Thread: Supercharger belt slipping?

2005 GTP no mods currently besides an open cone. I changed the supercharger oil a couple weekends back and I took off the belt to check the play in the pulley to see if it needed a new coupler (it was still tight). I put the stock belt back on and took it for a drive to make sure it still worked fine, no problems.

About 100-200 miles later I go to take off hard and spin a little bit, then when it catches traction the car starts to feel like it's sputtering, I can hear the supercharger making noise, but it gets loud, quiets down, gets loud, then quiets down again over and over fairly quickly. While it's doing that the car has lost quite a bit of power. I can free rev it and it doesn't sputter or act up at all. The car idles fine as well and there isn't a CEL on.

I can lightly accelerate to where I use the supercharger some and it will do just fine, but when I demand more boost from it, it will start acting up again. I cannot hear a belt slipping, but the Gen V is fairly loud. The belt is one of the few things I haven't replaced yet on this car as I recently got it.

The car has around 93K miles on it and this could very well be the original belt.

Before I go replacing this, is there something else you all think the problem could be?

If your belt is slipping you will find small rubber chunks/shavings near the belt area.

I'm thinking fuel filter or plugs

Originally Posted by Milestone

I'm thinking fuel filter or plugs

Yea plugs and wires should be done anyways. You will get a stuttering on load with bad plugs.

The plugs are new. Fuel filter has not been replaced yet. I will check on the belt when I get home.

Originally Posted by Lawngoose

Yea plugs and wires should be done anyways. You will get a stuttering on load with bad plugs.

The wires are brand new as well. As mentioned, I have done quite a bit towards basic maintenance to this car already since I've owned. If you check out my introduction thread you can see exactly what all I've done to the car, and when I did each thing.

Id check the fuel pressure regulator. Shuttering with boost increase alot of times is from over fueling, or spark issues. Pull the vac line off the regulator and see if theirs gas in there. My guess is the diaphragms tore. If this was noticed directly after the plugs/wires Id look at the porcelion where the boot slides on the plug. Alot of people crack them when installing them

Thanks for all of the comments guys, I'll be checking the easiest thing first, the belt, and if it isn't that, I'll start on the other suggestions!

I took a look at the belt this afternoon when I got home from work and the belt looked like it had been glazed in spots, so I'm pretty sure it has indeed been slipping. The next thing I will do is buy a new belt, put it on, test drive, and then I will report back! I'll do this probably towards the end of this week as I'm going on vacation during that time.

I put a new Gates belt on the supercharger and that fixed the issue I was having

Okay, so 300 miles later the new gates belt has developed a slight slipping, but nothing like the old belt was doing.

Does the supercharger belt tensioner go bad on these cars often? The car has a little over 93,000 miles on it.

Has anyone tried fitting a 3.5" tensioner pulley on a stock belt and stock sized supercharger pulley? Will it work?

Ok, any input about the question on the tensioner itself. Is it common for one of these to fatigue with less than 100K miles on it?

ive had a 3.5 tensioner on a 3.8 b4 it was just harder to get on but nothing rediculous.

Originally Posted by BoostJunki3

ive had a 3.5 tensioner on a 3.8 b4 it was just harder to get on but nothing rediculous.

Was that with a stock sized belt? If not, what belt did you use?

I know it would be pointless to get a belt that was .5" shorter as that would defeat the purpose
of what I'm trying to do.

Any idea what I should specifically check for on the tensioner? It takes some effort to push it down to release tension on the belt, but I don't have anything else to compare to...

I've ordered the bigger pulley first since it was the cheaper option out of all and it's also an upgrade at the same time. I'll try to muscle it on and will report back!