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yup
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Discussion Starter · #1 ·
For some reason my car will idle normally till i get on it for the first time once its warmed up. From then on the idle will stay above 2 grand. I can turn the car off and back on and the idle will still be at 2 grand. I've found several problems and have corrected them... no change...

Set the base idle and timing
Regrounded maf and tightened the connectors (ecu was throwing a code)
Checked tps voltage (normal)
bought and installed an entire new idle assembly (130 from vogel at quality... great deal on that part)
found that the hose on the top of the activated carbon canister which purges the fumes into the intake manifold was disconnected on top of the canister (reconnected it)
Found that one of the plastic nipples from the egr and canister control silenoid (the one under the tb) had broken off. JB welded it into place... silinoid still working and reconnected hoses.
check the tb for something holding it open (nope closes all the way)

here's a question. the hose that attaches to the large nipple on the intake tube closest to the throttle body (the one that sends air to the air regulator) has a vacuum even when the car is warmed up. I believe that the air regulator is the only thing connected to that hose and therefore this would mean that the air regulator is not fully closed when the car is warmed up right? i tried capping off the hose and the nipple to the air regulator since the car was already warmed up and i can't tell if this made a difference. So one more question are the jdm and usdm air regulators the same part??? i know that the idle assembly is not neither is the tps or the temp sensor... but what about the air regulator???

thanks.... and i will tell the entire forum how to download nissan FAST
 

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My Ass, your face
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Have you checked the AICV? This is located below the intake near the passenger side axel. When the engine is cold, it has a temperature sensitive piece that helps keep the part open and you idle a bit higher. Once the engine is hot, the heat "straightens" the piece and the idle is supposed to go back down.

If this isn't working properly, whether it's that particular part or the solenoid, your engine will continue to idle high.

Just a suggestion.

This is a picture
http://www.sr20forum.com/showthread.php?t=73216.

There is a nice writeup on se-r.net or in the se-r mailing list archives. If you can't find it, let me know, I've printed out the instructions and have them in my garage notebook.

Peace,
Mark
 

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i used to have my throttle cable get "stuck" on stuff under the hood. it would happen at totally random times.
 

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The JDM and USDM idle air regulators were different part numbers on my motors but I interchanged them and have had no problems.For a quick idle test take the hose from the iacr to the air tube off of the air tube,take 3 inches of 1/4 inch or 7/32 vacuum hose and stick it in the iacr hose,then put a heater hose clamp over it and tighten it until vacuum hose will no longer move easily.Reinstall iacr hose and start car you can then tighten the hose clamp,restricting the air flow,lowering the idle.If that works you know the iacr or the aac valve aren't working properly.Since you already changed the aac,it'll probably be the iacr.Give it a try,it only takes a couple minutes.If you can't lower the idle by tightening the clamp your idle problem is caused by something else.
 

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yup
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Discussion Starter · #5 ·
alright sounds like the best bet is trying to replace my old usdm air regulator/iacr with my jdm one... i believe that has to be done from under the car right? bah... dont know how im gonna get under the car here at college

getting closer to nissan FAST... it really is pretty cool
 

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My Ass, your face
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That's a great test V-Spec, honestly. I pulled mine and made sure that the "element" was responding correctly to heat and cold, your method is quicker and less messy.

Nj20de, park the front of your car on a curb. That might give you enough room to slide underneath and reach it ... if you don't have a jack or jackstands. I used to park my car half on and half off the bottom of our driveway, we lived on a hill... worked great.

One thing to consider, though. When I was problem solving my idle jump, all of the feedback and research I didn't pointed to one thing... no one had ever come across a bad AICV. No one had ever heard of one failing... they're actually made stoutly.

You replaced your AAC only, or was it the whole 3 part assembly... FICD AAC and IAC?
There's a test you can do with the FICD if you have a volt/ohm reader to see if it's good. My problem, which is similar to yours, is coming from the IAC, only. When I pulled and cleaned it, a made a slight booboo. I used a small o-ring when I replaced the idle screw... big mistake. It's jammed things up inside... must use rtv instead of an o-ring, I was trying to be smart;).

Good luck,
Mark
 

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don't overlook cleaning your throttle body, i had idle problems that drove me nuts, and when i installed my header i took off my throttle body and cleaned it out and scrubbed the throttle plate with carb cleaner, solved my problems, not sure if this will help you but i figured i might as well throw it in
 

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yup
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Discussion Starter · #8 ·
this is so weird guys.... the car idles really well.... that is until i "get on it" bringing it past 6 grand or so... after which time it will just sit at 2 or 3 grand... i am trying to think what would change during high full throttle operation? and the problem doesn't seem to go away when the car is turned off. It only goes back to normal after it sits for a while. its really perplexing...

