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computer problems? 94 olds 88


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01-30-03, 05:53 PM   #1  
bluetick82
computer problems? 94 olds 88

I have a 94 olds 88 royale, 3.8L AT. I have been having problems with what appears that the car is missing while idling and driving. It appears more when accelerating or under load like up hills. If I stopped the car and shut it down for a minute and restarted the check engine light would come on and the car would run better but not great. I had the codes read and they indicated that there were problems with the cam, and crank sensors. I have replaced both of them, all spark plugs, ohm'd out the plug wires, they were good, tried different coil packs, and swapped out the C3I module. After all that the car was still having the same problems. I replaced the computer (PCM) and the car ran great for about a month after. I started the car at a gas station on day and it seemed to have a hard time starting, after that the same symptoms appeared. I have not had the codes read agian but suspect they will be the same. Could the PROM be bad causing the computer to go bad after a while? I have looked at the wiring at the plugs of the different sensors on the engine and at the wiring harness and have not seen any bare wires or chaffing. I would appreciate any help or ideas anyone has.

 
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01-30-03, 07:33 PM   #2  
usually the prom does not go bad, and i doubt that would be the problem, perhaps a new problem has developed check the codes and maybe post back here and im sure you will get some more things to check, did you just fill up with gas when the car was hard to start if so maybe you should take a fuel sample in a glass container and let set a few minutes to see if it separates you may of just gotten some bad gas when filling up, also is the check engine light coming on now?

 
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01-31-03, 12:22 AM   #3  
I know you ohmed out the wires but they could still be breaking down under load and heat. The boots could allow arcing or they could be crossfiring,etc. Have they ever been replaced? If you do replace them use a good quality wire like the ones from NAPA or GM/AC Delco...there is some real poor cheap junk floating around now for parts. How's that fuel pressure?

 
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01-31-03, 06:10 AM   #4  
Joe_F
Could be a wasted Mass Air Flow sensor among many other things mentioned here by others.

Start with my posts and links below.

 
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02-05-03, 01:05 PM   #5  
bluetick82
The plug wires have been replaced with good 8MM wires, and I do not see any signs of arcing on the plugs, wires, or at the coil packs. I have not tried replacing the mass air flow sensor yet. I did read the codes and the car ran good for about 40 minutes after we reset the codes then it was back to the old symptoms. The codes that came up were 321 and 361. The information that came up on the scanner for 321 was "no 18x ignition pulses - below 1200 rpm and PCM detects 150 fuel control reference pulses and no spark reference pulses to control ignition timing."
361 said "EST line not toggling." We also noticed a cam/crank error 1 while we were monitoring to car with the scan tool while the car was running. I have not been able to find anything about the EST line in my Chilton, I am guessing that EST stands for Electronic Spark Timing, is this correct? Again I appreciate any help or suggestions, this is getting somewhat frustrating.

 
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02-06-03, 07:50 AM   #6  
I'm a little confused with the error codes that come up and maybe someone can explain them to me also. I didnt think there were any 3 digit error codes on a 94 model GM. Are these maybe supposed to be 32 and 36 or does this scanner have some sort of code conversion book? Regards-The striving to learn one

 
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02-06-03, 02:38 PM   #7  
Partially answered my own questions! Well, I did a little more research and this is what Chilton's says. Another book doesnt list the P0361 but lists the P0321 like you have posted(no 18x CKP pulses). Maybe there is something in the ignition that is taking out the computer? I'm sure you'll get some more posts on this one and I will look around for some more info.


Result for code: P0321

Manufacturer Description
SAE Standard Ignition/Distributor Engine Speed Input Circuit Range/Performance



Result for code: P0361

Manufacturer Description
SAE Standard Ignition Coil "K" Primary/Secondary Circuit Malfunction
Probable Cause=Wiring, Ignition Coil

Edit...I found a P1361 in diagnostics that refers us back to the diagnostic chart for P0321. On this chart it refers to having wiring problems, bad ICM, bad PCM. If you want a copy of the diagnostic flow chart Email me. Click on my Profile button and select Email.

 
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02-06-03, 06:18 PM   #8  
Joe_F
I agree with Stevo. Have you tried to test the crankshaft position sensor?

 
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02-16-03, 08:10 PM   #9  
bluetick82
I checked out the crankshaft position sensor, it appeared good but I went ahead and replaced it since I had the balancer off anyway. It appears that I am getting the signals that I am supposed to. The schematics in the chilton book shows the EST line which I believe is the ignition control line in the newer system was measuring 2.2v with the engine running. Other voltages I read while the engine was running ( Idle or increased rpm read the same) were 4.73v on the bypass line,
2.86v on the spark reference line,
2.36v on the fuel control, this line read 4.74 with the ign on but not running,
3.3v on the crank signal
4.18v on the sync signal.
Do these voltages sound right or are they low?
Also I talked with a shop that said that they had seen problems with the insulation of the wires in the wiring harness between the block at the firewall the sensors at the engine, has anyone heard of this issue? I am not really wanting to tear apart a wiring harness although that sounds like a probable cause for burning up PCM's.

