91 lx dohc at

[Zorix]

Hi Everyone. First time posting here. I have a 1991 protege LX model 1.8L 4 cylinder engine. I have noticed as the years go by, that the engine idle is getting more rough. In hotter weather it will drag the idle to below 500 rpm. In cooler weather it will be about 750-1000 rpm and run fine. I have had a few mechanics look at this, but I was wondering if there is something mazda specific that could be the problem. Thanks guys.

 

[Salmon_Rob]

check your intake piping for dry rot cracks

 

[racerboy]

check your intake piping for dry rot cracks

(stupid)

 

[Zorix]

Thanks guys. I didn't notice any last time I looked, but I will inspect it with detail. If it is cracked anywhere, where would I go for a replacement?

Edit: Nevermind, I found a few sources.

A friend told me I might need to adjust the idle speed while jumpering a connection in the diagnostic box. I know the idle has been messed with
a few times, could something need to be reset with the computer? (In case above suggestion doesn't work) Thanks.

 

[Salmon_Rob]

honestly i'd check the intake hose. i've got money that is your issue