rcacka

I changed the oil, oil filter, air filter, spark plugs and wires on Saturday, and went out Sunday to go to work and the engine was idiling really rough, normal idle is 700 rpm, and it would start up and idle at 1,000 rpm and surge and then it would drop and die.

Prior to changing the plugs and wires and air filter it was running great, just had some extra money and decided that I could change them. Do not know what the problem is, I cleaned the throttle body with carb cleaner and got a lot of dirt and build up out of it.

When I had the air intake hose off the engine did not want to run at all. One repair I saw was to spray carb and choke cleaner into the throttle body while the engine was running, but with the truck not wanting to run couldn't do it.

I do not know what the problem is, I changed out the parts out and then the engine starts doing this.

Any help please.

Robert

Shifferbrains

I believe that your engine has a mass airflow sensor, which means that you have to have the air intake tube hooked-up. Otherwise, you get a poorly running engine.

The first thing I would do is hook the air intake system back up. Then, disconnect the negative terminal on the battery and leave it disconnected for about ten minutes. This will allow the computer to fully reset.

Reconnect the battery cable and run the engine. Most times this will take care of the running issue.

If this doesn't remedy the situation, I'd look at the spark plugs. I believe these engines are pretty finicky on spark plugs. I personally would stay with A/C Delco plugs.

In the future I would refrain from running the engine without the air intake system buttoned up. I hope this helps.

rcacka

Thanks for the reply. I will disconnect the battery when I get home and see how that does. It does have a MAS sensor, it is right after the air filter box. I wish I would have found this forum before I tried the other suggestion. I hooked it back up after I sprayed cleaner into the intake.

As far as the spark plugs, I used autolite 5245s which is also a suitible sub for the AC Delco.

I will try the battery and if that doesn't work I will go to the spark plugs and change them out. ingers crossed it will fix the problem.

I forgot in my first post that the engine is 5.3l vortec.

in2pro

Welcome to the forum both of you,

give this a try, its pretty common

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.

rcacka

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.

How do I find if this has been done?

Thanks for posting the info, will give it a shot this afternoon after I sleep. <!-- / message --><!-- sig -->

in2pro

The main part of the bulletin is to clean the throttle body esp around the plate.
the updates could only be done by a dealer, if you still have issues after cleaning the TB then consider having the updates checked.
The TB is pretty easy to remove and clean.

rcacka

Thanks will try it now. I disconnected the negative terminal and let it sit for over 10 minutes and it seemed like it was okay for a while but then it started to surge, I am now putting the old AC Delco spark plugs back in to see if that will fix the problem and if it does it will be the last time I buy autolite plugs

in2pro

AC / Delco parts are the best bet... all the way around

rcacka

I swapped out the plugs and what do you know the truck is back to normal. Thanks for the help.

Robert.

Blindsight

Now I have a question; when you guys say 'allow the computer to fully reset' does that mean that I will lose my tune if I disconnect my battery cable?

The reason I ask is that my battery died a few weeks back, and I was wondering if I might have lost my tune from that happening. I doubt that's possible, but you guys would know. So, any clue?