Average acceleration to 30mph & none after that

[mundster]

Have a weird problem that haven't found an answer to on the forum despite a bunch of searches.

The car is a 2000 Bonneville SSEi with 140k on it. Stock. Had AAMCO rebuild transmission 12k miles ago.

Car had been running great.

Started hearing noise from supercharger. Discovered bearings in snout of supercharger needed to be replaced. They are on order. Removed belt to prevent additional damage.

This is my wife's car. She mentioned that the car was acting funny when she was driving the other day.

Took it out for a test drive and this is what I found:

Car started fine.

Put it in drive and started to accelerate. Initially couldn't tell there was a problem. Until I put my foot in it and nothing happened.

The car would accelerate to around 30mph but would take a long time to get there. To get above 30mph, I had to lightly push the accelerator to get RPMs around 2500-3000 and then take my foot off the accelerator to get it to shift.

Had to do this on each shift up to OD.

The car has no power at all. Even without the supercharger, the 3800 series II has decent acceleration.

Went to Autozone and had them read the codes, P0440 popped up. On the DIC is showed check gas cap.

Don't have a lot of time to troubleshoot so was hoping someone could give me some insight about what to check first that may be causing this problem.

From what I have gathered on the forum, it looks like a vacuum leak. Since the vac harness is relatively cheap and I've had a problem with a vac hose coming off the tee under the S/C I ordered one. Got it for $39 including shipping. Should arrive Friday. Change it out Saturday.

Just want to make sure that the vac leak is the problem and not masking something else.

BTW, I did check the gas cap and cleaned it, and that didn't solve the problem.

Looking for anyone to give me some additional info about what to check next.

Thanks in advance.

[95se]

sounds like a cat but if its not that i have no clue

[crash93ssei]

Need more information as far as the engine not having power. You get on it and the RPMs jump up but the car doesn't really move like it should (transmission slipping) or you get on it and the RPMs don't really climb and there just seems like a lack of power?

[Trinity]

cat
fuel pressure
air filtr or air restricted
Vac leak
MAF (Try and disconnect the maf connector and see how it runs)

Smoke test the car and find the leak, otherwise you will be chasing the thing. I did mine and found out it was the fuel pump gas tank seal. Best $40 I ever spent.

[mundster]

Wish there was a way to explain it.

I push on the accelerator and the car moves, but doesn't accelerate fast.

Its like there's a rev limiter on the engine.

The RPMs will not go above 2000.

The car accelerates to around 30mph and just sits there. It will increase in speed but very slowly.

The code that popped was P0440 and the DIC says Check Gas Cap.

I'm guessing it is a vacuum leak.

Sorry for the confusion. Don't have this problem with my F250 Crew Cab Diesel!

[RJolly87]

How was the car running before you pulled the S/C belt? How bad is the Supercharger? Will it still spin on its own?

Here is my theory: I believe when the supercharger belt is off, the supercharger will still normally freespin. While free spinning, it will allow air through it, but still proves to be a restriction. If the bearings are so bad that the rotors will not spin on their own, it is my belief that even less air gets in. Then there comes a point, where no more air can get in, and you hit a wall, and can't progress further (no power, no gain in RPMs).

I may be completely wrong however.

[mundster]

Supercharger is shot. Will not spin by itself. Bearings in snout are so bad that there is 1/4" slop in all directions.

Parts to arrive tomorrow.

Just need to find shop press to remove and re-install bearings.

Ran fine for 2-3 weeks without s/c belt on.

Thanks.

[repinS]

Are you sure that 1/4" slip isn't the coupler? That's another common failure point.

[BonnieBoy08]

Sounds exactly like my previous car did when the cat plugged. I'd start there. Cut that sucker off and see if it runs normal and has power again (wear earplugs lol)

[mundster]

Definitely not the coupler. Horrible grinding noise at the pulley.

Hope its not the cat.

Think the s/c may have been freewheeling before but now it doesn't.

Hope that may be it.

Just ordered the parts from Rolling Performance to replace bearings and coupler.

They arrived today. Now just have to find a shop press to remove everything and then re-install.

Needs to be done anyway. Not much fun driving without the s/c!

Will get the s/c repaired and then let you know what happens.

Will probably have the thing smoke tested.

Replaced the vac harness as one other poster suggested...no change.

Love to drive this car. Need to get it fixed.

Thanks for your help.

Together we can figure it out.

[mundster]

RJolly87 - you were on the money with your theory!

Just for grins I checked the supercharger to see if it was freewheeling. It wasn't. It was in a bind.

When I took off the s/c belt, it was turning a little but grinding.

Noticed that the s/c pulley was not moving very freely.

Grabbed it and rotated it until it rotated freely. It was very stiff at first.

Once I got it spinning, even though it was grinding, I could tell that something loosened up in the s/c.

Started the car and took it for a test drive. Ran just like it did before but without the s/c!



Thanks

The one reason I bought a car this old was my confidence in the people on this forum and their ability to help troubleshoot a problem. Its awesome to be a part of a community of people who help each other like this!

Thanks guys!

[RJolly87]

Another question. Have you done the Lower intake manifold gaskets? If you dont know when they were done, it might not be a bad idea to plan them soon. You are halfway there when the supercharger comes off

[myfirstbonnie]

I would inspect the SC really well and make sure there wasn't something in it and the housing or rotors are scored.