Agian I appreciate any suggestions or advice.

 
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02-16-03, 08:17 PM   #10  
Joe_F
Checked alldata.com to back up what the shop told you?

 
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02-16-03, 09:05 PM   #11  
bluetick82
I browsed the TSB titles and didn't see anything like that, but I have not yet subscribed for full access. I am thinking about subscribing though as there looks to be a lot of good information there.

Thanks.

 
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02-22-03, 09:45 AM   #12  
bluetick82
I will be tearing into the wiring harness this weekend, but I was hoping someone could confirm weather these voltages look ok or not.
The schematics in the chilton book shows the EST line which I believe is the ignition control line in the newer system was measuring 2.2v with the engine running. Other voltages I read while the engine was running ( Idle or increased rpm read the same) were 4.73v on the bypass line,
2.86v on the spark reference line,
2.36v on the fuel control, this line read 4.74 with the ign on but not running,
3.3v on the crank signal
4.18v on the sync signal.
Do these voltages sound right or are they low?

Thanks agian for any help.

 
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02-22-03, 03:59 PM   #13  
Have you tried unplugging the computer and replugging? If you want a diagnostic chart for Code P0321 Email me. My Email is in my profile.

[SIZE=3]Found this within Alldata:[/SIZE]

P0361

Invalid Diagnostic Trouble Code

This vehicle does NOT generate this Trouble Code.

AllData Editor Note: There is one in particular after market Scantool that still has not been updated and generates these and other Invalid DTC codes.

We've talked with numerous AllData users, and they've told us that the work-around is to use the DTC description, and find a code that matches it. A number of our users have used Code P1361 (close match to P361) when the description matches an Ignition Control Problem.

Our suggestion is:

If you have a second Scantool in the shop from a different manufacturer, it will probably read the Datastream correctly and generate a proper code.
If you don't have access to a second Scantool,

Call you Scantool manufacturer and let them advise you on a proper course of action.

CIRCUIT DESCRIPTION(P0321)
The spark reference signal (CKT 647) is used by the PCM to improve ignition timing accuracy during crank and at engine speeds of up to 1200 RPM. The spark reference circuit allows the use of ignition control mode below 400 RPM, eliminating the need to utilize module mode during start-up, and also allows the PCM to calculate true crankshaft position in 1/6 the time that use of the fuel control reference signal would permit.

During normal operation, the PCM uses the spark reference signal to control ignition timing until the engine speed exceeds 1200 RPM, at which time the fuel control reference signal (CKT 430) is used.

DTC PO321 WILL SET WHEN:
The engine is running.
The PCM detects 150 fuel control reference pulses (50 crank revolutions), and no spark reference pulses.
Engine RPM is below 1200.

ACTION TAKEN (PCM will default to):
When conditions for setting DTC P0321 exist, the fuel reference signal is used by the PCM to control ignition timing advance. This condition will cause module mode to be used for ignition timing below 400 RPM and PCM-controlled ignition timing to be degraded below 1200 RPM. DTC P0321 does not illuminate the MIL (Service Engine Soon).

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.


Verifies that CKT 647 is not shorted to ground or open in the ignition jumper harness.
If a window on the harmonic balancer is interfacing with the 18X Hall-effect switch, the ignition control module will ground the spark reference signal. Starter may have to be bumped several times to obtain a voltage reading.
Voltage reading should be lower than that obtained with engine not running indicating a pulsed reference signal.

DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.

Check for:


Backed out connector terminals or broken down insulation in CKT 647.
If connections and harness check OK, try monitoring voltage on CKT 647 with DVM while moving the related wiring harness and connectors with the engine idling. This may help to isolate the location of the malfunction.

 
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02-24-03, 10:10 AM   #14  
bluetick82
Thanks, that is some very useful information. I have tried disconnecting and reconnecting the PCM, I also tried putting the old one back in to see if it would run differently but the symptoms remained the same. I tore the wiring harness apart and inspected the wires, I noticed that the wires were stuck together as if they had gotten hot, but I did not see any breaks in the insulation. I also read all wires with the connectors disconnected for continuity and shorts to each other. All wires read good. I taped up all the wires to further insulate them and was inspecting a suspicious looking spot on the wiring harness to the fuel injectors for 4 and 6. When I got through all the tape I found the signal wire for cyl 4 terminated in the wiring bundle, and the signal wire from the injector for 4 was spliced in with the signal wire for injector 6 which means that 4 and 6 were injecting at the same time. I cut out the splice and metered it and found that the splice was also intermittent. I verified the wires read good all the way back to the computer and wired up the injectors correctly. The car still poorly but not as poorly. I will be installing a new PCM today to see what that does or how long that fix works.

Again thanks for the help and advice.

 
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