Lincoln vs Cadillac Forums

(This is the forums archive - If you want to get back to the main site simply click the banner above and you will be taken to our homepage.)

Lincoln vs Cadillac Forums is the Ultimate Online Resource for Owners and Enthusiasts of American Luxury Cars. Feel free to browse through our archive - but make sure you make it back to our main site - Lincoln vs Cadillac Forums

Cadillac XLR : Cadillac CTS : Cadillac : 2005 Cadillac STS : Cadillac Forums : 2000 Lincoln LS : Lincoln Mark VIII : Lincoln Mark VII : Car Wax
Lincoln Town Car : Lincoln Air Suspension : Lincoln Continental : Lemon Law : Do It Yourself Car Repair : Lincoln vs Cadillac Forums : Mesothelioma

Back to the Archive Main Page

Pages: 1

Need Help Please - Trans Problems!!!

(Click here to view the original thread with full colors/images)

Posted by: ruswin

I am really frustrated about my 94 M8 that has a gremlin running around somewhere. I have an intermittent problem that occurs only once in a while mainly when I am above 55 mph. The trans shifts out of OD and into 3rd, and then back to OD. Even if I switch off OD and try to drive in 3rd, every once in a while it will take itself out of 3rd and go into OD. At times it even seems to slip entirely out of gear momentarily. The other factor seems to be related to electrical draw because it mainly happens at night when my lights are on. This is the second trans that I have installed that has the same problem, so I doubt it is internal to the trans. This trans was installed about 8 weeks ago and ran great for about 2600 miles before the problem re-emerged. This is the same problem that the original trans had when I replaced it. The battery / charging circuit seems to be OK (no hard or sluggish starts) but I still suspect something electrical. I have quadruple checked all of the connections to the trans itself, and it does not seem to be a loose wire. It occurs on smooth highways randomly. I have tried replacing the MLPS. It does not seem possible to me that the trans has an internal problem, because most of the time it runs great and shifts great. I installed a 1998 Grand Marquis trans re-pinning the harness and replacing the lockup solenoid with the older version. Man... I really have no idea what else to look for. Any other ideas? Could a high electrical draw from the AC / stereo / lights cause these symptoms? Would Ford be able to diagnose the problem considering that it only happens once in a while?

Posted by: XLRVIII

man I hate to suggest this....

But a goofy or misreporting TPS sensor will cause all kinds of goofy shifting problems.
Since it's a first gen, changing the TPS isn't going to be a fun job.

TPS=Throttle Position Sensor.
when it goes "stupid" it makes your PCM think your giving it more or less gas than you really are.. and will make the shift schedule do "stupid stuff".

Posted by: wood_e

Maybe it's just me but replacing my TPS was easy... I just removed the throttle body.

Posted by: Moes8

Quote:

Originally Posted by wood_e

Maybe it's just me but replacing my TPS was easy... I just removed the throttle body.

i have yet to try replacing mine,but that sounds like a great idea,if i ever have to

thanks

Posted by: ruswin

Would a bad TPS actually be able to "command" the trans to disengage the OD over-ride function? A bad TPS would make sense if it was just downshifting, but when I put it in 3rd by activating the OD override, it will go back into OD on it's own and the Green indicator light for OD override turns off. I don't think a funky TPS could cause that. I would think the only thing that would disengage the OD override is the momentary switch or the computer....

I just drove it again today during the day for about 40 miles and it shifted fine again. Could there be a funky ground connection or something else simple to look for? I am even thinking about trying another MLPS, but I really don't think it is the problem either.

Posted by: chicken

the wires to the button could be chafed, somewhat common problem

Posted by: wood_e

Quote:

Originally Posted by Moes8

i have yet to try replacing mine,but that sounds like a great idea,if i ever have to

thanks

No problem - it was super easy with removing the TB.

Posted by: Markviiiedrea

Well if you already have a ne MLPS, try the TPS. If you don’t want to throw 40.00 away go get a few from the junk yard, I believe there the same on most fords. If it works then go get a new one.

Is the problem getting worse the more you drive the car or is it faulting out constantly?

