My 3.8L Windstar runs fine except often times on a warm start, it idles real rough, almost like its missing. But you put it in gear and drive away and it quickly goes away. I thought it might be a leaky fuel injector, but it does not show up in the UOA. What do you think it could be? O2 sensor? No check engine light coming on.
Rough Idle on Warm Start
- Thread starter Burt
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Originally Posted By: Burt
If it was a vacuum leak, wouldn't it rough idle all the time?
You bring up a good point, I would still check for any vacuum leaks to be on the safe side and to rule out the vacuum leak as a cause for your problems.
Maybe check to make sure your throttle body is clean. JMO
If it was a vacuum leak, wouldn't it rough idle all the time?
You bring up a good point, I would still check for any vacuum leaks to be on the safe side and to rule out the vacuum leak as a cause for your problems.
Maybe check to make sure your throttle body is clean. JMO
What about a potential exhaust leak? The metals in your exhaust expand/contract when hot and maybe you have a slight leak from your exhaust manifold? Just a shot in the dark.
It could be a number of things, as c3po said look for vacuum leaks, check the EGR valve, the brake booster, all vacuum hoses, and around the fuel injectors. These problems can be a real pain in the neck. Have you checked the IAC and made sure it is clean? Is the fuel pressure regulator good? You could have an injector leaking down a bit, and anything that makes it to the oil is burnt off.
It can become real easy throwing parts at an older vehicle and still not resolve the problem. Check out the above and hopefully you will resolve it without having to dig in further.
It can become real easy throwing parts at an older vehicle and still not resolve the problem. Check out the above and hopefully you will resolve it without having to dig in further.
Exhaust leaks wouldn't affect drivability unless the leak was large enough to cause a situation where the O2 or air/fuel sensors(basically a wideband O2 sensor) has insufficient flow.
I'm thinking IAC, or you got fuel pump problems on the horizon.
I'm thinking IAC, or you got fuel pump problems on the horizon.
Originally Posted By: nthach
Exhaust leaks wouldn't affect drivability unless the leak was large enough to cause a situation where the O2 or air/fuel sensors(basically a wideband O2 sensor) has insufficient flow.
I'm thinking IAC, or you got fuel pump problems on the horizon.
I agree with the exhaust leak comment, usually exhaust leaks make some kind of noises.
Exhaust leaks wouldn't affect drivability unless the leak was large enough to cause a situation where the O2 or air/fuel sensors(basically a wideband O2 sensor) has insufficient flow.
I'm thinking IAC, or you got fuel pump problems on the horizon.
I agree with the exhaust leak comment, usually exhaust leaks make some kind of noises.
I doubt that it is ignition - we can safely eliminate that 1/2.
So, it's fuel delivery or mixture.
But that leaves a LOT!
It could be the coolant sensor [maybe an air temp sensor]- it may be reading wrong, and telling the computer it is too cold/hot .
Vacuum and manifold leaks [esp the PCV system] are still in the picture. It is tedious, but check each line and it's connection, as well as manifolding.
So, it's fuel delivery or mixture.
But that leaves a LOT!
It could be the coolant sensor [maybe an air temp sensor]- it may be reading wrong, and telling the computer it is too cold/hot .
Vacuum and manifold leaks [esp the PCV system] are still in the picture. It is tedious, but check each line and it's connection, as well as manifolding.
If the ECT sensor is bad, the CEL would be thrown and there will be a code indicating failure to enter closed-loop mode.
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