Low Idle

[318hoe]

Hey all
So this may be something quite simple, but I do not know an answer lol
Lately I've noticed my 05 Tahoe will idle a little low. It usually would idle around 500-750 but lately when it's warmed up it'll stay around 200 or lower. Today I looked down and it was on 0, but the car was still running. I read it could probably be the MAF sensor, but I cleaned that not too long ago.
Any ideas?

 

[Chris2144]

Anywhere under about 400 it will start stumbling pretty bad since you say it was at 0 but still running I would imagine you're tachometer in the cluster is not working correctly

 

[OR VietVet]

Agreed. Pretty hard for the engine to be running when reading "0" at the tach. Plus you did not say that it idled rough or stumbled, so I would guess the tach or signal input source is the culprit. Did you look for any TSB's about this?

 

[SnowDrifter]

Is your idle truly low or is your gauge mis-reporting? Two very different diagnostics depending on what your issue is.

 

[Danny3737]

I had the same issue a year or so ago, turned out to be bad gas.

 

[Rocket Man]

Yeah I don’t think it would be running normally at 200, definitely not at 0. These clusters are known to have issues.

 

[318hoe]

I don't think the culprit is bad gas, I will say.

Also: It'll start running a little rough when it starts reporting being low, but I don't doubt the cluster could be bad. The PRND321 screen doesn't work on it, maybe that's a sign of something? I'm not much into repair stuff so I figured I'd ask y'all on here before I dug into looking deeper.

 

[318hoe]

Also, I took this yesterday morning while I was waiting to go into my classes. The tahoe was still running, although it was a bit "jumpy". The engine code that pops up is gas cap one, but eh it isn't worth it to me to dig into fixing the solenoid that's actually messed up.

 

[OR VietVet]

I am just guessing but you might have an evap problem and gas tank is not venting properly and the system is not allowing enough fuel to the engine and the idle drops. Or, you have two problems with a cluster causing probs. Or, I am pissing up a rope and it is totally something else. I would be interested in seeing fuel pressure when the problem occurs.

 

[HiHoeSilver]

A. Idle should be 600.

B. Use the scanner to see the actual idle rpm and compare to the gauge. This can easily rule out the cluster.

C. PRNDL not working is a common problem fixed with a solder reflow of the chip in the cluster.

D. EVAP code is common, and there are multiples that can help point at which solenoid to start with. They cost $20 and are changed in 15 minutes.