SR Won't come off fast idle

[martin]

New SR install, runs fine, but won't come off fast idle.

Other possibly related symptoms:- when started cold throttle response is terrible ie, you can move throttle pedel 1/2 way before anything happens.- when it warms up throttle response improves.- If I unplug the TPS it makes no difference to the way the engine runs.- using KA24DE TB and TPS for cruise hook up- TPS has correct resistance reading- Unplugging the ACC/FIDC plug it idles great.- using #63 auto ECU with 5 speed. I've read that thsi should be OK, but maybe it's related? - Timing is set correctly at 15BTDC- no vaccum leaks- Walbro fuel pump

I don't really know how to trouble shoot this, any ideas?

Thanks...Martin.

[quiksilvia]

check the mafs, clean it and check the voltage coming off it

[SpeedRacer1]

Well I run ECU 63 with a manual swap. I have the symptom where the (manual) TPS does nothing connected or disconnected. Like your car, my car has the same cold startup symptoms, but thats why I let mine warm up a few minutes before leaving. I am pretty much positive that is has to do with the AAC and maybe ECU 63. It doesnt have to do with the TPS, because I drove without one for a year and with one for 6 months and there is no difference either way.

I actually cut the AAC valve wire (light blue) for a long time to rid myself of the higher idle. Then I realized I could utilize it to my advantage, I use it to automatically recover for my BOV. I havent figured out why the AAC is open often but if your setup is like mine, the idle will stay high while the car is in any motion. Once you come to a stop and sit for about 5 seconds, the idle will drop about 500 RPM's to the proper location (which for my setup is 800RPM's). My advice, if this is really bothering you, would be to cut the AAC wire near the ECU and hook up an on off switch.

At 800 RPM's idle setting:

When the switch is on (on a stock recirc) the idle will be at about 1200 and can get stuck as high as 1800 while the car is in motion, however once you come to a full stop the idle will come back down to about 800. When you let off the gas in gear, the car will not jerk but instead decelerate while cruising constantly.When the switch is on (with a BOV) the idle while moving will be about 1400, and when you come off boost (depending on the BOV) your idle will hit 800ish usually and bounce back up. Everything else between the recirc "on" and BOV "on" is similer.

When the switch is off (on a stock recirc) the idle will be about 800 and will drop like a rock everytime you come off boost into neutral, hitting about 450 before rebounding up to 800. There is a slight boost loss at idle and while cruising with this option. When you let off the gas in gear, the car will slow down somewhat jerking during deceleration.When the switch is off (on a BOV) the car will die nearly everytime off boost unless you play the throttle tap dance game. If you win that game, your idle should be about 800.

[martin]

Hmm.. interesting info Speedracer, I'm glad someone else has seen this. The car has not been driven yet, so it's difficult for me to say if teh symptoms are exactly the same as yours, so far it's only been run on teh hoist, but the idle never drops below 1200 unless I disconnect the AAC/FICD plug, then it drops to 800 wheer it should be. Most of the time it's at around 1800, which is way too high! I have access to a #62 computer, although I'll have to "borrow" it from a friends car :-) I think I'll try this and see what the difference is without changing anything else.

I already cleaned the MAF before installing it, I haven't checked it yet, but will do toinght (I'll check it according to the 89 FSM). I also have another one that I could just try replacing it with as a quick test.

I like your idea of a switch for the idle, but this is something I'd rather avoid if possible :-)

Thanks...Martin.

[Cyberkreig]

This all sounds oddly familiar. Occasionaly my car will get 'stuck' on fast idle too...

(bov non recirced) Whenever comming to a stop without boosting my idle will stay very high and drop in 2 or 3 stages. 1700... 1300.. 850...

When comming to a stop after boost it will often crash to the 550 range and bounce back and forth for up to 45 seconds until settling around 850-900.

anytime letting off the throttle gently (especialy in 1st/2nd gear @ low speed) the car would bounce back and forth. An uncomfortable and embarassing condition.

I will check my ECU # tonight.

