'94 Eldo Random Stalling

[Ion]

For many years my Eldo has been having stalling issues. Now it's to the point I cannot rely on it anymore! It just sits in the garage until I'm able to figure out the source of the problem. OBD codes are present, ranging from MAP errors to TPS errors to the 095 stall code. I've been around the block enough times with this car to know that because a code is generated, ie, open map sensor, does not mean the sensor is bad. In fact, I have come to learn that a loose ground wire can cause the computer to freak out and generate non-relevant messages. Since someone on another forum suggested I check the battery connections and make sure they are tight, I have kept that info fresh in my mind and accessed it during the last time I had issues. I was driving back from an art show in Las Vegas at night, in the desert. While in cruise control, I noticed the tach drop down to zero and that sinking feeling hit again that once again, the car stalled. I coasted off the road onto the shoulder, grabbed my flashlight, opened the hood and because I remembered the advice about the battery terminal, I wiggled the pos and neg. cables, then made sure they were connected tight to the terminals, climbed back into the car and it started right up. Doing nothing might have (and has) given me the same results. After 4 more random stalls, the car decided to drive me the balance of the trip home without further issues. Other common symptoms were computer telling motor to go into limp home mode, where it would not shift out of second gear, then all of a sudden, that problem going away and car running perfectly for several weeks.

After speaking with some diagnostic people, the concensus seems to be that I have an electrical problem and the only way to solve it is to recreate it when car is running. this could potentially mean tracing each and every wire harness from beginning to end, trying to make the car stall. This could end up taking days and resulting in a bill that costs more than the old car is worth. I first tried to mess around with the battery connections while car was running, but I could not get the car to stall. The other variables I can recall since the problems began were changing the old blower motor with a new one. I had to "rig" the wire harness connectors, because one of the tabs broke. I have, like a fool, changed both MAP sensor and TPS sensor. During replacing the latter, I remember having to pull a wire harness out of the way to do the job. Could straining a wire harness or "rigging" another be at the root of all this evil? Maybe a wire has come to rest on a hot part of the engine and melted through insulation? I just don't know!

If anyone has encountered this random stalling nightmare and discovered a solution, PLEASE don't hesitate to share!

[rockfangd]

I would start with the electrical center at the left strut tower.

Check the fuses and relays for corrosion, check the 2 grounds that are located underneath the center. If you see corrosion you will want to give the whole area a really good inspection.

Have you ever changed the fuel pump/ sending unit?

[KHE]

I'd inspect the wire harnesses that you moved while replacing the various components - it is possible some of the wires were damaged.

Have you checked the fuel pressure? A weak fuel pump will cause stalling, lean O2 sensor codes, etc.

[Cadillac Jim]

Intermittent problems can be tracked through the OBD codes. Clear the codes and when something happens, run them again and work with just the ones that seem to be thrown when there are problems.

If you can, when it stalls again, run the codes right then from the A/C buttons and see what is CURRENT while it is coasting down. That will tell you what is causing the stall. If there are no CURRENT codes when it stalls, you have lost fuel pressure.

[Ion]

I would start with the electrical center at the left strut tower.

Check the fuses and relays for corrosion, check the 2 grounds that are located underneath the center. If you see corrosion you will want to give the whole area a really good inspection.

Have you ever changed the fuel pump/ sending unit?

I have changed the fuel pump, but have not checked the grounds under the fuse box (or for corrosion). I'll def. give it the once over.

[Ion]

Intermittent problems can be tracked through the OBD codes. Clear the codes and when something happens, run them again and work with just the ones that seem to be thrown when there are problems.

If you can, when it stalls again, run the codes right then from the A/C buttons and see what is CURRENT while it is coasting down. That will tell you what is causing the stall. If there are no CURRENT codes when it stalls, you have lost fuel pressure.

Jim...

Before this current round of issues, I did clear all codes. The resulting codes were TPS related as well as tranny solonoid related codes (sticking), thus randomly not shifting out of second gear after going into limp home mode. And...the old 095 stall code. Thanks for the new concept of checking for codes with cleared OBD history, while coasting or more safely, once coming to a halt. I never thought about fuel pressure being a possibility.

