Rough Idle for 5 min only.
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From: ontario,canada
Rough Idle for 5 min only.
I have a 93 aerostar 3.0 l with 210000km and all of a sudden It just runs rough ,surging up and down and wants to stall or bog out if given gas. I replaced the air flow sensor,oxy temp sensor,installed new plugs,fuel filter. Had the codes read which didnt reveal any. After 5 minutes of running rough it becomes like a new motor ,purrs like a kitten. Im stumped as to what this problem could be. Also I forgot to mention that at start up if you put it in gear the voltage meter drops way down then goes back up. Any thoughts or Ideas would be a blessing .
Thanks so much.
Thanks so much.
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From: Orland USA
My other 89 Aerostar does the same thing.......It has a leaky head Gasket. It's leaking small amounts of water into the cyl. overnight. When you start it in the morning or after it sits awhile it runs ruff and shakes for 5-10 min then idles down and runs smooth.
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dont assume that it is a head gasket problem unless you check the oil and it looks like chocolate milk, another suggestion would be is clogged passage way to vacuum lines, take a can of carb cleaner, spray 3/4 of it into the throttlebody manually reving up the motor just enough for it not to stall, when you empty 3/4 of the can spray the rest of it into the throttlebody causing it to stall
after spray can is emptyleave the engine sit for 10-20 minutes so the carb cleaner will finish cleaning, it will be hard to start for the first time so you may have to pump it to get it going, pumping a fuel injected vehicle doesnt cause flooding it allows air into the combustion chamber to start it. after running , take it for a drive and accelerate fast, slow, fast ,slow blowing all the crap out the exhaust, note: before you start this cleaning methood the vehicle has to be at operating temperature.
after spray can is emptyleave the engine sit for 10-20 minutes so the carb cleaner will finish cleaning, it will be hard to start for the first time so you may have to pump it to get it going, pumping a fuel injected vehicle doesnt cause flooding it allows air into the combustion chamber to start it. after running , take it for a drive and accelerate fast, slow, fast ,slow blowing all the crap out the exhaust, note: before you start this cleaning methood the vehicle has to be at operating temperature.
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I believe that is true, because a head gasket is designed to seperate the water from the oil keeping it out of the combustion chamber. a hairline crack in the head would fill the oil with water in a matter of minutes. when a head gasket is blown the only that it can do is mix water with oil and puff white smoke out the back causing the van to overheat.
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Although I would expect the computer code scan to catch it, I wonder if the temp sensor is not working right. If it is telling the computer that the engine is warmed up even though it is not then it would run really bad at first.
Just a thought.
Just a thought.
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Ha38349
that could also be a possibility due to the fact that the codes usually come up when you drive it so many kms/mls, maybe you arent getting a code because it temporarily fixes itself, maybe there is a small air leak getting in the threads around the iat when it is cold and when it heats up the air gap closes, maybe take it out and wrap some teflon tape around it and screw it back in. another way to check the head gasket if the leak isnt bad is to check the oil for white deposits(dots) and see if you have bubbles in the reservoir of your rad, (foam like) if you dont see any spotts or chocolate milk like on the dipstick i would eliminate that problem.
that could also be a possibility due to the fact that the codes usually come up when you drive it so many kms/mls, maybe you arent getting a code because it temporarily fixes itself, maybe there is a small air leak getting in the threads around the iat when it is cold and when it heats up the air gap closes, maybe take it out and wrap some teflon tape around it and screw it back in. another way to check the head gasket if the leak isnt bad is to check the oil for white deposits(dots) and see if you have bubbles in the reservoir of your rad, (foam like) if you dont see any spotts or chocolate milk like on the dipstick i would eliminate that problem.
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From: ontario,canada
I tried the carb cleaner today and I will let you know tommorow if it cured problem. I dont believe head gasket is leaking as I had them both done a year and a half ago ,and there is no discolor in oil and coolant is not leaking at all. What do them letters stand for ( iat) idle air ? Thanks so much for all of your replys.
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From: Orland USA
johnwa:
Pulled the engine in my 89 today.
Drained the oil and found no water in the oil.
When I pulled the head on the passenger side number 3 cyl shows water has been there and I can see a bad spot on the head gasket.
My dad had a Rancho one that never got a drop of water in the oil but oil would go into the Radiator. It had a bad head Gasket
That is why I said a bad head gasket doesn't always mean water in the oil.
Pulled the engine in my 89 today.
Drained the oil and found no water in the oil.
When I pulled the head on the passenger side number 3 cyl shows water has been there and I can see a bad spot on the head gasket.
My dad had a Rancho one that never got a drop of water in the oil but oil would go into the Radiator. It had a bad head Gasket
That is why I said a bad head gasket doesn't always mean water in the oil.
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From: ontario,canada
Same problem at start up today.My van goes into garage that did head gaskets 18 mths ago,so Im going to get him to do a pressure test on coolant system so it should reveal a drop in pressure if head gasket is leaking correct?
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My mechanic put a throttle pos sensor on it ,cleaned a lot of grounds ,but this did not solve problem. Today its back in garage and he put a new fuel pressure regulator on it. He is just waiting for engine to cool down to see if this solves problem. I told him also that its only getting about 13 miles to gallon,not the 20 it used to get.I will let you know how this garage visit turns out.
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