Question about 1990 Chevrolet C1500
I just bought this truck for cheap. It doesn't seem that it was maintained well. The oil cap was stuck so I had to take the valve cover off and the oil obviously hadn't been changed frequently. (Not sure this matters, just some context) The truck idles pretty rough when I'm at a stop light in gear. It doesn't do it so bad in park, but it's still noticeable. Occasionally, I've noticed power steering going out for a second, but have only noticed this twice (but I've only had the truck a few days). I'm thinking the signs point to a vacuum leak, but I'd like to hear what others may suggest. Would a clogged PCV valve do this? I'm sure there probably more than one thing causing the idle issue, so looking forward to thoughts.
Can of worms here my friend, first thing I would do, replace fuel filter, then , spark plugs, wires, distributor cap/rotor, air cleaner, fuel injector cleaner in gas tank, drygas in fuel tank, higher octane fuel to help mix up the two bottles of stuff I just mentioned, see how all these work, these items are cheap, but necessary, then located on the throttle body is a idle air control valve, which needs replaced no doubt, IAC valve, get it. hope you changed your oil & oil filter, also very important you change the tranmission filter & fluid. so ya see, this is what you purchased a lot of work!!!!!! believe me , it may not end here. good luck
Posted on Jan 13, 2013
Testimonial: "Good advice!"
Check the pcv valve as they will gum up if the oil has not been changed regularly. I would also check all vacuum hoses for cracks or breaks
Posted on Jan 13, 2013
Testimonial: "This solved the problem."
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Posted on Jan 02, 2017
SOURCE: 1995 Chevy silverado with a
I have experienced this problem on similar vehicles. You should try and replace the coolant temp sensor. If it is not reading the correct temp to the ecm, it will not get the right fuel map. Also, the cts will not always throw a code.
Posted on Aug 04, 2008
if you are not the original owner then the previous owner may have set the idle high, if you take off the throttle body there should be a little screw that will set the idle by keeping the intake valve open more if you unscrew it then the idle rpm will lower
Posted on Nov 20, 2008
This make/model has a chronic problem with EGR clogging. If you have a dashboard indicator showing "check engine" most likely it is a trouble code indicating and EGR (exhaust gas recirculator) valve problem. Symptoms are rough idle, and surging and stalls.
What happens is sediments from the exaust manifold get sucked up into the valve when it opens, then stick in the valve and keep it from closing. When the valve is open when it should be closed, the engine runs very rough.
I removed my egr and then dislodged the sediment (pea-sized debris) and then re-installed the valve. Three days later, the same "check engine" and same rough idle. I must have did this at least three or four more times.
What I found that gave me a permanent solution was an aftermarket filter gasket that keeps debris from clogging. I don't remember the name of the product, but a search for "EGR filter gasket" may lead you to the product.
Install the gasket between the EGR and the exhaust manifold and you should be good to go. Note: on 1995 and newer models, disconnecting the EGR from the wiring harness (common on R&R) may require the computer to be reprogramed.
Posted on Dec 24, 2008
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Engine stalling and rough run
issue at low speeds
is commonly caused by a dirty automatic idle speed control valve and
throttle valve. Buy a can of throttle valve cleaner (do not use
carburetor spray cleaner!) from NAPA or Carquest (made by CRC
chemicals) and spray it into the air intake while the engine is
running, use up about 1/2 the can, engine will try to stall hold the
speed up, shut it down and let it soak for 30 minutes, restart and
blow out the remaining fluid, shut it down and disconnect the
negative battery cable for 5 Min's to reset the base idle control. If this doesn't improve the problem you have mechanical problems in the engine like a low cylinder die to worn rings or leaking valve seats.
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