Cleaning and Adjusting the Miata Dashpot (1.6 liter engines)

Disclaimer:

Low RPM clutch engaged droops below 850 or stalls High RPM clutch engaged stalls usually if you do not catch it with a small blip from your throttle.

Tools required

8mm combo wrench (2 is better than 1, but 1 will work just the same)

PB Blaster/ WD-40/Engine oil

Brain

Step 1: Locate Dashpot

Step 2: Prep your pot

Step 3: Blast the cylinder

Step 4: Adjustment

Step 5: Test it

50 Miles

Step 6: Zoom Zoom Zoom

I am a college student, not a master mechanic. Everything in this article is from the experience I have had on my car, or read here on miata net/other service manuals, and should be taken with a grain of salt. I am not responsible for you crashing your car because of adjusting too much causing WOT.Pre Dashpot work: I recommend adjusting the slack in your throttle cable (if you have any) before working on the dashpot, as you might have to readjust later. All work should be done while the car is off, and you should have to walk around and turn the car on to re check if the plate catches the rev. (To prevent a noisy neighborhood when you do eventually get stuck at WOT, and the adjustment screw gets freakin shakey)Before working on the dashpot, a brief explanation of what it does: When you take your foot off the gas, your throttle cable snaps shut. This part keeps the throttle body butterfly valve from closing too quickly, which starves the engine of air. This is what causes your car to stall when you put the clutch in to stop. There are a few different ways to figure out if your dashpot needs adjusting:I cleaned and adjusted the dashpot on the car, as I was about to strip one of the bolts holding it on. I am sure it is a lot easier to clean it off the car, as a soak in penetrating oil or any other caustic liquid (gas) might make everything better.(if you have gone this far with a 1.8, turn back and re read now, you'll never find it)Visual Aid for what I call the parts, by no means the right namesTake it off the car!If you cannot do that due to corrosion (that's me),Hold open throttle with one handremove the black rubber cover from the Dashpot’s cylinder.Don’t mind the red lube ;) previous attempt to fix it with wheel bearing grease made it gummier, which might have helped (probably didn't), but people just use PB/WD-40/ or regular motor oil.If you can, remove the dashpot from the car and soak it in a PB blaster bath or gasoline. This will clear out the gunk easier and more effieciently then the following steps.Face the can upside down (or use the small red tube they send) and blast the dashpot's cylinder and up into the dashpot itself thoroughly to lube and break up the dirt that gunks it up. Make sure the dashpot has about half an inch of play and moves freely without seeming stuck.If you removed the dashpot, obviously now is the time to put it back on. (durr)The Spec for where the dashpot should be engaging when lubed and working properly is touching the adjustment screw at 2500 rpm.You might need a buddy for this one, or very good ears and the ability to figure out where your throttle pulley should be at 2500. Take an 8mm combo wrench and loosen the lock nut, then have a buddy sit in the car (or hold your throttle open by hand if you know what 2500 rpm on the throttle pulley like) and hold the revs at 2500 until you are able to line the adjustment screw up to the bottom. At this point all you want it to do it touch, not be dampened yet.Be sure to re tighten the lock nut. Even though it seemed tight when I first did it, our cars are vibrators on wheels and it lowered after a 5 minute drive down the road to test it, stalling the first time I tried to test.To check the adjustment, hop in the car and turn it on. Just tap the rev one time. If you adjusted too much, it will stick at the peak of the rev and you’ll just have to go through the steps to lower it again.I tested mine by starting and stopping. In a series of tests, staying in first or second gear, bring the car to 2k,3k,4k,5k rpm and engage the clutch. Let the revs fall without catching it and you should see it fall slowly down to 850. No more idle dips and stalling for me! I will have to give it a few more days to drive on, but it has held forFULL GAS TANKsince I did the change!Hopefully all this helps you out, I finally got off my butt to fix my idle droop/stall issue and you can too. Took a little bit of tinkering, but it was very easy and anyone can do this in 20 minutes or less.