Hi all,
Been trying to figure out what is going on with my 95... been having problems with intermittent chugging up hills and rough running.

a few days ago I finally got the DTCs out of my car:

P0321 - Ignition/Distributor Engine Speed Input Circuit Range/Performance
- Ignition System Problem, 18X Interrupts Lost Signal

P0341 - Camshaft Position Sensor Circuit Range/Performance

P0361 - Ignition Coil K Primary/Secondary Circuit Malfunction
- Ignition System Problem, Electric Spark Timing, EST Not Toggling

P0670 - Glow Plug control circuit error
- Quad Driver Module, QDM 4 Fault

I replaced the center and rear coils on the car and inspected the wiring.
The harness that feeds the oil pressure, crank & cam sensors had the outer protective shielding (the corrugated stuff) melted away but I closely inspected the wires and they were all completely fine (no discoloration, wires were flexible, no indication of damage).
I then inspected the firewall wiring and primary connectors and all looked fine (no corrosion at all)
Finally, I inspected the PCM (under the glove box) ... the blue connector seemed a little looser than the other 2 connectors. I disconnected the battery and removed the PCM (A rebuilt one by the way). Plugged everything back in and drove the car. It ran fine.

I have recently replaced the plugs and wires. the wires were not AC delco ( a mechanic sold them to me)

today I get in to use the car for work (havent been driving it lately) and the CEL was on. the next time I started it the "traction off" and the CEL were on. the next time I started both were off. car was running fine today with no sputtering or chugging.

took the car to autozone and re-read the codes and got the following:

P0670
P0321
P0361
P0670 (yes it came in twice)

I cleared the codes and came directly home to make this post.

the one code that didnt come up again is the cam sensor code (P0341).

Im thinking the cheapo PCM is going bad or maybe the ignition control module is failing.... any ideas? the chugging and sputtering seems to occur when Im driving up a hill after the car has been running for a while.

thanks for any ideas/input.

Jeff

Did you ever replace the front coil, or at least test it? You've replaced the plugs and wires, but this still seems like an ignition problem, or at least partly so.

I think the P0341 - Camshaft Position Sensor code starts out as random occurance, then gets more frequent. Keep an eye out for that one again.

How many miles on the engine? When & why was the PCM replaced?

143K... I didnt know the PCM was replaced. had the car for a year.

I checked the front coil by unplugging the coil wire and got the zap of my life... the coil seemed strong. the rear one had failed so it got replaced, then i bought and put in the center one just for laughs.

I was under the impression that coils just die and dont really give any warning (thats what happened to the rear one).

thanks AA

Jeff

P0321 Spark Reference Circuit - PCM Controlled
P1670 QDM #4 - PCM Controlled
P1350/1351 IC Circuit - PCM Controlled

When you said you disconnected the battery and messed with that plug on the PCM, you reset the codes. They came back......all of these codes are related to PCM circuits. Sounds like that PCM may be the culprit. I don't see how all of those codes could be thrown at once with a simple wiring problem, being that they (components) have nothing in common except the PCM.

The P1351 (P0351) sets when the IC circuit is grounded at startup (through the PCM)

P0321 sets when the PCM detects 50 crank revolutions and no spark reference pulses. (during startup only, spark reference is used to improve ignition timing up to 1200rpm's)

P1670 (P0670). In this case, the PCM controls the A/C Relay, Low Speed Fan Relay, High Speed Fan Relay, and the Series/Parallel Cooling Fan Relay (hence QUAD Driver Circuit). This QDM supplies the ground for all of these through the PCM.

In a nutshell, all of these are controlled/commanded by the PCM. It's possible that a ground driver within the PCM has taken a dump. Make sure and check that the PCM case has a good ground.

Hope it helps......

thanks abaddon

The PCM was in a plastic clip holder and not screwed into any gound. I didnt see a ground wire coming off of it ( I was looking for it from my readings here).

Is the PCM ground cable under the dash in that general area?

thanks

Jeff,

Coils don't just die. I am still running all three OEM coils at 205k miles, and I plan to run them for another 100k.

They die for a very specific reason: unmaintained plugs and wires. I bet the old ones were trashed. If the other two packs went bad, something caused that. There is good reason to properly test or replace the front coil pack. It may have shocked you, but this is a very high energy coil that puts out much hotter spark under load. You can't assume the coil will perform under boost, when there is more demand.

I wouldn't replace it just yet, but if you troubleshoot the PCM, wiring, and Cam Position Sensor with no luck, maybe try replacing the coil.

OK will do.

so I should not bother with the ignition control module and concentrate more on the PCM at this point?

do i find the test terminal online somewhere?

just got done reading the series II post about camshaft sensors (my eyes are bleeding!). Looks like there are quite a few failures of the wires between the ICM > CPS... ICM > firewall plug... firewall plug > PCM.

As far as testing the plugs... is it OK to use a carefully inserted paperclip to make contact in the plug or maybe insert a lead in the backside (where the wires are) of the plug?

The schematic and/or terminal layout would be a good help...Im not sure if the ones on the series II thread are correct for my 95.

thanks eldo

jeff

Here is the schematic for P0321



The schematic for P1670



The schematic for P1350/1351



On the top schematic (P0321), the wire you want to pay most attention to is the SPARK REFERENCE (647 LT BLU/BLACK). That's the wire that "sets" P0321.

On the center schematic (P1670), I'd start by checking the fuses. Actually, I'd probably save that one for last if needed......

On the lowest schematic (P1350/1351), you need to check the BYPASS (424 TAN/BLACK) wire between the PCM and the IC. Also check the IGNITION CONTROL (423 WHT) circuit.

I would check all of those wires for shorts to ground (you should have no continuity between any of those wires and ground), and also resistance (PCM to component). I did notice 1 other thing that these codes have in common besides the PCM and ICM.....The 8-WAY IGNITION JUMPER HARNESS CONNECTOR houses all the wires from the top and bottom schematics, although it is not shown in the bottom schematic?!

Hope it helps.....I also have flow charts if you need......

abaddon... you are da MAN! thanks!

I was digging under the hood today checking wires:

the wires leading from the ICM (along the front of the engine) are fully exposed! the plastic corrugated conduit is completely gone. There is oil all over the wires and I had a water leak there last year from the "S" hose that goes into the water pump.

I couldnt get the wires out without some dissassembly of the ICM mount but Im tearing into it soon. the wires i did see looked intact.

And of course I drive the car today... get about 2 miles down the road... it starts to sputter and stalls out. It started right back up and I limped it home. will pull the codes ASAP.

thanks again

Jeff

Np man. Now that I look at it again, you can test all the wires you need from that 8-way connector at the ICM (to the PCM). A, B, and C are it.

Now that you mention the harness was rubbed through, oil on them, and had a coolant leak there, I wouldn't be surprised if those wires are corroded/broken. Even if the insulation is still there, the smallest hole or cut can cause the internal copper to corrode. I've chased down quite a few bad wires where everything looked "good", only to find the copper broken inside.....