Thread: Just plugged in a JWT ECU

Well, as part of my VE-T build, I decided to get a used JWT ECU, programed for 8.5:1, Z32 MAF, 72# inj.

Since the VE-T is not ready yet, I decided to just plug the JWT in, test it, and see how it reacts to my current T25 setup with 555cc injectors, Z32 MAF, 9.5:1 USDM DE. It obviously ran very lean, I was expecting that since its programed for injectors bigger than the 555cc I have, so i richen it up with the emanage and AFRs are fine now at partial throttle and around 12:1 at WOT. What I was NOT expecting was a super rich idle, its idling like at 10.8:1 AFR I tryed to lean it out with the emanage but it didn't work, and if I lean it out too much, the idle starts to bounce between 800rpm and 1300rpm, with the AFRs still super rich. Any idea what's up with this????

You obviously have a wideband so thats good, have a fpr? If so, try dropping some fuel pressure and make up for it on the top end with the e-manage. 14-1 may be out of reach with your setup, but you should be able to get it leaner. 555's on a t-25 is obviously bigger than needed, so makeing them "smaller" by pulling some pressure should'nt get you anywhere near 100% dc at wot. On the other hand, emange uses maf signal to modify your afr, so you want to make sure you don't have to output more than 4.8-5 volts to get your desired wot afr with the new, lower fpressure.
The reason your idle goes to hell is because you are pulling maf voltrage at idle untill it falls below minnimum maf signal. once your up in the maf output window, say 3 volts, you can add or subtract a bunch with no problems but when the maf is only outputing .5 volts, you don't have much to work with.

Good luck

Thanks a lot for your post. I think I found the problem and it was my fault. Since the JWT is set for 740cc injectors, I set the fuel pressure to 4 bar, then forgot that and set the injector correction factor on the emanage (before= 740cc, after= 555cc), so the car was rich as hell. I put the fuel pressure back to stock and just leaved it with the emanage correction factor.

The reason why I got the JWT was because, the emanage was having a really hard time with the stock DE ECU and 555cc injectors, the AFRs were all over the place on anything but WOT, and it was flooding the cylinders at the engine start up. the difference was way too much from a 259cc program to what I needed with the 555cc injectors, so I thought it would be better to deal with a smaller difference from 740cc to 555cc.

Ok, after some days using the JWT in my car, so far it has been running great, but I still have one problem.

At idle, when the car is cold, like in the mornings, it gets SUPER lean, so lean that it can't hold idle. No matter what I do to the emanage it keeps doing that. Also, after the car heats up to a normal temperature, it gets super rich at idle wtf!. How can I find out if my coolant temperature sensor is shot? can it make such things?

temp sensor is resistance based, you can ohm it out to see if it is good. It is in the FSm. I suggest you just replace it though, they are super cheap and not hard to do.

Brent

I agree.
where does your idle valve tube go? The one from under the manifold to your intake on a stock sr.

right on the stock location.

Thanks ill check the fsm.