1995 Ciera running bad!!

Hello all, long time reader new member here. Sorry but this is going be a very long read as this is over 3 year on going battle with this car. I’m ready to go at it with my 15# sledge hammer. It is a 1995 Ciera SL with the 3.1 with a little over 139,000 miles on the clock. I’m going to try to be a complete as I can here so bare with me. It may seem irrelevant but it does apply. I currently own 3 of these (all the same color to boot he he). They all started as my mothers cars. The first is a ’94 with just over 300,000 on it. At 190,000 the check engine light came on and stayed on, car still ran great so she drove it. At 214,000 the tranny went. That’s when I got it, replaced the tranny. Wouldn’t pass emissions where I live so I replaced the EGR and O2 sensor but it still failed. So I just registered it to her house and drove it. She replaced it with a ’95 with 52,000 miles on it. At a little over 106,000 it got rear ended in front of her house and the insurance company totaled it. She bought it back from the insurance company and gave it to me for parts. She was then car shopping. I found her the ’95 I am having the problems with.
From day one it had a little stumble once and awhile when cruising and mostly in overdrive. New Delco’s and wires and it went away for the most part. About a year later my nephew could not make the payments on his Alero so she took over payments. She asked me if I wanted to swap the ‘94 one for ’95 and she’d then give that one to him. I did, but I swapped the newer EGR and O2 sensor with the ones out of the smashed one.
I drove this one for about 6 months and it started acting up. The stumble when cruising started happing more often along with the speedo dropping to zero and jumping back up when it would stumble. It would also make the check engine light pop on. This would not be on the next time the car was driven until it stumbled again. I lived with this for awhile until it progressed to jerking and stumbling under a load. This was like some one was turning the fuel pump on and off, no backfires or popping. Then it started stalling, always restarting. These cars are that messed up OBD 1.5 (thanks a lot GM) that the parts stores can’t scan and I couldn’t afford the dealer. In went new Delco’s, plug wires and the coil assembly off the smashed one (that still ran like a top). No change, I should note that this was a come and go problem. It would run good for day’s even weeks sometimes months, then run bad for a day or two then snap back out of it. It then got to stalling a lot and in the huge city traffic it really scary. I hooked up a fuel pressure gauge, 38 PSI. But one time I had it hooked up when it was acting up and as it would stumble the pressure would drop to zero and obviously stall unless I’d tickle the throttle, then sometimes the pressure would jump back up and it wouldn’t kill. But this did not always work. No excess gas in the regulator so in went a new fuel pump and filter, no help. Put the newer EGR and O2 sensor in, no help. After reading on here I cleaned the throttle body and IAC, again no help. Then I took the IAC, TPS, MAF and both coolant sensors off the smashed one and put them on all at one time (should have done them 1 at a time). Bam running like a champ again.
About 6 months down the road it started all over again. This time sometime when it would stall it wouldn’t restart. Sit a few minutes and it would, sometimes running good sometime not. One day it stalled and wouldn’t restart even after sitting. After a day and a half of trying with no luck I got a buddy to help me tow it home and low and behold it fired up and ran fine. Couple days later back to the jerking, stumbling and stalling. I bit the bullet at bought an Actron CP9150 kit with the CP9145 scanner that would read the codes on these cars. I got codes P0321 and P0341. That led me to look at the sensors and wiring. I unplug the pigtail for the 24X crank sensor and it is all oily (we all know these 3.1’s are oil leakers). While cleaning it out when I notice a pinhole in the pick wire (looked like from someone poking it with a tester). So it looks like someone has tried fixing this problem before. It has been there awhile cause the wires inside were turning white. So I clean it up and tape it up good, while doing this I notice that the black wire is bare in a spot really close to where the pinhole was in the pink one. The wires on this one were not corroded. I taped it up fired it up and boom it runs great. Weeks later it is still running great. So I figure the wires were getting oil and or moisture on them and shorting out.
Well a few weeks later same ole same ole all over again. So I cut the pigtail and a good length or wire off the smashed one and spliced it in using heat shrink connectors. Boom all good again, for about week that is. My mother calls and says the original one (’94) is spewing water everywhere and my nephew had abandon it. So I go get it and find the lower intake gasket had blown. So I put the motor out of the smashed one in it and drive it, parking the problemed ’95. After the motor swap the check engine light is still on. A quick scan shows P0321, P0341 and both quad drivers bad. Now at 280,000 miles the light has been on for 90,000 miles. After some reading on here I find there are some fuses behind the glove box. One of them for the 24X and upper cam sensor. I check and yup it is blown, put a new one in and no more check engine light or codes. This tells me that even if there is no power to these 2 sensors the car will still run fine.
Now at just over 300,000 the tranny is whining when cold and the rack is shot. So I pull the ’95 out of storage and it is running worse than ever. Unplugged both the 24X and upper crank sensor and no change. Checked the grounds on the transaxle stud, put the computer out of the smashed one in it and no change. Hook the scanner up and it runs good, take it off it runs bad. Last time I drove it, it was jerking and stumbling really bad and the speedo was back to dropping to zero and back up almost constantly. Every time it stumbled or jerked it did. And even when it wasn’t. I did notice this time every time I hit a good sized bump it would stumble and the speedo would drop. I do know the speedo’s on these are electronic. Maybe I have a short somewhere? But where? I checked the wires for the lower 3X cam sensor and they look good. I’ve swapped the coil assembly with the ’94 and no change. Can someone help me before I lose all my hair from this nightmare old’s? Sorry again for the long read. Douglas

