My wife drives a 2001 Suburban 1500 2WD 5.3 V8. In the mornings when she goes out and starts it to warm it up she said it starts fine but then will idle down real low like it's going to die and then will idle up real high and settle back out. She said it drives fine but at ed lights or stops signs says it hesitates. It does have a service engine light on. I hooked the scanner to it tonight and it threw the TPS (Throttle Position Sensor) low voltage code, bank 1 sensor 1 code and a random misfire code. Has anyone had the same problems and if so what did you do to fix it? Any advice and help is appreciated!

 

Is it a flex fuel engine? Is the 8th digit of the vin a Z?

 

No it is not flex fuel.

 

The first step should be to replace the TPS and the 02 sensor to see if that improves the problems with the truck.

 

before replacing anything I would consider cleaning the throttle body and plate, a lot of carbon build up will cause inconsistent idle....there is a TSB about it...

 

Here it is...
Bulletin No.: 04-06-04-040
Date: June 14, 2004
TECHNICAL
Subject:
Idle Instability, Low or Rough Idle with Electronic Throttle Control (Clean Throttle Body)
Models:
2002-2003 Cadillac Escalade, Escalade EXT
2000-2003 Chevrolet Silverado, Suburban, Tahoe
2002-2003 Chevrolet Avalanche
2000-2003 GMC Sierra, Yukon, Yukon XL
with 4.8L, 5.3L or 6.0L V8 Engine (VINs V, T, Z, N, U - RPOs LR4, LM7, L59, LQ9, LQ4) and Electronic Throttle Control
Condition
Some owners may comment on an idle instability, low idle speed or rough idle.
Cause
Condition may be caused by deposits in the throttle body bore.
Correction
Clean throttle body bore and throttle valve plate of carbon using a shop rag and an appropriate cleaner. Refer to Engine Controls Repair Procedures - Throttle Body Cleaning Procedure. This procedure may be performed at any mileage necessary. Check to determine if the PCM calibration has been previously updated to one that includes the update for throttle body coking. For 2003 model year vehicles, look in the operating system portion of the calibration. For 2000-2002 model year vehicles, look in the engine portion of the calibration. If not, then update the PCM calibration to the latest calibration.

 

Thanks for the input, i will clean the throttle body this weekend and i picked up a TPS sensor today i will put it on this weekend to. I will let you guys know how it goes!

 

So i cleaned the throttle body and put a new tps sensor on and cleaned the MAF sensor. It is not throwing the tps sensor code and more and the erratic idle going up and down went away. Now it is throwing bank 1 sensor 1 code, and a random misfire code. When i watch the cylinders firing on my scanner cylinder 2,3,4, and 6 have random misfires in them and at idle the truck is shaking a little from the misfires. What should i do next? Should i replace fuel filter and the bank 1 sensor 1 02 sensor and see if that helps? Thanks for any suggestions and info!

 

I replaced the fuel filter and the 02 sensor today and did a fuel pressure check, a vacuum and all came up good according to the Haynes manual. The 02 sensor code is gone and the only code now is random misfire. Any suggestions?

 

Spark plug wires.