Drop in RPM, low RPMs...

[Rocko973]

I have a 2003 Silverado 1500 HD, had it since new, and I've never washed the engine, nor have I had any problems with it. Since the engine was really dirty, I decided to wash it, and guess what, I now have problems. Basically, here's what I did:

 

First I disconnected the neg. battery cable. Then I removed the ignition coil bracket assembly, then I covered up every electrical connector that I can see and also all loose ends (few of them) that I had to disconnect in order to remove the bracket assembly. I wrapped them in seran wrap then with foil over that. I sprayed the engine with degreaser, then rinsed it off with a pump sprayer instead of a garden hose. I repeatedly brushed heavily greased areas and rinsed until it was all clean. Then took an air hose to it, then wiped everything down with a towel. I let it sit for several hours before putting everyting back in and starting it up. BTW, I did carefully wash the two ignition coil unit assembly by hand separately.

 

When I cranked the engine, it started up normally on first crank as always. Little bit of steam came out of the engine that I figure was normal after a wash. After several minutes warming up, I tried to drive it and it stalled on me. Then it took several cranks to start up. Once I have it started, the RPMs would be steady right about 500 RMPs, and if I try to put it in any gear, the RPMs would drop about 200 to 300 RPMs and sound like it was going to stall, then go back up to a steady 500. It wouldn't stall until I give it gas while in gear. I am afraid that I made a big mistake... any idea what is happening?? I must have got water somewhere despite how careful I was. I am really bummed and regretful about this....

 

Thanks!

[Chris]

Knock sensors are an issues with these engines. They get moist and then corrode

 

Sent from my DROID RAZR MAXX using Xparent Red Tapatalk 2

[Dilatory]

You may have also gotten enough water in/on the air filter to choke it up, make sure that's dry, beyond that I has no idea.

[Rocko973]

Hi,

 

Yesterday I originally posted "stalling after engine wash" for a 2003 Silverado 1500 HD, but I am beginning to believe that the problem had nothing to do with the wash.

 

It starts up normal on first crank now, and then it initially idles normal just below 1000 rpms, then slowly drops to about 500 rpms and holds steady there. Whenever I put it in gear, the rpms drop and almost stalls, but then it goes back up to 500 rpms and holds steady again. One thing i just noticed is that whenever I quickly push on the accelerator just part way, I would first hear a quick suction sound (or a hiss) before the rpms go up. It sounds like the suction sound is coming from right around the EVAP solenoid or just below around the Throttle Body or just past the TB inside the Intake Manifold somewhere.

 

Could my problem be a bad EVAP solenoid or a bad throttle body, or what? I am suppose to drive it up to SF (about 500 miles from me) in 5 days from now, and I would like to fix it myself, but I am in a time crunch. If I can't fix it in the next day or two, I may have to take it to the dealer, but that's my last resort. Any help would be appreciated greatly.

 

BTW, the reason i think it had nothing to do with the engine wash is that, before the wash, I did hear a slight hissing sound, almost like a whistling sound whenever I gave it gas, and the sound would occur only right as I give it gas and then go away. But I just didn't think anything of it, unfortunately.

 

Thank you in advance...

~

[TimmyG]

Water around the spark plug boots can cause a misfire if it idles I woukd let it run and get up to temp with the hood up and try to cook off any extra water in there anywere

 

Sent from my SCH-I535 using Tapatalk 2

[desrtrat]

i would check for a vacuum leak. hitting it with water may have broken a vacuum line/fitting that may have been leaking before the wash

[Rocko973]

Just an update:

 

I took my truck to the dealer, and turns out to be a strange case of coincidence. They said that my throttle body was all gummed up and dirty. That's it! Not a water probllem! They just hand-wiped it clean, and now it feels and sounds like new again. Funny how it decided to act up right after an engine wash. That suction sound I mentioned is still there, though, but they said that it was normal. There were no codes. I think that when I was diagnosing, I was just looking too hard for "something" amiss... Anyway, my truck runs like a champ now. I was apprehensive about taking it to the dealership, but they made good on their end, and I am very happy with them. They won my trust in them...

 

Thanks for your responses...

~

[Portdriver]

Good to hear the dealership made good!