ntomsheck

iTrader: (1)

Sorry for the long post, but I've included tons of information
For simplicity I have the L98, with speed density (730ECM).
Motor/trans have 70K on them.
Motor is almost completely stock (only the throttle body coolant bypass done on it, and the air system removed, including pump and cat tubes)
The car was sputtering Saturday when I went to move it. I figured I'd change the fuel filter since it hasn't bee changed since I brought the car to life. Well of course that 15 minute ordeal turned into a 2 day ordeal basically because nothings happens like it should. Today I finally got it on and leak free after 2 days and 9 trips to the auto parts store. Well the car still sputters, but if I rev it to 2000rpms and hold it, it will slowly smooth out, as if there was air in the fuel line.
The exhaust smells rich, the O2 sensor shows .600-.700mv at idle through winALDL, the spark plugs that I checked have a sooty deposit on them, indicating rich. Also, at certain RPMs, the catalytic converters will rattle, as if they broke apart. When I changed the fuel filter, ~5 gal (yes, gallons) of fuel leaked out. There was no power to the pump, it just dripped out over night. This leads me to believe there is something wrong with the pump, which may be the cause of the sputtering. However, this would not point me to the rich condition. The only code I pull is a 32 (EGR system). The timing is at what appears to be 5deg BTDC in park. As I check timing, for a split second the balancer line will disappear periodically as if the engine missed. Idle is smooth (when it's not sputtering), timing doesn't bounce around. The injector COILS are all good. The injectors have not been leak tested/cleaned, but the coils all read 17.4 +- 0.2 ohms. Ground is good, only 0.6 ohms from battery to top of plenum. The sputtering has no preference, warm or cold. Occasionally the starter has a hard time cranking the engine if it's hot, but I also need to shim it.

My question is, what parts should I replace first. Money is definitely and issue, so I can't upgrade to the nice accell 8.8mm graphite wires etc. Also, should I replace the fuel pump now before I end up stranded somewhere? I would like to add that the only maintenance I have done on this engine is an oil change and trans fluid change. I have only put 4,000 miles on it since I bought it, and it was running strong so I didn't replace anything else.

edit: I also get 14-16mpg without beating on it.

formula_novice

iTrader: (1)

In my experience, if the cats are broke inside, then the ceramic can cause an obstruction in the exhaust which will result in the car stalling/sputtering at various RPM's.

If your cats are rattling, then at least one of them is broken inside. With the car cold, hit the bottom of the cat with your palm in an upward motion. If you hear a rattle, then that cats' ceramic is broken and will need replaced.

Get the cats replaced before you buy anything else. After all, having fancy 8.8mm graphite wires won't do a lot of good if the engine can't breathe

Hope this helps!

ntomsheck

iTrader: (1)

Well I removed the exhaust system, except for the manifolds and ran it. It still sputters/stalls, and runs rich. I will replace the cats while it is out though, because they are clogged. Today I'll pull the dist cap and check it/clean it.

formula_novice

iTrader: (1)

Do you have a fuel pressure guage? If so, hook it up and see what the idle pressure is. Then turn the car off and see if the fuel pressure remains constant or if it bleeds down.

Hope this helps.

ntomsheck

iTrader: (1)

It wont even idle anymore, so if I did have an FP gauge, it would be somewhat useless. BTW, I found out that the cats rattling was a washer stuck in side . The cats are completely whole otherwise. But I still removed them as preventative measures. I appreciate your help though.

ntomsheck

iTrader: (1)

Well I fixed it so it can idle and drive now, but it still runs rich so I'll begin an extensive tune-up as well as replace the fuel pump, due to running bad on the first start up of the day. Gonna remove and clean the IAC too. Btw, the miss was because the #8 spark plug wire barely disloged from the distributor, so it wasn't visible, but if you touched it, it was loose. So I fixed that and it runs again, just not as good as it should. I think I'll buy a fuel pressure guage tomorrow, thanks for reading guys.