Just wanted to give an intro to everyone out there. My name is Ryan, and I live in L.A. I have a 99 Tahoe with a 5.7L, 4x4 and a 3 chamber flow... basically I got nothing. Its saving grace is that it is a 2 door model, and it is lifted 3 inches with 33s. I am brand new to the whole computerized engines thing, as I had a 73 Blazer on 35s w4.11s, 3/4 ton running gears, a bad *** 400 hp 350, a th350, np205, true dual... it was a 4 tire smoker. I miss it, but now I have air conditioning and heat, so that makes it nice. Just wanted to say hello, and make sure it is okay that I pick your brain a few times. I already have a couple of questions for you...
1. My truck has a bit of a rough idle all the time (in gear, neutral, hot, or cold), what in the hell is it?
2. Is a 5.7L considered an LS1? How do I know if I have an LQ4 (or 9)?

So many questions...

 

no not that engine it isnt. you have the vortech engine. rough idle can be contributed to lots of things. how long has it done this. what was the last thing you changed.when was the last tune up

 

It has done this since I got it (labor day wknd). I haven't changed anyhting yet, but I am getting it tuned soon. I believe it was tuned right before I got it, but who knows.

 

I would do a nice tuneup on it .. plugs, wires, cap, rotor, injector cleaner, etc. See how far that gets ya.

The guys over at FSC ( www.fullsizechevy.com ) know a lot about that series engine.

 

Thanks!

 

Welcome. Many of us have some experiance on that engine. It is a L31 vortec. What they said, do the tune up first for sure. Cap, rotor, wires and plugs and fuel filter. Also run a couple bottles of Techron through the tank. Those post-injector poppet valves have a tendancey to stick every so often. That will give you a rough idle every time. Good luck and let us know...

 

Good. I have to ask, because I know nothing of these engines, is it a piece, or is it a decent block, decent heads, and guts?

 

I had a '98 that did'nt see much but WOT and idle and I never had a issue with it. Even after changing the cam. Good solid 350.

 

I had a 97 Z71 and the only problem I ever had in 84k miles is new water pump, intake gasket and a bad sensor that made the service engine soon light come on. By far the best truck i have owned. Great engine and tranny.

 

Welcome to the site. But I would like to clarify something about your engine. In 1999 the LS1 based engine came out in the truck only. It did not come out in the Tahoe until 2000. Your engine is a completly different design than ours. While many guys on this board have experiance with this engine, this site is "dedicated" to the new LS1 based engine. You are more than welcome to ask any question you want here since so many of our members will be able to help. I just wanted to clarify the differance (incase you didn't know) so there would not be confusion on the mods that we talk about here. Simply put, nothing between these 2 styles of engines will interchange. But please stick around, maybe we can talk you into getting a new truck or something.

Welcome to the site!!!