Chevy Silverado Idle Problems

[chevy123]

I am having problems with my 2007 Chevy Silverado 1500 LT 4x4 (New Body Style) V8 5.3. All of a sudden as I am driving on the street my truck accelerates on its own and the speedometer needle stays stuck on zero and the RPM's increases and if I hit the accelerator pedal the truck will even go super fast as if I had Turbo. The only way it will stop from doing this is if I stop and put it on park and then put it on drive again and then the truck is fine. It does this problem every once in a while but almost every day and there is not a check light at all. Can you help me?

[ProTech]

At first thought, I would think this might be a problem with the throttle body on your truck. They are electronically controlled and can have this type of issue if they are beginning to fail, or have an excess of carbon build up around the throttle plate. The only thing that throws me is you saying the speedometer stays at zero when this happens. That is not usually a characteristic of a throttle body issue.

With you stopping the truck, putting it in park and then drive again, and seeming to fix the problem would tell me that you might be stretching a wiring harness or have some sort of short/wire problem that with the movement of the engine might cause this.

You might want to start first by getting the truck scanned at any auto parts store to check for engine codes. I know you say the light is not on, but that doesn't mean something hasn't set a fault or recorded a problem. This would be the quickest way to head in the right direction to diagnose this particular problem.

Other than that, you could be looking at some sort of wiring issue like I stated before, or a possible module (computer) that is faulty. If you take it to a shop, it's always best to go on a test drive with the technician while it is acting up so he can definitely see what is going on. There are also ways he can record the functions of the computers and sensors on the truck while it is acting up to better diagnose it.

[Silveradofanatic17]

Ok, I got a 2000 chev silverado 1500 Z71 4x4 5.3L truck, my problems with it are really getting frustrated and irritated. First of all, I got a knocking noise which sounds like it's the push rods, rockers, rocker arm springs. It's coming from the driver back end if the motor. I did just finish getting the heads re done by a mechanic and didn't spot it out (anti- freeze leaked into oil pan)
Secondly, my trans seems to be stuck in 2nd - 3rd gear (I assume it is my solenoid A-B) or stuck in "limp in mode" when I'm idling at a red light and take off on green, it seems to be underpowered and seems to take off in 2nd-3rd gear.
And thirdly, when I turn my key on the ACC position the gauges and everything works, but soon as I start the truck up it all shuts off(only the battery and temp gauge work)
And fourthly, the air box seems to have a miss. Have my oxygen sensors gone bad. I'm pretty new to all this stuff. I've just been googling and googling and can't seem to find the correct answers to my problems.

[carriedi]

have you talked with the repair place that did your heads? Did you have a shop work on it or just some mechanic? If you have a problem with a lifter or a rocker arm that may be ca contributing factor to and engine miss. Any engine miss will affect your oxygen sensor readings. If your SES (service engine soon) light comes on it may put your vehicle in limp mode and make your transmission stay in second gear. Your gauges not working may also put you into limp mode. Some things may be related but it's also possible that you have a separate problem for each defect. Talk to the shop about the engine noise. Scan for all the codes that are stored and start from there.

[Silveradofanatic17]

Yes they have did shop work. I'm aiming more toward the PCM. I went out as bought the repair manual and all the things listed under misc. PCM is accurate, well seems to be. I've called to get the push rods, valve springs, and rocker arms ordered. Just want to make sure before I go out and pay for them. How much does a PCM usually go for in Canada(Saskatchewan)

[carriedi]

for pricing you will have to call around. NAPA in the US retails the ecm for around $272 reman. $344 dealer. but then you have to flash it to your vehicle. Are you sure that's what you need? Just askin'

Have you taken your valve cover and seen what the problem is on the valve train?