to answer a few questions...
1) the throttle body has been cleaned recently and there is nothing mechanically that is holding the throttle open (throttle cable nor throttle plate stops)
2) the idle air assembly which consists of the ficv and the aac, was replaced with the new part from nissan. the third valve (the air regulator) is not built onto the idle air assembly but is rather a differnt part entirely even though it is one of the idle air control valves (aicv). so vladha... im not sure which parts you are referencing... there is not a single aic valve but rather three valves that make up the idle system

to clarify there are three idle air control valves (iacv)
1) the iacv-aac = auxilary air control (actively controls idle speed through on off operations
2) the iacv-ficv = fast idle control valve (adjusts idle under the heavy load of the ac and power steering
3) the iacv-air regulator (creates the high idle for the car as the car is warming up)

please refer to the valves using the above designations... the signal to noise ratio can go through the roof if you referrence the wrong part... thanks
 

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i don't know man, because of the fact that the idle remains perfect until you get to WOT, I still want to put money on a faulty TPS, you mentioned JB welding those plastic nipples for the EGR, you didn't by any chance clog any passages with the JB weld?
 

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yup
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Discussion Starter · #10 ·
nah i used basically a paper clip to align them and to keep the passage way open... then of course i removed it before installing it... i also blew through it to make sure that the right passage way was open when no power was supplied to the silenoid.

i guess further inspection of the tps might be in order... i dont remember if the idle changed at all though when i would test the car with out the tps connected... also tried disconnecting the heated o2 sensor... i also pulled each spark plug out for a second and each cylinder made the engine drop...

but your definately right about it being a weird problem... and its not really wot throttle that is the problem but in particular wot at a high rpm... i can floor the gas at a low rpm and as long as i shift before five grand or so im fine... so still more investigation needed...

i knew it this thing wasn't going to be a simple fix... i knew it wouldn't be anything major but ill bet its something minor that is causing all the problems which makes it that much harder to diagnos.
 

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My Ass, your face
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IAA Unit - Idle Air Adjusting Unit, consists of the AAC, FICD and the idle adusting screw.

For some reason, when I pulled the IAA unit, I was thinking that the AAC could be separated from the area that holds the idle control screw... I'm pretty sure that I separated them in order to clean them better. But, it's been awhile, and for once, I didn't take any pics. Since I've got to go back pull it again, I guess I'll see for sure.

My (mis?)understanding was that the portion that holds the idle screw is also called the IAC. But, maybe that's just another term people have used to describe both the AAC and the idle screw as a unit.

I may have to end up purchasing one from Greg V., especially if he only charges $100 for it. I'll recheck the volt/ohm readings on my FICD while I'm at it... I lost the brass/copper o-ring/washer... I reassembled it anyway. I wonder if this will mess up the readings:(.

It almost sounds as if the bimetal, heater and rotary shutter on the Air Regulator are not functioning properly, maybe it's sticking?

Peace,
Mark
 

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yup
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Discussion Starter · #12 ·
yeah i know the aac can be seperated from the iaa unit but they have to be purchased as a complete unit... the entire iaa. and the whole assembly costs 130 from vogel... which yeah definately is a nice deal...
 

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we have a problem at the shop with throttle body services. customers gas pedals stick so we clean the throttle body. sometimes if enough carbon was in there for a long enough period of time the ecm would "learn" the new throttle position. so after cleaning(with carb cleaner and toothbrush) adjust tps using THE FEALER GAUGE METHOD. the last part is kinda important. the old voltage method usually works, but nissan ammended all of the fsm's for a reason. the feeler gauge method works way better. you got any?
 

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yup
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Discussion Starter · #14 ·
i guess im not exactly sure what the feeler gauge method is... care to elaborate?
 

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My Ass, your face
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Yeah, nj beat me to it... what in the hay is a feeler gauge and what method are you talking about?

My TPS reads just like the FSM says it's supposed to.... what's this about Nissan redoing the FSMs?

Be interesting if this solves a few problems.

Peace,
Mark
 

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ok, off the top of my head i dont know what size feeler gauge to use for your particular application. the only service manual i have here is for an s15 silvia. its still an sr20 so the thickness may be the same. a feeler gauge is a thin sheet of metal that is an exact thickness.
heres what you do...
take feeler gauge a(size .75mm or .0295in) and stick it between the throttle drum and throttle stopper. this will keep the throttle open ever so slightly. adjust tps so that there is continuity between terminals 4 and 5.
do the same thing with feeler gauge b(size .85mm or .0335in), but now there should be no continuity.
then check with a again. this is not the throttle position sensor voltage. this is the closed throttle position switch continuity. this is more important and is integral to the tps unit. your tps has two plugs right? if not then disregard this whole thing. if you have a single connector on your tps then just adjust to .35-.65 and forget the feeler gauge method.
 

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another thing is to check operation of the fast idle cam. its all that funny linkage around the throttle. i could not possibly explain that without pictures.
 

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yup
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Discussion Starter · #19 ·
will likely know tommorrow (sat)... im considering just installing the thermoblock spacers so i can check every hose and the condition of the air regulator... im hoping it might just fix itself if i take everything apart and put it back together... it is just such a random symptom... hopeful i'll have this fixed soon and then will pass on some nissan fast knowledge
 

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Adam, talk to me on AIM. I might have a few suggestions for you.
 
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