Correct shifting when cold, hazardous shiftings when hot (or no shift).

[GEN 3 SHO FAN]

I don't know what to think about these symptoms...

I just finish to replace all the rear coils because I have misfires at low and high rpms. I realize finnaly that it's a broken spark plug... Did the rear coils change anyway and replace the intake. I took the car some times since to go to work (25% city and 75% highway). Starting : ok, RPM : ok (no more misfires), heat : ok (25% gauge), shifts 1-2-3-4 : ok. Problem resolved, great.

But yesterday I decided to take the car and give a saturday night concert with my yamaha music instrument. After around 30 min. of city driving only, the car begun to have hazardous shifts. The RPM go up past the normal shift point and then it shifts with a **** or just not. It never does this when going to work. this trouble was there before I remove the surge tank and I tought I was caused by a bad coil. The trans fluid is clear red but not sure is the good one. I also notice that this seems heat related trouble (hot day or city driving). Downshifts are ok. Not sure it is related but I noticed the idle RPM was little irregular going between 600 and 700 (motor relearning to work with 8 cylinders ?)

I rode a lot here and on V8SHO site. I think about the things causing this (many). I didn't rode the codes recently, I will do this this week-end. Great thanks to you guys here I know some had probably face this kind of problem and will help me with it. I'm a little lost by now. Here it's the possible causes (from what I rode) :

1) The rear wiring harness which was toasting on the rear valve cover. I was forced to scratch it out from the cover. I checked the wiring and some isolation still there. I put isolation all along and modified the two metal brackets holding it to keep it away from the cover and not sticked on it (very good idea Ford !). Maybe it's damaged after all and I have shortcuts in it ?

2) The TPS (throttle position sensor) is not working correctly. I rode some posts on that. It's play on shifting. I don't remember the symptoms of a bad TPS... This part take time to gets hot it's why I'm thinking about it.

3) A faulty camshaft position sensor or a faulty crankshaft position sensor. These parts give the RPM to PCM. With time, they seems to accumulate carbon on the part inside the motor giving bad readings or simply no signal (with no start).

4) The possible bigger problem, a faulty transmission. From what I rode, it's may be the trans have faulty seals that when trans heat build up make the trans working not correctly during mostly in 1-2 shifts (something called ''flare hot''). When I bought the car, the guy selling it was a transmission guy saying he have too much cars and said to me that all was good on the car... The trans fluid seems to be almost new... (Bad fluid or bad guy ?) However, I took the car many times in hot summer days last year and I didn't notice that trouble. (Note : try first the Lucas Transmission Fix just in case if it's worn seals or dirty valves)

5) Also in last summer, we changed the gas tank (leaks). Maybe something went wrong with the fuel pump during replacement ? I rode in troubleshooting section that a guy had acceleretion problems and it was the fuel pump relay. I put the link for reference. From what I remember, I noticed the trouble after that (later in last summer). But I'm not sure how it can be a heat related trouble.

http://www.shoforum.com/index.php?threads/96-sho-bogs-down-on-acceleration.129479/

6) Something on the intake was not replaced correctly when I rebolt the intake last summer. Less possible but possible too, no ?

I don't want to scrap this car even if I hadn't paid a lot for and because I worked a lot on it. Thanks again guys,

 

[sperold]

Y0u have to start by reading the codes. That is your best and easiest path to solving this problem.

Of all your guesses, the TPS is your best one, but wait for the codes before you buy anything.

A lot of people add either a better or an additional transmission oil cooler and larger, usually flex lines. This is done to prolong the life of the automatic transmission, not to solve a shifting symptom.

 

[GEN 3 SHO FAN]

The classical P1413 : the secondary air pump (probably the relay)
and the P0453 : a sensor on the top gas tank which I removed because I bought the wrong tank... (96 only IIRC, three holes on the top).

The cams are welded and are in perfect position (before someone ask).

I will first try to change the trans fluid because I had heat issues last summer with the 3rd cat bottled with broken parts. It's seems that the fluid can lose quality with too much heat even if it stay red and clear... But I don't know we can put flex line. Where we can find this kind of thing ?

I found this that can explain why heat build up with time in transmission...(figure 1)
http://www.v8sho.com/SHO/TSB981312TransaxleFlushing.htm

Do you know the symptoms of a bad TPS ? It's affect all the shifts or just the one for overdrive ? Does he have a link with IMRC ?

Thanks for the infos,

 

[sperold]

If there is no code, then the TPS is OK.
I would only change the fluid in the tranny if it smelled burnt, and don't bother with larger lines just yet, as I doubt it is contributing to the issue.
I would work on clearing those codes, try to get that air pump working correctly (and make sure it is not seizing or something) and that gas tank sensor too. I don't know enough about those two things, but maybe they disable something as part of their job of having you limp home when they fail. Someone on here will know the downstream affects of these things.

 

[GEN 3 SHO FAN]

It's look like the trans have difficulty to cool down with time. Some had this issue but with diffrents symptoms. I found this other link on V8sho.com :

http://www.v8sho.com/SHO/SHO RadiatorTransmission Cooler - How To Clean.htm

It's seems the flow thru the rad cooler is not the same for 96-98 (enter by the top) vs 99 (enter by the bottom) ? Maybe I miss something.

For the 2 codes, I think they are not related but I want to eliminate them, I must first find a good gas tank ($$). Will see after a fluid and filter change and a backflush of the rad how it goes.

Thanks,

 

[GEN 3 SHO FAN]

Update:

Today, at the end after 30 min. of my ride to work on highway, I try to accelerate enough to have a kickdown but nothing just a light accel... Maybe the trans going hot. (?)

Is the TPS throw always a code when goes bad ? Is it interchangeable with SLO ? I want to make some tests. What it does if I deconnect it (no overdrive) ?

