: 1993 Eldorado Northstar running rough



Seany
03-01-09, 04:17 PM
Hi all. My ETC has close to 200,000 miles on it and is running rough.

Things done recently: Full tuneup with original type plugs, wires, PCV, etc. New fuel and air filters and new oxygen sensors. It ran like a rocket after everything was changed. Like new, actually.

Cold idle was still an issue though. I could never figure out why it idled roughly for a few minutes when first started. The engine would usually run rough for a few minutes until it smoothed out (you could hear the difference in the exhaust). Eventually, it would even out and drive smoothly so I let that go. A short time ago, I did experience a miss in the engine but after putting Techron fuel injector cleaner in, it smoothed out and ran well once again.

Then, it started running rough while driving...

The present trouble: Same rough idle at cold start. When I would accelerate in traffic, the car would hesitate slightly until I backed off of the peddle a bit. Then, the engine responded alright. The hesitation problem persisted but the car was still driveable. This past week when I drove it, right off it definitely had a miss of some type because it sputtered away as I drove (I actually had to turn around and get another vehicle because it was running so roughly). At idle, the car continues to sputter and the exhaust smells rich.

I cleaned the throttle body and EGR valve, but no change. I did pull the front plugs (not the back, yet) and the #4 plug was wet and the others were dry. Otherwise, they looked alright.

Could this be a fuel pressure problem, coil, or fuel injector problem? If so, does anyone have any suggestions on how to tell if a coil or fuel injector is bad, or how to check the fuel pressure?

Any suggestions you all may have on what may be going on, I would surely appreciate. Thank you.

Sean

Ranger
03-01-09, 06:33 PM
Check the fuel pressure. Get a fuel pressure gauge and put it on the service port on the fuel rail. Check for a leaky FPR. When you did the tune up, did you replace the cap and rotor?

Seany
03-01-09, 07:09 PM
Thanks, Ranger. Being that it's a four-coil distributorless ignition, I didn't know that there was a cap and rotor to replace.

Please help me with my ignorance.

Sean

Ranger
03-01-09, 07:23 PM
Oops sorry, I thought it was a 4.9. I should know better. Consider that part a figment of your imagination.

Seany
03-02-09, 11:23 AM
I neglected to mention that there are no codes showing a misfire or anything else, so that adds to the mystery.

KCMO94Eldo
03-03-09, 03:36 AM
If the spark plug was wet its the Ignition coil , my #8 coil went bad last week #3 was still good , so half the coil failed? I had same symptoms sudder/missfire , checked the plugs , noticed plug 8 was wet , swithed a coil , 8 fired up (Dry), went an bought a BWD one up at Advanced Auto for 24$ . Problem solved 48069

Seany
03-03-09, 10:47 AM
Thanks for the info on the coil. I attempted to open your attachment, but all that came up was... "Invalid Attachment specified."

KCMO94Eldo
03-03-09, 02:57 PM
Its a diagram for Firing order , I cant find the picture on this forum (were i got it) . It was posted by submariner409 , i searched their posts , but , came up empty

Seany
03-03-09, 06:46 PM
No problem about the attachment. I appreciate your information and will check it out after we thaw out a little here in the Philadelphia area after a big snow fall and low temps.

Thanks again. Sean

Ranger
03-03-09, 07:05 PM
Sub has posted it many times. I'm sure if you do a search it will come up.

Seany
03-11-09, 12:49 PM
Hi all. I replaced the 4,1 coil and the car is back to running smooth again. It's amazing that a $25.00 part can make all the difference.

Thanks guys, for taking time out to help me figure out the problem. It's great to be back on the road again!

Submariner409
03-11-09, 12:58 PM
................Once more, with feeling........copy and put on the shop wall.

Seany
03-11-09, 01:19 PM
Thanks, Sub. Much appreciated.

Krashed989
03-12-09, 01:06 AM
Here's a fun trick for you to try. Only us OBD-I guys can do this. 93-95. You can override the fuel injectors from the dashboard to see what cylinders are missfiring.

-Go into diagnostics mode and wait for it to get to "PCM?"
-Press the fan up button to go into the PCM menu
-Press the fan down button until you reach "PCM OVERRIDE?"
-Press the fan up button to go into that menu
-Press the fan up button until you reach "PS04" The rpm's should raise and in the small display over the fan button it should say "01" That's the cylinder number.
-Press the cooler (blue) button to disable the fuel injector for that cylinder
-Listen and watch if the rpms change. If they change, then that cylinder is working fine. If there's no change then you know that cylinder is missfiring.
-Press the warmer (red) button to cycle to the next cylinder
-Repeat the last three steps till you've found the all of the cylinders which are missfiring.
-Turn the key off to exit diagnostics mode