It's Gone Flat

[brienkd]

I have a 02 GMC Savana 5.7 That is all of a sudden gome flat. I mean that there is no power like there is no ignition advance.

I bought the truck used with 65k. I have had problems with it since the day I bought it. I have been to the dealer more times than I can count and get one lame excuse after another. Now my warranty has run out and my transmission quit. One of the things that I had it to the dealer for was poor/soft shifting. Of course the S*/m service writer looked at me like I had three eyes in my head and tried to pretend that he had no idea as to what I was talking about.

Anyway back to the trans. Since it was out of warranty by 500 miles I had to change the trans myself. I picked up a junkyard trans changed the pan gasket and filter flushed the cooler and lines and threw in the "new" trans.

I tell you I had been suspicious of the trans right from the begining but WOW I thought that I had a new truck. Not that I want to roast the rubber off of my $200 tires but I sure could if I wanted to. I thought that I had cured my problems. My gas milage went from 8 to 11. I was dooing the happy dance until Friday when it all went south. Here we are back to the same lame dog that I have been fighting with. I knew as soon as I started it that morning that my gremlins had found their way back into the brain of my truck. You know when you turn the key it begrudgingly sputters to life. For a whole 2 weeks she started and ran like a real truck.

[brienkd]

What should I be checking? Where should I start?

[Stevens03]

PCM

[brienkd]

ok how?

[Silverado_Monkey]

Is it throwing any codes? Do you have access to a code reader?

 

I bought a cheap ebay Bluetooth ODBII scan connector and use free Android software (Torque in the android matket) on my cellphone to monitor PCM system stats, and read/clear any visible codes.

 

Since you were able to install your own tranny, I'm guess you've checked all the easy stuff right? Spark plugs, Wires, Coil packs, Gas filter change, etc, etc... Any chance the thing just needs a good tune-up?

 

Good luck!

B

[brienkd]

No codes. It would be nice though it would give me somewhere to start.

When I first put it back together I checked the cap and rotor. They look good with no pitting or corosion. I did notice that when the dealer changed my leaking manifold gaskets they did not put a new gasket under the distributor and it was loose. So I installed a new gasket and made sure that the distributor doesn't wiggle around.

I also noticed that they let one of the spark plug wires lay on the manifold, sure way to create a misfire, so when I got it running I checked, in the dark, that there was no arcing from that wire or any others.

This is a 350 vortec, just 1 coil and it seems to throw a good spark.

Have not changed the fuel filter yet.

Looking at the scan tool .net software for my laptop. I'm self employed and money is very tight. I have to wait to get anything until I get my next progress check.

 

The thing is it ran well for almost 2 weeks.

 

So in the interim what sensors should I be checking and what values are acceptable for said sensor.

[Debo511]

Check the fuel filter, have seen similar low power complaints caused by plugged filters .

[Stevens03]

Check the fuel filter, have seen similar low power complaints caused by plugged filters .

 

And clogged cats.

 

But with that said, You changed the transmission and it ran like a champ. I'd assumed you had the battery disconnected while working on the truck allowing the PCM to reset. If thats the case and the truck ran great for a while, then went back to poo, then the computers not adaptive learning very well and why I'd think it could be a faulty computer. Try disconnecting the neg side of the battery for 10 minutes, see if the truck runs any better once reconnected.

[brienkd]

Yes it does. Just an FYI the key needs to be in the acc position to disable the security function.

[Silverado_Monkey]

Yes it does. Just an FYI the key needs to be in the acc position to disable the security function.

 

Might be a good time to get a new PCM from Justin and Blackbear tune! ;)

 

If you really want to "wake up your truck"!

 

Good luck! Glad to see you're making some headway!

 

[brienkd]

I would really like to know that it is not a sensor acting goofy before I invest in a new PCM.

Any Ideas on what I should be checking and what the values are?

It only has 91k and I really need another 110k out of it.

[brienkd]

No professionals are willing to weigh in on this?

[[email protected]]

Have you even checked you fuel pressure yet?

[brienkd]

I just bought a Palmer performance ScanXL Pro scanner.

 

So in the interim what sensors should I be checking and what values are acceptable for said sensor.

 

It doesn't apperar that the ecu supports fuel rail pressure monitoring.

[brienkd]

What should I be scanning?