1996 k1500 4x4 5.7 automatic misfire mystery

[Randy_H]

I have never posted for help on a forum before........but I am at the end of my rope.

Multiple random misfires on random cylinders under load.

I have installed new:
Cam Position Sensor
Crank Position Sensor
Distributor cap and rotor
Plug wires
Spark Plugs
Catalytic converters
All O2 sensors
Fuel pump and sending unit
Fuel filter
MAF sensor
Air temp sensor

I haven't had the truck long.....not even long enough to get inspection and tags. I drove it for 70 miles Friday afternoon without incident.....later that evening the misfiring started.

No codes. Seems like it is losing current....the reason I say this is because without disconnecting the battery the clock on the radio resets randomly.

PS: no miss at idle no matter what rpm.

Any input would be greatly appreciated.

Thanks,
Randy

[MrShorty]

Seems like it is losing current....the reason I say this is because without disconnecting the battery the clock on the radio resets randomly.

I've had similar problems that I traced to a loose connection at the battery post. Grab a wrench and quickly check to make sure those connections are clean and tight.

[moogvo]

What kind of plugs and wires did you use?

[Randy_H]

I've had similar problems that I traced to a loose connection at the battery post. Grab a wrench and quickly check to make sure those connections are clean and tight.

I will try this in a few.....I didn't even think of that.

- - - Updated - - -

What kind of plugs and wires did you use?

omni pro OE wires (don't know much about them took Oreilly's advice)
acdelco iridium (every chevy I have had spark knocks without ACDelcos)

[Randy_H]

PS: cam retart at 0

just thought I would add that info.

[moogvo]

I don't know anything about omni pro wires other than that I wouldn't use them. you need to use AC Delco wires. If you can't find them, you can use Borg Warner (BWD) wires. I have had good luck with those. Get a good set of wires and go from there. I can't begin to tell you how many times I replaced plug wires with something other than AC Delco or BWD and the problem didn't go away. The guys at Advanced O'Reilly Zone stores don't have a clue! You'd be better off buying the OPPOSITE of what they tell you most of the time!

PS: cam retart at 0

What do you mean by that? Did you adjust the timing? After 1996 you can't adjust timing without a scantool... Just so we are both on the same page... Input from the knock sensor (among other things) tells the ECM how much to advance or retard the timing. Yes, base timing is 0*, but you can't set the base timing with a timing light. you have to use a scan tool.

[Randy_H]

I don't know anything about omni pro wires other than that I wouldn't use them. you need to use AC Delco wires. If you can't find them, you can use Borg Warner (BWD) wires. I have had good luck with those. Get a good set of wires and go from there. I can't begin to tell you how many times I replaced plug wires with something other than AC Delco or BWD and the problem didn't go away. The guys at Advanced O'Reilly Zone stores don't have a clue! You'd be better off buying the OPPOSITE of what they tell you most of the time!

I will pick some up in a few and install them.

What do you mean by that? Did you adjust the timing? After 1996 you can't adjust timing without a scantool... Just so we are both on the same page... Input from the knock sensor (among other things) tells the ECM how much to advance or retard the timing. Yes, base timing is 0*, but you can't set the base timing with a timing light. you have to use a scan tool.

I have a snapon ethos scan tool on it....from what I have read (I am no expert) when you change the distributor these are the steps:
1. cylinder 1 TDC
2. rotor to spark wire 1
3. bring to operating temp
4. bring engine to >1000 rpm
5. read cam retard position and turn cap until within +/-2 degrees of 0

- - - Updated - - -

I pulled both battery terminal wires and wire brushed them.

This in turn reset the PCM, I drove very easy until operating temperature then I did 5-6 crank and turn offs. I received a P0304 code.

I changed the Camshaft Position Sensor reset PCM and still has code.

The miss is not "as" bad as it was however it is still there.....does not show up on the live data scan tool now. And it seems like it does not have all of the power....well I know it doesn't it bogs down during a power brake instead of turning the tires over.

[Randy_H]

I just installed brand new BWD plug wires

I let it idle 5 minutes, then cut it off and cranked it a few times then backed out of the garage and drove to the end of the driveway.....where it started missing and the clock flickered a couple of times and reset to 1:00...then the engine sputtered and cut off.

It started right back up but now it idles horribly and I have a couple of codes.....
P0118 Engine Coolant Temperature Sensor High Input (scan tool reports the engine temp at -40 F)
P0304 Camsahft Position Sensor Problem
P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage


I am headed to pick up a temp sensor now.


- - - Updated - - -

Could it be the PCM?

The PCM in this truck (1996 k1500) has no tags but I have researched out that it should have a PCM with service # 16244210
I have a great running 1997 c3500 with 454 with PCM with service # 16229684

Question is.....can I test with the PCM from the c3500 with 454?

[Randy_H]

Installed new BWD temp sensor....idled OK

Test drive....misses horribly.

P0304 code gone (even after several test drives)

Initially it had these codes:
P0118 Engine Coolant Temperature Sensor High Input (scan tool reports the engine temp at 180 F)
P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

I traced the temp sensor wire and found the PO had either broke the wire or something so he had put in 2 butt connectors....I pulled the pin out of the connector and removed the butt connectors and connected the wire back to the OE connector.

Still has the two codes:
P0118 Engine Coolant Temperature Sensor High Input (scan tool reports the engine temp at 180 F)
P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

I will add that before the temp sensor change the inside gauge showed about 150F and now it shows about 235F

It is back to idling OK but misses during test drive whether it is hard or soft acceleration.

:(

[moogvo]

This is a bit of a head scratcher... Let me think on this one before throwing more parts at it...