96 Riviera with SC Accelation Problem

[joneslb]

My 96 Riv is hesitating on take offs & has dead spots of power at various peddle levels. I took it into a shop & they advised me that my SC is inoperative at times and needs to be replaced. However the shop advised me that they couldn't guarantee that by replacing the SC would fix my problem, so needless to say I'm looking for another suggestion.

The check engine light is on, and the following codes were found: PO300, PO341, P1870, P1645, P0171.

When I step on the gas peddle hard the car takes off fine. When I'm on the freeway and shot the gas it accelerates fine, however if I try to gradually accelerate from 0-20 its running like something is bogging the car down. Also if I’m on the freeway and I try to gradually accelerate speeds it feels like something is clogged up and the car doesn't accelerate properly until I step on the gas peddle fully...

Based on the codes listed above and my brief description of the problem, can anyone help me figure out what's going on?

[96riviera18]

vac leak? chedck all the vacume hoses for leakes and cracks.
p0300 is random misfire code which is caused by the cam sensor not reading right (p0341). the EVAP code, TCC, and system lean codes may all be different problems.
do the rpms climb when you try to accelerate and the car just doent move? (ie the converter isnt locking up and your in neutral?)
in my experience, the superchargers rarely go bad and there is almost no way for a roots blower to not work at low rpm and spin at high throttle levels since it is run by the belt and spins along with the crank pulley. but you should replace the coulpler in the snout if you really want to rule out the s/c, and check the bearing. (pull off the belt and see if the pulley has any play)

[joneslb]

Response to your comments & questions:

Thxs for the info...No the car doesn't hesitate when I shoot the gas to it, and the RPM's go up in normal working fashion, in fact it takes off with the correct amount of power.

It's only hesitating on low or gradual gas peddle (ie going 25mph then gradually accelerating to 35mph) or when I’m taking off from a complete stop position & not putting the gas peddle all the way to the floor (ie 0 - 20mph gradually, it stalls & feels like its hesitant to accelerate, but if I give it a lot of gas it takes off just fine)

A little maintence history:

I just changed the top pulley that's attached to the actual supercharger nose about a month ago because the old pulley wore out and the belt came off....the SC doesn't seem to be bad from my perspective seeing how when I shoot the gas to it the car has the same accelerating power as the day I bought it....

I had two fuel pumps installed because the first one was defected ( the car still doesn't crank up on the initial attempt all the time after the new fuel pump was installed, however after reading other post on this site I've learned that by turning the ignition half way and allowing the fuel pump to charge up before fully turning the ignition all the way over would help in this area)

I had the transmission rebuilt a year ago

I had fuel feed lines installed about 2yrs ago

My Comments & Questions:

I just have a gut feeling that the problem is more along the lines of what you suggested with the Vacuum hoses?

Could the Catalytic Converter also be a possible problem?

Would a code have shown up from the diagnosis report for a bad Catalytic Converter?

Could the wires or spark plugs cause this type of hesitation?

I'm guilty of running 89 fuel octane instead of super with these high gas prices, could that be playing a role in this?

Lastly, where are the vacuum hoses located for me to inspect them?

What should I be looking for? Do I need any special type of tools to perform an diagnosis? Or should I just take it into a shop....(i'm familiar with routine things around the motor, but if this will require any type of computer diagnosis I don't have the proper tools....

Thxs for all your help on this problem...

[96riviera18]

the vacuum hoses are under the engine cover and they go from the port on the front of the supercharger to a few different locations. like the tranny on 96's.
new plugs and wires are always a good idea if you dont remember the last time they were changed. our engines like the autolite 605 plugs (1 heat range cooler)and stick with acdelco or packard wires.
89 is not a good idea, but it shouldnt make it hesitate that bad on low throttle. (however it can cause engine damage at WOT if your getting KR).
a bad/clogged cat can cause hesitation but it would be all through the rpm band, and more so at full throttle.
you do not need any special tools to diag the vac lines. just listen for air hissing and go over all of them for cracks, especially at the joints.

maybe someone else can give their expertise on your problem. if not then you can try posting on rivperformance.com since it has alot more traffic

[joneslb]

YOU ARE THE MAN!!!!

When this problem first occured I pulled into the driveway popped the hood & heard a real loud hissing sound like air was leaking from a hoes or something. I was looking for some antifreeze or something to that effect spilling onto the ground. But when I didn't see anything I just dropped the car off at a shop immediatley & told them to fix my hesitation problem.......


Thxs to you & your knowledge I can take the car into a different shop of course & have them double check the vacuum hoses & fix this problem...

THx U!!!! I really appreciate your help...I wish I would have found this site a long time ago....I could have saved thousands of dollars....hahaha...I will definitely be referring this site to everyone I know.....

[scoopy03]

Originally Posted by joneslb

Response to your comments & questions:

Thxs for the info...No the car doesn't hesitate when I shoot the gas to it, and the RPM's go up in normal working fashion, in fact it takes off with the correct amount of power.

It's only hesitating on low or gradual gas peddle (ie going 25mph then gradually accelerating to 35mph) or when I’m taking off from a complete stop position & not putting the gas peddle all the way to the floor (ie 0 - 20mph gradually, it stalls & feels like its hesitant to accelerate, but if I give it a lot of gas it takes off just fine)

A little maintence history:

I just changed the top pulley that's attached to the actual supercharger nose about a month ago because the old pulley wore out and the belt came off....the SC doesn't seem to be bad from my perspective seeing how when I shoot the gas to it the car has the same accelerating power as the day I bought it....

I had two fuel pumps installed because the first one was defected ( the car still doesn't crank up on the initial attempt all the time after the new fuel pump was installed, however after reading other post on this site I've learned that by turning the ignition half way and allowing the fuel pump to charge up before fully turning the ignition all the way over would help in this area)

I had the transmission rebuilt a year ago

I had fuel feed lines installed about 2yrs ago

My Comments & Questions:

I just have a gut feeling that the problem is more along the lines of what you suggested with the Vacuum hoses?

Could the Catalytic Converter also be a possible problem?

Would a code have shown up from the diagnosis report for a bad Catalytic Converter?

Could the wires or spark plugs cause this type of hesitation?

I'm guilty of running 89 fuel octane instead of super with these high gas prices, could that be playing a role in this?

Lastly, where are the vacuum hoses located for me to inspect them?

What should I be looking for? Do I need any special type of tools to perform an diagnosis? Or should I just take it into a shop....(i'm familiar with routine things around the motor, but if this will require any type of computer diagnosis I don't have the proper tools....

Thxs for all your help on this problem...

if it is 89 with ethanol where you are located you are fine. 89 detergent gasoline not sure though