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Solved My 1992 Aerostar has a rough idle, and a weird starting issue.

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HotWheelsAS

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1992 Ford Aerostar
Hello!

So, I'm new to the forum (and new to Ford's if I'm honest), but I just bought this wicked cool Aerostar and I really want to keep it going. Here's what I need help with.

First issue, it seems to idle kind of rough. Not a high idle, and never so bad that it dies, but it's definitely not smooth. Once it's running and you give it any gas it smooths out and is fine. No seeming power loss on acceleration. As far as I can tell MPG is still good (got about 21 on my 600 mi. road trip home after getting it). So far I've changed the PCV Valve and the two hoses to it, cleaned out the IAC valve and MAF sensor. A friend and I pulled a spark plug and it looked decent, so I don't know that that's the issue. The only other thing I can say is that when we were checking the MAF, unplugging it would change the idle for maybe 10 seconds and it sounded good before reverting back to a rough idle. Same thing plugging it back in, good for a short bit and then back to rough. Does this indicate a MAF problem?

Starting: First star after not having been run for a while is always great. First start in the morning it starts right up no problem. After having been run for a while and it's hot, sometimes it will crank for a long time before starting up or not crank at all. I turn the key, all the dash lights come on, but nothing, just like a click. Turn the key right after that and it sometimes starts. A starter? Solenoid?

This forum has already helped so much. Anything else would be most appreciated. Thanks everyone, Chris.
 



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Welcome to this forum! Did you do the paint job or a body shop? Did you clean the mass air flow sensor with CRC MAF spray? My 1995 Aerostar has the same issue starting occasionally. I've replaced the starter but not the starter relay, so you might want to look into this.
 






regarding the Starting 'clik' Issue, if not the starter Relay (the one located near the battery), check the terminals at the battery are properly seated and tight.

I had this issue with my '97 and it turned out to be the Negative cable Terminal which was too big for the negative battery pole, and though it was as tight as possible, you could still move it around. I went to Autozone and got a smaller diameter replacement Terminal and problem went away.

Rough idling... do you have the proper spark plugs installed? Maybe they look fine but are they the right ones? Triple-check that. The Label on the cowl or hood should tell you which Autolite plugs to use, if no labels, the Owner's Handbook will have that info too.

a vacuum leak will cause a rough idling too.
 






As much as I would like to take credit for the paint, I cannot. After I bought it I put the white letter tires on it and cleaned it up a bit. The paint though was done by the gentleman I bought the van from. He did well.

Did replacing the starter fix the issue for you? I don't think its the battery terminals, I think those are okay, but I'll double check.

I did use CRC MAF sensor cleaner on the MAF. Used it on the IAC too and they both seemed to come out cleaner, but haven't changed the idle. I don't know about the spark plugs. I bought NGK Iridium IX Tr5IX plugs from Oreilly's because they said they would fit, but when I pulled the old plug, it's the shorter thread size, the NGK plugs have longer threads; I was afraid to install the new ones. Will the NGK's work?

I also have a new O2 sensor to put that just came in the mail.
 






I don't know about NGK, I use the Autolite Iridium but mine is a '97 4.0

The next check would be to check the Idle Air Valve mounted on the intake manifold, same area as the butterfly.
 






I had a rough idle and rough running engine (3.0) recently, changed the plugs and wires and the roughness went away.

The plugs I pulled were new a year ago and they had short threads. The plugs I put in had long threads, just like the plugs I replaced a year ago. Don't remember which brand or type of plugs any of them were, so can't help you there. All I know is that the plugs I replaced a year ago were not missing (only replaced them because they had over 200,000 miles on them), the replacement plugs were problematic from day one, and the current plugs never miss a beat.

You might want to find some place where it is pitch black, start your engine, and see if you see any sparking anywhere. One of my issues was the middle passenger wire was sometimes shorting out near the spark plug. Running the engine in a very dark place made it easy to see the problem.

Even when mine was running rough, I was still getting 21.5 MPG around town, and more on the highway. Have not done a mileage check lately so don't know what I am currently getting, but it should be near 23 around town and 26 on the highway.
 






All,

Thank you, again! So far, the problem seems to be solved. I ended up replacing the mass airflow sensor and 02 sensor in addition to the idle air control valve and pcv valve, but that didn't seem to make much of a difference.

What does seem to have made a differnce is new spark plugs and wires (the NGKs worked out okay) and cleaning carbon buildup from the intake.

Thanks again.
 












Spark plugs were the NGK Tr5IX's, the plug wires were OmniSpark part #9081 and both of them came from O'reillys. All the spark plugs and wire set ran about $73.
 






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