[Touring240]

*raises hand slowly*I also have these same symptoms. awful response and stumbling when the car is cold. but fine once fully warmed up. as well it will get stuck at a high idle and fall in 2 stages ... 1800 to 1300 to 800. perhaps this is normal?I hate it when it idles up that high it is embarassing.

ecu #62 5 speed (no auto swap)stock bypass with recirc

[ItzGenX]

*raises hand slowly*I also have these same symptoms. awful response and stumbling when the car is cold. but fine once fully warmed up. as well it will get stuck at a high idle and fall in 2 stages ... 1800 to 1300 to 800. perhaps this is normal?I hate it when it idles up that high it is embarassing.

ecu #62 5 speed (no auto swap)stock bypass with recirc

Wow, we should all join the Bad SR Idle club. Mine idles higher in colder weather (even after fully warmed). In cooler weather, it will only go low idle if you park the car, shut it off, let it heat soak, then turn it back on. Procede to drive and idle bounces up higher again. It also will get the "surging" idle in cooler weather (bounce from 1100 - 2000 for a lil while at a stop or neatral). My car has awful response and stumbling when it is cold also. During warm weather, my idle seems to stay steady down around 750. Stalling happens after boost in warm *good idle* weather.

[martin]

Interesting... It seems I have started a thread wheree everyone can confess that they've been having this problem too and are embarrassed about it :-) I was hoping to find an answer here!

We'll work on one together I guess. It's a little dissapointing to hear that Toruing240 is seeing the same symptoms with a #62 ECU. I was holding out hope that the right ECU would fix the problem :-(

I didn't make too much headway last night, I got called in early for "Daddy duties", only managed to check the ECU codes. There were three, all expected, TPS, Temp Sensor, and .. and .. mind has gone blank... but they were all things I had run the engine with un-plugged for some period of time trying to diagnose. Cleared the codes, ran the engine upto operating temp, with everything connected again, no codes.

Have any of you that are seeing this replaced you Oxygen sensor?

The investigation will continue as I have time, I'll keep you posted if/as I make any headway. The car is supposed to go to the bodyshop soon, so I might have to resume this testing after it gets back.

-Martin.

[Cyberkreig]

J4 ECU.

have not replaced my o2 sensor.

question: Those of you with this problem, have you used Heavy Throttles revised wiring information for the battery area? includes a brown wire that needs to be hookedup for 02?

[ItzGenX]

62 ECU on a S13 Blacktop, NEW 3-wire O2 sensor and wired correctly. I think it is my water temp sensor or something (the one the ecu uses not the dash one).

[martin]

J4 ECU.

have not replaced my o2 sensor.

question: Those of you with this problem, have you used Heavy Throttles revised wiring information for the battery area? includes a brown wire that needs to be hookedup for 02?

That brown wire needs to have +12volts when the ignition is on if anyone wants to check at the O2 sensor plug. I've checked, mine is fine.

So far everything I have read shows that everyone having this problem has nothing in common except the symptoms (and SR20DET's of course!). I think I might dig in under the intake and pull off the ACC/FICD valves and take them apart, maybe they are clogged up with ****. This motor had a lot of white crap in the intake when I got it, maybe the result of moisture?

I have found that sometime things settle down after a few hours of driving, but for this praticular problem it appears that some of you have driven for a long time like this and it hasn't improved so I'm guess mine won't either.

-Martin.

[martin]

62 ECU on a S13 Blacktop, NEW 3-wire O2 sensor and wired correctly. I think it is my water temp sensor or something (the one the ecu uses not the dash one).

I wondered about temp sensor too. I know I checked it the other night, can't remember if I just checked wiring or the sensor itself.. Jeezus.. I wish I had some uninterrupted time to diagnose this properly!

-martin.

[Touring240]

yes I used HT's wiring and brown is hooked up to 12volt and o2 sensor is fine.

[SpeedRacer1]

I am not so sure its a sensor issue. This high idle has occured on both my SR's. I think its an issue with Auto ECU's. None of you other guys seem to have my symptom where the idle really will not from 1400+ drop unless I stop moving. But with the recirc the idle while moving dropped to 1100. I would think it has to do with the ECU since just turning on and off the light blue wire causes the entire problem. But if everyone else wants to check, try unhooking the connector with the 4 wires in it and one is light blue, this should drop the idle considerably.

[martin]

I am not so sure its a sensor issue. This high idle has occured on both my SR's. I think its an issue with Auto ECU's. None of you other guys seem to have my symptom where the idle really will not from 1400+ drop unless I stop moving. But with the recirc the idle while moving dropped to 1100. I would think it has to do with the ECU since just turning on and off the light blue wire causes the entire problem. But if everyone else wants to check, try unhooking the connector with the 4 wires in it and one is light blue, this should drop the idle considerably.

