im new, idle issues - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ho1ywars · 10-04-2006, 02:50 PM

Hey guys, my name is shawn. i picked up a two forty in may that had a bad ka and swapped in the SR. EVerything went smooth, did a bunch of searching and basically got the car running and most of the bugs worked out so far. what i am left with is two idle problems.

first one is the engine will not hold an idle AT ALL with the maf plugged in. it will start, the rpms will jump around for two or three seconds surging between 1000 -300 and then it will die.

the second one is when the maf sensor is not plugged in, i understand this put the car "limp mode". is this true? when i run the car like this, it idles for about two mniutes then will start to go into this phase where it wants to shut off every thrity seconds. i will kick the gas, and then it will idle for another thirty seconds, untill it is up to running temperature. once it reaches one ninty on my water temp guage, it idles fine at about six hundred.

these are the only things left that really have me confused. i checked to see if the ecu is throwing any codes when the maf is plugged in, and it is reading fifty five. i remember reading somewhere that fifty five is a clean ECU. The only thing i can think that owuld be cuaseing this is because i am doing all thie idling without a intercooler. But, technically, when idleing the engine is not under boost, so the ecu should have a fuel map that works. Right now i just have the MAF sitting ontop of hte TB with a silicone cuppler holding it on.

i have brand new ka ecu temp sensor im about to throw in, but wouldnt the computer be throwing a code if the current one was bad?

Any suggestions would be helpful, i searched, didnt find anything that helped.

95 240
s13 red top
the engine is completely stock

BC240 · 10-04-2006, 02:57 PM

The air temp sensor on a KA is only for diagnostic purposes. When I took mine off it threw a code but did not effect performance, as for your idling problem im not experienced with SR's ill let someone else chime in

cotbu · 10-04-2006, 04:18 PM

You don't need to have an intercooler, But the loop needs to be closed or you'll have a vac leak. You maf can't meter the air correctly, because it is failing or there is a leak. No piping = leak. Fix that, then see what happens.

*NemeGuero* · 10-04-2006, 04:27 PM

You need 12" of tube between MAF and inlet.

Are you bypassing the turbo then if your MAF connects directly to your TB?
What Cotbu said.. get your piping handled.

s13coupedrfter · 10-04-2006, 04:54 PM

Had similar problem with my sr20. I took the iacv out and cleaned it with carb cleaner. When you have it out do a resistance check of the aac (the aac is on the iacv unit and is held on by 2 screws), should be 12 ohms. Next put a 12v power source to the solinoid (looks like a long 6 point bolt head on the iacv unit) and you will hear a clicking noise. If all checks out you have a good iacv. Finally do a continuity check of the iacv wiring. In my situation I had 2 open wires, one for the iacv (black with yellow stripe) and the other was a solid brown wire can't remember what it was for though. After the repair the car runs perfict! I ended up pulling the entire wiring harness out for continuity testing just to be sure. Don't let the harness intimidate you, it only takes about 15 min. to remove.

Another reasond I point out the iacv is because during the sr20 swap process, the wiring to that sensor is spliced in to a ka connector (the shop who did my swap forgot the 2 mentioned wires). Checkout www.heavythrottle.com for info. There are diagrams for the wiring conversion, and there the best Iv'e seen.

I almost forgot to mention, every time my MAF is unplugged with the car running it doesn't want to hold idle and die. I have never tested the MAF so I can only assume mine is good since the wire repair did the trick. G/L

ho1ywars · 10-04-2006, 09:04 PM

alright, thanks for the help guys.

