Engine/Transmission (1998.5 - 2002) One Chip works and one doesn't, why?

[Turbo359]

A couple of weeks ago my truck started missing when on the throttle. Got a PO253 code. Checked electrical connections and cleaned grounds because I've had ground problems before. Truck still missed and had a PO253 again. Figured it must be the injection pump. Read alot of posts leaning toward the VP44 being bad. So I installed a reman VP44, truck still misses and has PO253 code again. :{ I've had my edge comp(no pump wire hooked up) stacked with my tst powermax competition for two years and worked great. The tst makes my truck miss. If I disconnect the tst or turn it off and hook the edge to the pump wire the truck runs fine, no engine light or miss. I put the tst in a buddies 98 2500 and it works fine, plug it into my truck, get the miss and engine light. I have good fuel pressure and tried a new map sensor and swapped injectors. Still no change Sorry for the long post, any ideas would be greatly appreciated.

 

[GarrettPetersen]

Did ya try removin the comp out of the system and hookin the TST up by its self??

 

[JCutter]

I have the same problem with my TST. When i get on it hard its like it is missing. Its done it a couple of times all i have done is disconnect and then reconnect the pump wire and make sure it has a good connection. I have the j-hook for my pump wire tap.



Hope this helps.

 

[Turbo359]

I've tried running both chips individually, the tst misses and the edge works fine. I have the pump wire soldered and it seems to have a good connection.

 

[GarrettPetersen]

I wonder if the wireing harness has a problem on the TST just shootin in the dark but maybe thats the case??

 

[RacinDuallie]

Have you ensured that all your ground wires have a clean and proper connection?

 

[Turbo359]

I put the tst chip and complete wiring harness on another 98 2500 and it works great. I have cleaned and checked the grounds, I installed individual ground wires from the battery to the ecm, pcm and an extra battery cable from the battery to the engine. I had the tst wire harness grounded on the battery, in the VP44 wire harness, and on the block. I've had ground problems before and was hoping that was it.

 

[Gary - K7GLD]

Under the circumstances, I would lean towards a borderline engine mechanical issue - weak injector, low compression or similar. Is your miss predictably regular, like it is a single cylinder, or random?



The added demand of one of the performance boxes may be placing enough extra stress on the engine to produce your problem where the other doesn't.



In any event, it seems clear it is an engine issue, not a box issue...

 

[Turbo359]

The truck starts to miss as soon as the tst box starts fueling. It is a random miss, any cylinder when the tst box is fueling.

 

[gitchesum]

Use dielectric grease on your connections.



I had the exact same problem. I took all the connections apart, cleaned and greased them. Haven't had a problem since.