So I'm working with a 97 100% stock with 176,000 miles. I dd some basic maintenance after the car had not been taken care of very well and of course, things starts going wrong. Replaced plugs, wires, oil and filter, valve cover gasket, pcv valve, pcv grommet, clutch slave cylinder, tranny oil, charcoal canister, vapor purge valve. All that was done and ten had some fuel issues. High tank pressure along with fuel smell. Pulled the injectors and the o rings were blown and tips broken. Also decided to clean out the intake manifold which was caked 2mm in carbon along with the throttle body. New manifold gasket but reused the throttle body gasket. I cleaned because I was having some serious bogging, running lean, and loss of power if I tried to dog it (which the bad injectors explained). I changed the injectors and no more hesitation but my idle Sits at 2000rpm and eventually drops to 1500-1600 but never lower along wit some white smoke (coolant?). Thinking it was the iacv gasket, that was opened up and sure enough it was blown. Also had a sucking noise (mysterious vacuum leak) coming from the engine bay I couldn't find to save my life. Car is not back together yet, but any ideas? I'm sure it's just the 2 bad gaskets but I'm getting sick of pouring money into this car trying to make it run normal without results. Mainly looking for second opinions.

 

Check the gaskets around the the intake manifold if you removed/dissembled it. Make sure ALL vacuum lines are in excellent condition, with zero cracks, fraying. You probably have a vacuum leak. If you want to be really pedantic, you can simply remove, reinstall all the gaskets you touched, with a good coating of gasket maker on both sides. Are you sure the intake manifold seated properly against the head?




White smoke is generally from burning coolant. Have you checked the coolant line that runs around the throttle body plate?

 

Manifold gasket is definitely sealed well. No leaks at all coming from manifold. I tried smoke near the manifold, no leaks. But closer to throttle body, smoke blows away. But it's hard to tell with the fans. The rear coolant line to the throttle body hasn't been clamped down with te collar, and I'm sure that has something to do with it. But I'm thinking those 2 gaskets because there are multiple paths of coolant to the manifold from the TB and IACV. Being the IACV gasket was blown, sort of explains high idle, but not entirely. Again I didn't change the TB gasket at all. It was re used (I know that's a no no but slipped my mind while ordering parts)

 

With this info, I would put fault on the known-to-be-blown gasket.

 

Oh and vacuum lines are in good condition other than the 2 brake booster hoses will need replacement soon which I am aware it can cause bad vacuum leaks. But they've been that way and this is a whole new leak/idle issue.

 

Lol are we talking the IACV both IACV and TB gaskets?

 

Which ever one/s are bad. Fix the problem you know of before you look for others.

 

I have the similar problem. I cant locate my miatas idle issue either.

 

I'm waiting on payday to order the gaskets. Once replaced, I'll let u know what happens. I am also replacing my brake booster lines (which I have read can be the culprit of a large vacuum leak). Also, does anyone know about the (solenoid?) coming from the fpr? What is the **** on that for?