1st to 2nd hard shift

[Spiral]

I picked up another SHO today, 1997, 106,000 miles, white with chrome wheels. The transmission shift pretty violently from 1st to 2nd, every other gear seems fine though. To me it actually feels like a delayed shift, as in the line pressure has built up tremendously before the passage opens.

Is there any easy way to check the solenoids in the valve body? Does it sound like a valve body issues?

Thanks for any help in advance

P.S. Anyone know of shops in the Twin Cities, MN area that welds cams? Or the closest?

 

[bacernate]

Mine did that when the epc solenoid failed. But I also had a flashing o/d light. Any codes in it?

 

[Spiral]

Mine did that when the epc solenoid failed. But I also had a flashing o/d light. Any codes in it?

No SES light, when I get home Ill scan it for codes. my hunch is that it would be the EPC Solenoid also, just based on my experiences with rebuilding transmissions.

Is this something I can access with the transmission in the vehicle? I guess I could see if ford could get me a fiche of it, or stop at the shop I worked at and pull it up in ALLDATA.

 

[Spiral]

Well, I am idling around 500 RPMs so I checked the voltage output on the TPS. at idle no throttle I get .90-1.00V at WOT I get 4.75V. This seemed to be in range but I figured I would pull the plug and drive it around for a little bit per a friends suggestion. To my surprise the shifts were absolutely beautiful! I bought a new TPS and popped it in and I have the same problem.

What are the general thoughts here on what could be happening?

 

[Spiral]

I also do not have cruise control. By my research the SHO does not use a VSS, does it?

 

[SHOZ123]

The V8 uses the ABS for vehicle speed input.

 

[Spiral]

That is what I read.... Hmmm....

 

[SHOZ123]

I guess you could see if the TPS sensor output is the same at the PCM.

Does the cruise light come on when active?

 

[Spiral]

When I turn it on the light illuminates on the dash. However when I set the speed it doesn't take or lock at that speed.

 

[SHOZ123]

Make sure the cable did not come off the throttle.

 

[rubydist]

I would disconnect the battery for a half hour to make the pcm re-learn all the adaptive stuff. Maybe it has learned something badly.

 

[NebraskaSHO]

I would disconnect the battery for a half hour to make the pcm re-learn all the adaptive stuff. Maybe it has learned something badly.

I just had a ton of codes, which you can see in my other thread, disconnected the neg. cable for about 4 hours, reflashed the PCM with a new tune, and I have not had any of those codes come back.

Disconnect your neg. battery cable and see what happens.

 

[Spiral]

Ill try that... I am going to my uncles shop probably tomorrow night to pick up his scan tool, that way I can see what the PCM is receiving for signals on all the sensor and make sure nothing is out of tolerance

 

[Spiral]

Well, unhooking the battery overnight didn't do anything.

 

[Spiral]

I opened up the transmission Saturday and checked the resistance on all the solenoids and they were all within spec. The veins and the pump body looked good. Put it all back together, flushed out the old fluid put in mercon v and a new filter and I am still having issues.

seems like 45-50 steady driving the RPMs move up and down a little, almost feels like a downshift/upshift.

and steady driving at 65-75 it does about the same thing.

1-2 is still HARD

 

[Spiral]

Also when I had everything apart I noticed that there is a sensor on the transmission housing (same location as the VSS). Would this be a VSS that would report back output shaft speed and send it to the PCM for it to regulate transmission pressure / shift points / tc lock-up

 

[Mr Anonymous]

You need a rebuilt valve body. Or just live with it.

The bore for the boost valve and/or the 1-2 modulator valve is scored and fluid is exhausting by it.

I lived with it for well over a year in my car with no ill effects other than the banging 1-2. Even with the line pressure turned as far down in the PCM calibration as it would go, it would still bang 1-2.

 

[1madSHO]

useful.

 

[Spiral]

Thanks for the useful feedback.

My only thought is, why does disconnecting the TPS make the shift much better? Does the PCM default to a limp mode dropping line pressure?

 

[Spiral]

You need a rebuilt valve body. Or just live with it.

The bore for the boost valve and/or the 1-2 modulator valve is scored and fluid is exhausting by it.

I lived with it for well over a year in my car with no ill effects other than the banging 1-2. Even with the line pressure turned as far down in the PCM calibration as it would go, it would still bang 1-2.

You seem to really know your transmissions, or at least the AX4N. I inquired about an AX4N "F4" valve body that has been rebuilt and this is the response I got back from company.

You are correct about the "15" plate number. We install the larger ratia boost valve in all of our AX4N's so they will work on the SHO. As far as the plate goes, we use only (4) different ones, they are all interchangble and work for all AX4N applications. If you are skeptical, we can build you one with the "15" plate. The pumps are used of they are good or we have them re-surfaced. All of the pump covers are resurfaced. Solenoids are incouded with the valve body. Thanks, Donny