pressure makes since. Part throttle bog may indicate lean condition. I have noticed that STFT seems to climb right after part throttle acceleration.

I saw where you connected the fuel pressure gauge at the end of the fuel rails. I have a fuel pressure tester I'll just have to plumb it in with some fittings.

 

I am using the hand held SCT programmer as a data link to my laptop running Live Link Gen II data logging software. It's actually not too shabby for a freeby as I can log any 20 items at one time BUT no A/f of course. In other words it's what came with the SC package. Think God for that or I would really be screwed!

I have the demo HPTuners and a copy of the generic Edelbrock tune which I have been inspecting and learning from.

I suppose it could be jumping back and forth between High and Low Octane. What causes it to switch?

 

Red where in Ga. are you? I know MTI and Vengence are near Atl. There is also someone in south Ga just can't remember their name right now. He has done alot of Vipers and several Vettes.
Good Luck with this issue.
Oh if you need plug wires, I have some MSD's available if you would like to try them.

Kelly