Posted by: ruswin

The problem occurs VERY randomly, not very often. It did not happen for the first 2500 after I installed the used trans. Besides shifting from 4 to 3 or 3 to 4, it also seems to completely come out of gear (neutral) rarely also. That is why I have a hard time believing that it is the TPS.
What would command the trans to go into neutral except the MLPS? I have an assortment of MLPS from past projects as well as the new one I installed. I have tried installing the others, with basically the same results. This problem really sucks because it is impossible to predict when it will happen again.

Posted by: XLRVIII

Quote:

Originally Posted by ruswin

What would command the trans to go into neutral except the MLPS?.

a blown up or nearly blown up 1 way clutch

Posted by: ruswin

Would a blown one way clutch allow it to run without a problem for 50+ miles and then randomly start failing again? There is really no pattern to it, it runs great most days, then every once in a while it will happen again. I don't know squat about internal trans workings but mechanically I would think it is OK or else it would be progressively be getting worse and not allow freeway blasts at 85 mph for 20-30 minutes at a time without any problems. Hmmmmm.......

Posted by: Rich88LSC

This sounds like MLPS symptoms to me. Just because it's new doesn't mean it's not bad. I would look at that or like chicken said look at the wiring.

Posted by: ruswin

I have 2 other MLPS that I have tried... used but they seem OK. The problem happens when either of them are installed, I guess it is possible they are all bad? I have replaced the shifter handle previously because the thumb button was broken. Is there anyway to completely eliminate the OD switch from the circuit to test if it has anything to do with that switch?
Is it at all possible that there is a charging system or electrical problem with the alternator, battery ect. I have noticed lately that when the car is first started, it cranks for 5+ seconds and does not fire usually. Releasing the key and turning it a second time and it fires right up. Could these symptoms be related? I don't remember having that problem when the trans was working perfectly. What a pain in the A@#!

Posted by: ripped camel

Where's the tps located?

Posted by: ruswin

TPS = Throttle Position Sensor is mounted on the intake throttle body.

Posted by: Chadly

If the OD OFF light goes off too by itself, I would agree its the wires getting chafed. Thats at least something easy to check and rule it out if its not the case. I would start there.

Posted by: ruswin

I checked the wiring to the OD switch, it seems OK. I do not think that is the problem because when it downshifts to 3rd on it's own, the green OD over-ride light does not turn on. I am thinking it may be the TPS because feathering the throttle will sometimes cause the problem to occur. XLRVIII was the first to suggest that as being the problem. I am going to try a new one. I just want to confirm that the TPS for the 94 Mark 8 is Ford # F2AF-9B989-AA? Autozone has 2 different numbers for it, the other is wrong according to Ford.

Posted by: chicken

id only go ford, fukk auto zone!!!!!!!

Posted by: ruswin

Normally I'd agree... but the Motorcraft part was $78, Autozone was $35. I just got done installing it an unless it is bad out of the box, the TPS is NOT the problem. I just took it for a test drive and it is still doing the same thing.

How and why would it take itself out of OD over-ride is what I do not understand. I might still suspect the MLPS if it was not for that symptom. The wires going to the OD over-ride switch are fine. How can it drive perfectly fine one day and then like

e the next? I am soooo frustrated with this car!!!! WTF?

Posted by: ruswin

Just a follow up... yesterday the car ran fine for the entire trip back and forth to work, 40+ miles. When I got back home, I checked the trans fluid level, it is a little bit high... could too much trans fluid cause anything like this to happen? The only thing I did to it since installing the new TPS is to remove and re-connect the battery terminals. I swear there is something going on electrically, charging system, a bad ground, alternator problems, something intermittent. I am hesitant to bring it into to Ford to diagnose because it is so intermittent, they may not find any problem while testing or driving it.

Posted by: XLRVIII

Was the engine running when you checked the fluid or was it off.

If it was running and it seemed high it probably IS high
If the engine was OFF and it seemed high it wasn't.

ALSO, you want to check, re-check the fluid level and re-check it.
each time turn the dipstick a little bit so you are very certian your getting an accurate reading and not scraping fluid off the stick, or scraping fluid off the inside of the dipstick tube.

I've seen .5 qrt differences in level depending on how I stick the dipstick tube in
Just check, check and recheck until you get "repeatable results".