The key here is loosing the speedo, sounds like a bad pcm or connections to it.

Hello Maxwedge thanks for the reply. Sorry it took so long to reply myself but my plate has been pretty full as of late.
The speedo only bounces around ever once and awhile (except the last time I drove it). It runs poorly even when it is not bouncing around.
As I stated I have taken the PCM out of the smashed car and put it in and it made no difference. To be sure though today I took the PCM out and put it in the '94 and it ran just fine with no check engine light or bouncing speedo. I checked over all the wires at the connectors for the PCM and none seemed loose, backed out or broken. One did look squished but I tested it with a digital multimeter with the sound alarm activated. I wiggled it, jiggled it, pushed and pulled on it and never lost sound. I looked over the wires all the way to the firewall and they looked good from the outside :runaround:.
The instument cluster has been out multiple times to change bulbs. So I will pull it out again and check the connections and make sure that they are not spread open to far making a loose connection. But I don't see that being part of the running issue.
I really don't want to take it to a shop and have em say well the computer said it is this sensor and that sensor and want to change em and it not fix it. Alot of shops seem to :jerking: around. The only 2 sensors left for the fault codes it is popping up are not cheap and labor intensive to change.
I read that these cars have a TSB (technical service bulletin) about
repeatedly popping out code P0321. Anyone know anything about this. I have the dealer type service manual and it says nothing about this.
Why does it run OK with the scanner hooked up?
ANY CLUES ANYONE???

You need a full scan to see if the pcm is getting a signal from the speed sensor.