[Ion]

I'd inspect the wire harnesses that you moved while replacing the various components - it is possible some of the wires were damaged.

Have you checked the fuel pressure? A weak fuel pump will cause stalling, lean O2 sensor codes, etc.

I have changed the fuel pump and through the years of dealing with this mess, I have never seen an O2 sensor related error code...ever. Thanks for your input!

[KHE]

I'd inspect the wire harnesses that you moved while replacing the various components - it is possible some of the wires were damaged.

Have you checked the fuel pressure? A weak fuel pump will cause stalling, lean O2 sensor codes, etc.

I have changed the fuel pump and through the years of dealing with this mess, I have never seen an O2 sensor related error code...ever. Thanks for your input!

Did you install the new generation pump with the modifications to the wiring? There were issues with the harnesses both inside the tank and just outside the tank.

[airmike]

Rereading the original post, I am wondering if the tach went to zero before the engine stalled or if it died and then the tach went to zero. I had a wire get broken that goes to the coil pack, causing the engine to die. Mine was caused from a broken engine mount that allowed the engine to move to the point of breaking the wire. The tach would sometimes stay on zero or maybe 2-300 rpm, then rev up again and repeat. In any case I am suggesting checking the wires going into the coil pack. I think you should be able to tell the difference in the fuel shutting off and a wire causing the engine to die. A fuel problem may not be instantaneous, like turning the key off.

[Ion]

I'd inspect the wire harnesses that you moved while replacing the various components - it is possible some of the wires were damaged.

Have you checked the fuel pressure? A weak fuel pump will cause stalling, lean O2 sensor codes, etc.

I have changed the fuel pump and through the years of dealing with this mess, I have never seen an O2 sensor related error code...ever. Thanks for your input!

Did you install the new generation pump with the modifications to the wiring? There were issues with the harnesses both inside the tank and just outside the tank.

Wow...I really don't know. I installed the new one a few years back. Do you have any way to identify the bad (or good) ones? I keep every invoice and can reference any serial numbers necessary.

[Ion]

Rereading the original post, I am wondering if the tach went to zero before the engine stalled or if it died and then the tach went to zero. I had a wire get broken that goes to the coil pack, causing the engine to die. Mine was caused from a broken engine mount that allowed the engine to move to the point of breaking the wire. The tach would sometimes stay on zero or maybe 2-300 rpm, then rev up again and repeat. In any case I am suggesting checking the wires going into the coil pack. I think you should be able to tell the difference in the fuel shutting off and a wire causing the engine to die. A fuel problem may not be instantaneous, like turning the key off.

Interesting! Among the numerous repairs I've made to this old Caddy, replacing a copilpack was one of them. BTW...all mounts are solid. Re: symptoms of the shut down....it's really hard to distinguish when in a multi-hour roadtrip zone, buzzing on a 5 hour energy drink, on cruise control, on a dark desert highway, with the stereo on and suddenly you notice you have no accelleration. But...your description of tach going to 0, then bumping back up, then going back to 0, sounds familiar. Almost like it was trying to hang on, but ultimately died. ANother thing that might be relevant. After sitting in the garage for, say, a week, then needing to move it out of the way for whatever reason, it has great difficulty starting...even after priming the pump before turning the key all the way. Maybe we're onto something? Bad pump or coilpack connection?

[KHE]

I'd inspect the wire harnesses that you moved while replacing the various components - it is possible some of the wires were damaged.

Have you checked the fuel pressure? A weak fuel pump will cause stalling, lean O2 sensor codes, etc.

I have changed the fuel pump and through the years of dealing with this mess, I have never seen an O2 sensor related error code...ever. Thanks for your input!

Did you install the new generation pump with the modifications to the wiring? There were issues with the harnesses both inside the tank and just outside the tank.

Wow...I really don't know. I installed the new one a few years back. Do you have any way to identify the bad (or good) ones? I keep every invoice and can reference any serial numbers necessary.

The '94 uses a different pump than the later years - the pump can be replaced independent of the sending unit so my question on the latest design pump doesn't apply to your car - sorry about that,