I can't say driving vs. not driving, but I see the exact same sysmpoms in the shop. My original post says unplugging the AAC/FICD (4 wire plug) causes it to idle great (once warmed up). I was supposed to take the car to the body shop tonight, but they won't be there so maybe I'll pull the #62 ECU from the other SR and try it tonight to prove the theory... I hope. If my 5 week old daughter will stop crying tonight and my wife isn't having a breakdown :-(

[martin]

I managed to find some time last night.. not enough though :-(

I tried #62 ECU which works perfectly in another SR. It made absolutely no difference.. bummer!

I tried another known to be good MAF and it made absolutely no difference.

I now think it's down to TPS or the ACC/FICD valves. I've already checked the TPS according to the'92 240 FSM. The resistance readings all matched what the book said 2kOhms, 5-6kOhms 10kOhms (at different TB settings). I checked the harness plug to the TPS, again using '92 240FSM specs (does anyone have the SR specs?) - ignition on .5v(I think) on one wire (brown?). Ignition off continuity to ground on another wire (black)... still need to check continuity of the signal wire (white) to the ECU plug... need someone to help me with that. There was also a proceedure for adjusting the TPS, which indicated that I should have approx .5volts (?) when correctly adjusted across two wires (white/black I think). I don't have anything. To me this points to a problem. So this is where I'll look next. I have the original SR TPS (remember I'm using teh 240 TPS to get the cruise). I'll have to make an adapter harness to try this one, but that's not a big deal. After that it's pull off teh ACC/FICD valves... I have a spare SR intake so maybe I'll check it out first and see how they work etc.

I'll let you know what I find out when I get back to this.

-Martin.

[RobDET]

I definately have this issue. Including the drop when the car is not moving. I have a 5spd SR i na 5spd 240. It is worse when the timing is not set exactially. Could it be that Ambient air temprature sensor everyone says yo udon't need? Maybe i'll plug mine in and see what happens

I also get a wierd sound right at spool up. It's worse when it's cold out side. Sounds like crickets. Ive been told it's the trubo and i just bought another one so we'll see.

[ItzGenX]

I think it has something to do with temperature. My idle will be sky high (1500-2k+) on a cooler day around 60-70 degrees. If I park the car after driving it and turning it off, turning it on will let it idle correctly again (heat soak). Then when I drive around again, it will begin to idle higher and higher because of cooler air entering the engine bay. On warmer days, my idle eventually drops to the correct rpm. Also, when my car idles higher then usual, my car will stutter/miss/choke at hard throttle in boost 4.5psi and higher. This is why I think it has something to do with temperature, either ambient air temp or water temp sensor. I do not have an ambient air temp sensor hooked up, dont know where it goes, or dont even have one. I have one on my stock KA.

[Cyberkreig]

GenX as far as i know IAT's were only used on the S14 ka. Unless you have an s14 sr (and i dont know even then) i dont think you have/need an IAT

[ItzGenX]

GenX as far as i know IAT's were only used on the S14 ka. Unless you have an s14 sr (and i dont know even then) i dont think you have/need an IAT

I own a 95 240SX and the STOCK KA contained a ambient air sensor. I never said I have an SR air temp sensor. Well now that I know the SR doesn't even have an air temp sensor, I am thinking it could be water temp sensor or something else temperature related. Whatever is in control of telling the ecu that the motor is warmmed and no longer needs to idle high is possibly at fault.

[RobDET]

A while back i posted a "what is this thign thred"

http://www.nissaninfiniticlub....31304

It has a pic of the sensor that may have something to do with it. I'll plug it in tomorrow and let you guys know... If i can find it that is.

[ItzGenX]

If the sensor was mounted on the same bracket as the ignitor, it is the boost solenoid.

[RobDET]

that one wasn't on the bracket. It actuially came off of my Harness.

[Cyberkreig]

that sensor from the "what is this" is a sensor off of an s13. Mounted infront of the radiator.. i dont have a fuggin clue what it does.

[martin]

that sensor from the "what is this" is a sensor off of an s13. Mounted infront of the radiator.. i dont have a fuggin clue what it does.

