This has just starte happening recently. Recently, when I'm at a stop light my car randomly does as described in the title. I don't have an SES light in and the car runs just as strong on the road as it ever did. Could it be the alternator? I don' thave time to get things checked out so I'm trying to draw up some hypothesis before I start to get into it.

 

I installed a new battery on my car and the cables came alittle loose, and wasn't getting a good connection. It was doing the same thing your talking about, lights would dim, and engine idled very low. Check your battery first, and if it doesn't solve your problem it's probably you alternator.

 

Could also be a stuck EGR valve. If that thing is stuck closed, it'll cause engine stumbling. That turns your alternator slower and can't provide enough power to lights so they dim a little bit.

 

I'm almost 100% certain that '01+'s don't have egr valves.

 

Only time my idle "hunted" and did that at lights (sometimes even died) was right after my TC install before tuning, never threw a code. I think a bad alt would be dimming/plusing the lights all the time??? Wouldn't hurt to put a digital volt meter on it cold/hot just for the heck of it.

 

I took the car to autozone and they seemed to tell me everything looks good on their machine. And now I'm thinking it might be the TPS. It feels like I have MORE boost lag than I should have. I tap the gas cruisin' at 2000 rpm, just to give it a little gas, and there's a second delay before anything registers on my tach. I think the throttle position isn't responding fast enough. Does that make any rational sense?

 

Now that makes me feel like an old timer!

A faulty TPS would definitely cause your symtom but I figured that would throw a code.

 

That was what I was thinking too. It feels like it's actin' a little weird but nothing's registering in the fault stack. It's only like 30$ so I'm gonna go throw one on and check it out. Hopefully, that works.

 

EDIT: Problem not solved w/ new TPS. Car actually died at idle today. Thought it was MAF fuse again. Still good and no SES light. I'm lost.

 

T T T T

 

Just like 273sunsetZ's problem, I also had a car with a bad battery that gave me fits; low/rough idle. Today's cars are very sensitive to voltage flucuations. You need to make sure you have a sound battery & charging system before trying to diagnose a problem. That being said...

I saw this with my own eyes on a 2001? Denali...
Rough 350-400 rpm idle, no codes. The mechanic cleaned the throttle body throat and plate with some carb cleaner and a toothbrush. It had what I would consider a thin coating of black carbon(?). Ran perfect after that.

I couldn't believe it. But it's cheap and easy to try.

 

Anything's worth a shot. Thanks for your help.

PS. That's a sweet ride you have.

 

How did they "hook" it to their machine? I'm thinking that its a battery connection also. If autozone hooks it up and it looks fine, that probably does not confirm that your battery connections are tight. When they hook their machine up, it could temporarily tighten the connections during the test (just a thought). Also, make sure that your terminals are not corroded.

What kind of test did autozone do?

 

Let's bring it back from the dead. So cleaned the MAF (it was absolutely disgusting. That's probably want happens when you drive for a day or two w/o an air filter) :-x and now I think it's idling a little better. I wouldn't know because while driving back from the shop I boosted and knocked off my piping going into the intake because I forgot to tighten one of my new T-bolt clamps. Wow, a car runs like **** when you do that! haha. I'll take it out for a joy ride later tonight and see what goes down.

 

I had an idle issue recently as well. The car would start, idle like sh*t

I took in to the shop, they cleaned the throttle body and flushed the injectors. The car now runs AWESOME.

 

I should get that done. Allah knows it needs it.

 

Yeah, especially if you arent throwing any codes.....

 

I'm in a similar situation. Got a camshaft installed...tuned...worked fine. A few months later the battery went dead. I replaced the battery and the car wouldn't idle..it would just shut off...unless I had my foot on the gas at every stop. Luckily i have manual. Anyway I drove it about 10 miles and it shut off on me about 4 times that short trip. I parked it for night. The next morning it started fine and idled fine. Very odd. One week later (today), the car started fine, put it in reverse and then the idle goes south and car shuts off. Couldn't start it back up. Gauges dont' move, radio doesn't come on. Windows roll up very slow. Only 2 dash lights come on and I hear dinging. I know there was corrosion around the battery cable so I'm gonna try cleaning that after work. I'll let you know how that goes.

 

well, Let's recap my wonderful day

(be forewarned. This isn't a pleasant post)

1.) Wait at a GM Dealer to get car diagnosed because of the car repeatedly throwing a p0171 Bank 1 lean code (for 4 hours!) only to be told they can't even touch my car because of how modded it is...he even went so far as to ask where my MAF was. Did he even look!!!? It's not like I just completely modded the MAF out. By my superior technical skills (of not even being able to diagnose an SES light), I amazingly removed the MAF and instead put in a really cute pipe that does everything for me. AHH! All I wanted was for them to test my injectors to make sure each of them were operating properly because I don't know how to do that. Sorry, nope. So, I left.

2.) As mentioned in a previous post, I thought it was time to get my fuel injection system clean. I take it to the same shop I always go to and they give me a clean and I take off. Everything seems to be fine. No SES light for now. I get home, put the car in park and the son of a bitch dies. AH!!!

So far, I've inspected for leaks, removed my secondary AIR system/blocked off pipes, cleaned the MAF sensor, cleaned the FI system. It's still actin' up and now I'm at a loss for a place to take it to. :-/ I could use some help from some pretty experienced people. Any suggestions?

 

update from earlier. The SES light is still on. I've searched here and camaroz28. What are some other LS1 forums? I'm running short on ideas and help. Just tryin' to keep this going so people who have this problem later have a thorough answer.