Transmission Issues With New Foxbody

Giovannylara · May 11, 2017

Hello guys, new to the forum. Expect to see a lot of me here from now on lol. I just recently bought a 88 foxbody. It's a lx vert with a 5.0. It's got 75,000 original miles on it and most of the car had been left stock.I've been having some issues with it. I believe it is a torque converter issue. The car has been idling strangely. Whenever I first shift it into reverse the rpms go to about 500 or so and it sounds like it's going to stall but doesn't most of the time. I've replaced the throttle position sensor and got it to the correct voltage. Could it be a stall speed issue? Also, it seems the car loses power anywhere over 2200 rpms. Anything after that and the engine revs up as if it were in park. Any ideas or suggestions would be greatly appreciated. I went to automotive tech while in high school, but sad to say I didn't pay as much attention as I should've (regretting it now). So if you guys could explain in detail that'd be great. Cheers

90sickfox · May 11, 2017

Does the transmission fluid level look normal ? Is the fluid red or black ?

Change the filter and transmission pan gasket. Use a bottle of Lucas Transmission treatment along with the transmission fluid.

These cars weren't known for having great AOD transmissions

Giovannylara · May 11, 2017

90sickfox said:
Does the transmission fluid level look normal ? Is the fluid red or black ?

Change the filter and transmission pan gasket. Use a bottle of Lucas Transmission treatment along with the transmission fluid.

These cars weren't known for having great AOD transmissions

Give me a second and I'll check.

Giovannylara · May 11, 2017

90sickfox said:
Does the transmission fluid level look normal ? Is the fluid red or black ?

Change the filter and transmission pan gasket. Use a bottle of Lucas Transmission treatment along with the transmission fluid.

These cars weren't known for having great AOD transmissions

Dexron III? Also would I drain the torque converter? I've read replacing fluids on a high mileage vehicle can affect it because old fluid builds up on parts which make everything work. Sorry to bombard you with all these questions.

Adieu · May 11, 2017

Dexron III and Mercon fluid are usually the same (may not be true for all braands), most will even be labeled "Dexron III/Mercon" or "Dex/Merc". Ford even labeled the Motorcraft Mercon with "Dexron III/Mercon" at some point, I still have two bottles somewhere from when the Mercury dealership I worked for went under and I got a case of that as part of my "severance".

When I had an AOD fox, it would intermittently act like it went to neutral with no warning unless I kept it filled up about 1/4" past full on the dipstick. The guy that built my AOD (and two GM transmissions for me since, and will be building ElSuperPinto's C4 if I don't go with a stick) was the one that told me it'd fix the problem, and he was right.

Also, verify that the bushing on your throttle valve cable hasn't cracked and fallen out as well, it will wreak havoc on an AOD if that's happened. A brass replacement bushing is available from Latemodel Resto. If the bushing is good, fluid level is good, and fluid condition is okay (red-ish and doesn't smell burnt), you can check the throttle valve pressure if you're willing to crawl under the car with it on jackstands, hot, and running and use an oil pressure gauge (Harbor Freight sells an oil pressure test kit with right adapters and a good long hose), and adjust the TV cable at the throttle body to set it correctly. (I'm willing to bet @jrichker has a detailed how-to... )

Giovannylara · May 11, 2017

Giovannylara said:
Hello guys, new to the forum. Expect to see a lot of me here from now on lol. I just recently bought a 88 foxbody. It's a lx vert with a 5.0. It's got 75,000 original miles on it and most of the car had been left stock.I've been having some issues with it. I believe it is a torque converter issue. The car has been idling strangely. Whenever I first shift it into reverse the rpms go to about 500 or so and it sounds like it's going to stall but doesn't most of the time. I've replaced the throttle position sensor and got it to the correct voltage. Could it be a stall speed issue? Also, it seems the car loses power anywhere over 2200 rpms. Anything after that and the engine revs up as if it were in park. Any ideas or suggestions would be greatly appreciated. I went to automotive tech while in high school, but sad to say I didn't pay as much attention as I should've (regretting it now). So if you guys could explain in detail that'd be great. Cheers

Update on the fluid, the fluid is filled up, and is of a darker pink color. Whenever I pulled the transmission dipstick it smelled burnt.

Giovannylara · May 11, 2017

Giovannylara said:
Hello guys, new to the forum. Expect to see a lot of me here from now on lol. I just recently bought a 88 foxbody. It's a lx vert with a 5.0. It's got 75,000 original miles on it and most of the car had been left stock.I've been having some issues with it. I believe it is a torque converter issue. The car has been idling strangely. Whenever I first shift it into reverse the rpms go to about 500 or so and it sounds like it's going to stall but doesn't most of the time. I've replaced the throttle position sensor and got it to the correct voltage. Could it be a stall speed issue? Also, it seems the car loses power anywhere over 2200 rpms. Anything after that and the engine revs up as if it were in park. Any ideas or suggestions would be greatly appreciated. I went to automotive tech while in high school, but sad to say I didn't pay as much attention as I should've (regretting it now). So if you guys could explain in detail that'd be great. Cheers

Update on the fluid, the fluid is filled up, and is of a darker pink color. Whenever I pulled the transmission dipstick it smelled burnt.

