Guest Nd4Spd Posted July 21, 2004 Share Posted July 21, 2004 This thing is driving me crazy and the Nissan place has pretty much banned me from ever coming back. I have a '90 4x4 standard (probably doesn't matter, but what the hey) that will idle high - around 2k. Then it will drop to normal. Now, I can't really reproduce this. Some times it will, some times it won't. It will do it on cold days, hot days, rain, sun, cloudy, doesn't matter. If I'm at a light or just idling, it will actually rev itself. People at lights think I'm going to race them or something. It will idle 1200, then back to 500, then jump to 2k, then back down. It might stay down, might stay high. Might stay in the middle. I'm going nuts trying to figure this out. It's not so much the fact that it's doing it as I think it is causing me to wear my clutch out faster. If I'm starting from a stop @ 2k, there is a differnent clutch/gas pedal mixture... know what I'm talking about? And when I let off to shift gears, I'm already rev'd up too far or higher than it should be for coming back in with gas. Anyway, they have tried adjusting the idle, no luck. They don't know what it is or what is causing it. I personally think they don't care. I'd think the computer would have to be doing something. Now, my guess is there is a temperature sensing idle in this rig. And the temp sensor is going bad so it doesn't know how hot or cold it is. Does this sound plausable? :confused: Thanks Aaron Link to comment Share on other sites More sharing options...
jjdwyer Posted July 21, 2004 Share Posted July 21, 2004 hey, You could have a million and one problems there. But first of all you have to look at a few things. First look at your air intake pipe that goes form your Mass Airflow to the intake. Is this cracked at all, or any holes? Do you have any hoses off that go onto the intake pipe? Are your clams loose that hold this pipe on? Second, look at your idle air control motor located under the throttle body housing. Is it clean or working?? This will cause these problems. Jason Link to comment Share on other sites More sharing options...
Guest Nd4Spd Posted July 21, 2004 Share Posted July 21, 2004 Thanks Jason. Will take a look at those when I can get back outside to the rig. I know the mass airflow intake had a crack in it and was replaced. This was very recent. There is a small tube coming off of it, about midway between the butterfly valve and the air filter box. It is starting to crack and wear. If I had to guess, it is about the diameter of about 3 toothpicks, if that. It's very small. Other than that, I'll have to go and look. I've had to take that mass airflow off to get to the butterfly (I have a wicked sticky gas peddle that no amount of carb cleaner can seem to fix (2 cans to date)). thanks again. Aaron Link to comment Share on other sites More sharing options...
94extreme Posted July 21, 2004 Share Posted July 21, 2004 have you checked for ECU codes or done any diagnostics with it? it also could be loose vacuum connection somewhere; that'll do it too. Link to comment Share on other sites More sharing options...
MatterHorn Posted July 21, 2004 Share Posted July 21, 2004 if your temp sensor is bad, you should really replace that too ... also check all vacuum hoses for any signs that there might be leaking ... usually you can take a can of hair spray and spray a few quick shots on areas - if the throttle advances, then you have a leak ... Link to comment Share on other sites More sharing options...
Mr. Pickles Posted July 21, 2004 Share Posted July 21, 2004 Could your sticky gas pedal be this? Link to comment Share on other sites More sharing options...
MatterHorn Posted July 21, 2004 Share Posted July 21, 2004 he has a 1990 ... so he doesn't have throttle body injection ... Link to comment Share on other sites More sharing options...
Mr. Pickles Posted July 21, 2004 Share Posted July 21, 2004 he has a 1990 ... so he doesn't have throttle body injection ... Sonuva... +1 Link to comment Share on other sites More sharing options...
87pathy Posted July 21, 2004 Share Posted July 21, 2004 sounds like a vaccuum leak. Chech all the vacuum hoses for cracks and holes ect. Link to comment Share on other sites More sharing options...
nige Posted July 22, 2004 Share Posted July 22, 2004 his check engine light should be on if it's a bad sensor. then he can pull codes. I just got my truck a new ex. temp sensor and installed it today ahhhhhhh i have my milage back again which is good 'cause petrol is $0.84 here for reg Link to comment Share on other sites More sharing options...
mikesmaximase Posted July 22, 2004 Share Posted July 22, 2004 Been there done that, I posted all about it, The idle air control motor on the underside of the back of the intake manifold. Link to comment Share on other sites More sharing options...
gacruiser Posted July 22, 2004 Share Posted July 22, 2004 As several others have suggested, check the Auxillary Air Controller (AAC). It's located at the rear of the engine on the driver's side, right behind the EGR valve. There's a 2-conductor plug on the top which you can remove and test resistance on. I had a similar problem on my '91 this weekend, which I diagnosed as the AAC. Resistance should be approx 10 ohms. Mine was over 70 ohms. Here's a link to the part: http://catalog.thepartsbin.com/?year=1990&...imageField.y=11 Link to comment Share on other sites More sharing options...
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