air/fuel problems?

[SR20JonBoy]

I have an SR20det (it's the one in Jason's sig) that I just installed in a 240sx. I haven't tuned it yet, because I just finished installing everything, so I know some of the problems may be eliminated by that, but I noticed that when I ran the car for the first time, it seems to run extremely rich at idle, and extremely lean above 3000 RPM. The engine stutters when I try to rev it higher than that, so as a result, I don't do that. I have a JWT tuned ECU for a ford lightning MAF. At the time of the first run, I was still using stock ignition coils and ignitor chip. I was wondering if there is anything I can do pre-tuning to fix this. I plan to have it tuned next week in Jacksonville, Fl.

[Jason@JGY]

2 things come to mind that may not seem logical but that have helped with other installs

1. reduce your spark plug gap to .022 and see if that seems to change your a/f.........I know that seems odd, but do it and see what happens...........then gradually open the gap to tolerable

2. check your fuel filter and fuel pump filter................ this one is weird
but M.P.'s setup got clogged and experienced the same issue of rich down low and lean up high

make sure that you don't push it when it goes too lean
also.................what a/f gauge are you using?

on a totally side note............because of the bearing decisions that we made.......what is your oil pressure when you are at idle and the motor is warm........as I am curious

[SR20JonBoy]

I checked the fuel filters. That was my first course of action. I have the fuel pressure set at 40psig at the moment, but I am playing with it as I make adjustments to other things. I am using AutoMeter gages for air/fuel, boost, and oil pressure. Tomorrow my ignition controller and splitfire coil system should get here, so I am gonna see how that helps out. I will also try changing the gaps on the plugs at that time. Should I maybe go with a colder plug? My first thought was to go hotter, like an NGK 9 series, but a guy who tunes mustangs said go colder....

As for the oil pressure, I haven't run the car long enough to give you good numbers. If I can fix this air/fuel problem, I will be comfortable running the car longer and I will let you know.

[bruce240]

ya, sounds like a clogged filter!

You might have a leaking vacuum hose on your FPR, what is your base fuel pressure, BTW, you can hook up a simple in-line fuel pressure gauge, might help ya trouble shoot some fueling problems faster.

[Jason@JGY]

You are a Ford Lightening Maf program right?

I have a very very very very very slight concern on JWT's programming of those. Before I get the rumor mills started and the ecomony slows, I'm only prematuring guessing and probably wrong..............

We have had a few issues ONLY with the lightening maf programs with them being a little finicy (spelling?) Spend a little extra time finding what is right before you start adding all that stuff.

You want to run 7plugs. Honestly, for tuning and playing around, 6's are the best to get everything set.............and after that and when you get stuff dialed in and not have pushed the motor too hard, then go to 7's, 9's are crazy crazy crazy wrong for what you are doing. 9's are colder by the way

Every Autometer A/F guage that I have seen does NOT work with Nissans. If it is the kind that taps into your existing O2 sensor, it won't work because your factory is a 0 to 1 volt sensor. Buy a Greddy or an Innovate from us.

Where do you live now?

[SR20JonBoy]

Well, here's the latest. The autometer a/f gage was giving me a reading, whether or not it was a good one, I don't know. However, the car won't even crank now. I didn't change anything. In fact, the only thing I did was replace the fuel pump filter and clean the spark plugs. It acts like it is going to crank, and it fiires up for a half second then dies. This is really wierd to me since it wasn't doing this yesterday. I don't have any engine codes, and I made sure the fuel pump was still primed before trying to start it. I will say that after going through everything I know to look at, the only thing I can think would possibly be wrong is the ECU. I might just pick up a stand-alone system and see if that changes anything.

[SR20JonBoy]

actually, instead of that, can I just send the whole car to you guys so I know this thing will be done right? I would have to find a place to ship it without it running, but I could ship it there, and you could make sure it's installed the right way, and it runs how it's supposed to run. If you still have my phone number, you can call me some time about the details.

[Jason@JGY]

I would like to have that car here. That motor in itself, is super rare.

1. I bet your plugs are dead. "Bruce240"'s car was sensitive to that.
2. Call us Monday and speak to Pam or Scott and they can schedule the shipment of the car here. We have about 13 groups that do it. It's if it not too far, I'll send one of my guys to get it.
3. With the dyno being installed tomorrow, I will take care of figuring out what is wrong and fixing it.
4. Most likely the ECU tuning is perfect, but if needed, we can go to something else.

Call us after 9am

P.S. I personally thank you for your service to our country and your patronage to JGY.

[SR20JonBoy]

I talked to Terry's transport, and they are going to pick it up next week. I will let you know the exact day after he gets back to me. I'll put everything I have for the engine in the car.