Ok, I just put in a new streetport motor bult by BDC. I was running a stockport motor before with a A-spec GT40R turbo kit. Only changes I made this time was the motor and fuel system including dual pumps, 1000 primarys, 2 feed lines and a rx7store relay. First off once I got it fired up I had a very hard time to doing that as I keep flooding out the motor. But once it started up it sounded like a bridgeport lumping at idle. Brian (BDC) told me to change my settings for the 1000cc's to act like my stock 550's (setting on the PFC changed from 100% to 52ish and of course the inj. size) That help keep it running a bit but I still had an bad idle and lots off raw fuel coming out the exhaust. So I eliminated the second pump, second feed line and put the stock priamary rail and 550 inj. back in changed the PFC back to 550's and uped the inj. back to 100%. So now evrything is back to were it was before except I am using a -6 for the feed line. Still had the same idle. Last night I kept pulling the % down on the primary's until 78% and it smoothed out but will not keep at idle on its own. Had to keep my foot on the pedal a touch to keep an idle. I have went over almost everything 3-4 times now. I would think a streetport would want more fuel not less? Could my fuel problem be with the heavy guage wire and realay? I also unplugged my secondary INJ. to make sure one was not stuck open or miss wired. I also wondered if maybe it could be a mistake on my part and maybe I have the return line mixed up with the vent line? Easy to check but I would think it would die out if the return was not flowing enough to keep the fuel preasure down.. Maybe a ignition problem? Idle sounded good, reved ok. Any suggestions or thoughts are welcomed! The car ran perfect before the motor started going out. So I know evrything was working correct. Mike

 

mike, have you messed with the idle adjust screw on the TB? what about the map sensor? is it hooked up? is it on the correct setting in the commander?

 

Well never touched the idle screw, Map sensor is hooked up, never touched the commander settings in that aspect. Basically car ran perfect before motor starting going bad. So out with old and in with new. Everything else is the same. Really seems like a fuel issue.. Or maybe a ignition problem were fuel is not getting burned. But the car idles (with slight pedal) like ignition system is working ok. ????????????????????????????

 

What is your idle set at? Street port should be around 900-1000RPM if you want a smooth idle. What is your base fuel pressure?

Jason

 

your problem could be the primary injectors leaking (or secondaries)....

1. pull the primary rail out and pressurize the system to see if your leaking through the rail.
2. also make sure your primary injectors are not stuck open or not getting a signal...
by taking a stethoscope to the actual injector to listen for tapping while your cranking it.

good luck

 

I agree with this...if you change the ports in the motor, most likely the reason it wouldn't hold idle is the idle adjustment. As Jason said, you'll need a higher idle and it will pull less vacuum.

More fuel, less fuel...can't comment on that. Health of engine as to do with that. Not saying this motor is suspect, just your last motor became weak and probably required more fuel to keep it "happy".

good luck.

 

if you never pulled the old injectors out of your old fuel rail, chances are, it wasn't the injectors. your engine builder should be able to tell you what he would expect the vacuum to be at idle. If it is lower than he expected, it could be the engine. things that are suspects are the following.

your settings on pfc (fuel map)
fuel pressure
compression numbers
idle rpm
and spark (more specifically, leading spark).

 

Thanks for the input guys. I have the idle set at 1200 on the pfc. The motor will creep down to 700ish before it cuts off. I will mess around with the idle screw next. Base fuel pressure set at 38, I guess I should bump that a hair up to 40psi. I have run 1000 cc new inj. in a new rail for primaries and also the stock primary rail and 550's with the same result using both. So I can not imagine it is a stuck open injector or leaky inj. I also unplugged the secondaries while doing this to confirm they were not the cause, one being stuck open. But I will need to check for a signal as poweraxle sugested.

Now, Leading spark as Steve mentioned would explain alot. I need to confirm I do not have an issue there.
Compression numbers= Have not checked this and do not even like talking about that!
PFC settings are the same as you last tuned them Steve except for me changing the inj sizes and inj. pri. %.
I will post results once I check each one. Thanks, Mike

 

If you're still using my map, it'll not work well with the ported engine since it was used for stock port (which has higher vacuum) than a Street port. Like I said earlier, you need to find out what vacuum you should idle at and adjust your fuel map from there.

also, if your compression is low, it'll explain why it doesn't want to hold idle either. There're many factors that could attribute to your stall at idle so a little here and there would make a difference.

 

Thanks Steve, I will look into that.

 

If the leading coil is bad: changing IGL with the commander will have no affect on the idle, but increasing IGT will have a noticeable affect.

 

call us on the tech line I can walk you thru it. I've been running you set up for a year now. www.rx7store.net

 

I had a very similar problem to what you describe and it was a clogged map sensor hose. My map sensor was connected but not seeing the vacuum.

It would idle at like 9:1 afr and smoke like crazy...then I would pull my plugs and see that they were all wet with fuel. I thought ignition problem, dripping injectors..etc..then Chuck told me to check my map sensor hose...I replaced it with fresh line and it finally idled decent. A little tuning later and it was idling well.

Just thought I would share....

During the process I also changed my battery... A weak battery could be a cause too.