Dashpot UIM
 

I don't know about you guys but I have seen a lot of FD's with the dashpot near the UIM not working. A friend of mine has worked on 4 cars in the past year and on 3 of them the dashpot was no good. I found another one the other day on an FD that wasn't working. That is a total of 4 dashpots shot in 5 cars. Is it just me or do these things fail alot.

By the way from what I have found the dashpot does have an effect on the idle on your car when you pull up to a complete stop. If your car appears to be hunting for a good idle speed then this could be the culprit.

I attached a picture so everyone could no what I'm talking about. The dashpot is outlined in red.

- Cody

Sorry about the picture. I took a high quality pic and tried to shrink it. That was the best I could do with the file size restrictions for the forum.

- Cody

im still not sure what the dashpot is? can you just cut out the circle section only??

Here is an up close picture. The blue arrow is pointing to the part that usually fails. This little white plastic cylinder should move in an out like a dashpot (damper). Most of the time the little white plastic cylinder is stuck all the way back which means it needs replaced or fixed. I haven't found a way to fix it yet so I just replace it.

If you push on it and you move your fingernail (or finger) it should come back out after you let go. If it doesn't come back and make contact with the bar in front of it (attached to your throttle) then it is no good.

- Cody

Forgot the picture.

i had to change mine. its no big just 15 bucks and like 5 minutes. just remember if your car doesnt idle at a stop in gear its probably that piece of shit dashpot thats broken. its really easy to tell just look under your dash by the clutch and if the white thing isnt long then its broken. hope this helps some other rx7 owner.


later sully

what does that thing do anyway?

puma, its main function (to my understanding) is that it slows the throttle mechanism down when you get off teh gas really quick so that there is not an abrupt deceleration 'trauma'... so when you get off the gas, the mechanism turns and then right twards the bottom hits the dashpot rod, and the rods slows it the rest of the way down

That's not the dashpot, that is the clutch switch.. yet another idle gremlin on the 7. I wish a dashpot was only $15, I had to replace mine recently.. more like $100 if I remember correctly.

Matt

ah, that makes sense, thanks

that is why i was confused, i couldn't understand what the "under the dash" at to do with the dashpot...

we always learn on this board, i like it.

thanks

My point in bringing this up was to simply let other FD owners now that this part of our cars seems to fail on a LOT of cars. As for pricing. Here is what one of our local club members found:

UIM dash-pot (damper)
mazdamotorsports.com price: $ 47.83
Dealer price : $114.76

Hopefully this thread got at least a few FD owners to check their cars. If this thread helped at least one person then it was worth it.

- Cody

I wonder if it is used on any other mazda cars... hmmm... junkyard :D

Dashpot is there to minimize the backfiring, when deceleratin it doesn't allow the trotle to close imediately so some air can still come in and basicaly push away the unburned fuel out faster to minimize backfiring, and they tend to fail allot and a new one at a dealer costs 106.00+tax,(:mad: sucks right?) I just changed mines few weeks ago.

Could someone take a look at this picture of my dashpot and tell me if my rod looks too short? (no pun intended :D). I have to screw the dashpot practically all the way in to get it to touch the bar in front of it. Thanks..

Yeah i think mine is broken. My idle sucks once the car is warmed up. Hunts all over the place. I thought it was the wax valve but may be this part.

That looks like it is probably broken to me. It would be easier to tell with it on your car. If the white (plastic) end is not touching the metal rod in front of it when you are not on the throttle then it is probably broken.

If it were me I would probably say it is broken and replace it, but it is up to you.

- Cody

I recently installed a light-weight flywheel, and sometimes when the rpm is above 3500 and I shift to neutral, the engine dies. I know this can be fixed with adjustment of the dashpot, but I am not sure of the exact procedure. The shop manual says to simply "loosen the locknut and turn the dashpot". How would you turn the dashpot?

This is a great thread. Mods, you might want to think about archiving it :)

i removed mine

i dont fully understand how it works... is it some sort of a stopper?? i have my throttle body next to me and the white thinggy doesnt touch the metal... can i just put attach something in between? or on the metal part so dat i dont have to spend a bloody $100 for a small rubber? :D

Yes the dashpot can cause poor idle problems (something I have been preaching for years) but they are usually just dirty, and in need of a good cleaning and lubrication.
The dashpot is found on many cars, and it is used to "slow the throttle" at its final travel.
You can tell that it is working by simply trying to push the white rod in. It should then retract slowly back to its original position.
The Dashpot can act like a throttle stop if it is not working correctly, and hence will cause poor idle. The real throttle stop is the bolt and nut combo on the UIM usually painted with a white mark. (Never turn this unless you know what you are doing).

What happens if you remove it? The scary thing is, I found mine just loose in the engine bay last year after I bought the car. I figured the car was running fine, so I just left it out.

The dash pot helps to keep the engine speed from dropping too quickly when you let off the throttle. The correct adjustment procedure is to first loosen the lock lut. Have someone in the car accelearate the engine to 2800 rpm, and hold it there. Turn the dashpot until the white button just touches the throttle lever. Tighten the locknut. Check to make sure the throttle lever does not depress far enough to touch the dash pot housing. If it does, replace the dash pot.

does any1 have a pix of how long should the dashpot UIM be?? i have had problem wiv idle and maybe this is it!?! I know i have idle hunting sometimes so i adjusted the screw near the daspot! the gap of the daspot to the rod is approximately 3cm. is it still good??