Any more opinions/experiences with EcuRepairNow out there?

Thanks,

John

 

One more bump before I commit to anything.

Thanks,

John

 

Sounds like you caps need to be replace in the PCM before any damage is done to the board.
That said I would not get your hopes up to high on it solving the sporadic miss/stumble after warm problems.
Those problems are more associated with the TPS and the IAT & the ECT sensors. Although the fuel pumps can also cause these problems.

Another thought is if your PCM is not causing these problems and if you send it off it can come back with other problems that you do not have now. That is why I change my own caps in my PCM Computers. As long as nothing else is burned up or shorted in the PCM there is a good chance that the caps would be the only thing wrong with the PCM.

 

Thanks very much for the insight. I'm planning on swapping the PCM's today.

So that should give me a better clue of what to do next.

I'll takes pics of both and we'll see what they tell us.

Thanks again for the input.

John

 

Made a little progress today.

Swapped the PCM's, test drove it, and scanned it.

The capacitors on the '94 were worse than I remembered. The '95 looks fine.

The blue capacitors are the '94 also see the dark spot above by the pins:

 

Here's the '95:

 

So I test drove it about 15 miles. The stumble is less but still there. Mostly at light throttle and stopped in drive.

Scanned it three times with Innova 3145:

KOEO: 111

CM: 111

KOER: 311 (air pump is removed, so this makes sense)

One thing that I noticed that may mean nothing or something:

During each KOER test, approximately 1 1/2-2 minutes after the last code flash, the idle would hiccup from 1050 rpm to 900 and then up to 1600 all with in 5 seconds or less. It would take about 10 seconds to return to 1050.

Once I turned off the scanner, the idle would return to about 900-950 rpm.

So I'm thinking it's time to start again with sensor testing and see what I get.

What should I do with the '94 PCM? replace the caps, have it rebuilt, or get another?

Any input is appreciated.

Thanks,

John

 

I would just replace the caps in the 94.
My 93 was a lot worse than that when I replaced the caps and it worked out just fine.

 

So what makes you think there is anything wrong with the PCM? I would start smaller first. Start testing things related idling/warming up. Having a 460 myself, 96, when I had idle issues it was fuel related or vacuum.

I'd go with what Subford said. Replace the cap. It sounds like a firing issue. Make sure your TPS, IAC, and all that other fuel/air related parts are good.

 

Well at this point, after swapping the PCM's and discovering the capacitors degrading, replacing them is a preventative measure.

The fact that swapping the PCM's didn't make for a big improvement, leads me to believe that it's not the PCM. Looks like it's time to retest all the sensors and fuel pressure again.

As I stated earlier, the vacuum lines have all been inspected, tested, and replaced as necessary. I discovered that the heat/AC selector switch was brittle and compromised. Replaced that also.

The truck starts much better/faster now with a lot less cranking than before the vacuum line work.

So I'm going to start fresh with the diagnosing/troubleshooting.

Stay tuned, there will definitely be more questions.

Thanks for all the input so far.

John

 

**Quick Update**

I got a chance to do a little testing today. Concentrated on the EGR, sensor, and solenoid.

All three tested good, but I discovered that I had shot myself in the foot with the vacuum lines.

Both lines leading to the EGR valve and solenoid had fallen onto the EGR pipe and melted. So my new vacuum line work was not "new" anymore.

Replaced both lines and rerouted them away from the pipe.

Took it for a test drive and seemed better, minimal stumble under light throttle. Only stumbled once when stopped in drive.

So I got back to the shop and shut it off for 15-20 minutes.

Restarted it and it had an obvious multiple miss. Popped the hood, looked at the shuddering engine, went back to the tailpipe to hear pronounced misses. Got back in, goosed the gas a little and it cleared up. Total time was 45 seconds or so.

On the way home going up the hill it stumbled again like it always has.

Anybody want to buy a truck?

So next chance I get will be looking at fuel, ECT, MAP, etc., and possible intake leak.

The saga continues.

John

 

Next time it starts missing, start pulling plug wires until you find the cylinder that's misfiring.

 

Well I took your advice and found an old school electronics store still in business that I had forgotten about.

The fella that runs it looked at the capacitors, went into the back room and came out with three new ones.

I asked him if he did repair work, he said he had a guy that worked for him for years but was now retired. But he still does repair work part time.

I asked him for an estimate, he said it could be as much as $25.

I'm OK with that. Soldering and plumbing are two things I don't do well with.

So I'm waiting to get the '94 PCM back. Probably next week.

I did a little more testing.

Fuel pressure KOEO: 40psi-steady

Fuel pressure KOER: 30psi-steady

Both fuel pumps run for a second or two when key turned on.

Both fuel pumps run continuously when grounded at test connector.

TPS connector-key on: 5 volts

TPS-key on: 1.0 volts-idle, 4.6 volts-WOT

I still have to test the ECT and IAT. Hope fully this weekend.

**And just to clarify, the IAT is located on the upper intake manifold under the throttle body?**

I had the same hot restart issue as before. Drove about 60 miles pulling the enclosed trailer, turned it off for about 20 minutes.

Restarted it and it ran really rough, more like fuel starvation than a miss. Shuddering for about 30 seconds, goosed the pedal a couple of times and eventually it smoothed out. Then parked it because I was late for dinner.

Any additional thoughts are appreciated.

Thanks,

John

 

Haven't had time to do anymore work/testing.

But I have another question:

Does the plug wire crossfiring issue apply to the 460 as well?

If so, which ones?

Thanks,

John

 

Anybody?

Thanks,

John