1990 with Transmission Problems??
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1990 with Transmission Problems??
I just bought a 1990 Aerostar XL with only 47,000 miles on it. Engine runs good and tranny shifts well except - when it is warm it won't shift into OverDrive. And now, sometimes it won't shift into 4th when I am going more than 45mph with it in drive (not OD) . I've noticed that the fluid level is too high, but doubt that is the culprit. It started with going into OD at highway speeds and downshifting back and forth quickly(surging), then not engaging OD at all. Is this a common problem and what have you had to do to remedy?
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From: PNW
1990 with Transmission Problems??
[font size="1" color="#FF0000"]LAST EDITED ON 02-Aug-01 AT 10:07 AM (EST)[/font][p]First of all, get the fluid level to the correct height and see what happens. I know of people who have had weird things happen from seemingly simple things like fluid levels and it doesn't make any sense to start troubleshooting if you know that the fluid level isn't correct.
Are you confusing OD with torque converter lockup? My Aerostar won't go into 4th (which is OD) when it is in D (it's not supposed to) but the torque converter will lock up in D. I'm just guessing here but I would check the wiring and connectors for the torque converter clutch solenoid and the overdrive solenoid (aka 3-4 shift solenoid) to make sure there are no intermittent connections. Check the ground for these circuits as well.
Are you confusing OD with torque converter lockup? My Aerostar won't go into 4th (which is OD) when it is in D (it's not supposed to) but the torque converter will lock up in D. I'm just guessing here but I would check the wiring and connectors for the torque converter clutch solenoid and the overdrive solenoid (aka 3-4 shift solenoid) to make sure there are no intermittent connections. Check the ground for these circuits as well.
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From: PNW
1990 with Transmission Problems??
One other thing I forgot to mention. There are a couple of engine sensors that could affect shifting into and out of OD and torque converter lockup: throttle position and engine coolant temperature. The computer uses throttle position to help determine 3-4 shift scheduling and torque converter lockup. Engine coolant temperature is used to inhibit lockup (and I think the 3-4 shift but I could be wrong on that one) if the engine is either too hot or too cold. After reading your message a second time, I would think that the TPS is the culprit. But don't just go replace it, test it first. If that doesn't fix it, check the other stuff. That's my $.02.
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FYI for the next guy...I changed the overdrive solenoid (aka 3-4 shift solenoid) as mentioned above. When I dropped the pan it was obvious that the solenoid was burned and the wire was melted off. I replace it with a new sensor from the parts store, about $50, and it drove great from then on.
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From: Central Oregon
My 90 Aero with a 4.0 did this also and after changing the torgue converter, spark plugs and wires and checking the sensers, it turned out to be a bad fuel filter. Now I change the filter each spring in all my cars and trucks so I don't go through that again.
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The 3-4 solenoid has a little screen behind it. That often gets clogged up with stuff, and causes problems. They have a new design now that doesn't have the screen. You might want to take the valve body off and check that. But beware, all kinds of little pieces start falling out if you turn it over with the seperator plate off. That's MY $.02.
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Sorry, above I said I replaced a sensor, but I meant I replaced the solenoid. It was the new style you mentioned. Everything is running great now.
bertha66, I also found the importance of changing fuel filters regularly. Every oil change gets a new fuel filter. Someone told me also that that will keep the fuel pump from having to work so hard. Seems to be a common cause for fuel pumps going out. I have never had an issue with the fuel pump. Must have been good advice.
Thanks.
bertha66, I also found the importance of changing fuel filters regularly. Every oil change gets a new fuel filter. Someone told me also that that will keep the fuel pump from having to work so hard. Seems to be a common cause for fuel pumps going out. I have never had an issue with the fuel pump. Must have been good advice.
Thanks.
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