So the story begins...

Washed the engine...got water into the rail pressure sensor...it shorted out after 7 miles of driving (truck took off like I floored it, then it started to buck and the surging began, Pulled over and towed it home. Got a new rail pressure sensor and went for drive. 10 min later, P0148 code. Got home...long crank on startup twice in a row (since then it been fine starting).

Changed the fuel filter and unplugged the MP-8, starts fine and plenty of power but can feel it surging at cruise then it's fine then it will do it again. Code won't go away.

Replaced the rail pressure relief valve and the FCA valve. The code is gone and runs fine with the TST turned off, but it can be felt with the TST on and the Mp-8 unplugged.

With the engine running, I opened the fuel drain and there was a good flow of fuel.

Starts good and idles good and no codes right now.

Most expensive engine wash in my life!!!!

 

Well after driving it for 40 miles.....p0148 is back.

 

Are you using rail pressure adjustment with the TST?

 

No, it's a older one without.

I was using the mp-8, but I haven't hooked it up since replacing the rail sensor and relief valve.

 

These are just wild guesses. I'd like to see you run with a rail pressure gauge to see what is happening when you surge.

I'm thinking you've got an issue with connectivity somewhere in your plugs. If not FCA then rail sensor plugs.

I'm guessing as you surge, your rail pressure is all over the place as the signal is gained and lost due to faulty connectivity.

However, the TST being on causing it and then it is ok when off would tend to discredit my hypothesis.

 

Well after numerous calls to TST and messages.....no one answers or calls back.

Are they still in business?

 

I would recommend that you remove the TST completely.

While the factory ECM has excellent protection from water shorting out sensors, the TST may not and the TST may have gotten damaged from the water.

Once you have the TST removed, put it up for sale and purchase a Smarty programmer. Leave the TST & that mess of a harness out of your engine bay.

 

The TST unit is out of the truck, the harness has the bypass plugs in except for the map which is the factory plug (TST plug was giving a the p0069 code with the bypass plugs)

 

LOL, man you're stubborn! Get that TST completely out of your engine bay including the harness, anything else attached to the TST and any other modules, interceptor boxes, etc, etc...

 

Excuse you!!! A little arrogant are we???

The TST/MP-8 combo has been in the truck since 2006 and flawless. I made the mistake of washing the engine and not checking the weather seal on the rail pressure sensor.

Anyways...TST offered to check the box out for defects for free. It's in the mail, harness and all. And if it bad they'll contact me. As for the Mp-8 it's in the garage. This way I know for sure.

 

If you read your previous post, it sounds like you still have the TST harness connected while 2 of us recommended to remove the entire TST unit.

That's why I was calling you stubborn!

Has the truck had any issues or thrown any codes since you removed both the TST harnesss and the MP8 module?



IMO, the older interceptor type modules/fooler boxes are not the way to go anymore.

Adding all those harnesses just increases the risk of issues. Plus those interceptor boxes are trying to intercept and "fool" the ECM.
A programmer changes the firmware directly with no extra harnesses and connections.
This is why you see so many modules and boxes for sale and so many guys running a programmer like Smarty or EFI Live.

 

Truck runs flawless without the two boxes.