Stephen Bannworth

So I have driven close to 200 miles and the truck seems to be driving well. Sometimes when accelerating I hear a rattling sound coming from the engine. Sounds like a diesel engine for a few seconds, I lose some power and then it goes away, but if I stomp on the gas it definitely comes back. Not sure what that is. If anyone has any thoughts its the 5.7 engine.

in2pro

That sounds like spark knock, you probably need to check your timing advance, if you have a turner chip installed, you may need to step up the octane that you are using, i'd try mid-grade first then premium... but check the timing first...

Stephen Bannworth

I just want to punch this truck in the face. So after about 400 miles the kicking and no over drive has returned. I went and replaced the new TPS with a replacement and it is still kicking on me. Sometimes the overdrive stays and sometimes it goes. Is there a computer on this truck that I can replace or something maybe that is spitting out some kind of stupid signal. I disconnected the battery and the kicking stops but after about 15 minutes it will return and that is with the new sensor.

The TSS I haven't replaced but when I checked it there was fluid inside the wire connection housing, not sure what kind of fluid it didn't have a smell.

kevinkpk

Harley ever is it the ecu, but in your case I'd say so. Reason I say that is I had issue with my lumina with crank sensor reference. I replaced the ecu, then I had maf reference error, it wouldn't go away even with replacing it twice. The other issue was it wouldn't read the injector pulse at times (this was after I replaced the ecu with an autozone recondition), car either would'nt start, start die, or start run. I thought I was back with anti-theft crap. Took it back to autozone, got another one, ALL problems resolved.

Stephen Bannworth

Well in this Suburban the diagram says if it is 4 wheel drive then it should be a Powertrain Control Module, but I cannot seem to locate it for the life of me. I am afraid it is behind the dash or something and that would suck.

kevinkpk

I'd suggest a Haynes (or Chiltons) manual should direct you with this.

Stephen Bannworth

So I went to a different shop and had them test drive/scan the Burb and they came up with a bad input speed sensor. So I replaced that and everything is working again. I will keep everyone updated, and thanks for the help.

kevinkpk

Glad it's fixed, and thanks for the update. What was the sensor?

Stephen Bannworth

I think they said the Input Speed Sensor. For some reason the sensor wasn't sending the speed back to the transmission therefor, the transmission would drop out of Overdrive.

Hopefully this will save someone from rebuilding their trans, when all you need is a stupid sensor.

So far I changed the Throttle Positioning Sensor (TPS), Vehicle Speed Sensor (VSS), and Input Speed Sensor (IPS). The Input Speed Sensor has helped the most. Hope this helps and I will keep everyone updated.