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PostPosted: 15 Sep 2014 15:55 
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Joined: 13 Jul 2009 16:44
Posts: 31
Country: Trinidad and Tobago
Hi ,

I have a GEN 2 mivec-md 4g92....I am having a problem when the air con is on...Whenever you are driving and come to a stop , the idle fluctuates and sometimes drops low to stall....I normally have to put it in neutral to get the idling to stabilise...Is there some sort of sensor for the air con that causes idling problems ? I read somewhere that there is a sensor inside near the blower that can cause idle probs but i cant find the post again....

I set the TPS but it still has the problem...There is a little screw that adjusts the throttle to increase idling..Does anyone know what position this screw should be in or how much should it be turned to adjust the throttle or should it just be adjusted to touch the throttle and not to turn the butterfly?

Hope you can assist....


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PostPosted: 16 Sep 2014 08:45 
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Joined: 13 Aug 2011 12:33
Posts: 376
Country: ireland
Try cleaning the throttle body, also idle control valve.

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PostPosted: 16 Sep 2014 14:48 
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Joined: 13 Jul 2009 16:44
Posts: 31
Country: Trinidad and Tobago
Hi,

I did all that and still the same problem , however i adjusted the TPS to the correct settings (0.5 v throttle closed ) but noticed when the throttle is fully opened it goes up to 4.38 v and when i release the throttle to close position , it goes down to below 0.5 v and fluctuates up and down a bit before settling to 0.5V...Is this how it is suppose to work?


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PostPosted: 16 Sep 2014 19:26 
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Joined: 04 Jul 2005 13:25
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Location: Lower Hutt
Country: NZ
That sounds normal.

It's a waste of time cleaning throttle bodies. Likewise airflow meters. If they get dirty ....there's a big problem somewhere else. That somewhere else is where to look.

There's 2 ways to adjust the idle speed screw.

One is by the book, done by grounding a test terminal and adjusting to the correct RPM.
The other way is to unscrew it a bit at a time then road testing to see how it works, if it's better or worse.
I guess you've already checked that the idle stepper motor works properly.
An easy test is to have the engine running, warmed up, no aircon. Read idle speed then turn the steering wheel to put load on the power steering. The revs should increase then drop down again to the starting RPMs.
Otherwise use an ohm meter and check for the same resistance on all 4 coils, probably about 30 ohms.The exact numbers don't matter.....so long as they're the same.

Steve

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PostPosted: 18 Sep 2014 16:04 
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Joined: 13 Jul 2009 16:44
Posts: 31
Country: Trinidad and Tobago
HI ,

today when the idle was fluctuating i inplugged the ISC valve but the idle still continued to fluctuate...There was no change in the idling? Does this mean the ISC is not functioning or is the problem coming from elsewhere?


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PostPosted: 19 Sep 2014 16:32 
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Joined: 04 Jul 2005 13:25
Posts: 1207
Location: Lower Hutt
Country: NZ
OK well it won't be a faulty ISC valve then.
Have you checked for split vac hoses. Maybe the signal to the MAP sensor isn't right?
Evoscan would be handy?

Steve

_________________
6G72 mivec Twin TDO5 20Gs up and running.
Scrapheap special making exactly 280 horses at some unknown rpm.
Engine dyno under construction.

It's easier to fool someone than it is to convince someone that they've been fooled.


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PostPosted: 20 Sep 2014 06:45 
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Joined: 29 Mar 2009 13:11
Posts: 370
Location: Co. Cork
Country: Ireland
I take it you didn't attempt to flash the codes for starters? Go ahead and do that first if it hasn't been done.
If no codes are present:

You might as well ensure that the throttle valve isn't sticking slightly.
Did you check the TPS properly or just set it?
Disconnect the TPS connector and check that the resistance across pins 2 & 4 varies proportionally as you open it up from idle


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