A full scan?? As in dealer wise?? I have one of the few scanners that read these cars as well as almost anything else. It is not a cheapo plug it in and the light flashes. It has the real time, freeze frame and everthing. Just these cars don't support much of that. I've drove it several times with the scanner hooked up and reading all the functions the crappy PCM supports. Has always showed the speed I was going, but never had it hooked up when the speedo was dropping to zero and back up. I had to rob the battery for the '94, but this weekend I'm getting a new battery. So I'll drive it again and if the speedo is dropping again I'll hook the scanner up and see if the reading on it drops too. If the speed sensor was bad would it not throw a code? I could care less about the speedo dropping it is the running issues that bother me. And it runs bad moving or sitting, in park or in drive. Does the speed sensor tell the PCM to change engine functions even when the car is sitting still? I thought it only functioned when the car was moving. Also wouldn't it affect shifting (it is the electronic controled 4 speed) and other things if it was bad? I doubt this has anything to do with it but my dome lights don't work when the front doors are opened (but work for the back doors and with the switch, auto locks don't lock when the brake is applied and put in gear (but they unlock when the car is shut off), and none of the warning chimes work. Thanks for trying to help Maxwedge I need it. I take it your a Mopar (and a 426 Wedge fan)? I sure do miss a few of my Mopars!! '69 Road Runner w/440 4 speed, '69 Charger R/T w/440 auto and my favorite a '68 1/2 Super Bee w/383 (440 cam and upper half) auto. I loved opening up the 4 brl and letting her wind up then pull the switch for the ram air and the feel of another 4 brl opening. Man the cars of them day were so easy to work on. Makes me want to restore my '68 Ambassador SST and the gf's '75 Stang and junk all this computer controled crap. Why the heck when I go to submit my post does it say it can't cause I'm not logged in and on this screen it says I am and in fact I am?? Thats alot of typing to keep redoing over:banghead:.

The car is my former NHRA record holding 426 Ramcharger. 0321 is a code for loss of engine rpm input to the pcm. If the code is not false, the ign control module or wiring to and from it can be at fault. Have you corrected the quad driver issues?

Hello Max, the quad drivers were in the '94. I was using that as a reference to even if the cam sensor and the 24 x crank sensor were dead that the car would still run and drive fine (and the fact that the PCM said the quads were bad too). The fuse behind the glove box was the guilty party there. Replaced the fuse and the 0321, 0341 and the quad drivers codes went away.

Back to the '95 that has the issue. Not the ignition module, it is the third assembly on it, and all 3 work fine on the '94. I've been changing the whole units coils and all. I am leaning twords a bad wire somewhere, but dang there are so many and they go everywhere. I get codes 0321, 0341 and sometimes 0342. Usually P0342 after the car misfires really bad and stalls. I am seriously thinking about pulling the harness from the PCM to the engine compartment out of the smashed '95 and putting in this '95 but my god that looks like a huge mess. I'm not sure I want to go through that kind of hassle. If I knew a dealer would do a good job and find the true sorce of the problem (without replacing this sensor...oops that didn't fix it lets change this one...oops that didn't fix it and so on and so on) and wind up with a car in the same boat and a several hundred dollar bill I would be going to one.

One of these days soon I'll get some time to pull a bunch of stuff off it so I can get to the wires easier and start ripping tape off wires and looking at em close. Or put full coverage on it and clobber the first idiot that cuts me off or whips out in from of me. And where I'm from I could do that 20 times a day. The tranny whine in the '94 is only when it is cold and only for a few seconds at a wack so I've been driving it. The explorer is so bad on gas I want the gf back in the '95 though.

Hello to anyone reading. I put a new battery in Saturday. It fired right up and ran good. So I shut it off and hooked the upper cam sensor back up. The check engine light went off and it still ran good. Back it out of the garage and it stalled. Started right back up and away I went. Did not even get a block and it started missing and the speedo jumping everywhere. I pulled over, shut it off and hooked up the scanner so I could see if the speed reading on it jumpped around too. The car ran fine and no more speedo jump. Drove around the block a few times with no issues. Pulled over, shut it down and pulled the scanner power off. Fired it up and missfire city. Turned off and put power back to the scanner and bang running fine again. Prolly not supposed to do this but took off and running fine speedo working, pull the power plug for the scanner and wham misfires and speedo jumpping plug it back in and it runs fine. Did this several time and the same thing. Scanner on no issues, scanner not on issues. So what gets bypassed when a scanner is hooked up?? Cause this seems to be the circut the issue is in. An no turnning the scanner on and off while driving did no damage to the ecm cause I put it in the '94 afterwards and no issues. ANYONE with a clue??