So i have a '91 eldorado with a 4.9 It sounds like its running on 4 cylinders. Barely drivable. any hill, forget about it. It had a slight miss before, but now its bad.

The self diag is spitting out codes E025 - (Ignition Control Module) 24x Reference Low Indicator
What exactly does this mean? Kind of a lame description.

And code E034 - MAP Sensor Signal Out of Range
The hose to it is in good condition, no splits and it fits tight. Any ideas? I'm assuming the map sensor is bad...

Car idles at about 700rpm at 15in/hg and fuel pressure is 39 psi at idle. The lowest i've seen FPress. was 35 (high vacuum - decel) and highest (key on not running) was 42psi.

Any ideas?

TIA
Marv

Replace ignition control module.

yeah, its telling you whats wrong.

So i just changed the coil driver (under dist cap) and the car runs worse... I don't get it. Is this what caddy calls the ignition control module??? Spark was minimal before the change. There was serious carbon on the plugs and little pin sized clean spots on the center electrode (where i assume the tiny spark was jumping from) but the plugs were dry. Now the plugs are soaked with fuel. They are probably fouled. I'm changng those now.

Also i measured the injector ohms for the ones i could get to, so far, 16.7 ohms, 7.5 ohms, 1.4 ohms, and 5.5 ohms. This is the worst variation i have ever seen for injectors. Who makes the injectors? They are supposed to be between 14 and 20 ohms.

The car is backfiring/poping in the intake manifold, so it makes sense that it thinks the MAP is bad. I also tested the map with a handheld vacuum pump and checked it against the map kpa diag mode and it was dead on.

I assume that because of the low ohm injector(s) it fried the injector driver(s) and is causing the rough running condition.

I just cleared codes and tried to start it, it starts fine for .5 seconds then chokes out badly and backfires in the intake. There are no codes in the ecm but the ignition module and the map show up in code history??? How do you clear the history?

Anyone had experience with bad injectors cooking drivers in the ECU?

TIA
marv

I had a similar experience in my 93 Deville (4.9L). Started out as a miss. Eventually, the car died backing out of my driveway (lucky!!!!). Pulled codes and it said it was missing the signal from the Distributor - codes E12, E53 (I love computer diagnostics!). It would happen only if the engine was hot. Troubleshooting a hot engine is real fun.

The part you replaced in the dist cap is the ignition coil. The ignition module is a little flat piece that sits under the rotor. It's real expensive and if your car has as many miles as my 93, it will be real fragile.

To make a long story short, I did a ton of electrical diagnoses with my multimeter and the FSM and I was about to replace the ignition module, when things started to fall apart when I touched them. Then I looked up how much the ignition coil, pickup coil, etc would cost. This is all inside the distributor. Car has a lot of miles on it. Rather than spend another 6 hours troubleshooting or spending hundreds replacing this and that, I called the junk yard and got an entire distributor assembly including cap and harnesses for $75. A complete new assembly costs somewhere between $300 and $400 if you buy it in pieces.

I Marked the rotor position relative to the distributor body and performed a simple swap. Voila! The problem disappeared. The swap took all of about 20 minutes. I shoulda done that to begin with, it would have saved me two or three evenings of screwing around with it.

BTW, your fuel pressure numbers are similar to those in my 93 Deville. It looks like your fuel rail pressures are OK. I would also assume that your MAP is fine. I dunno about your injectors, but I'd quit fooling with them until you get the ignition fixed. Perhaps the injectors are fine.

i had the same issue...and ive heard about this so many times. replace the Ignition Control Module ..that fixed mine. and YES those hills are impossible.lol

Yes, i did replace the ignition module (under the cap & rotor) and every clip i touched fell apart. The car no longer displays the bad ign. module code but now spits a code - something about one of the distributor triggers... I'm gonna take it all apart again...

I just found # 6 fuse underhood (injector fuse) is shot. I'm about to spin the distributor with a drill, and with an oscilloscope check the waveforms for the hall and mag pickups. I'll post my findings shortly.

I'm about to spin the distributor with a drill, and with an oscilloscope check the waveforms for the hall and mag pickups. I'll post my findings shortly.
Man, that sounds like WAAAAAY too much work. If you can isolate the problem to the distributor, why not just get the whole thing from the junkyard?

yeah... pick up a new distrubutor... go to Advance they aren't too bad...

yeah... pick up a new distrubutor... go to Advance they aren't too bad...
Hmmm....last time I priced an entire distributor from Advance Auto (with everything inside it that you need), it cost several hundred dollars.

Should just go to a junkyard and get the whole kitten-kaboodle for less than $100 and they'll pull it for you and even make sure you have enough wire and all the harnessis (if you ask).

So i pulled the distributor, removed the brittle electrical 'protectors,' and made sure the wiring wasn't going anywhere. I connected test leads to the hall and magnetic pickups. Key on, fuel pump fuse out, the distributor and each 'tower' on the cap grounded and all electrical connectors connected up i spun the dist with a drill while i watched the waveforms on an osciloscope. They were very good.
So to make sure the injector drivers were working i used the hall signal as a reference and tested each injector. To my surprise, they were all getting signal from the computer.
I put the distributor back in and it fired right up. The slight miss was still there That its had for a long time. It must have had a short in the distributor with the broken brittle stuff in there.
So i just put a set of injectors in, with 1.5 ohms i cant imagine the injector was opening properly, and the computers days would be numbered if i left them in. I just have to time it and go for a ride.

Yes, i did replace the ignition module (under the cap & rotor) and every clip i touched fell apart. The car no longer displays the bad ign. module code but now spits a code - something about one of the distributor triggers... I'm gonna take it all apart again...

I just found # 6 fuse underhood (injector fuse) is shot. I'm about to spin the distributor with a drill, and with an oscilloscope check the waveforms for the hall and mag pickups. I'll post my findings shortly.

Did you ever solve the problem??