KA24DET Idle Issue

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Joined: Sat May 13, 2006 2:45 am
Car: 1996 Nissan 240SX SE

KA24DET Idle Issue

Postby apollo500 » Tue Jan 31, 2012 3:20 pm

The car is fully functional. There are no vacuum leaks that i or the shop have found, the z32 maf is working correctly, the car was professionally dyno tuned(tuned for 7psi) and inspected. The iacv and tps have been replaced. The car has all factory emission equipment installed and hooked up. I am not getting any CELs except when i unplug the top tps plug as described bellow.

The setup is as follows:
5-speed swapped 3 years ago with no problems or CELs since.
1996 KA24DE stock internals and head
jgs starter package with 50 trim agp turbo and 40mm jgs wastegate
600cc injectors
walbro 255 fuel pump
z32 maf
emanage ultimate unit with boomslang harness
1996 OBDII CALIFORNIA model ECU(dont know if it makes any difference except for the fuel cut at 5500 RPM)
hks ssqv
godspeed fmic
iridium ix spark plugs and new ngk wires
3 inch greddy downpipe, flowmaster 3inch high flow cat, and 85mm hks hi power cat back
innovate wideband
(probably forgetting something)

Here is the problem, when i first start the car it idles fine for 20 to 45 seconds then it starts sputtering going down to 400-500 rpm range then bumping up to 1250-1500(the air/fuel ratio jumps around from 12,2-17.6), repeating this cycle once in a second. When the coolant gauge shows 120-130 the idle usually evens out(idle air/fuel ratio is set around 13.5). When i rev the engine it responds fine except for the fact that i cant hold the throttle at 1500-1750 because the car will die. When i release the throttle(after any kind of acceleration) the car starts sputtering for 6-10 cycles then it evens out. Also the car will not start properly when the coolant temp is above 120, i need to pump the accelerator for it to start up. Idle adjustments did not make much difference except for the fact that the rev ranges of the problem changed but the problem persisted. Now when i unplug the top plug on the tps the idle instantly evens out and the car runs and idles fine except for the fact that it runs rich when accelerating and on low throttle(when keeping the car at speed the fuel ratio is at 9.5-10.5 while it was at 14.6-14.9 when both tps plugs were in. when accelerating the ratio was at 14.6-14.9 with both plugs were in but with top plug removed the ratio starts off at 13.5 and decreases to about 11.7 at 4.5k rpm) .Also the car starts fine when cold or hot when the top plug is out. Any help would be appreciated.

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Re: KA24DET Idle Issue

Postby lexcrob » Tue Feb 07, 2012 12:19 am

WOW i got about halfway thru reading your entire complaint but i didnt waste my time i found the problem.

YOUR USING EMANAGE and to top it off your using 600cc injectors and a monster turbo can you say your base timing might be alittle err retarted......

Ill do my best to be nice but here it is in a nutshell. Can you resolve a loping stumble whatever idle? Yes your ecm needs certain feeback from sensors and the correct amount of mechanical limits in a sense (amount of air/fuel) while at idle so that the ecm can make an attempt to get it within "specs". If you fall out of this window wether that be a electrical signal sent by your maf at idle to an irradic air flow across the maf...all the way to say retarted base timing*** that is so far out while at idle the ecm doesnt know what the nutz is going on!

Remember base timing and idle speed go hand in hand its really something you have to mess with to understand. I dont believe emanage has ignition capabilities come to think of it? If it does id imagine its just like a MSD BTM.

I would recommend looking into a MSD BTM for shur sounds like a good solution from what ive read if emanage doesnt. It may be an add on feature but im not shur id have to research it.

My friends car will soon have BTM too! Similar problems over here but worse no recirc bov exhaust manifold leak(he didnt even bother to put one of the bolts in.......then he got a ticket other day for noise ordinance BACKFIRE from his car hahahahahhaahhahahhahahhaa

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