10-04-2006, 02:50 PM	#1
ho1ywars Leaky Injector Join Date: Jun 2006 Location: Trenton, New Jersey Posts: 127 Trader Rating: (3) Feedback Score: 3 reviews	im new, idle issues Hey guys, my name is shawn. i picked up a two forty in may that had a bad ka and swapped in the SR. EVerything went smooth, did a bunch of searching and basically got the car running and most of the bugs worked out so far. what i am left with is two idle problems. first one is the engine will not hold an idle AT ALL with the maf plugged in. it will start, the rpms will jump around for two or three seconds surging between 1000 -300 and then it will die. the second one is when the maf sensor is not plugged in, i understand this put the car "limp mode". is this true? when i run the car like this, it idles for about two mniutes then will start to go into this phase where it wants to shut off every thrity seconds. i will kick the gas, and then it will idle for another thirty seconds, untill it is up to running temperature. once it reaches one ninty on my water temp guage, it idles fine at about six hundred. these are the only things left that really have me confused. i checked to see if the ecu is throwing any codes when the maf is plugged in, and it is reading fifty five. i remember reading somewhere that fifty five is a clean ECU. The only thing i can think that owuld be cuaseing this is because i am doing all thie idling without a intercooler. But, technically, when idleing the engine is not under boost, so the ecu should have a fuel map that works. Right now i just have the MAF sitting ontop of hte TB with a silicone cuppler holding it on. i have brand new ka ecu temp sensor im about to throw in, but wouldnt the computer be throwing a code if the current one was bad? Any suggestions would be helpful, i searched, didnt find anything that helped. 95 240 s13 red top the engine is completely stock

10-04-2006, 04:18 PM	#3
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 50 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	You don't need to have an intercooler, But the loop needs to be closed or you'll have a vac leak. You maf can't meter the air correctly, because it is failing or there is a leak. No piping = leak. Fix that, then see what happens. __________________ LoverTechnologies "Half Broken Things!"

10-04-2006, 04:27 PM	#4
NemeGuero No more nissan. Join Date: Jan 2003 Location: RAIN, Washington. Age: 40 Posts: 8,132 Trader Rating: (10) Rides Gallery: NemeGuero Feedback Score: 10 reviews	You need 12" of tube between MAF and inlet. Are you bypassing the turbo then if your MAF connects directly to your TB? What Cotbu said.. get your piping handled. __________________

10-04-2006, 02:57 PM	#2
BC240 Zilvia Junkie Join Date: Aug 2006 Location: Richmond, BC Age: 43 Posts: 472 Trader Rating: (1) Feedback Score: 1 reviews	The air temp sensor on a KA is only for diagnostic purposes. When I took mine off it threw a code but did not effect performance, as for your idling problem im not experienced with SR's ill let someone else chime in

10-04-2006, 04:54 PM	#5
s13coupedrfter Zilvia Addict Join Date: Aug 2005 Location: Socal Posts: 839 Trader Rating: (8) Feedback Score: 8 reviews	Had similar problem with my sr20. I took the iacv out and cleaned it with carb cleaner. When you have it out do a resistance check of the aac (the aac is on the iacv unit and is held on by 2 screws), should be 12 ohms. Next put a 12v power source to the solinoid (looks like a long 6 point bolt head on the iacv unit) and you will hear a clicking noise. If all checks out you have a good iacv. Finally do a continuity check of the iacv wiring. In my situation I had 2 open wires, one for the iacv (black with yellow stripe) and the other was a solid brown wire can't remember what it was for though. After the repair the car runs perfict! I ended up pulling the entire wiring harness out for continuity testing just to be sure. Don't let the harness intimidate you, it only takes about 15 min. to remove. Another reasond I point out the iacv is because during the sr20 swap process, the wiring to that sensor is spliced in to a ka connector (the shop who did my swap forgot the 2 mentioned wires). Checkout www.heavythrottle.com for info. There are diagrams for the wiring conversion, and there the best Iv'e seen. I almost forgot to mention, every time my MAF is unplugged with the car running it doesn't want to hold idle and die. I have never tested the MAF so I can only assume mine is good since the wire repair did the trick. G/L

10-04-2006, 09:04 PM	#6
ho1ywars Leaky Injector Join Date: Jun 2006 Location: Trenton, New Jersey Posts: 127 Trader Rating: (3) Feedback Score: 3 reviews	alright, thanks for the help guys.