Kredz28

Check mods in sig before reading entire post. Now here is my issue. In the lower RPM range, the car pulls strong but once i get into higher boost at about 4k, the performance seems to drop off. I know that the car is running really rich, due to the fact that it smells like gas all the time. I had a mail order tune done on the car, and a wide band was used on the car before the catalytic converter. It has the stock injectors with an FMU (dont recall the brand, but its a silver unit) as well as a 255lph FP intank. It seems as if there is a sputter once i get to a bout 4-5 psi (4000 rpm) and I do not know what it is. I was thinking that it could be detonation (we only get 91 octane in CO) or knock retard. I am going to be pulling the plugs and check the gaps and make sure they are burning right, but i havent had a chance yet (50 hour weeks at work). What could cause this? It annoying

97WS6Pilot

Its either too rich or too lean or an ignition problem. I would check your O2 sensor readings at 4000rpm and WOT to see if you have a fueling problem first. Also check your knock sensor readings in that area. FMU's and stock injectors can be finicky to get right. When do you smell fuel?

Kredz28

I smell gas all the time! When I get in the car it smells like gas...might be a dumb question, but how do you check knock sensor readings and O2 sensor readings for a 93? Should I pay the 550-700 dollars to get a dyno tune? I know the mail order tune was adjusted several times after the wide band was put on, and 3-4 degrees were taken out of total timing, but a spring in the first FMU broke and a new one was put on. After that was fixed, the highly reputable shop called RMCR told me my car ran better than a simlilarly set up cammed and blown LT1! I think dyno tuning is my only option at this point...

97WS6Pilot

If you smell gas all the time you should check for leaks or maybe the carbon canister purge system. It sounds like you have something mechanically wrong. I would not spend my money on a dynotune unless the car is mechanically sound. There is nothing a dynotuner can do about an ignition or fuel problem.

This is just my humble opinion and I hope I'm helping you. I don't really know enough about 93's to be sure how to check for knock and proper fuel air ratio. I know on 94-97 all you need is a scan tool. I had stumbles at 4000 and once it was from a faulty opti resolution wire and the other time it was due to the fmu being adjusted too rich.

94SLUG

I had sim problem I'm not sure If have it worked out as I blew another blower belt and I' now going the sd concepts rout. Some of the problem was blower belt slip. On the dyno the car quit making power at 4500 rpms, gave it some turns and pulled 80 hp. I also have the DTC low res pulse which could be giving me some problems. I'm also super rich like you 12 to 1 all the way across the board. If you think your detonating go to bartkis bragins oil on old pearl just off of pearl you can buy 114. Any pics of your car I wonder if I have seen you before.

EDS Z28

Disconnect the blower, run N/A and see what happens. This way, you can rule out anything associated with the blower. I've done this several times and it works.

94SLUG

If he has low comp piston and PCM tune it wont help at all. It will be a dog, I have tried this.

Ponyhntr

Check your vacuum lines for holes in them. I had nearly the same problem, and it turned out that the vaccum line going to the FPR has a slice out of it, and was causing the exact problem.

EDS Z28

I know it will be a dog, but it may help w/diagnosing the problem as a last resort.
If the engine revs good without the blower to redline, it may be the spark is getting blown out, belt slip, or a fuel problem.

Hopefully Kregz28 has a fuel pressure gauge in his car. This would tell you if there is a fuel supply problem.

Keep an eye on the gauge. One time I had a clogged fuel filter which caused a drop in fuel pressure and caused big problems.

The pressure should increase from around 40-45 psi at idle to 80 lbs under boost w/an fmu. With an adjustable fmu, there is a little adjusting screw. With it turned all the way closed, this is max rich. As you open the screw, this makes it leaner. Maybe tinker with that.

Actually, if you could switch to bigger injectors (such a 42lb svo or 60's mototrons), eliminate the fmu, and retune it for the bigger injectors this would be a lot better.