Bogs under load

**inition** · 06-16-2010

Hi everyone, I just bought my mom's 2000 Grand Prix GTP. I love the car but it needs a ton of work since it has 100k miles. Under light load the car runs fine. If I try to excellerate up a hill or try and pass the engine stumbles and bogs down. I don't have a computer, I was wondering if this is a common GTP problem. I'm not sure if it is a fuel or spark problem. The accelerator pedal actually vibrates a little when I try to accelerate hard. My guess would be a TPS or possibly MAF. I doubt the exhaust is plugged. If there is a search term for this let me know. I tried "engine bogs under load" "bogs".

I didn't replace the fuel filter because the line was very rusty. I replaced the plugs, they were NGK and completely burned out. I replaced the wires and one of the head shields was melted. The center coil pack (5 & 2) had rusty terminals. I wire brushed them clean and used dielectric grease. Car runs great and pulls hard. I took my mom for a ride and she is mad she sold the car so cheap. Thanks.

**Bio248** · 06-16-2010

you doubt the exhaust is clogged, but it sounds exactly like a clogged cat. just food for thought.

**inition** · 06-16-2010

Thanks for the quick reply. My mom had the cat converter tested (I asked how it was tested, mom didn't know). The exhaust is pretty loud, it may be another exhaust problem. The mechanic suggested plugs and wires. I know it needs them, so I'll do it but I think something else is wrong.

**QUICKSILVER462** · 06-16-2010

DO a fuel pressure check with the engine running. Check it at idle in park, and goose the throttle rapidly a couple of times and watch the fuel pressure reading, it should hold steady, if it dips down, and judging by your description, it will probably dip down alot, that means fuel is being restricted, usually by a dirty/clogged fuel filter.

Dean