Transmission downshifting problem

[las59]

1998 Windstar 3.0 engine with the U vin code, 229K original engine and AXAS transmission.

I have posted on other forums on this issue without any results. I realize this is a Taurus forum but the 3.0 in the Windstar is not very popular so I am asking for help here.

Issue:

When driving in town and after making turns, accelerating the engine will ping. When it pings the transmission does not shift down, upon letting up on the accelerator and then accelerating again it downshifts. ( acts just like the old tranny's with the vacuum solenoids for shifting) This does not happen all the time but quite frequent.

Work I have done.

Complete fluid and filter change
New Spark plug wires and spark plugs
New Ford TPS
New aftermarket TRS
cleaned IAC
CLeaned MAS
NO CODES (Laptop with OBDCOM software)

My next move is to replace the Transmission speed sensor or the VSS.

Would having a transmission shop check for codes do any good? Would their scanner read any codes that my scanner would not detect, Are the tranny codes all PXXXX????

No speedometer, cruise control issues.

Any thoughts, thanks

[Breeves002]

Ping as in knocking? Like a pre ignition ping?

VSS sounds like a possible issue.

I would have a trans shop read codes unless your software reads specific ford trans codes. It is possible you have none.


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[las59]

Like pre=ignition ping (detonation)

thanks

[The White Falcon]

When you say 'pings', do you mean it revs up and won't downshift out of overdrive?

I had the 'false neutral' condition like you describe, and it was a bad MLPS/TR Sensor, but you say you've replaced that. And if it slams in the shifts, which it seems like you're implying, that again points me to the TR sensor.

That being said, it does have 230k miles, which is pretty good for any car. You can check for codes, it wouldn't hurt. But if it's an intermittent problem, there might not be any. Hopefully someone else has ideas.

[las59]

Originally Posted by The White Falcon

When you say 'pings', do you mean it revs up and won't downshift out of overdrive?

I had the 'false neutral' condition like you describe, and it was a bad MLPS/TR Sensor, but you say you've replaced that. And if it slams in the shifts, which it seems like you're implying, that again points me to the TR sensor.

That being said, it does have 230k miles, which is pretty good for any car. You can check for codes, it wouldn't hurt. But if it's an intermittent problem, there might not be any. Hopefully someone else has ideas.

No it does not rev up, it pings like it in the old days when the timing was advanced too much. The transmsission does not shift down from overdrive , and I have also had the overdrive turned off to see if it made a difference and it also did it in third, not shifting down to 2nd. I should also add that it does this when coasting to reduce speed. The engine is lugging causing the pinging.

I will check into getting codes read but if it too costly to get them read I am going to replace the transmission/turbine speed sensor on the driver side of tranny first then if all fails the vehicle speed sensor. We are supposed to get a cold snap and I do not have a garage, doing work in the parking lot.

Thanks and any other suggestions are very much appreciated.

[behlinla]

Sorry I don't have an exact answer but rather a list of things to check or report:

• Did you check for strong spark on all cylinders to make sure the ignition coil isn't weak? (There's a video in the misfire help topic)
• What are the fuel trims at the time of the pinging during acceleration? What RPM does it occur at?
• Just to be clear, are you feeling pinging or is it a bucking or jerking feeling?
• Does the TPS voltage respond smoothly and properly on the scan tool? It should be less than 1 volt at idle and go up to about 4.5 volts at full pedal travel.
• Did you disconnect the battery (5 min) after replacing the TPS to reset the throttle closed position?
• Does the engine perform at wide open throttle (WOT)?
• If you have a vacuum gauge, what does it read at idle (include your rough elevation), and what happens when you hold the revs at 2500 RPM for 10 seconds? How does it respond to quick throttle snaps open and closed?

[las59]

Originally Posted by behlinla

Sorry I don't have an exact answer but rather a list of things to check or report:

• Did you check for strong spark on all cylinders to make sure the ignition coil isn't weak? (There's a video in the misfire help topic)
• What are the fuel trims at the time of the pinging during acceleration? What RPM does it occur at?
• Just to be clear, are you feeling pinging or is it a bucking or jerking feeling?
• Does the TPS voltage respond smoothly and properly on the scan tool? It should be less than 1 volt at idle and go up to about 4.5 volts at full pedal travel.
• Did you disconnect the battery (5 min) after replacing the TPS to reset the throttle closed position?
• Does the engine perform at wide open throttle (WOT)?
• If you have a vacuum gauge, what does it read at idle (include your rough elevation), and what happens when you hold the revs at 2500 RPM for 10 seconds? How does it respond to quick throttle snaps open and closed?

I have not checked the spark.

Have not watched fuel trims. Hapens after deceleration and coasting. The pinging occurs after deceleration and coasting then accelerating the transmission does NOT downshift propeerly. Upon accelerating then quickly letting up on the gas pedal and accelerating again it downshifts.
(Not jerking or bucking)

I have not double checked the voltage on TPS yet.

Battery has been disconnected a couple of times since TPS was installed.

Engine performs fine at WOT,

Vaccum at idle is at the red/green line on vacuum gauger at idle (normal operating temp idle @650rpm.) It does idle a little rough @650rpm. I need to get the idle a little higher, have not messed with it to date. Cleaning the IAC did not help. No vacuum leak that I can find.

Responds fine when snapping accelerator.

Timing does jump from 14.5 to 21 degrees while idling. WHich I contibute to timing chain wear. Chain is not noisey. I have not removed camshaft sensor to inpect for any wear on it from the syncronizer.

If other half gets home before dark I will try to get more answers for you.

I believe it is a electrical sensor not operating up to par and not telling the PCM to control the EPC correctly.

[behlinla]

I also found this: http://www.revbase.com/BBBMotor/TSb/...adPdf?id=44661

You should check the transmission fluid level and condition while hot. Low fluid causes air to be sucked into the transmission and creates a rough shift after a turn.

[las59]

Originally Posted by behlinla

I also found this: http://www.revbase.com/BBBMotor/TSb/...adPdf?id=44661

You should check the transmission fluid level and condition while hot. Low fluid causes air to be sucked into the transmission and creates a rough shift after a turn.

I will check the fluid level again. I have never seen any air bubbles on the dip stick.

This issue was present before I did the fluid and filter exchange with Mercron V.

Maybe I need to slightly overfill the fluid level and see what happens.

thanks

[behlinla]

Originally Posted by las59

I will check the fluid level again. I have never seen any air bubbles on the dip stick.

You probably know this, but make sure you're checking on a level surface with the engine running in park.