Posted by: XLRVIII

too much fluid could cause problems due to foaming..
too little fluid can also cause problems with overheating and pump failure ect.

Posted by: ruswin

I have checked the fluid level and found that maybe it was a little high, I took out about 1/2 quart. It has NO EFFECT on the problem. Saturday it ran great for normal trip of about 45 miles. Then Sunday on the same trip, it kept having the same problem. I am noticing now that it is not only going from 4th to 3rd, but also 4th to 2nd occasionally. It happens most frequently as soon as it shifts from 3rd to 4th and the torque converter solenoid locks up. I am beginning to suspect something going on with either the TC or a solenoid / wiring issue with it. When I installed the 1998 trans in my 1994, I did change out the TC solenoid and modify the connector to fit onto the newer style wiring "harness" inside the 1998 trans. Any chance that is screwing up? What are the chances of Ford being able to test and find the "problem" if I take it into them? Can they check all of the sensors and solenoids for proper operation?

Posted by: XLRVIII

"maybe" a goofy connection to one or both of the shift solenoids?

only way to tell would be to pull the pan and check/reseat the connectors.

could have it scanned, but if the problem isn't occuring they might not find anything, you'd have to scan it while the issue was occuring.

They have a "test" harness they can put on teh trans and command each of the solenoids, but if it's a loose connector it may or may not show anything.

might be time to drop the pan and check it out.

could be the fluid is moving something around causing the intermittant problem.

Posted by: ruswin

If nothing else... I am going to end up knowing a lot more than I ever wanted to about the 4rW70!!!! Yeah it sure does seem 99% likely that is is electrical, solenoid connection possibly. What if the TC lockup solenoid was just cutting in and out, do they go bad? It really now feels related to the 4th gear and / or the lockup solenoid....

Posted by: ruswin

Some new developments. The problem continues, but I am now zeroing in on some other symptoms. When the shifting problem occurs, I can smell exhaust inside the passenger area and at times the AC compressor will stop running. It now seems that whatever is causing the trans to downshift is NOT the trans itself. Could clogged cats or something else related to the O2 sensors have anything to do with it? I have cut off my mufflers and extended the tailpipes back. Normally there is no exhaust smell inside the cabin, but when the shifting issue occurs, I notice a strong exhaust odor. The problem also seems to occur when the vehicle is not warmed up, about 1/2 way home on my 20 mile trip, it will start shifting perfectly. The last hint is that it NEVER happens on acceleration, only while cruising at a set speed of 50-65 mph. As long as I am in the gas fairly hard, it pulls strong without hesitation. Any other ideas?

Posted by: ruswin

The nightmare continues... I brought the car to Ford today (of course it drove PERFECTLY the entire 20 miles) and I assumed if ANYONE could figure this out, it would be them. After doing pressure test and checking for any engine codes or errors, he said they could not find anything wrong. He also said that because I installed a 98 trans in a 94, their scanner cannot "talk" to the trans? He suggested I take it to an aftermarket transmission shop because they have different scanners. I think it is bull

, so I have no idea what to do next. The more time that goes on, the more it seems the actual cause of the problem is NOT transmission related, but the trans shifting is just one of the symptoms of the actual problem. Help?

Posted by: rayner601

Quote:

Originally Posted by ruswin

The nightmare continues... I brought the car to Ford today (of course it drove PERFECTLY the entire 20 miles) and I assumed if ANYONE could figure this out, it would be them. After doing pressure test and checking for any engine codes or errors, he said they could not find anything wrong. He also said that because I installed a 98 trans in a 94, their scanner cannot "talk" to the trans? He suggested I take it to an aftermarket transmission shop because they have different scanners. I think it is bull

Last I remember, scanners don't "talk" to 4R70Ws...it's the PCM the scanner talks to and the PCM actuates solenoids or reads sensors

Do you have an oil leak? If so, check the harness that the trans is connected to. My 95 Cougar and 97 Mark 8 had oil leaks when I got them. The insulation on the wires fused together and caused all kinda hell...gear position data errors, rear o2 sensor codes, horrible shifting, blowing fuses when in reverse, no hazard flashers, no turn signals, auto lock not working, speedo not working right....