90sickfox · May 11, 2017

New fluid in a worn out transmission can reveal issues...that's why I recommend the Lucas Stop Slip transmission additive.

I've seen issues where the seal on the transmission filter is bad...or the filter is dirty causing the transmission fluid pressure to drop which can cause it to do some weird stuff.

If the " kick down " cable is adjusted properly and the filter and seal are in good order....you can rule those things out. The only way to know about the filter or seal ( without a trans pressure gauge ) is to drop the pan.

The transmission could need a band adjustment...however, that's not something I could walk you through. I'm sure someone else here knows how to do it.

A locked up torque converter can make the idle drop to the point of making the engine stall. But it won't do that and cause the trans to slip. Usually, if a converter is locked up it'll cause a harsh shift between gears and a jerk between 1st and 2nd when slowing down.... Something else that can cause a jerk when stopping is the brake light switch. The brake light switch disengages the torque converter on a lot of vehicles.

If in doubt take it to a reputable transmission shop and have them diagnose it.

Burned smelling fluid is never a good thing. Good luck and keep us updated.

Davedacarpainter · May 11, 2017

A local boy, welcome to Stangnet.

I'm in Broken Arrow as well.

I'd like to help you here, but the most I know is how to put one in a Mustang. Going inside of them is currently beyond my skill set. What the fellas said sounds logical though.

If you need, I can find a good transmission shop for you locally.

Good to have you with us brother.

Post a picture or two of your mustang so we can see it. We're picture whores here.

Giovannylara · May 11, 2017

90sickfox said:
New fluid in a worn out transmission can reveal issues...that's why I recommend the Lucas Stop Slip transmission additive.

I've seen issues where the seal on the transmission filter is bad...or the filter is dirty causing the transmission fluid pressure to drop which can cause it to do some weird stuff.

If the " kick down " cable is adjusted properly and the filter and seal are in good order....you can rule those things out. The only way to know about the filter or seal ( without a trans pressure gauge ) is to drop the pan.

The transmission could need a band adjustment...however, that's not something I could walk you through. I'm sure someone else here knows how to do it.

A locked up torque converter can make the idle drop to the point of making the engine stall. But it won't do that and cause the trans to slip. Usually, if a converter is locked up it'll cause a harsh shift between gears and a jerk between 1st and 2nd when slowing down.... Something else that can cause a jerk when stopping is the brake light switch. The brake light switch disengages the torque converter on a lot of vehicles.

If in doubt take it to a reputable transmission shop and have them diagnose it.

Burned smelling fluid is never a good thing. Good luck and keep us updated.

Well guys, I bought some Lucas additive but have yet to add it. I think I found one of the culprits , like you guys said the throttle valve cable holder broke off so it has been dangling for some time I imagine. I spoke to my old transmission teacher today and he believes it may also be the band.

Giovannylara · May 11, 2017

Davedacarpainter said:
A local boy, welcome to Stangnet.

I'm in Broken Arrow as well.

I'd like to help you here, but the most I know is how to put one in a Mustang. Going inside of them is currently beyond my skill set. What the fellas said sounds logical though.

If you need, I can find a good transmission shop for you locally.

Good to have you with us brother.

Post a picture or two of your mustang so we can see it. We're picture whores here.

That's awesome! Okies represent. I cannot catch a break, today with the heavy hail my top was ripped up. It's a never ending process .

90sickfox · May 11, 2017

Those look like bullet holes...that hail must've been falling pretty hard.

Giovannylara · May 11, 2017

90sickfox said:
Those look like bullet holes...that hail must've been falling pretty hard.

It was coming down! Btw Lucas treatment plus a temporary plastic tv bushing has got it shifting like it should now. Got a brass one form late model coming in. Hopefully that holds until I can get my hands on a t5. Can't thank you guys enough!

mikestang63 · May 11, 2017

Got some bad news for you,, If you;ve done any amount of driving with the TV cable disconnected, chances are the AOD is damaged. These transmssions operate off of line pressure and the TV cable is used instead of the traditional vacuum modulator. I've seen AOD's fried within miles of driving with an incorrect or broken TV cable.

Do not drive the car until you fix that, and I would recommend replacing the plastic bushing with a brass one. The plastic ones are prone to breaking, causing the TV cable to fall out.

Regarding adjustment, I strongly encourage you to bring the car to a transmission shop unless you can adjust the line pressure accurately. To get the setting in the ballpark, you can follow this video.

Davedacarpainter · May 11, 2017

Giovannylara said:
That's awesome! Okies represent. I cannot catch a break, today with the heavy hail my top was ripped up. It's a never ending process .

Holy crap! I work in a bodyshop. I was watching out the door today.

We were hoping for some work from this. If you had hail tough enough to rip up your top then there must be some damage out there.

Sucks for you though buddy, sorry.

5.0specialist · May 14, 2017

That sucks. I recommend using Lubegard (red bottle) for your transmission. It loosens-up and keeps the valves in the valvebody from sticking and enhances the protective properties of the transmission fluid. I'm running Dexron III/Mercon I fluid with a bottle of lubegard. It definitely made a nice difference in my 91' AOD.

Transmission Issues With New Foxbody

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