Modified ATX Trans Issues - Resolved!!!

[whiteguy3]

My built trans in my 94 is giving me problems. This is the same trans that was in Alex's turbo SHO. I have had it of probably 8k now and have had nothing but smiles on face with it...Until now. Car has 3.98 gears, tri-flows, solid mounts, tweecer, etc...

Was driving normally the other day and it downshifted randomly. It now shifts at 3k in each gear no matter what. O/D does work, every gear works. When it downshifts/upshifts it does it hard but does not slip. I have replaced the PCM, cleaned ports and tweecer module, TSS, VSS (might try another), the wiring from the engine harness to VSS, checked pan with nothing out of the ordinary, filter was fine and fluid level was good!!???

This trans has never seen over 190 degrees and has always hit it's shifts great. This is feeling like either a selonoid issue or electronic/sensor issue not internal. For it to do this out of the blue is weird.

I am stumped. Need some help from the forum???

 

[SeanMc]

When mine wouldn't go above 3500 it was the VSS. I also had the random downshift issue.

 

[St Louis SHO]

Vss fee shizzle

 

[whiteguy3]

I just don't get it. I guess the only thing left is to replace the VSS again and maybe zip-tie the connector tight on it. I'm in agreement with it being a VSS issue. Just don't understand how...Weird

Any other suggestions?

 

[St Louis SHO]

Wasnt Alex having issues with the VSS and/or associated wiring before he sold the car? If so, I'd dig up those old threads and take a look/see.

 

[whiteguy3]

^ Yes sir. He was. I have read a number of those threads and also talked to him today and we passed ideas back and forth.

I believe that it could be an issue of the VSS getting fried. They are very sensitive to heat and it could be an issue where the heat is killing them. idk...weird.

 

[St Louis SHO]

You running the heat shield on it? If so, then I got nothing.

 

[whiteguy3]

Negative. I don't even know where it is. Don't know if someone has one I could rob off of them though?

 

[rubydist]

there is a thin metal shield that snaps on over the vss to keep the radiated heat from the exhaust manifold from toasting the vss. if that is missing, you will have a short life of the vss. and since it is such a pain to change, adding the shield would be on my short list.

 

[St Louis SHO]

Negative. I don't even know where it is. Don't know if someone has one I could rob off of them though?

I've got one. Pay the shipping, and it's yours.

 

[whiteguy3]

I've got one. Pay the shipping, and it's yours.

Great. I'll PM you shortly.

The issue was solved yesterday when I rewired the harness from the VSS to the engine harness and swapped out a new VSS.

There have been many issues and threads started by Alex about his issues which were similar to mine when he had his Turbo ATX. He went into depth about the issues he was having and you can search the forum for those, but I have figured his and THE issue out.

He had a lack of VSS signal below 45 mph from the VSS. He changed the VSS, TSS and PCM. When that didn't fix anything he ran new wires straight from the engine harness straight to the PCM. Even though he ran those new wires it did not fix the issue. I finally found his issue when looking through his old wiring harness. He ran new wires straight to the PCM, BUT the wires from the engine harness to the VSS were fried and melted together. I am pretty confident that his problem was that those wires were fried and arching. I talked to Alex yesterday and he was bummed, but glad that this issue was figured out.

I am going to come up with a setup to try and reduce heat on the VSS and associated wiring. I hope that this clarifies for those that might have this issue.