Rough idle when in drive
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Freshman User
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Rough idle when in drive
Hi all,
I bought this truck used and when it's in drive the engine idles rough and seems about to stall when the ac is on at a stop sign or red light.. I've tried it w/o the ac on and it seems a little better but not as smooth. Idle in park is fine.
Do you know when I should start looking?
Spark-plugs? spark plugs wires, disturber cap, fuel filter ect...
Please i'm not that mechanical but I can get most jobs done. So I don't have any master mechanic tools... if it's something easy i can do...
I bought this truck used and when it's in drive the engine idles rough and seems about to stall when the ac is on at a stop sign or red light.. I've tried it w/o the ac on and it seems a little better but not as smooth. Idle in park is fine.
Do you know when I should start looking?
Spark-plugs? spark plugs wires, disturber cap, fuel filter ect...
Please i'm not that mechanical but I can get most jobs done. So I don't have any master mechanic tools... if it's something easy i can do...
Posting Guru
Joined: Jun 2009
Posts: 1,908
Likes: 20
From: Fort Smith, Arkansas
We can't see which truck you are pointing at.
Also some history of the the maintenance on this vehicle would help narrow it down. And code scan it. Or looking at live data is a really great diagnostic tool for computer controlled engines.
Also some history of the the maintenance on this vehicle would help narrow it down. And code scan it. Or looking at live data is a really great diagnostic tool for computer controlled engines.
Thread Starter
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Freshman User
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Oh sorry forgot to add it
1997 Ford F-150 XL model it has over 194,000 miles on it. As for maintenance I have no idea as it was used. I have changed the oil and transmission oil but other then that nothing else that I know of. That's why I was maybe thinking its the spark plugs as the seem a little black when I removed one to see what conditions they were in
1997 Ford F-150 XL model it has over 194,000 miles on it. As for maintenance I have no idea as it was used. I have changed the oil and transmission oil but other then that nothing else that I know of. That's why I was maybe thinking its the spark plugs as the seem a little black when I removed one to see what conditions they were in
Lead Driver
Joined: Sep 2006
Posts: 7,907
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What is the hot Idle RPM in Neutral or Park?
Should be close to 650/700 +/-.
If not the IAC is not functioning.
When A/C is turned on, an Idle correction is made to keep the Idle in the 700 rpm range.
If that does not happen the A/C loads the motor down.
The hotter it is out, the more it loads the motor.
Good luck.
Should be close to 650/700 +/-.
If not the IAC is not functioning.
When A/C is turned on, an Idle correction is made to keep the Idle in the 700 rpm range.
If that does not happen the A/C loads the motor down.
The hotter it is out, the more it loads the motor.
Good luck.
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Freshman User
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Update:
I've replaced the pcv valve and cleaned the iac valve. Now it seem to be miss firing around speeds for 45 and above. What else can I be looking for? New iac value?? Do you think I can take it to advance auto and they can see if any codes come up. The check engine light doesn't come up or anything. I'm drawing at straws here guess what the fix is.
I've replaced the pcv valve and cleaned the iac valve. Now it seem to be miss firing around speeds for 45 and above. What else can I be looking for? New iac value?? Do you think I can take it to advance auto and they can see if any codes come up. The check engine light doesn't come up or anything. I'm drawing at straws here guess what the fix is.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Taking it to an auto store won't likely result in any solution to the misfire without code............unless they know how to access mode 6, test 53.
At that data location will be found the misfire monitors for each cylinder.
One or more may show misfire counts out of limits.
If so that cylinder will need the coil replaced.
Good luck.
At that data location will be found the misfire monitors for each cylinder.
One or more may show misfire counts out of limits.
If so that cylinder will need the coil replaced.
Good luck.
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Freshman User
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You mean replacing the Ignition Coil?
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