What is this part on MTX?

[Warren]

Hey guys, What is this part circled in red thats attached to my MTX trans and is it supposed to be sticking out this far?

I also have been having a weird problem recently. Sometimes while im driving doing 40 or 50, if I put the car in neutral, sometimes the RPMs go to 1100 then drop to 400 and back to 1100 and stays there and then once in a while it bounces but then the RPMs drop so low the car stalls out and I have to re start it. This happens randomly. Sometimes Im driving and put it in neutral and the rpms just drop to 1100 and stay there until I put it back into gear. Any Ideas? Oh and my cruise control works fine.

 

[intimdatr]

The staying at 1100rpm is designed to help getting back into gear. Once you drop below i think 10mph it will fall back to idle. That normal.

The randomly dying? dropping: i have no idea My does that but when it drops it just dies there is no saving it either which is weird.

 

[Devin]

Hey guys, What is this part circled in red thats attached to my MTX trans and is it supposed to be sticking out this far?

I also have been having a weird problem recently. Sometimes while im driving doing 40 or 50, if I put the car in neutral, sometimes the RPMs go to 1100 then drop to 400 and back to 1100 and stays there and then once in a while it bounces but then the RPMs drop so low the car stalls out and I have to re start it. This happens randomly. Sometimes Im driving and put it in neutral and the rpms just drop to 1100 and stay there until I put it back into gear. Any Ideas? Oh and my cruise control works fine.

Usually in my experience idle problems are IAC or vacuum related.

 

[intimdatr]

If i had to guess its likely a sticky IAC.

 

[SHO1]

speedometer cable/speed sensor in pic.

 

[jelloslug]

It item in the pic is the VSS (vehicle speed sensor).

 

[Warren]

Ok thanks for the info. The stalling/drop in RPMs only happens when the heat or AC is on. Would that still point to a sticky IAC? Also, I notcied my speedometer is off by about 5MPH. Would this be a bad VSS? Anyway I could figure out why my speedo is off? I have 225/60/16 size tires on my car.

 

[hawkeye18]

Also, I notcied my speedometer is off by about 5MPH. Would this be a bad VSS? Anyway I could figure out why my speedo is off? I have 255/60/16 size tires on my car.

If that's not a typo, that's your problem right there.

 

[Warren]

If that's not a typo, that's your problem right there.

woops sorry, its 225/60/16

 

[hawkeye18]

That would also explain it. Stock size is 215/60/16, and anything other than that size will affect the speedo. If you get a 225/55/16, it'll be a lot closer - I want to say it's .9% off. The rule of thumb is, if you go one size wider, you need to go one size shorter (width is in 10mm increments, height is in 5% increments) in order to keep the same total tire diameter.

If you get a 225/60, then your speedo will read slower than what you're going. Here's a website that'll help explain it for you. It's been a standby for me for many, many years and is probably the #1 tool on the internet for tire size calculations.

http://www.miata.net/garage/tirecalc.html

 

[Warren]

That would also explain it. Stock size is 215/60/16, and anything other than that size will affect the speedo. If you get a 225/55/16, it'll be a lot closer - I want to say it's .9% off. The rule of thumb is, if you go one size wider, you need to go one size shorter (width is in 10mm increments, height is in 5% increments) in order to keep the same total tire diameter.

If you get a 225/60, then your speedo will read slower than what you're going. Here's a website that'll help explain it for you. It's been a standby for me for many, many years and is probably the #1 tool on the internet for tire size calculations.

http://www.miata.net/garage/tirecalc.html

Thanks! you have alot of info and I appreciate it. I had a feeling my speedo was off, then I turned on my GPS app on my phone and when I was doing 65 on the speedo the GPS said 70 and I know the GPS is accurate cause when I was in my friends car the GPS and the speedo were almost exaclty the same. Im confused though because when I check that website, it says the speedo is 1.8% too slow so it reading 60 i would actually be going 61.1 but im going almost 5 MPH faster

 

[hawkeye18]

Another point to consider is that the speedos and cabling on all our SHOs is getting pretty old and crusty. I think there are very few SHOs on the road today with accurate speedos. I always had my GPS up for this reason.

 

[Warren]

Happen to know the part number for the speedo cable and the accelerator cable? I might want to replace both Im on rock auto now but am confused about the right part.

 

[hawkeye18]

IIRC neither have been made in a long time. They are unobtainium. Except for possibly the lower cable (there are two halves to the speedo cable). That is mainly why very few SHOs have accurate speedos.

 

[frosho]

I bought new upper and lower speedo cables from Rockauto.com last year. Dorman p/n's 03239 (upper) and 03246 (lower). It appears that they no longer carry the Dorman lower cable, but there is an ATP part listed.

For the throttle cable, I think you'll have to find a good used one. Ford discontinued them, and I don't know of anyone selling aftermarket replacements.

EDIT: Forgot to mention, I don't think new cables will have any effect on the accuracy of the gauge. If it's reading pretty close, and it doesn't seem to jump or get hung up anywhere, then the cable is working fine. That cable is spinning pretty fast when you're driving on the highway. If something was causing it to hang up, you'd most likely hear it too. That has been my experience.

 

[Devin]

Ok thanks for the info. The stalling/drop in RPMs only happens when the heat or AC is on. Would that still point to a sticky IAC? Also, I notcied my speedometer is off by about 5MPH. Would this be a bad VSS? Anyway I could figure out why my speedo is off? I have 225/60/16 size tires on my car.

So it doesn't ever happen when the EATC shows OFF? If so it could be a problem with your compressor bogging down the engine due to a bad clutch or something. I know that the AC kicks on when defrost is on, but I'm not sure if it also engages in other modes as well during heating.

Does it sounds like the compressor is cycling okay?

 

[guse1096]

To address the stalling/ idle problem: I had the same thing happen to me from time to time and resetting the IAC always corrected the problem. This is preformed by unhooking the battery for 30 seconds, holding the brake pedal down (im assuming this drains any stored energy in the computer) and then hooking battery back up, starting the vehicle and it will relearn the idle position on its own from there. Its been awhile since I did it but I think thats all there is to it...good luck

 

[frosho]

Its been awhile since I did it but I think thats all there is to it...good luck

There's a little more to it than that.

IDLE RESET PROCEDURE