I have posted a few times on a hesistation problem and I recently noticed a problem with the idle that may be the actual cause.
When I'm driving the car and stop for a light(car is auto), the idle will of course settle down to about 700 rpm. Generally it's a very smooth idle.
However, sometimes, after 10 secs or so the idle will suddenly drop to about 550 and there is noticeable roughness also. When this happens, I nearly always get a hesistation when I take off.
I didn't notice this before bcause I have never seen it happen as far as I know when I just start the car in my driveway (even warmed up). It seems as you have to driving the car before the problem will show and even then it does not happen every time.
This does not appear to be a situation where the idle drifts down to 550 rpm or is hunting. It seems as if the ECM is activating a valve or something that immediately lowers the idle.
I'm going to run some of the checks in the manual but I was wondering if anyone has an idea what to check first.
Thanks
92 240sx idle down
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adrianfromthecastle
- Posts: 18849
- Joined: Wed Jun 29, 2005 5:36 am
- Car: 1992 Nissan 240sx
- Location: California
Re: 92 240sx idle down (alexh)
it only happens when engine is warm right? have you checked your mafs? It sounds to me like its your mafs...
Re: 92 240sx idle down (adrians_s13)
Definitely only when it's warm. In fact I noticed that car seems to have a little more power in general when it's cold.
I cleaned the MAF rcently by spraying it with electrical contact cleaner but of course it didn't help. Are you thinking replacement?
I cleaned the MAF rcently by spraying it with electrical contact cleaner but of course it didn't help. Are you thinking replacement?
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adrianfromthecastle
- Posts: 18849
- Joined: Wed Jun 29, 2005 5:36 am
- Car: 1992 Nissan 240sx
- Location: California
Re: 92 240sx idle down (alexh)
well, when it happend to me (i.e. started to idle like sh1t), I pulled over while it was still in crappy idle mode, and pulled out the mafs plug and it corrected its idle... ... I suggest trying that that way you know if it's your mafs or something else...alexh wrote:Definitely only when it's warm. In fact I noticed that car seems to have a little more power in general when it's cold.
I cleaned the MAF rcently by spraying it with electrical contact cleaner but of course it didn't help. Are you thinking replacement?
I had the problem in my 5 spd and it looks to be the intake manifold gasket. The leak is allowing a vacuum leak of sorts and warm air is thinner therefore bypassing the leak to a larger degree. But that might not be your situation. I haven't fixed mine because the engine will be getting replaced eventually and I don't feel like messing with it, haha. Bump for more help!