VEC3 keeps frying!!! HELP!

[2001 GTS]

I've had my VEC3 rebuilt by Sean twice now. Both times the slave board fried.

Both times the car ran great for 2 weeks then out of nowhere #2 and now #4 cylinder stop opening the injector. I just don't understand how last Tuesday the car ran the best it has ever ran, then the next day I fire it up, take it out then 5 miles down the road it starts missing and backfiring.

Now it looks like it has fried AGAIN! The VEC is installed right, I've been over it ten times now.

I'm starting to wonder if a stock wiring harness was hit when the motor was put back in, but if it was then why would it run great for 2 weeks????

Any help would be greatly apprecited!

I'm going to try Bobby's Split-sec next week, but I don't want to fry that too.

Steve

 

[plumcrazy]

id guess its a wiring harness somewhere thats doing it. maybe have another set of eyes go thru it for ya...

 

[BOTTLEFED]

yeah, sounds like something in the wiring harness - either in the stock injector harness or the VEC harness going to the injectors

you may have a break in the wires where they are shorting out and taking out the VEC

also check the injector connectors

 

[britospeed]

You can always use an SCT with the proracer package to do the tuning yourself, or working with a tuner and dyno.
Feel free to call if you have any questions on the SCT.
Michael
BritoSpeed - Need Has Nothing To Do With It - Home

 

[2001 GTS]

id guess its a wiring harness somewhere thats doing it. maybe have another set of eyes go thru it for ya...

Thats what I am going to do Monday! I might be in a daze from looking at it so much...haha

yeah, sounds like something in the wiring harness - either in the stock injector harness or the VEC harness going to the injectors

you may have a break in the wires where they are shorting out and taking out the VEC

also check the injector connectors

I'm hoping it is just a break somewhere. I already changed the injector connectors with the MSD ones after the last time.

You can always use an SCT with the proracer package to do the tuning yourself, or working with a tuner and dyno.
Feel free to call if you have any questions on the SCT.
Michael
BritoSpeed - Need Has Nothing To Do With It - Home

Might have to do that, thanks Michael.

 

[GTSnake]

I'm going with a short in a wire somewhere. Maybe something got pinched or cut and is shorting intermittently.

 

[99 R/T 10]

I have a spare injector harness Steve, let me know if you want to give it a try.

 

[BOTTLEFED]

I have a spare injector harness Steve, let me know if you want to give it a try.

yep, that would be the next step
try an injector harness that you know is good to see if yours has a short in it

 

[2001 GTS]

Sounds like the next step, I'll give you a call Mike!

 

[Joseph Dell]

Injector clips were recently replaced... And the problem is always on the same side of the motor. Definitely sounds like a short, but what would make the VEC fry but not a stock PCM?

SCT is probably the way to go... At least it will mask the problem for now and get you on the road!

 

[dansauto]

i had a problem with mine, I was unplugging the injector harness to find a plugged injector and that caused the vec to short out, dont unplug your injectors while the car is running!

 

[Greg Good Cylinder Heads]

Sounds like the VEC does not have *open load protection*, in which case Steve should be looking for a break in a wire also.

 

[BOTTLEFED]

Injector clips were recently replaced... And the problem is always on the same side of the motor. Definitely sounds like a short, but what would make the VEC fry but not a stock PCM?

SCT is probably the way to go... At least it will mask the problem for now and get you on the road!

Although the injector clips have been replaced, the harness itself could have a short inside before the clips

the reason the VEC is getting fried is because it is in series of the injector wiring
it is burning up the VEC before anything happens to the PCM

 

[Joseph Dell]

Although the injector clips have been replaced, the harness itself could have a short inside before the clips

the reason the VEC is getting fried is because it is in series of the injector wiring
it is burning up the VEC before anything happens to the PCM

So are you speculating that PCMs would fry if the VEC wasn't there?

Interesting...

 

[BOTTLEFED]

Possibly
unless the PCM has some sort of over load protection - which I doubt it does

 

[GTSnake]

I can't believe that the PCM doesn't have any overload protection.

 

[Jack B]

Sounds like the VEC does not have *open load protection*, in which case Steve should be looking for a break in a wire also.

To expand a bit, most power supplies or dc converters regulate the the voltage output and are not load dependent. Some circuits are load dependent to keep the voltage in a specific operating range, therefore the removal (an open circuit) creates an overvoltage and components can suffer. This would not be a good practice (design) in a circuit that has to add a very precise level of voltage.It would be interesting to know if an open injector can create this issue. It is almost certain that the PCM itself has some type of current limit circuit in the injector output.

 

[BOTTLEFED]

I would have to find the thread, but I remember an owner saying that he fried his PCM when he disconnected an injector while the car was running...

so this could be the answer to the load protection question

 

[2001 GTS]

I would have to find the thread, but I remember an owner saying that he fried his PCM when he disconnected an injector while the car was running...

so this could be the answer to the load protection question

So could a bad or loose injector connector cause it all?

 

[BOTTLEFED]

I think it would have to be a pretty bad connection where no connection is being made at all

if you think about it, it is taking 2 weeks for your VEC to fry, so it must take a while for it to finally burn it up

I just saw that thread the other day
I'll try to find it again