Okay,

Did a 4V swap a month or so ago on my 98 GT. Been running the Cobra engine on the GT ECU, and that works pretty well, but the rev limiter is too low and the GT ECU can't give the Cobra engine the fuel or timing advance that it probably needs. So, I bought a Cobra ECU. Problem is, when I hook it up the engine will start right up, but then dies within 2-3 seconds of starting. So, it just won't run. It runs fine on the GT ECU, and I've even tried using a Lincoln MkVIII ECU, which works about the same as the GT ECU in terms of power, but not all the guages work for obvious reasons.

Any ideas why this is happening? I wouldn't think the anti-theft would do this, it just wouldn't start at all, right???

If anyone knows why this is happening please let me know!!

 

I don't know how much it'd help brudda, but I would think the Cobra ECU should work. Did you try using a hand-held to re-flash the tune on the ECU's? If you're not re-flashing the ECU's before you mix and match them like that, that COULD be the problem brudda, because each one probably has stocktune settingsfor a completely different set up on it, and sticking them all in the same car would probably screw things up a bit methinks.. I would think the Cobra's would be closest to what you need, but the speedo wouldn't be calibrated for the gears, and I could be wrong here broham, but I THINK the ECU has to be calibrated to the specific engine you have too..

I'm sure the more experienced guys will chime in here, but my first thought would be to try researching a good hand held programmer, and re-flashing the ECU to see if that works..

 

are you using a Pats key to start the car? this could be a pats issue, but im not sure.

 

I am using a pats key. In the past when I've tried starting the car with a regular (non pats) key, it would just turn over, which is a little different than just not starting.

I wouldn't think the ECU should need to be re-flashed to work on what's essentially a stock COBRA set-up, the GT ECU I'm running is stock GT and it runs it okay, the Cobra ECU I would think is even a better match for my set-up.

Thanks, anyone else????????????

 

I wouldn't either, since you're attempting to run a COBRA ECU in a COBRA engine, but the fact still remains that the ECU you're trying to run in the car did NOT come with the engine. It's just like using a canned tunefrom a handheld, sure it might work, it might not, but if it does work there are probably going to be a few hick ups because it hasn't been calibrated for the application it's being used on broham.. Any time you stick a new ECU into a vehicle, used or not,you should get it re-flashed or else you risk it either not working (as in your case, the car won't crank..), or screwing up the set up you've got. That's just me though..

I don't think the anti-theft would be the problem unless you're still using the Mark VIII ECU because those were flashed to work with the removable kill switch chipthat came in them from the factory. The only other thing I can think of is thatwhat year 4V engine do you have, and what year COBRA did the ECU come out of? The Tune for the 00+ Cobra's is different out of thefactory than it is for the99 and previous year Cobras out of the factory.. Granted I don't know if the ECU is any different, but maybe that's an issue brudda..

 

YOu're using the wrong key thats assigned to the ECU. Either turn the PAts off on that ecu or go back to the GT ecu. The pats will start the car then realize it's wrong and shut down, thats how they work. You're wrong if you think they don't start at all.

And for the record, the GT ecu works fine and gives plenty of timing and fuel. As for the Rev limiter either get the car tuned or don't rev it so high. YOu're trying to cut corners and you're just going to have an expensive lawn ornament if you don't do it the right way. Go back to the GT ecu and be able to drive your car or find a tuner that will drive to your house and turn off the pats.

 

I would go get a TUNE.... I dont know much about the motor you have. Im sure u have a Different Fuel System- Tank/pumps that the Cobra ECU.

After doing a Motor Swap why WOULDNT u get a Dyno Tune? thats like Throwing a Blower on it and not getting tune to get the MAX potential out of it.

Good luck!!!!