My truck needs more help from AT

[Sluggo]

Using the ZV form:

About the vehicle:
- Year 1999
- Make chevrolet
- Model Silverado
- Engine 5.3
- Mileage 220,000

About the issue:
- Started long ago, gradually worsened in the past 2 months
- When engine is under load and at low RPM
- Only noises and smells are from driver
- No CEL so far.


My truck seems to surge/buck when the motor gets under load and its at low RPM, it almost feels as though its running out of gas. I really dont suspect a fuel issue in that in the past 6 months it has had a new fuel pump, fuel filter TPS sensor and Fuel pressure regulator. The TPS and regulator are stuff that I had suspected were causing this problem and they were relatively cheap and easy to replace.

The truck really doesnt seem to have problems until it reaches operating temps, and the problem seems more pronounced when it is warm outside. I say this beacuse the today and a couple of days ago it was much cooler (50-60 degrees) and the truck did much better. In the past couple of weeks in has been as high as 80 degrees, and the truck really ran badly on those days.

Any thing that comes to mind that would relate to air density?

 

[Black88GTA]

Mass Air Flow (MAF) sensor? (not sure if your truck has this, but the symptoms sound about right). Or, possibly leaky EGR valve? Leaking vacuum line / hose?

 

[JeffreyLebowski]

replace the thermostat. If it is running like crap when it warms up, you may have a temperature problem, and if you say you're getting a smell, it's probably that. Also, change the temp sensor.

 

[radioouman]

Originally posted by: JeffreyLebowski
replace the thermostat. If it is running like crap when it warms up, you may have a temperature problem, and if you say you're getting a smell, it's probably that. Also, change the temp sensor.

He can look at the temp gauge to make sure that it is at the right temperature. No need to change the thermostat.

I agree that it could be a temp sensor though. I believe that the 5.3 has a MAF (mass air flow) sensor, and that could be causing the problem.

You might want to have the codes scanned... that's a good place to start.