mx5cartalk.com

Hey guys

The car is acting quite funny lately, especially cold start. It stalls easily when you quickly dab the accelerator, and the situations are as below

1. Cold start, it stalls easily unless you rev it up to 2.5k and above (worse with A/C on), ie, slowly releasing clutch pedal or lightly depress the accelerator. This seems to happen quite often lately
2. When is warm and you quickly dab the accelerator, the rev will drop slightly below idle if the A/C is off and while the A/C is on, it drops more and chances of stalling. This however doesn't happen very often and quite hard to replicate

Did some troubleshooting and realize that when I switched on light or wherever the electrical power load changes the idle drop slightly, searched around and found this http://www.miata.net/garage/KnowYourCar/S7_Idle.html

Now the thing is, after I bridged the GND and TEN cells, nothing changes. I then turn (counter-clockwise) the rev adjuster to see if previously was perfect but again nothing changes. I tried bridging using several materials, metal paper clip, metal scissor and unused speaker wire (both side of the connectors were plated in gold), but again no effect.

So what am I doing wrong??

P.S when the A/C is on, I also realize that the rev dips much quicker while changing gears (depressing the clutch pedal)?

P.P.S When I was replacing the filter, I realize the piping from the filter to the turbo is a bit oily. Is this normal? If yes, may I know why?

How to do this was sonsolidated recently into one thread:
viewtopic.php?f=76&t=60434

ya I did found that post when I was searching for this matter.

My question is why doesn't the bridge work? And today I went and set it again, and I realize that even without the bridge between TEN and GND cells, the rev changes as I change the rev adjuster. I thought the ECU was suppose to control the rev when there is no bridge between TEN and GND cells?

klvru wrote:I thought the ECU was suppose to control the rev when there is no bridge between TEN and GND cells?

"On the MX-5, the car's computer (ECU) regulates the idle speed. However, when you come to a stop it takes a few seconds for the ECU to take over and regulate the idle speed. In the intervening period the mechanical idle setting is in control. Let's call that the 'ambient' idle setting for purposes of explanation.
If the ambient idle setting is lower than the ECU-controlled setting (850 to 900 rpm) the car will commence idling at ambient (low) level and, within a second or two, take up the proper ECU setting. The cycling of the idle dip is as if the car senses the increase in rpm and is tricked into thinking that the car is not at rest any more and switches off the ECU idle. The revs then drop down again to the ambient level, the ECU kicks in again, the revs increases, and so on. The car finally settles and idles as if nothing is the matter."

klvru wrote:My question is why doesn't the bridge work?

From a quick look at a couple of relatively recent threads, it seems it's not uncommon for there to be no change to idle after bridging TEN & GND. Off the top of my head I'm not sure that a single definitive cause to this has been found.

klvru wrote:P.S when the A/C is on, I also realize that the rev dips much quicker while changing gears (depressing the clutch pedal)?

There's a clutch pedal switch which along with gearbox neutral switch & throttle position switch controls idle speed:
viewtopic.php?f=57&t=47158&p=591954&hilit=clutch+switch#p591954

More info here:
search.php?keywords=clutch+switch&terms=all&author=manga*&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search