Rough Idle, Sluggish Acceleration
 

Anyone have any ideas why my 7 might be idling and/or running rough? its an '85 GSL carborated with a 13B. When it sits at an idle it runs pretty rough, almost like the timing is off. i need to check the timing, but i was wondering if anyone knows of anything else i should check? I can only say that it runs rough compared to my '85 GSL-SE which is a fuel injected 13B. Plus, when i accelerate it seems sluggish compared to the SE, should there really be that big of a difference between carborated and fuel injected when they are running right? is there anything else different about them that could affect the acceleration, i.e. gearing? Any help would be great, thanks

welcome to the forum.

are you sure the carb'd '85 has a 13b? only the GSL-SE models have the EFI 13b. all the rest of the 1st gens have a 12a which can make 30 less HP than the 13b.

that would explain the sluggish acceleration as compared with the 13b w/ EFI.

http://www.luxury-import.com/TSA-Stuff/shutterplug.jpg

also check to see that the hole that is pointed to in this picture is not sucking air at idle. if it is, it's probably a bad shutter valve. as a quick-fix, you can plug this hole with anything that won't fall out while driving and clog up your carb, otherwise, you'll need to remove your carb to replace the part. while the hole is plugged, your valve is stuck open and your combustion chambers are recieving too much mixture (or so i've been told by don at hayes).

mine's broken. i live with the rough idle for now. i'll replace it when my carb is off; i'm not about to remove my carb to replace the part.

im not sure if it is a 13B now that you mention it...it may not be...i could just be confused...but anyway ill be sure to check the valve thing, thanks for the tip

http://www.mazdatrix.com/c-5.htm

the anti-afterburn hose cracking is another common problem. that web page has instructions on how to change the shutter valve.

removing the carb isn't as hard as they make it out to be... and i have zero patience.

It should go w/o saying that a quick check of all your vacuum lines would also be in order. Use a can of starting fluid or Gumout's carb cleaner to lightly "spritz" around your lines until the idle jumps. Check all the lines in that vivnity and replace.
Capt. Gloval sure is gettin' his money's worth outta that shutter port shot, ain'ts he?:p

i actually stole that from someone else's post :D

Hey! Stop stealing my pics! :p

That's for the 12A. He's got an aftermarket intake and carb if he's got a 13B.

You can chekc the type of engine if you look just behing the distributor, where it attaches to the engine. It will say 12A or 13B, right near where it says MAZDA.

If you have that blue intake and a 12A, follow that shutter valve diagnosis and plug it up securely. That shutter valve is one huge vacuum leak.

my small hole beside the big hole that sucks air also sucks air. (plus the one you mentioned) Should I plug this one too?

No, not till you know where it goes. It may need to suck air. We're not just pulggung random hoses here. ;)

Try plugging the one I'm pointing to in the pic with your finger. Idle should smooth out. That one, I'm sure should not be sucking air at idle, and should be plugged if the valve is not replaced.

If you wanna, try plugging that other one with your finger. Or stick some tape over it and go for a test drive.