Still running rough

Ok, sorry to start a new thread about this, but figured its best to have all the info in one place.

Still running rough, seems to smooth out once she's rolling 40+, but a slight miss prob wouldn't be felt there anyways.

Replaced: plugs, wires, cap, rotor, injectors, plenum gasket, fuel pressure regulator, coil, ignition control module.

Checked by dealer/indy shop: fuel pressure, dizzy gear; ecu reflashed, all OK. Cam timing reset to 0* by indy shop after injector job.

NO SEL, no pending codes.

I just checked the fuel pressure again before starting to pull the tank for pump replacement. Key-on pressure is 60psi, after a sec or so it pops down to ~58. Running @ 59-61psi, no drop when revving the engine. I don't have the capability to check fuel pressure while driving (unless I pull the hood to see the gauge)

The wires are cheapo 'oem quality' 7mm. Plugs are single platinum Autolite AP605's.

From what I've read, both cam and crank position sensors will throw codes if bad, so I'm passing over those as suspect.

I'm going to pull the plugs, check the wire ohms while I have the plug out.

Anything else that could/would cause this %$#@$#$ miss? :banghead::banghead::banghead::banghead:

Thanks!!!

Looks like you about covered it. My experience is that Delco plugs work best in the GM stuff, may want to try a set of those. Other than that, maybe carbon build up on pistons and valves?

BTW, how's things in the Black Forest?

Things are good in BF; finally got some rain, and its starting to green up a bit.

Thanks for the info. I checked the plugs and wires. Wires ranged from 2-3.7K ohms. #1 plug is totally black. The plug I previously pulled was black also. I'm going to get a new AP605, see if it runs better. I know there is fire to #1 since I've had the timing light on it in the last week or so.
The other 7 look normal; white with a bit of tan.

I replaced the #1 plug, still has a miss. :banghead::frown:

What should the timing be at idle? I know the ECU controls all that, but what should it be if I just throw the timing light on it? At idle its at 28-29*, at least that's where I'm dialing my advance on the gun to align the groove and timing marker.

If it is carbon buildup, what is the best way to tackle that? Seafoam in the tank, or pull the plugs and load the cylinders with it directly, let it sit, crank it to blow most of it out, reinstall plugs and fire it up and enjoy the smoke show?

Best way is to pull pull the plugs and add about 4oz to each cylinder, like you said, the crank it to blow it out, reinstall the plugs and smoke out the neighbors! Seafoam would work, I use GM Top Engine Cleaner.

Good luck!
Say "Hi" to Jules for me

Don't know about the Seafoam, but if you use the GM stuff, let it sit for 2hrs.

Is that you Timmy? LOL
I ran it for a few with the new plug, higher RPM for a while too. Once it cools, I'll pull #1 and see how it looks. I had a bit of Seafoam left (about 1/2 can), so I just put that in the tank (about 1/2 full now). I'll have to stop tomorrow and get a couple cans to inject in the cylinders.
I'm taking it to Wichita to pick up a boat on Friday, so I hope she'll be running OK.

Just got back from Chicago today. Man, I just LOVE my '98 Aurora. One of the best cars I've ever owned! We averaged ~30mpg doing 80-85 with the AC on both ways. I'm sure you worked on your fill of them over the years. She hit 180K on the trip, and runs like a champ. Hopefully I can get another 20-30K before a head gasket decides to let loose. Then I'll look for another, low mile Gen 1!

Things are good in BF; finally got some rain, and its starting to green up a bit.

Thanks for the info. I checked the plugs and wires. Wires ranged from 2-3.7K ohms. #1 plug is totally black. The plug I previously pulled was black also. I'm going to get a new AP605, see if it runs better. I know there is fire to #1 since I've had the timing light on it in the last week or so.
The other 7 look normal; white with a bit of tan.

I replaced the #1 plug, still has a miss. :banghead::frown:

What should the timing be at idle? I know the ECU controls all that, but what should it be if I just throw the timing light on it? At idle its at 28-29*, at least that's where I'm dialing my advance on the gun to align the groove and timing marker.


with the #1 SPARK PLUG BLACK that would indicate a bad injector.

all the other plugs normal in color. check compression. make sure the #1 wire to plug is not with cracks/cut .

Is that you Timmy? LOL

DING DING DING!!! We have a winner!

with the #1 SPARK PLUG BLACK that would indicate a bad injector.

all the other plugs normal in color. check compression. make sure the #1 wire to plug is not with cracks/cut .

I think the plug was black due to the original injector being bad. I hope. Wire is virtually new, in good condition. I'm going to run it for a while tonight, fairly hard. I'll check the plug tomorrow. Hopefully one of the new injectors isn't bad.

I think the plug was black due to the original injector being bad. I hope. Wire is virtually new, in good condition. I'm going to run it for a while tonight, fairly hard. I'll check the plug tomorrow. Hopefully one of the new injectors isn't bad.

when replacing injectors it is quite possible to have contamination enter.

could also be black due to poor spark or low compression/valve issues.

OK, got the injector replaced tonight. Was able to get it done without pulling the dizzy. :biggrin: And only 3hrs total time.
#1 plug was dark compared to the other plugs, but not jet black like before. Most of the driving I've done with it lately has been towing the new boat or highway cruising where the effects of the bad injector were minimized.

Another thing I found was the FPR hose had a nice kink in it and was very cracked in the area of the kink. Looks like it was the original hose. I installed a new vac hose, longer than the original so it has a nice curve instead of being kinked.

Still have a very slight roughness at idle, but she's running much better and seems to have more power now that 1 cyl isn't flooding at lower rpm.