J4J1 Cobra computer in a GT????

[mr-xcr]

I'm looking at doing an upgrade on my 94 GT. Gt 40 heads, cobra intake, E 303 cam, 24lbs injectors with 80mm maf, 70mm TB.
My question is will a J4J1 computer work in my car. I here all kinds of horror stories about the car not running very well with the T4MO computer??
Has anyone ever tried this???
I'm thinking this way or a custom tune or maybe both???
Thanks

 

[Zero Signal]

With those mods, it should run smoother in theory with the J4J1. When I had a similar setup, I was running a tune based off the J4J1 strategy because the T4MO (CBAZA strategy) wasn't cutting it. It has a more conservative timing curve though, if I remember correctly. For the hassle and potential problems with swapping computers, I would opt for a tuner like the tweecer instead.

 

[nmcgrawj]

Well it depends on the MAF....is it tuned for a GT car or a Cobra? The MAF transfer curves will be different since the GT expects 19lb injectors and the cobra computer expects 24. Since you have a GT im gonna assume that its for a GT.

That said, its not gonna run "smoothly" since the curve isnt exact. So you'll need a tune anyway. Outside of that, even if you had a MAF for a cobra ready to run, i still feel like its gonna need to get tuned to run the best possible.

So IMHO, go straight to a custom tune. Whether or not you do it with a tweecer or you pay someone, the T4MO is fine when you tune it. I had a PMS on my 95GT that i tuned a 302 h/c/i, 351w h/c/i and now back to a 302h/c/i and it was EASY every time to get it running damn near as smooth as stock....with a nice lope . So you dont "need" the J4J1 to get these cars to run smooth.

 

[NotQuik]

seems like more work than it's worth...i've read people putting A9L's in the 94-95 but to try and get away from having to tune it...i'd keep what you have, if anything get a tweeker or somekthing but regardless get a real tune on the car.

 

[revhead347]

The MAF in the Cobra and the GT are identical. The computer in the Cobra is tuned for 24lb injectors.

Kurt

 

[nmcgrawj]

dammit, you're right. I forgot that!!!!!


Can someone re-explain that for me though...so a stock maf sends the same signal for cobras and GTs....the computer then makes them work for 24lb and 19lb injectors.

But when u step up beyond 19s the mafs are no longer the same calibration for GTs and cobras right? So a stock cobra maf is a factory 19lb maf. Anything after that and the two are different.
I still think you'll need a tune anyway so y waste that money...

 

[revhead347]

Basically. When you get another MAF for bigger injectors, they have to tune it for a Cobra and a GT differently. Or you can just retune the chip for the computer.

Kurt

 

[final5-0]

Yes the meter is exactly the same for GT and Cobra

Now ... the transfer curve each pcm is slightly different

If one has h/c/i and larger inj's with their GT and using a Tweecer

Moving over to the j4j1 can be a very easy way to gain a lot of
advantages with one quick upload :Word:

Many have done it with success
but
Yes ... you should be able to manipulate the t4m0 to what is needed

The j4j1 just has a lot of whats needed already inlcuded you could say

Grady