'03 Yukon loud at ignition - poss. causes?

[drno4]

2003 Yukon Denali XL 188k.

Last couple of months immediately at startup, the engine BA-ROOMS when it turns over and then settles back down normally for the rest of the trip. Doesn't usually occur unless the car has been parked for a day or two and then started up again.

No codes. No other obvious issues. Help me out.

Bad ignition coils? Injectors leaking fuel while parked and causing too much combustion? Bad sparks or wires? Something else??

TIA!

 

[rockola1971]

Not sure what "Ba-roooms" even means. Are trying to say that the engine is running at a higher rpm than idle when you first start engine?

 

[drno4]

Not sure what "Ba-roooms" even means. Are trying to say that the engine is running at a higher rpm than idle when you first start engine?

Oh, that's not a technical term?

For about one second, it sounds as if I had the pedal all the way to the floor; the throttle fully open. And then it settles into a normal rpm, yes.

Have owned this one for 13 years (110k miles) and never had this issue previously.

 

[SnowDrifter]

If you could nab a video and chuck it on youtube or something, that would be super helpful

 

[rockola1971]

Watch your tach. Is the RPM actually climbing higher than idle or are you just hearing your fan which could be making it sound louder than the engine is actually revving?

 

[DirtDigler]

Mine does the same. Pretty sure it's just the fan on top of the cold idle

 

[MassHoe04]

Is the situation where your engine is racing for that second or two, then settles to normal idle?

One scenario that you would expect brief period of higher RPMS on start-up is when it is cold.
The computer has the engine run higher RPMs until the temp starts to come up, then RPMS begin to drop down to normal idle.
That process is mainly controlled by readings from the temperature sensor.

Since most of the US is not cold right now...
Maybe temperature sensor is telling the computer it is really cold (or nothing at all), then figures out it is not that cold or suddenly starts working.
Possible short of failing sensor could give bad readings.
Check wires and connections to the sensor to be sure there is nothing damaged or broken.

Then, get the scanner out and check live data.
See what the engine temp. sensor is reading before starting, while running and after it should be up to operating temperature.
If the engine is cool, initial temps should be kind of close to ambient air temperature (unless sitting in the sun).
Then readings should be about 210 (+/- few in either direction) after warmup.

Does it read at all and is it reading accurately?

Verifying temps is easy and costs nothing. I would want to rule that out before diving in too deep.

 

[S33k3r]

If you did have an injector leaking causing this, I would expect some unburned gas to be coming out the tail pipe as well. Do you have a liquid spot when you first start up? Is there a smell of gas?

 

[Melram]

If you did have an injector leaking causing this, I would expect some unburned gas to be coming out the tail pipe as well. Do you have a liquid spot when you first start up? Is there a smell of gas?

Hi I’m new here. I have a 2003 GMC Yukon XL Denali that starts like this in the morning and sometimes in the over 90 degree weather we are having in Cali. I do have some water or something that comes out of my tail pipe and a bad smell of gas or something. It doesn’t blow out any bad smoke just nasty smell and I don’t think that it is a gas smell, but I could be wrong. When I start it it sounds like I had my foot on the gas pedal but I don’t. The RPM’s do start high and immediately go back down. It’s driving me crazy.

 

[S33k3r]

This is my opinion, but it sounds like you are having a catalytic converter issue.