90 Grand Prix, no power

[Fishhead5]

I've got a 90 Grand Prix with the 3.1. We have gone over everything. It's got good fuel pressure, 32 psi at an idle. All the sensers are within their paramaters. Checked the timing chain to make sure it didn't jump a tooth, it's good. It starts fine and idles fine. It's set up for racing on dirt so it doesn't have a catalitc (sp) conveter. Anyone got any ideas??

[robertisaar]

elaborate more on "no power". have to put foot to floor to get it above 10MPH or what?

[bszopi]

It should have more than 32psi on the rail at idle. Also, make sure all plugs are sparking, as you may have a bad coil or 1 starting to go out.

But yeah, a little more info would also be helpful...

[Fishhead5]

By no power I mean you put your foot to the floor and it hardly goes. It doesn't spit or sputter, it's like you were hardly giving it any throttle. When you get up to around 4000 rpm's it will start to go. Once it shifts into second gear it takes forever to get it up to 55 mph and it will only hit 4200 rpm's. The average lap speeds are 67 mph and I'm running 52 mph. I went to pull it up on the ramps to crawl underneath and it didn't have enough power to get up on them, I had to get a foot away from them and get a short run at it. If you want to see how bad it is follow the link, we are after the sprint cars and I'm the orange #20 I have the poll position and I'm getting a hard run for the start, or as hard as the car would go. Watch them all blow by me.

http://www.youtube.com/watch?v=gAH6U5Sx-EM

If a coil was going bad would it miss? The front 3 plugs all have bright spark, I haven't checked the back three.

We changed the fuel pump and fuel filter. It has 40 psi fuel pressure when we rev it up.

I'm going to cut the muffler off and see if it's plugged up. I'm sure it's a cheap glass pac.

Thanks for taking the time to reply!!

[robertisaar]

if its the factory muffler, its not a glasspack; they are extremely restrictive though.

does it throw any codes?

[bszopi]

Almost sounds like it might be running in limp mode. Check to see if your PROM is fully seated in the ECM.

[Superdave]

check the knock sensor.. if it's pulling timing then it'll be a dog.

[Fishhead5]

It's not a factory muffler, looks like the cherry bomb type. We have changed out both the ecm and prom, no difference.

It isn't throwing any codes. I took it up to an auto repair shop and they hooked up their tester. They went through each sensor, changed out the ones that were throwing codes.

I guess the best way to explaine how it runs is it's like you are trying to tow a heavy car up a hill.

Thanks!

[robertisaar]

it does sound like it isn't getting ANY advance at all...

and you said it idles fine... as brad mentioned, fuel pressure does seem low.

the easiest way to diagnose a motor running like shit is to remember the four things it likes:

fuel
air
spark
compression

now what do you think out of those four might be causing issues?

[Superdave]

check the ICM and make sure all 3 plugs are snapped in.. longshot but it's happened before.

[Fishhead5]

it does sound like it isn't getting ANY advance at all...

That's what they thought at the shop so I checked the timing chain.

They checked the coil pack and ICM....good. Knock sensor, good.

I'll grab another fuel pressure gauge. The one I have has a small leak where the hose hooks up to the gauge so it might be more than 32 psi.

I have a K&N air filter, so it gets plenty of air.

I made sure all the plugs for the ECM were tight.

I haven't run a compression check. There is a touch of blue smoke when you first start it up when it's cold, but nothing after that.

If they would let me I'd switch it over to a carb and do away with all the electrical crap the four things would be a heck of a lot easier to check!

Thanks Again!

[Fishhead5]

It wasn't a plugged muffler

[60dgrzbelow0]

Cracked, loose or leaking vacuum hoses (Power Brake Booster) anywhere on the IM?

[Fishhead5]

I've taken brake cleaner and sprayed every vacuum hose I could find. I'm headed out fishing for a couple of days. When I get back I'll see if I can't find a diagram of the vacuum hoses, maybe I missed one.

[60dgrzbelow0]

This may be way off the mark, because I'm not certain if the EFI manifold/arrangement on your engine looks anything like the ones of the VIN "S" L-32 engines... but I have found one occasion where the rubberized bladder in the bolt-on Fuel Pressure Regulator under that "TOP HAT" bolted on with Torx screws developed a pin hole inside of it that caused a serious drop in power... and an uncomfortable smell of gasoline after shut down. Any symptoms like that under your hood?