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**IH8EVRY1** · 10-21-2010, 07:37 PM

1997 Silverado Z71 5.7 Vortec

So my truck has been doing this thing where it sputters at lower rpms. It idles fine but occasionally it does this. Normally I've just put the truck in gear and I'm moving at parking lot speeds. Tonight I got back to work and was sitting in the truck idling waiting on everyone else to catch up and it sputtered hard and the SES light came on. I shut it down and checked for anything obvious. I'd checked for lose cables and plugs a few weeks ago. I didn't find anything and thought it may have been bad fuel or something. I scanned it and got P0107, P0122, P1107 and P1122...I'm thinking it's time for a TPS? Any opinions?

Additional info...it didn't matter which direction of travel for the original sputter...it did it in drive or reverse.

Also, the trucks shifting pretty hard right now.

**IH8EVRY1** · 10-21-2010, 07:50 PM

just for troubleshooting purposes, with the truck idling I went and pulled the TPS sensor...nothing different happened. I don't know if that means anything or not...any advice is appreciated.

**Oldgoatherder** · 10-21-2010, 08:39 PM

I have a friend that has that engine, it has a problem with intake manifold gaskets becoming distorted. That creates a vacuum leak which would have many of the symptoms that you have described, including the harsh shifting.
The intake and heads are different from the older small block Chevy and have a long unsupported space between the front intake ports and the back. Several gasket manufactures make gaskets that have been reinforced to fix that problem.

In his truck he was sucking oil, using up a quart every 1000 miles, he pulled and rebuilt the engine, at a couple of hundred thousand miles, it had no wear, just that gasket letting oil into the intake ports. He did a very minor rebuild, just honed the cylinders and put new bearings and rings in. And of course got the new gasket, had to buy it separate from the kit.

**IH8EVRY1** · 10-23-2010, 05:26 AM

So I got a great idea and put a programmer on it again but did real time view data logging so I could see some values. TPS read 0.0%...off...at idle...with a little throttle, with a lot of throttle. I changed the TPS and everything is back to normal.

FWIW if anyone didn't know(I didn't before last night) and finds this in a search, the TPS had a female connection in the sensor that "mates" with a male "shaft" on the TB. That female connector turns but should return to its starting location. If you turn the connector with your finger and it doesn't have resistance or return to the starting spot...get a new TPS.