2002 Impala, NO POWER

[IsaacHayes]

Update: Changed fuel filter. No change. It feels like it surges a bit, but it has no power still. It feels like lack of fuel to me. I looked at the plugs, and they have a bright white on the electrode tips, so I'm thinking it's running lean. Air box is clear, and I disconnected the MAF, and it made no change. And there was no check engine light either. Reconnected the MAF and drove it for some more and it did a little better, but still surges/is weak as hell. It sounds like it starts to ping under load and then downshifts and pulls a little bit as long as you don't have the throttle open much.

But if it's spark related, what would it likely be? Weak ICM? I do have a spare one of those I could try. I doubt it's the CPS cause its not cutting out or dying or anything. The ICM with a weak spark is the only thing I can think of that would be spark related :P

So. What do I check next for fuel issues, and how can I check it out easily?

If someone could type out a list of things to check and in the order of the most likely ones/easiest to check ones first that would be awesome. Without a scanner I really am lost here. How do I check the FPR BTW?

[gectek]

you can test the fpr by tapping the fuel rail with a gauge then testin press, then remove the vacuum line from the FPR and see what it reads then. i would do a compression test also, and maybe a spark test to make sure it isnt just a weak spark by bad coils or a bad ICM. also you can test the coils for a no load resistance, it might tell you something but a DSO would be better for that. just make sure the coils are on the primary side like a an ohm max and the secondary should be about 5K ohms or more. that is not the ideal way to test, but it can show you a shorted coil. with the strength of the spark, use a spark plug tester, the kind that has the screw out electrode and go from really small to really big gap to see what happens.

[IsaacHayes]

Were can I get a fuel gauge? any auto parts store? How much are they usualy?

When I took out the spark plug, it wasn't in there super tight, and there was oil on the threads. Is this normal? Mine is always pretty tight and I use anti-seize. Is this a sign that it's loosing compression due to loose sparkplugs and blowing out oil/exhaust through the threads?


What is a DSO? A weak spark I guess could be the problem. I think next chance I get I will swap my spare ICM on and use my DMM to check the ohms of the coils. I may also check & tighten the other sparkplugs...

Thanks.

[gectek]

dso is a digital storage oscilloscope, its a voltage/amperage tester. and yah you can get a fuel press gauge at any auto parts store. no oil on the threads isnt normal, i would def tighten them back down. if you dont have full compression it wont give you full spark. its fuel, air, spark, time, AND compression. no compression no fire, weak compression, bad spark

[IsaacHayes]

Ok I didn't think so. I replaced a friends sunfire sparkplugs once and it had the same thing (oil and loose) but it ran fine. I'm building a list of things to do to it next time I get to work on it.

[96MonteZ34]

I had a issue with a 01 impala and it would not shift into 4th gear and sometimes 3rd but it turned out to be a bad cat. I guess the way these cars are designed it will run on limp mode and will cause it to be really slow. It boggled my mind and there was no code so there is just an idea for you.

[IsaacHayes]

Yeah I'll keep it in mind, but the car is missing/surging a little, so that makes me think it's fuel/spark/etc engine related.

Tuesday I'll get to work on it again. My plan of attack is:

1) Spark Plugs -Clean & re-tighten. Test.
2) ICM - swap on spare, Test. (also ohm test the coil packs).

3) Get Fuel pressure gauge and see what pressure is at idle and WOT (take vacuum tube off FPR).

Hopefully it won't get to #3, and if it does, hopefully it's just the FPR and not the pump. If #3) passes Ok and still problem, then it's gotta be injectors or clogged cat...

We'll see.

[IsaacHayes]

Update: Well I couldn't get the spark plug boot off of the 3rd front sparkplug, and figured the back would be just as hard. The 2nd plug didn't look too bad at all, and I looked to see signs of blow by, and couldn't find any. Swapped ICM and no change. Then drove it myself and I could hear exhaust quite easily. I called up a friend/mechanic and he says he has serviced a TON of impalas recently with bad cats, it's a known issue. He asked some questions which described it exactly, and I told him of the noise that I thought might be pinging from running lean, and he said it's the downpipe bolts poping open/closed since they are spring loaded. BINGO that makes perfect sense.

Called the dealership and found out that the warrenty on an 03 runs out at 80k, but an 01-02 runs out at 120k, go figure this 03 has 111k.

I didnt even loosen the downpipe to test it out, I knew it had to be the cat too since he recently got an EGR out of range code, and I bet it's not due to being clogged, but due to back pressure interfering with it's operation. It just makes sense now even though I figured a clogged cat would feel different, but this thing is severe, and he told me it's been getting worse and it's better after coming off the highway. Bingo. The car could barely go down the road.

Told him to get a new cat welded on, and he got quoted 150, they thought he said 93 impala, and then tried to charge him 250 later, he complained and they let him have it for 150. Hehe. Not bad price installed considering the shops around here are pretty shady and like to not weld and just put a clamp on and charge you $12 per clamp... crazy.

Car is up and running just fine. So everyone keep in mind if you have an impala/etc or a friend that is running slow/like crap, that they are having issues with the Cats (bad batch I suppose). The cat looks just like my 94, but it sure isn't clogged like my friends 03. When I called one exhaust place for a quote, they knew of the problem right away and even asked if it was in warranty still and to check that out (already did). So it's a common problem apparently. It happens on both the 3400 and 3800 cars.


Questions:
1) He's been driving it for a long time like this before he finally decided it's something that has to be fixed. What could possibly be damaged/worn from this? Head gaskets, valve seals? Just curious.

2) I noticed his exhaust is larger than mine, didn't measure it, but looks almost as big as ehxaust on a 3800. Anyone know what a 3400 impala stock size is?