Here's one for you..
Discussion
A couple of you may have seen my mention of idle "stutter" when the lights and/or blower fan are on, in this thread:
http://pistonheads.com/gassing/topic.asp?h=0&t...
I'm experiencing similar symptoms, in that when the fan is switched to position 1 (lowest speed), I get idle "droop" - in that when the engine returns to idle, it dips down to about 400rpm, shudders for a split second, and pops back up to it's correct 850-900rpm. It only seems to do it with the lights on, and if the fan is at a higher position, it won't do it.
Pmansion in the above thread mentioned his idle was "sticking", mine isn't doing that, there is absolutely nothing else out of the ordinary with mine, it runs beautifully other than that, and it's not really the end of the world I guess, just very curious!
Any bright ideas anyone?
http://pistonheads.com/gassing/topic.asp?h=0&t...
I'm experiencing similar symptoms, in that when the fan is switched to position 1 (lowest speed), I get idle "droop" - in that when the engine returns to idle, it dips down to about 400rpm, shudders for a split second, and pops back up to it's correct 850-900rpm. It only seems to do it with the lights on, and if the fan is at a higher position, it won't do it.
Pmansion in the above thread mentioned his idle was "sticking", mine isn't doing that, there is absolutely nothing else out of the ordinary with mine, it runs beautifully other than that, and it's not really the end of the world I guess, just very curious!
Any bright ideas anyone?
Sounds like it needs the idle system setting up again.
There is a procedure for it, which I won't list here (search on the web for it) - but a quick fiddle with it can be had by popping open the small black cap on the LHS of the throttle body (as you stand in front of the car), then using a medium size slot head screwdriver to tweak it up or down. I'd suggest just try undoing it a couple of turns first and see what happens.
The method I mention above is trial and error, and the lazy way, but I'd probably do that first (I have this bad habit of doing it on mine)
Also, just check there is a little slack in the throttle cable when it is at idle. That was the source of another small amount of idle idiosyncracies mine used to display.
Hope this helps
There is a procedure for it, which I won't list here (search on the web for it) - but a quick fiddle with it can be had by popping open the small black cap on the LHS of the throttle body (as you stand in front of the car), then using a medium size slot head screwdriver to tweak it up or down. I'd suggest just try undoing it a couple of turns first and see what happens.
The method I mention above is trial and error, and the lazy way, but I'd probably do that first (I have this bad habit of doing it on mine)
Also, just check there is a little slack in the throttle cable when it is at idle. That was the source of another small amount of idle idiosyncracies mine used to display.
Hope this helps
Sorry - just to add, the idle speed valve will control the idle speed within a 'band' - so adjustment of the screw should not move the idle speed if the idle speed valve can control the airflow right. What I'm trying to say is that if it is idling at 850 rpm (+/- 50 rpm) then it's probably in control, so don't think you have to keep turning it until you notice a difference. Open it up a couple of turns and see if it still does it.
If whenever you move the screw it always move the idle speed, it suggests the idle speed valve is not operating.
Lastly - do this with the engine warm at operating temperature, or you'll be fighting the cold start/ fast idle system.
If whenever you move the screw it always move the idle speed, it suggests the idle speed valve is not operating.
Lastly - do this with the engine warm at operating temperature, or you'll be fighting the cold start/ fast idle system.
Mine was suffering from droop quite badly (!) but having the fan on setting 2 or above made it much better.
I then reset the timing to about 10 degrees which involved grounding one of the diagnostic pins then adjusting the cam position sensor, and since then it has behaved much better.
Perhaps grounding this pin caused the ECU to reset the idle speed or something, as it now sits at a steady 800rpm and it's not stalled since.
Check your clutch switch also - it's a tiny spring-loaded switch bolted to the top of the clutch pedal. The spring in mine had broken into 3 pieces so although the plunger still sprung in and out, it wasn't moving far enough out to activate the switch, leading to a tendancy to stall as the car didn't know whether the clutch was pressed or not. Very easy to fix with a new spring from one of those click-top ball point pens! Make sure you note where it is positioned and refit it at the same angle to avoid crushing it with the pedal top.
I then reset the timing to about 10 degrees which involved grounding one of the diagnostic pins then adjusting the cam position sensor, and since then it has behaved much better.
Perhaps grounding this pin caused the ECU to reset the idle speed or something, as it now sits at a steady 800rpm and it's not stalled since.
Check your clutch switch also - it's a tiny spring-loaded switch bolted to the top of the clutch pedal. The spring in mine had broken into 3 pieces so although the plunger still sprung in and out, it wasn't moving far enough out to activate the switch, leading to a tendancy to stall as the car didn't know whether the clutch was pressed or not. Very easy to fix with a new spring from one of those click-top ball point pens! Make sure you note where it is positioned and refit it at the same angle to avoid crushing it with the pedal top.
Howard- said:
Interesting. Why would engaging or disengaging the clutch cause more or less load on the engine? It does it when sitting there in neutral also
I don't think it puts any load on the engine, but the idle speed increases if you put the clutch down, perhaps to help you not stall as you pull away?Lights/fan both increase the demands on the charging system. It could just be that your battery isn't quite up to the job now. It's always this time of year when batteries start showing signs of failure. Try giving it a good overnight charge and see if it improves at all - charging will likely only help for a day or so, it's not a permanent fix. If not, get the battery tested (most tyre/battery suppliers will do this for free but don't buy a battery off them).
I have to say my wandering idle has been fixed again with the cambelt. The tensioner wasn't working so the cam belt wasn't tight, so the cam wasn't perfectly positioned so the spark wasn't perfectly timed. Thats my theory...
Anyway 1st time It got better with new HT leads. This time Cambelt. Next time I presume it'll be the Coil Packs....
Anyway 1st time It got better with new HT leads. This time Cambelt. Next time I presume it'll be the Coil Packs....
Howard- said:
Well folks..
It does it with the lights on, and fans off. It does it with the lights on, and the fan on position one. But it's fine with the lights on and the fans on position 2, 3 or 4, aka hurricane mode.
Bizarre!
Same as mine was - check your engine timing and using the jumper wire on the diagnostic connector reset it to about 10 degrees, then see if the problem goes away - it did on mine.It does it with the lights on, and fans off. It does it with the lights on, and the fan on position one. But it's fine with the lights on and the fans on position 2, 3 or 4, aka hurricane mode.
Bizarre!
Either way it's bizarre, I can't see how the timing would affect it! Gassing Station | Mazda MX5/Roadster/Miata | Top of Page | What's New | My Stuff