Posted by: ruswin

Thanks rayner601, the car is real clean underneath, only 64,000 miles and NO leaks. I would hope it is simple as that. Well I went ahead and dropped it of at another trans shop to see what they can find... I will let you know what is found in the end hopefully.

Posted by: ruswin

This is an update. I have recently installed a new battery, alternator, ground wire, cleaned and reconnected all other main wires. That seemed to help a rough idle and hesitation, but did nothing to solve this problem. REFRESHER... While driving above 50-75 mph, the transmission will downshift to 3 and sometimes to second if my forward speed is low enough. When it happens, my AC clutch is also turning off momentarily which leads me to believe it could still be a bad TPS or a short or something giving the computer a WOT or similar signal causing the AC to shut off and the trans to kick down. My question is this, I have replaced the TPS already, what else should I look at? Where do the wires from the TPS go? What terminal on the ECU does it connect to? Is there any way to monitor the TPS signal while driving by using a volt meter in parallel? Any other ideas would be HUGELY appreciated.

Posted by: NoLimit95

Your idle problem is going to most likely be the IAC. It's next to the TPS but over to the left and has 2 bolts holding it in.

Your O/D problem is the 3-4 shift solenoid or w/e others call it. My 94 done the same thing. It only happened after the car warmed up but while it was cold, O/D would work perfect. It will eventually not have O/D at all. I'll show you a picture of mine and the hardest part about changing it was removing the Trans pan. The 3-4 shift solenoids are held in with 2 bolts and it plugs in. I changed mine in 2005 and I have had O/D ever since. Look below and you will see two silver boxes with black dots in the center. That comes all in one piece and it will fix your problem. Take yours with you to make sure the bolt pattern matches up. I learned the hard way that some parts stores carry them but bolt patterns do not. The cost of the part was around $60 and the IAC you need for a good idle will be around $65.

Posted by: ruswin

I am not ruling it out... and I appreciate ANY suggestions at this point, but why would the shift solenoids affect the AC clutch? I am looking for a common cause for the symptom of the trans down - shifting and the AC clutch turning off at the same time. Ford has no fricken idea what is wrong with it.

Posted by: NoLimit95

OK, I'm just now catching on to the AC problem. Now that I see you have put in a 98 trans and having AC problems when the shifting things starts, scratch out what I said about the 3-4 shift. It still could be some of theproblem but your idle I can almost say for sure is the IAC. I had a bad idle and sometimes would kill out at the first start and then crank fine on the 2nd start but idled very low. I changed out the TPS and it made it better by 100 rpm's and then finally changed out the IAC and now I couldn't ask for a better idle. STarts up at around 1000 rpm's and then lowers on it's own down to around 700 to 750 rpm's.

Posted by: turn_on68

Quote:

Originally Posted by ruswin

I am not ruling it out... and I appreciate ANY suggestions at this point, but why would the shift solenoids affect the AC clutch? I am looking for a common cause for the symptom of the trans down - shifting and the AC clutch turning off at the same time. Ford has no fricken idea what is wrong with it.

A/C shuts off because of higher RPM's, when you go above a certain RPM the compressor disengages to give more power, then re-engages after it shifts.

Posted by: ruswin

The IAC is about the only thing I have not replaced... what the heck... I will give it a try for the idle problem. I can live with a slight high idle but... it is the other crazy problem I still need to solve?

The RPMs do not climb above 3000 even if it downshifts at 80 on the highway. I thought the only way the AC clutch is disabled is under WOT conditions?

Posted by: XLRVIII

Quote:

Originally Posted by turn_on68

A/C shuts off because of higher RPM's, when you go above a certain RPM the compressor disengages to give more power, then re-engages after it shifts.

The AC "shut off" is not RPM based

it's TP/Load based..the setting is "turn off AC at WOT".

Unless something is tellling the PCM he went to WOT the AC shouldn't shut off at "any RPM".

I'd test the TPS

At idle you should have between .9-1.0 volts on the signal wire
{usually a green wire) and 4.9 volts at WOT.

Once you verify these two voltages then you need an "analog voltmeter" to see if the TPS has any "bad spots".
Using a digital guage wont work in this case.....

You want a smooth sweep of the analog needle, from idle TO WOT.
If the needle jerks, hangs or otherwise doesnt sweep smoothly then you have a bad TPS {irregardless of the fact it's new).

