2005 Pontiac Sunfire 2005 Sunfire lacks power while acceler

SEBASTIAN007

MEMBER
2005 PONTIAC SUNFIRE
4 CYL
FWD
AUTOMATIC
39,000 MILES

I bought this car as salvage at auction. It has the 2.2 ecotec engine with 4 speed automatic transmission. It was in a frontal collision. Apart from the radiator/condenser the engine seemed untouched by the impact. I had the front unibody components straighened and a new rad support welded on- the frame shop did an excellent job.

The car starts perfectly and idles smooth but acceleration is very poor. I get a PO0300 multiple cylinder misfire when I drive it but if I clear the codes and
just idle, I get none. It behaves as if it's running too lean.

I've checked for air cleaner restrictions
spark plugs ( all 4 fouled with dry black deposits)
swapped the ignition module
Swapped ECM
replaced fuel filter
checked for leaks at intake manifold and throttle body
i have fuel pressure-just don't know how much

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

If the plugs were black, it sounds like you are getting too much fuel. Was the temp sensor replaced?

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Monday, September 7th, 2009 AT 10:49 PM

SEBASTIAN007

MEMBER
4 POSTS

Well I got sick of guessing what the problem might be-took it to a dealer and they perfomed a back pressure test turn out the catlytic converter was plugged severly.

I thought it was either fuel pressure or back pressure but didn't have the tools to measure these.

Both the dealer and I agreed that it was rare for the catalytic converter to fail at such a kow milage but there was no warranty on it as it's a salvage vehicle.

It was worth the $122.00 for the diagnostics.

Thanks Jacob and Nickolas for your reply