So after filling up today, I was in the car wash when the vehicle starting idling really rough, as if it was going to stall. I revved the engine a bit but it was still suddenly running rough. I made it out of the car wash but then drove around the parking lot a bit to see if the problem would correct itself.

If I feather the gas the vehicle will go but if I step on it a bit there is a complete hesitation and a bit of a lurch and engine sounds quite rough. So I managed to limp back home by luckily hitting the lights ok and not having to come to a stop.

I seem to recall an issue like this way back when I had a Jeep - it turned out to be a clogged fuel filter. I hope that is all it is this time around as well, as opposed to a toasted fuel pump. I keep the vehicle between 1/2 and full at all times to avoid stressing the fuel pump.

Is there a test I could perform myself to confirm this as the problem (remember I have two left hands mechanically) or is the best bet just to limp down to the mechanic. I had Allen Nelson install one of those fancy gauges that reads out about 32 things (horsepower, air intake temp, mpg, etc) when he checked the vehicle out for me back in San Antonio before it was shipped to Canada - would any of the readings on there give me a clue?

And just for clarity, this problem is on the procharged Escalade (tune by Allen Nelson), not the maggied Denali. Not sure that matters as fuel system for both likely the same but just wanted to be more specific.

The fancy gauge with all the readings (trim, oil pressure, etc) is an AEROForce.

I also have an Air/Fuel ratio gauge and a boost gauge. Are there certain numbers at certain RPMs that I should be looking for? At idle, the ratio is around 15 or so.

Additionally, if I call up Onstar, will their diagnostic be any help?

Thanks in advance for your help.

D

 

any codes?

 

Can I get those from Onstar? Or any of my gauges? Or do I need a scan tool? I will go try Onstar right now.

 

Onstar ran their diagnostic and got back an error message saying there is a problem with the air intake system. No reported codes.

And the check engine light is on as well

I wonder is some water got into the engine area at the damn carwash. The air intake on a procharger is right up near the top of the hood near the windshield.....hmmmn.

Not good if I sucked in some water.....scanning memory to try and recall if that is the first time I have been in an automatic carwash with the Sclade. ..... So frustrating.

 

Your Aeroforce gauge can pull the code I think. You hit both buttons and go through the menu. I'm not exactly sure, I've never tried.
Have you popped the hood to make sure the MAF was not blown off the intake tube or something? I had this happen and it ran just like you said, with a code. I put the intake tube back on and it was fine. Maybe you'll get lucky and it is easy.

 

Just went out and recorded the readings from the AEROForce and the Air/Fuel while the vehicle was idling. Not sure if this info helps or not:

So at idle, 590 rpm, I get the following readings from the Aeroforce:

• MAF LB/M 0.85-0.89
• MAF Frequency 2750-2800
• Manifold psi -8.6
• Throttle % 8
• Ignition advance 22-24
• Short trim b1 0.7 – 2.3 – 0 all over the place
• Short trim b2 0.7 – 2.3 – 0 all over the place
• Long trim b1 8.5
• Long trim b2 9.3
• IAC position 310
• Pulse width 2.3 -2.5
• Engine load 2
• Oil Pressure 32
• Intake air 123 degrees F
• Coolant 197 degrees F
• Transmission 143 degrees F


From the Air/fuel ratio 14.6 – 15.2

 

Well, the AFR looks fine. Idle seems low (Stock cam?)
Were you sitting still when it started to act up? Under a waterfall?

 

Am I giving away too much to tell you I don't know what the MAF looks like? Should be between the Filter and the Procharger right?

 

Yes - sitting still in one of those carwashes where the machine moves all around your vehicle. So basically under a waterfall yes.

And yes, stock cam, I think (I have not done anything but this thing was owned by the son of the owner of the SA Spurs so God only know what he had done to it).

 

Well, since you were sitting still I doubt it is the MAF, but go check anyway
Right after the air filter there is a round hard plastic part with a wiring harness coming out of it. It will be after the filter but before the throttle body



http://images.sporttruck.com/techart...maf_sensor.jpg