Rough idle

reconrangerll · #1 10-10-2020, 01:37 PM

I have a 97 2.3L 5 speed. For the first few minutes of driving the engine will sputter. When I come to a stop the engine will shake and sometimes stall. If I just let it idle it will smooth out then idle fine. After driving for the first few minutes it runs fine. Any suggestions would be greatly appreciated.

tomw0 · #2 10-12-2020, 06:31 AM

Clean the IAC, check the ECT and ACT temperature sensors, and make sure there are no vacuum leaks or deteriorating hoses connected to the manifold and that they are tight. If the Air temperature is incorrect, or the Coolant temperature ditto, the computer won't add extra fuel to enrich the mix for cold conditions. If the IAC is gummy, it may not be able to bump the idle as much as it is told to do by the computer. If there are loose vacuum lines, or PCV or vapor canister lines, they will leak extra air and may make the mix a bit lean, causing misfire and stumble.
Also check that the ribbed conduit feeding air to the intake after the MAF is not cracked. Some have seen cracks that allow un-metered air into the intake, again causing lean mix because the computer doesn't know about it, though it will try to correct with fuel trims.
tom

reconrangerll · #3 10-12-2020, 10:50 AM

Thanks Tom for your reply. My engine just threw the code P0303 (misfire cylinder 3) I replaced the plugs and wires. Replaced coil packs. Replaced ECT. Replaced the IAC. I couldn't find any vacuum leaks. I used carb cleaner to check for leaks. Could it possibly be the fuel injector?

tomw0 · #4 10-15-2020, 07:12 AM

You did not have a misfire code BEFORE doing the basics of a tune-up, and now you have misfire. That to me indicates something wrong with the parts or something wrong with the installation. Previously you stated that it idled smoothly after warming up, does it now idle with misfire? Does it shake at idle? Do you hear misfire if you listen at the tailpipe?(the sound will be normal with intermittent bmmp sounds.)
IOW, check your work and make sure all the wires are in their connectors solidly, the plugs are intact and tightened. (screw until contacting the head, tighten 1/8-1/4 turn more)
tom