What causes rough idle on startup?
A rough idling engine can be caused by spark plugs or spark plug wires. A plug that is damaged or installed incorrectly can result in fuel being burned at an inconsistent rate. If the damage is bad enough, you may also notice your engine running rough while driving.
What causes rough idle and misfire?
Many system malfunctions can cause misfires or rough idling. Ignition system components, including spark plugs, plug wires, ignition coils and ignition timing are culprits as are lean air/fuel mixtures and mechanical issues within the engine.
Why is my Chevy Silverado running rough at idle?
Really, your Silverado will be running rougher at any RPM, but a misfire will be most pronounced at idle. Spark Plug Wires – While not every model and engine combination of vehicles today comes with spark plug wires (a lot are now coil on plug), if your Silverado happens to have them, they can go bad and cause a rough idle.
What should rpm be on cold start 5.3L?
Recently my 5.3L has been giving a rough idle on cold start only, no drivability issues. It starts fine, goes to 900/1000RPM as usual and after a few seconds it starts to stumble. The RPMs drop to 500 and bounces to 700 for a few seconds, 5-10 maybe.
What kind of engine does a Silverado 5.3 have?
I recently bought a 2008 Silverado 5.3 with 77k on it. After a couple weeks I noticed that at idle the engine would stumble and my rpms would drop slightly. It eventually set off the check engine light with cylinder 1 misfire and random cylinder misfire. A couple days later the light went off but the issues remain.
Why is my cold start 5.3L running rough?
If the coolant sensor is giving a bad reading the mixture could be too lean or too rich, causing the problem. The O2 sensor will take a minute or so before the PCM looks to them for readings. Just one warning unplugging the MAF on the 5.3. Shifts may be brutal, especially 1-2 shift.