Hey guys, we just finished up my motor build and we started up the motor and it cranks perfectly....only thing is that it wont idle worth ****. It'll stutter for a few and then shut off. If we rev it, it revs perfectly, no timing problems, and its smooth as anything. But when it drops down to idle, itll stutter, and then shut off. Some new parts we added were a JWT clutch and flywheel, crawford plenum, and DC headers. And the flywheel was put on to the exact timing specs, so it wasnt that. You guys have any ideas?

 

What engine management?? MAF installed and hooked up correctly?

 

im runnin split second R4

 

What all did you do to the motor?

 

for the motor itself we just did pistons and rods and the basic other little things you need like, headgaskets and stuff...we still have injectors and a new fuel pump to put in after the motor gets broken in....if we can figure out this idle problem

 

Is there a loud noise like a vacuum leak from the plenum or headers? Are all of the hoses hooked up to the plenum and TB? What about the hose into the air filter on the back of your Vortech A/F?

 

yeah we double checked everything to make sure there are no leaks. were are thinking it may be an ecu problem?

 

Did you put in camshafts?

 

Nope, no cams...

 

Out of the box tune?? I wonder if the injector correction is off.

 

He said they hadnt done injectors yet . But you might want to hook up the laptop and read the piggyback ECU to see if the original maps got wiped out some how . But that maybe what you mean when you said it may be off

 

Sorry....thought Vortech came with upgraded injectors.

 

I think it might be the ECU problem though. Are you using the new ECU to control the electronic throttle body? If that's the case, it is very hard to get it tuned correctly. It is better to leave the throttle control to the original ECU.

I had the same problem with my car when I converted my engine to nismo spec1 engine with motec computer... the idle was **** house and it was very hard and time consuming to get the idle right... so I hooked the electronic throttle control back to the standard ECU and the idle is good now when the engine is warm (when it isn't warm up, there are a few idle hunts for about 3 minutes or so, then it settles down).

Also, found that the flywheel was the problem to get the idle nicely too... I was running JUN flywheel (6kg), the idle was ****, then I swapped it to Nismo flywheel (nearly 10kg), it improved by A LOT... especially when the rev comes down from the rev up, the engine does not stall out now..

Best of luck!

cheers,

richie

 

The SplitSecond piggyback does leave the vacuum side of the maps to the cars ECU in control .
He may want to try a throttle learning procedure to see if thats it

 

Yup... I am not too sure what SplitSecond is... thought it was a full replacement ecu.... I think booger might be right.... try the throttle learning procedure... that might work though!

cheers,

richie

 

Yeah i hooked up the laptop and checked the original maps, the maps are still there. I was thinking about the throttle learning procedure too, havent tried it yet though. those of you that had the idle problem becuz of the flywheel, was it bad enough to shut the car off by itself?

BTW, at this time, the car now is at the Nissan dealership for them to figure it out, they should tell me whats wrong with it.

 

mine had the same prob, it would almost always die on decel. i saw the jwt idle stabilization fix, but it will only work on draw through type turbo or s/c applications. i fixed it by drilling a 1/8th inch hole in the throttle plate (which is nearly identical to the jwt fix just going about it differently) and the car has never died again. i lost about 1-2 inches vacuum, and it also did bump the idle up to about 725rpm. but as i said, hasn't died once since.
i have cams though and my heads are ported pretty far too. i would try the idle learn first and if it doesn't work, then this might be an option. the throttle plate is brass, so it would be easy to solder the hole back up later if needed.

 

So does mostly everyone that has the JWT flywheel have this same idling problem?

 

When my motor was built my car wouldn't idle at all. It stalled ALL the time. I took it back to Infiniti and they told me that the ECU Was failing the 'idle learn' procedure because too many sensors were outside of their specs.

The tech forced in an idle setpoint and I haven't had any problems since.

 

Oh ok, so Nissan should be able to figure this out...i was just hoping that it wasnt a mechanical problem...