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house2go · 07-26-2020, 01:34 PM

Have 99 Mountain Aire Had transmission rebuilt(maybe coincident)but since then it starts and idles.Throttle up and sometimes wont rev. Changed fuel filter added seafoam and below 1500RPM acts up sometimes. Drove to get inspected ran fine there but put it in gear to leave and had no power finally got on the road, it had hesitation til about 1800 RPM (foot on brake and gas pedal didn't work). No code, no check engine light. Any suggestions?

John Hilley · 07-26-2020, 01:42 PM

I would take it back to transmission shop. Sounds like a sensor on the transmission possibly. A loose wire maybe.

house2go · 07-26-2020, 02:10 PM

Thank you that is where I will head next

Waiter21 · 07-26-2020, 02:29 PM

There is a TSB for the transmission shifting weird. i.e. starting out in 2nd. This could be misinterpreted as sluggish.

F53 – TSB Transmission shifting weird in 1st and 2nd gear – 1999 Southwind 35S

..

Mark_T · 07-26-2020, 02:33 PM

Why did you have the transmission rebuilt?

house2go · 07-26-2020, 02:49 PM

Mark_T Acted as the torque converter was bad. Started on a trip while stuck in traffic.

house2go · 07-26-2020, 02:52 PM

Waiter21 Interesting read I will follow up on it. Awesome site I have some reading to do Thanks

Waiter21 · 07-26-2020, 07:32 PM

ALSO - When they rebuilt the tranny, did you also have them replace the engine radiator and plumb it for the transmission cooler.

Your 99 didn't come with an integral transmission cooler in the engine radiator.

leadman · 07-30-2020, 06:24 PM

If it is not the trans, but probably is, symptoms sound like a bad cat. Has this been giving you problems like this before the trans rebuilt?

Waiter21 · 07-31-2020, 06:41 AM

Code.. Any codes set???

house2go · 07-31-2020, 04:41 PM

@Waiter21 It has a transmission cooler. Radiator not replaced was flushed. I was told that is was a trans sensor yesterday( at a different shop) and when I stop by he will give me the codes. He said it was reading 50mph while idling.

house2go · 07-31-2020, 05:18 PM

Quote:

Originally Posted by leadman

If it is not the trans, but probably is, symptoms sound like a bad cat. Has this been giving you problems like this before the trans rebuilt?

Started when in traffic, felt a slip. Took it to a recommenced transmission shop. When it was done the owner called and said they test drove it. He she it has a hesitation, did I want his mechanic look at it. The conversation did not end up calm or polite. I have my motorhome, he has my money.

Waiter21 · 08-01-2020, 06:33 AM

house2go, After reading your #11 post, I believe you have two issues that are causing your problems. Please read carefully

1) You said that the VSS was showing 50mph, even though the vehicle wasn't moving. The TSB link I gave you in post #4 is for weird shifting in 1st and 2nd in 1999-2001 F53's This is caused by contaminated speed sensor data due to noise introduced by bad grounds. The transmission thinks the speed is different that what it really is. This sounds like what your experiencing. Make sure your transmission shop is aware of this TSB. Quote from the TSB:

"... A vehicle speed input to the Powertrain Control Module (PCM) may be noticed ... even when the vehicle is not moving..."

2) 1999 / 2000 did not come with an integral vehicle coolant transmission cooler, (a transmission cooler as part of the vehicles radiator) they came with their own dedicated cooler (radiator). This cooler was OK at highway speeds, but offered little to no cooling when the vehicle wasn't moving or moving slowly. (stop and go traffic)

Ford replaced a lot of 4R100's because of overtemp events (transmission overheating)

Without the integral cooler, on warm days, if you're in slow or stop and go traffic, there is little / no airflow through the transmission cooler. The transmission is producing a lot of heat because of the torque convert slipping, and with limited transmission cooling and reduced airflow, you could have a transmission over-temperature event, and enter a LIMP mode. This was common for these two years of F53 with the 4R100 transmission.

In 2001, Ford started installing the integral radiator in addition to the external cooler. With the integral cooler, transmission heat is transferred to the vehicles coolant. when the vehicles coolant starts getting to warm, it causes the fan clutch to engage and cools the vehicle coolant.

When I had my engine tore apart for exhaust studs, I didn't replace my radiator with one that had an integral cooler radiator because I wasn't aware of this issue at that time. URGH.....

I found out about this later when I started looking into why I had a external in-line transmission filter. Whenever Ford serviced one of the early F53's, they were instructed to add the in-line filter. It didn't solve the cooling problem, but I guess they figured it could delay any damage that an over-temp event could cause.

How to reduce transmission heat

Torque Converter slippage is the source of heat. To mitigate over-temp events on mine, when I'm in slow or stop and go traffic, I'll shift into "N" to eliminate torque converter slipping. I also have a PID on my Torque app so I can monitor transmission temperature. I like to see it below 200 deg F.

If I ever have a reason to remove my radiator, I'll replace it with one that has the integral transmission cooler.

Waiter21 · 08-01-2020, 07:42 AM

My recommendations:

1) Do the TSB. The special harness called out for in the TSB is no longer available but you can use the existing harness, I cut and spliced the ground wires to one piece of wire a couple feet long. I then moved the existing ground to a new ground point and installed the new ground wire to the old ground point. clean away all paint from the ground point, these MUST be clean fresh metal.

2) Install a new Speed Sensor on top of the differential.

3 Either install a transmission temperature gauge, or use the Torque APP and the special transmission PID to watch transmission temperature if in slow traffic.