Stumped
#1
Stumped
I'm having a reoccurring problem, alomst seems like some gremlin is ****in with me.
About 2 months ago I was on my way to work, sitting at a light when it started shuddering a bit at idle. CEL light flashed on and off repeatedly, first time I have seen it do that.
I've seen it lit, but never flashing like that.
Lost almost all power, seemed to be in limp mode, so I did just that - Limped home and used my car to go to work.
Was working 14 hr night shifts at the time and really needed the truck, so I changed the rotor & distributor cap, cleared the codes and that seemed to do the trick.
Truck drove fine for about 2 weeks, a couple hundred miles, when the same thing happened, again on my way to work.
So I limped home, took the car, and next day I changed the spark plug wires.
Did the trick again, drove fine for a couple weeks, then it did the same thing.
Changed the plugs this time, again drove fine for a couple hundred miles, now it did it again today.
Codes I am getting:
PO300 - Random multiple misfires
PO740 - TCC circuit malfunction
PO 041,42 & 43 - Misfires in cylinders 1,2 & 3
All three times before, when I changed the rotor, wires and plugs, the codes cleared.
Am baffled as to why the problem is apparently cleared up, then comes back as if nothing had changed.
Haven't routed my wires to TSB specs, am going to try that, though the truck has run fine for 6 years with the wires the way they are.
Am doubting its the plenum.
No oil consumption, and why would changing the wires or plugs make it run fine for 200 miles if it was the plenum ?
I did swap PCM's a few months back, and this little gremlin has started since then, I'm wondering if the gremlin could reside in that box ?
About 2 months ago I was on my way to work, sitting at a light when it started shuddering a bit at idle. CEL light flashed on and off repeatedly, first time I have seen it do that.
I've seen it lit, but never flashing like that.
Lost almost all power, seemed to be in limp mode, so I did just that - Limped home and used my car to go to work.
Was working 14 hr night shifts at the time and really needed the truck, so I changed the rotor & distributor cap, cleared the codes and that seemed to do the trick.
Truck drove fine for about 2 weeks, a couple hundred miles, when the same thing happened, again on my way to work.
So I limped home, took the car, and next day I changed the spark plug wires.
Did the trick again, drove fine for a couple weeks, then it did the same thing.
Changed the plugs this time, again drove fine for a couple hundred miles, now it did it again today.
Codes I am getting:
PO300 - Random multiple misfires
PO740 - TCC circuit malfunction
PO 041,42 & 43 - Misfires in cylinders 1,2 & 3
All three times before, when I changed the rotor, wires and plugs, the codes cleared.
Am baffled as to why the problem is apparently cleared up, then comes back as if nothing had changed.
Haven't routed my wires to TSB specs, am going to try that, though the truck has run fine for 6 years with the wires the way they are.
Am doubting its the plenum.
No oil consumption, and why would changing the wires or plugs make it run fine for 200 miles if it was the plenum ?
I did swap PCM's a few months back, and this little gremlin has started since then, I'm wondering if the gremlin could reside in that box ?
#5
#6
Thats the thing, the changing of parts making it run great for a couple hundred miles seems to rule out something like cracked heads.
But yeah, might well be a combo of things, and I'm due to check compression anyhow.
Not sure about the coil, it cranks and starts great is all I can say.
Idles fine, it just doesn't want to move over 25 mph.
I dunno, like I said, I'm stumped on this one, I don't know where to begin.
Alls I can do is rule out the distributor cap, rotor, wires and plugs.
The old plugs, by the way, which I took out a couple weeks ago looked fine, but I changed them anyhow.
They weren't fouled or stressed at all, probably been in there a couple of years.
But yeah, might well be a combo of things, and I'm due to check compression anyhow.
Not sure about the coil, it cranks and starts great is all I can say.
Idles fine, it just doesn't want to move over 25 mph.
I dunno, like I said, I'm stumped on this one, I don't know where to begin.
Alls I can do is rule out the distributor cap, rotor, wires and plugs.
The old plugs, by the way, which I took out a couple weeks ago looked fine, but I changed them anyhow.
They weren't fouled or stressed at all, probably been in there a couple of years.
#7
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#8
FIRST THING when troubleshooting. FIX ONE THING AT A TIME.
Here are some solutions since I HAD THE SAME THING HAPPEN:
1. Ensure that the wire going from the coil to the distributor is not touching any spark plug wires on its way to the rotor. I ussually set mine in the valley between the head and intake on the left side. That can cause interference sometimes.
2. Ensure all your fiel injector connections from the wiring harness are tight. Ones without the little metal clips might be your problem. If they do not have the clips it will cause a missfire.
you might have a busted coil as well. Replace that as the last effort. ANd keep doing ONE THING at a time until it is solved.
For me it was the INJECTOR CONNECTIONS WITHOUT CLIPS.
It could also be the cam sensor (disc underneath the distributor that has a connection to the wiring harness by the firewall). That controls the fuel injection firing.
--Dan
Here are some solutions since I HAD THE SAME THING HAPPEN:
1. Ensure that the wire going from the coil to the distributor is not touching any spark plug wires on its way to the rotor. I ussually set mine in the valley between the head and intake on the left side. That can cause interference sometimes.
2. Ensure all your fiel injector connections from the wiring harness are tight. Ones without the little metal clips might be your problem. If they do not have the clips it will cause a missfire.
you might have a busted coil as well. Replace that as the last effort. ANd keep doing ONE THING at a time until it is solved.
For me it was the INJECTOR CONNECTIONS WITHOUT CLIPS.
It could also be the cam sensor (disc underneath the distributor that has a connection to the wiring harness by the firewall). That controls the fuel injection firing.
--Dan
#10
Also, the wire going from the coil to the distributor (center wire) could be bad. the MSD wire is a quick fix. But start with the cheapest way then go from there.
ALSO: INSPECT YOUR SPARK PLUG WIRES! if any are cracked, then that will cause a missfire (shuddering) any time the wire touches something metal. I burned a wire because it was laying on my header and I had to zip tie it up to another wire until I got to an auto shop to get a new wire set. I was moving from OK to Calif.
--Dan