Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

Researched... Starting issue with high idle.

1170 Views 5 Replies 3 Participants Last post by  RayVoy
02 Envoy. Sometimes, well more than sometimes, Id say about every other ignition cycle it takes like 4 or 5 seconds to actually start. Cranks but no start. Then when it does finally start the idle is around 1200 for about 10 seconds. Other times it starts right up with normal idle. I have searched on mitchel and searched for TSBs about this issue. I have done the GM fuel system clean and throttle clean. Im a Tech at a small shop and were all puzzled by this issue. Any advice?? Thanks so much.
1 - 6 of 6 Posts
You have a good challenge, all right. Fuel pump getting old - low pressure? How many miles on her? Plugs changed at 100K if it's over that? Ignition switch could be flaky, especially if it works every other time. Starter cranks, but the ignition could be suppressed during cranking by a bad switch that has a problem in RUN/START mode. Excess fuel injected gets burned off after it lights up, causing the high idle? Can you check the PCM data for ECT? Excessively low ECT could engage the high idle table until it thinks it's warmed up.

See less See more
I replaced the fuel pump a month ago, fuel filter as well with the pump change. Spark plugs in august. Fuel injector cleaner and TB clean as well. The ignition switch was what I was thinking it could be, but with the scan tool theres no dropping of ignition voltage or anything like that. Ive even jiggled the switch to see if I could get it to act up. Its really strange. I have also noticed that the MPG has been progressively getting worse... Im only getting 14.8 when I bought the car in august it was getting 18.1 or 18.2. I dont drive it hard at all.
How's the air filter?

Your a tech, so I can assume no codes?

When you cleaned the tb, did you check the free movement of the butterfly?

When you have the problem, is the motor hot, or cold?
No codes. Engine temp doesnt matter at all. I have monitored engine data with the scan tool for like 45 mins starting and stoping the engine hoping to pick up on some fault with the electronic throttle or ignition switch even a cam or crank sensor falling out but noting... Ill be embarrased, but Im thinking about taking it to a GM dealer and seeing if they can find more with the Tech 2. Maybe theres some reflash update that it needs.
Well, there are some updates, but I don't think any addressed that problem.

But, they might include the updates when running the tests.
They normally charge 1 hr labour to do the reflash, but if your paying for the test, you might get it included.
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.