ok so i went to auto zone to have some codes pulled due to my 99 si coupe lagging under 3 rpm!! well only 2 codes came up being P1508 and P0420

ive already replaced the ignition coil, spark plugs, fuel filter, fuel injector, fuel pump, distributer cap and wires, and intake air temp

what else could it be can anyone help me

 

Code P0420 suggests that you should check whether the cat is clogged. This could contribute to a lag or low power problem.

P1508 suggests that you may be having an idle problem. The problem could be the wires, the ECU, or the IACV itself.

 

thanks a bunch! ill get the boyfriend to take a look at it

 

yep, p0420 is for catalyst efficiency below threshold, replace the cat and go from there.

 

but would that also cause it to hesitate and jump alot??

 

When driving or idling?

Have you inspected or replaced the rotor in the distributor? Have you checked the ignition timing with a timing gun?

 

i feel so used! j/k haha

The cat will cause the hesitation and lack of power, sounds like the IACV is causing your idle surge, try cleaning the IACV with carb and choke cleaner before spending money to replace it, but with it setting a code, it more than likely will need to be replaced.

 

lol don't feel used but thank you so much i really wanted to get this car fixed cause my truck is doing it too lol.. but my truck is totally different if anyone has anymore ideas send them this way!! thanks

 

while driving it jumps a little when idling at a stop light but not much its worse when the AC is on

 

Fix the IACV and your idle problems will likely disappear.

Regarding the problems while driving, inspect or replace the rotor in the distributor and check the ignition timing with a timing gun.

 

would the oxgyen sensor throw the p0420?

 

If you don't have an O2 sensor code, then P0420 indicates a bad cat or an exhaust leak.