If the TPS is bad and voltage is jumping around it'll make all kinds of goofy stuff occur.

If the analog needle makes a smooth uninteruppted sweep from .9V-4.99V then the TPS is NOT the issue.

Posted by: XLRVIII

Quote:

Originally Posted by ruswin

I thought the only way the AC clutch is disabled is under WOT conditions??

That is correct

Posted by: XLRVIII

IAC valve is not causing a downshift nor AC cut out... it simply "CANT".

Posted by: ruswin

Thanks ALL!!! I will get an analog meter and test the TPS. I also was wondering if it is possible to tap into the TPS signal and actually watch it inside the cabin while driving? The TPS just has 2 wires, a 5 volt and a signal correct?

One more question... what do you guys do that allows you to be online all times of the day and respond to questions like mine?

Awesome... thanks!

Posted by: NoLimit95

Quote:

Originally Posted by XLRVIII

IAC valve is not causing a downshift nor AC cut out... it simply "CANT".

Correct but it could be causing his rough idle. It will have no effect with the 3-4 shift. Bad TPS, possibly but doubtful. 98 trans swapped into a 94, bad solenoids is where I'm leaning for some reason.

Posted by: XLRVIII

MLPS would be suspect before Shift Soleniods...IMHO

Might give it a shot to adjust the MLPS, it's been known to cause some goofy shifting stuff just like he describes.

I smoked my shift solenoids and the car only had 2 gear.

Posted by: NoLimit95

Quote:

Originally Posted by XLRVIII

MLPS would be suspect before Shift Soleniods...IMHO

Might give it a shot to adjust the MLPS, it's been known to cause some goofy shifting stuff just like he describes.

I smoked my shift solenoids and the car only had 2 gear.

True too! His also seems to be different than mine was. I didn't have O/D after the car warmed up. From a cold start, I could drive 100 miles as long as I didn't have to stop and I would still have O/D but if I ever did stop, all I would have is 1st, 2nd, 3rd. I did buy a new MLPS first but it didn't do any good until I got the 3-4 solenoids and put them in. I wished that parts store was still open. He was one of the old school guys, about 70 that had been in business for 40 or 50 years and always had OEM parts but the chains eventually put him out of business.

Posted by: ruswin

I have finally been able to test and monitor the output voltage (0-5vdc) from the TPS inside the cabin. Here is how I did it.

http://www.lincolnvscadillac.com/sho...737#post575737

Posted by: ruswin

This is like a soap opera, but maybe there is a happy ending. My AC clutch finally gave up working a couple weeks ago. After removing the pulley, it appears the clutch has burned up electrically also? (see photo) So I purchased and installed a brand new compressor, receiver-dryer and orifice tube. My hope is that since the shifting issue I have been experiencing seems to have occurred when the AC was operating, and since the AC cut-out at the same times that the shifting problem occurred, that somehow the shorting or damaged AC clutch could have affected the shift schedule or send a bad signal to the PCM? I have now driven it for only about 60 miles or so since the installation, so far so good. Time will tell if this really solved the problem. Check out the photo of orifice tube I removed from my "working" AC system, and the new one. Amazing how much crud accumulates and how important it is to change the orifice tube when possible... Using a small pick I ground down to fit inside the tube, it came out about the third try. I try to keep my AC working up to specs... especially here in Arizona where we run the AC 10 months out of the year! Keeping my fingers crossed.

Posted by: kustomizingkid

Holy crap!!

I know nothing about AC servicing... all my cars have had working ac, never had to dig in and fix it... yet

Posted by: rayner601

It appears that you have a failing compressor...

Posted by: kustomizingkid

Quote:

Originally Posted by rayner601

It appears that you had a failing compressor...

Fixed that for ya...

Posted by: ruswin

This is a follow up to this lengthy problem. I just hope this thread helps someone else someday. After replacing the melted A/C clutch, the car has run perfectly for about 2500 miles. No more shifting issues. How the burned up AC clutch could have possibly affected the transmission enough to downshift I have no idea? Thanks for everyone's help!!! Now on to the next problem... I cannot communicate with the computer to pull codes... that is another thread...