 

[sperold]

The TPS is pretty important, and I would not disconnect it. It has a voltage range it operates in, and if it is above or below, it will send a code. Small chance it is acting up but still in range. I have heard of people moving them manually and watching a voltmeter to see if it is a linear event. Check on RockAuto to see if the TPS is the same part number for all Taurus models.
The TPS has a larger affect on how the motor runs Vs tranny shifting issues. When the motor runs like crap, then the transmission can act up in response to the motor.

The Spectrum gas tanks are made in Quebec, so you could hunt around for a deal.

There is a transmission cooler in your system, so look around, find it, and clean it up.
The "cooler" in the rad doesn't do a lot of cooling in the summer, it is more for warming up your fluid in the winter, so you can get into overdrive quicker.

If you felt like experimenting, you could plug-off your rad and tie the two cooler lines together with some flex and see if things improve in the half hour test.

Take the belt off that air pump, give it a spin by hand to make sure it is not seizing.

 

[GEN 3 SHO FAN]

Ok thanks, lot of work. I will put the results here when I can. The TPS can be cleaned too (break cleaner ?), I will check his plug at least.

 

[GEN 3 SHO FAN]

Ok, I changed fluid and filter.

Seemed to better yesterday (more nervous) but today, in the heavy traffic, the car become weaker and weaker and the trouble strike back (but it's take a little more time). I talked about that with a friend specialized in transmission. He said that is could be a heat issue from the cooler restrainig fluid circulation or as valve and pistons ages, they create heat too and then = transmission rebuilt. I will try to bypass the rad cooler to see if the problem still there.

Anyone have an idea about that ?

Thanks everyone,

 

[stephen newberg]

Certainly sounds possible. Adding in a cooler that bypasses the run through the radiator certainly cannot hurt, regardless.

pax, smn

 

[jimtash]

The torque converter in mine let go at roughly 83K miles. Shifted fine when cold but erratic when warm. Engine felt like it had a bad misfire but it was actually the converter locking and unlocking rapidly and the transmission shifting to compensate. And this is all due IMO to having a shop force the fluid out with one of those pressurized ATF transfer pumps they use.

Had it replaced along with the transmission rebuilt and a shift kit installed at the same time. Runs nice and shifts like it should.

 

[GEN 3 SHO FAN]

Interesting, looks like my symptoms. I don't know if you rode the TSB Jimtash but Ford said in it that the flush must be in the reverse or it will be aggravate the problem (the cause isn't described).

"Power flushing MUST begin with back flushing followed by forward flushing, otherwise, the restriction could be further trapped in the internal mesh-type baffle of the cooler and flushing will not be effective or possible."

Maybe their power flush was in the same direction as normal flow...

Yesterday, we put a finned tube in place of the rusty metal hose behind the rad fans and a rubber hose bypassing the rad going directly to the factory upper front cooler. I remarked that my front trans cooler isn't finned but the power steering one is... (factory error ?) I saw many normals Taurus and it's the reverse.

The trans seems ok today, but it's a cloudy and cold day, I will see in the next days.

 

[jimtash]

I also installed an auxiliary cooler when it started acting up. Didn't do anything because by that point, the damage was already done. I do know when we were test driving it and he had it hooked up with a scanner, the trans temps were excellent with the extra cooler. Can't remember the exact number but it was in September and the ambient temps outside were in the 80's.

 

[GEN 3 SHO FAN]

Ok, but did you bypass the radiator cooler because he has tendency to clog (and then less cooling and flow) ? I had no problem even in medium trafic from now but the temp had not reach 75 (the problem will occurs automatically at this temp before)...

Keeping watching...

 

[GEN 3 SHO FAN]

Update :

I tried the car yesterday in heavy trafic and a temp around 82 for 45 min. and the trouble comes again but in a softer form (no hazardous shifts just skip shifting point). Now, I know it's relative to the flow of oil and heat. As some said before, I can put a aux. cooler (small rad form).

But I have a question. When I searched Mercon V for my trans in store (Canadian Tires), all I can find was a all purpose trans fluid made for Honda, Toyota and replacing Mercon V in old vehicules... Maybe it's not the best for this trans. Someone knows which brand is the best for this 1996 trans ? I put this same oil in the SLO and no probs.

Thanks for your help,

 

[stephen newberg]

I would not buy that stuff from Canadian Tire. Go to your local Ford dealership if you must, or a LordCo or such, and buy a real Mercon V rather than a no name substitute. The cost will be higher, but you will know for sure what you have.

pax, smn

 

[GEN 3 SHO FAN]

Well, Ford still have Mercon V for 7$/liter... (x12) I'm beginning to be tired of this...

 

[SHOdded]

No Castrol Transmax available? That would be a good alternative.

 

[GEN 3 SHO FAN]

I already took Motorcraft one. But I will wait to have an additionnal cooler to put to change oil in the same time.

I found this maybe it's related :
http://www.shoforum.com/index.php?threads/od-light-flashing.93445/#post-963582

The symptoms are similars and it was the electronic pressure control solenoid (EPC) that was in cause.

 

[GEN 3 SHO FAN]

I tried a bottle of Lucas Transmission Fix (because someone here tried and it's worked for him). Before putting this, I rode many customers comments on this stuff and 9/10 there were very good (reduce trans heat, eliminate hard shifting, slipping and seal leaks). I put this stuff tinking if the things get worse I only have to put my Motorcraft fluid which I already bought.

Well, this thing do really what is written on the bottle ! No more hard shift, no more slips and less hesitations (-80%). The weather get warmer here and the trans works great even that. It's take some time to the product to "clean" the trans (between few days and 2 weeks) but the problems fade away progressively during this time.

Some will says that it's probably just a "bottle of time" but time is money...