Frustrating issues with a 94 Eldorado

958 Views 7 Replies 3 Participants Last post by Kingston2001, Jul 8, 2020

Kingston2001

Discussion Starter · Jun 14, 2020 (Edited by Moderator)

Hello everybody, I have a 1994 Eldorado that's having issues with a misfire followed by the car refusing to start.

The car will be out and about just fine, but after some use I will feel a distinct vibration and the rpms will become unstable, when I feel this vibration, turning the car off will result in a no start state afterwords. The only way I have found to fix this is by disconnecting the battery and touching the leads to reset the sensors. After that it (usually) starts again. But every single time I use it, the cycle repeats.

The cylinder 1 plug was coated in oil, I have changed plugs, replaced my PCV valve, cleaned the TB, and some other things.

EDIT: The ISC motor is making a distinct clapping noise. Seems to go away if the car starts, or after an idle relearn.

I have no clue what's going on, and I want to love this car, but it's just confusing me. Please help, I can't find any reliable documentation that refers ONLY to my version of the Northstar v8.

PS: I'm referring to the cylinder furthest to the passenger side, in the rear bank, as cylinder 1. I don't know if that's correct

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Ranger

· #2 · Jun 14, 2020

Always start by pulling the DTC's. Post them AND their definitions.

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Submariner409

· #3 · Jun 14, 2020

Here's the cylinder numbering on your 1994 Northstar - Check the plug wires and, if necessary, replace them with the expensive AC Delco set from RockAuto. Use the diagram to make sure the wires connect the correct coil towers and plugs. Make sure the ICM ground cable terminals are clean and tight.

Your engine takes AC Delco double platinum plugs #41-950. Nothing else.

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Kingston2001

Discussion Starter · #4 · Jun 16, 2020

Alright so I checked the wires on the plugs that are misfiring, with my multimeter set to 20k on the ohm side, cylinder 1's wire tested at 2.18

I have NO clue what this means

please tell me.

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Kingston2001

Discussion Starter · #5 · Jun 16, 2020

Also worth noting; we connected a handheld OBD scanner to the OBD1 port under the dash, and got NO CONNECTION. Is this a symptom of a dying PCM? Or should my car not accept OBD connections in the first place?

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Ranger

· #6 · Jun 16, 2020

Are you using an OBDI or an OBDII scanner? Not sure if an OBDII scanner will work on an OBDI car.

Kingston2001 said:
Is this a symptom of a dying PCM?

Not positive, but I don't think so.

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Kingston2001

Discussion Starter · #7 · Jun 17, 2020

Its an older multi scanner, the type that can tweak values and erase codes, we've used it on OBD1 cars in the past.

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Kingston2001

Discussion Starter · #8 · Jul 8, 2020

Alright everybody, so I believe I fixed it. Its sitting in my driveway running right now, and Im gonna leave it for an hour+ just to see if it exhibits any issues.
It was the fuel pump.
We noticed when it wasnt starting, we couldnt hear a whir when the key was turned. So we banged on the bottom of the tank and tried again. Lo behold, crunchy, glass in a rubber tube, squishy gross sounds. So we replaced it by cutting an access hole in the rear of the car. And in doing so, found a MOUSE NEST the likes of which I have NEVER SEEN on TOP of the fuel pump. So, I got some closure as to WHY the pump failed, and now the car is running like a champ.
Again however, Im gonna let it idle for wayyyyy too long here. Hopefully itll do an idle learn on its own, and wont start misfiring.
Thanks for the help everybody, but I think I got it

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