Ok so here is the issue i am having...

after i start my car i will let it just sit at idle and it seems like the idle jumps up and down a little bit.

while driving it i have no issues UNTIL i hit about 20mph. at that point the car bogs, the jumps like its goign to accellerate and bogs again. it will do this repeatidly and make you feel like you are jerking back and forth in the car.

the only way i avoid this is when i am in boost or nearly at WOT. so pretty much the car will only move if my foot is mashed to the floor and on my boost gauge it reads 0 or more psi

if i accelerate then let off the gas and try to maintain a cruising speed it will do the same thing and accellerate, bog, accellerate, bog ect over and over

i just replaced the plugs about 2 weeks ago but i think im going to pull them to check them again tonight.

also my car is the ld9 with the m45 supercharger/ 2.7 pulley

my resonator is bad because i can hear it rattle but otherwise i think my cat is fine because when i pulled off my exhaust a few weeks back i could see through my high flow cat and there was no damage/broken pieces.

from what im told about a clogged cat it seems similar to that but im almost postive that is not the case

any ideas?



Eat my shift

oh i was also thinking it might be the injectors and to run some cleaner through the tank or that a vaccuum line migth be an issue somewhere but for some reason i doubt both of those :shrugs:



Eat my shift

Off the shelf injector cleaner will do nothing if your injector has buildup enough to cause issues. It's far too weak to do what needs to be done. If you seriously think your car has a restricted injector, take them to a professional fuel injection place (around here it's Kinsler Fuel Injection). I recently had all of mine flowtested and they were absolutely perfect (to my dismay while diagnosing problems). I have NEVER heard of anyone having a restricted injector, especially with the current design of them. Older ones were far more prone to such issues.

To me it sounds like your TPS is at fault. I once had an issue similar where I would get lean spikes at random, but the car would run great at higher throttles. Clogged cat will make you overboost significantly and it would take forever to get to 25MPH and that would likely be your top speed (happened to me, no more catalytic converters ever again on my car).


2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero

you sir can feel like a genius, tps it was.





Eat my shift

Nevermind that did not fix the problem.

The car ran well for about an hour or so ans now i have a CEL and the issue persists. I guess i will be heading down to autozone to check the code tomorrow



Eat my shift