It is a temp sensor, but not "the" ambiente air temp sensor....

The one is the picture is normally mounted in front of the rad, I believe it's something to do with the AC.

The Ambient air temp sensor is usually mounted in teh stock air bow, it senses the temp of the incoming air, helps the ECU determine mixture.

The Temp sensor that the ECU uses to determine how warm the engine is measures water temp. It's located at the left front side of the head, above and to the right of the TPS, it uses two of the three wires of the three pin plug at that location that has a bracket that mounts to teh rocker cover. The other wire (3rd wire)is for the other coolant temp sensor, it's only used for the gauge on the dash.

-Martin.

[ItzGenX]

Is the water temp sensor interchangable with any other motor? I want to change mine out to a known good one to see if it fixes it.

[Cyberkreig]

The Ambient air temp sensor is usually mounted in teh stock air bow, it senses the temp of the incoming air, helps the ECU determine mixture.

if this is true, than where is it now? I dont know too many people that have stock airboxes on Srs... and i dont *remember* seeing one on my ka. But still i dont know of any un-used plugs in that area..

Quote »The Temp sensor that the ECU uses to determine how warm the engine is measures water temp. It's located at the left front side of the head, above and to the right of the TPS, it uses two of the three wires of the three pin plug at that location that has a bracket that mounts to teh rocker cover. The other wire (3rd wire)is for the other coolant temp sensor, it's only used for the gauge on the dash. [/quote]

I know about this one, i accidently unpluged it once. IT made the car idle consistantly at 1200+++ rpm and the temp gauge did not work.

[martin]

if this is true, than where is it now? I dont know too many people that have stock airboxes on Srs... and i dont *remember* seeing one on my ka. But still i dont know of any un-used plugs in that area..



I know about this one, i accidently unpluged it once. IT made the car idle consistantly at 1200+++ rpm and the temp gauge did not work.

Most loose the one from the air box when they go K&N. On this latest swap I just have teh temp sensor tie wrapped to something. It's not in teh actual air flow, but I really don't think it matters. On previous swaps I'm not even bothered with it. Most people don't use it from what I can tell.

-Martin.

[martin]

8 months later I finally solved this problem! I still can't believe what the problem was. It was the neutral position switch on the transmission. Yeah right I can hear you all saying, but that's what it was. Apparently this signal is used by the ECU as one of the things that brings teh idle up, in this case it's used to bring up the revs when the trans is not in neutral. My switch was not working so it never looked like the car was in neutral, and the revs were always being brought up. I tested 2 additional KA ones before I found one which worked, so including the origibnal SR one that's 3 out of 4 that were bad.

All of this made me wonder.. how come the KA's that these trannys were in didn't have the same problem, surely the ECU on these would raise the idle too? Yep, according to the FSM's they do, my guess is that the KA's ECU only raises teh idle a little, say 200rpm, vs the SR which raises it 600rpm or so. Why the difference? The KA has more displacement, heavier flywheel, higher compression, more torque at idle, selecting a gear is less likely to drag the rev down and stall the motor.... that's what I came up with , others views may vary :-)

Anyway, since a number of your were having the same problems I thought I'd share the solution I found.

-Martin.

New SR install, runs fine, but won't come off fast idle.

Other possibly related symptoms:- when started cold throttle response is terrible ie, you can move throttle pedel 1/2 way before anything happens.- when it warms up throttle response improves.- If I unplug the TPS it makes no difference to the way the engine runs.- using KA24DE TB and TPS for cruise hook up- TPS has correct resistance reading- Unplugging the ACC/FIDC plug it idles great.- using #63 auto ECU with 5 speed. I've read that thsi should be OK, but maybe it's related? - Timing is set correctly at 15BTDC- no vaccum leaks- Walbro fuel pump

I don't really know how to trouble shoot this, any ideas?

Thanks...Martin.

[Gladius]

Well your theory is feasible. My sr has the same idle problems and my neutral position switch isnt even hooked to the ecu. Maybe if I hooked it up this idle prob will go away.

Well let me rephrase, I dont really have the high idle of like 1600 or anything. The highest it gets is 1300 after running it hard, but it eventually settles down to 850 - 900. Normal driving I will see 1100 alot times, but after idling for about 30 sec. it goes back down. On the cooler nights it settles to 850 imediately. My guess is this is still a valve problem.