well i just finished the vacuum line and y-pipe install. the reason this had all begun was because of a fluctuating idle from 1500-1800RMP with no electrical load and a steady 2000RPM with an electrical load such as the fan, or headlights. I took the car to mostly mazda (the shop that is owned by M2) for diagnosis. they told me that it was caused by a vacuum leak.

So i finally got the vacuum lines and y-pipe installed (thank you jonski and everyone in the forum!!!! my only previous expierience working on an FD was changing the air filter ) After everything was done i went to start it up. when i did it did not do the normal warm up routine, and had a very rough idle. it was pouring out white smoke/steam from the exhaust pipe and it smelled sort of like burning charcoal. i shut it off after about 30 seconds and there was steam coming from the turbo side of the engine. i checked all the pipes and everything was fine, and there were no coolant drips under the car. i was really stunned, cause it seemed strange. then i checked the coolant level and it was down a good amount. i refilled it and left the cap off and started it up. still smoke/steam pouring out of the exhaust. i ran it for a while to make sure all of the bubbles came to the surface. the coolant was up to the very top... and when i started it up, the car seemed to be "drinking" coolant. i ended up adding a good amount of coolant a few times. well i finally gave up on it and went inside cause i didnt know what else to do. I came out a few hours later and went to start it again.... no smoke/steam from the exhaust or under the hood, it had a smooth idle and went through the normal warm up procedure.

anyone have any idea what happend????? my theory is that there is a bad housing seal or something and since the car wasnt started for a while it somhow contracted, letting coolant be sucked into the combustuion chamber. im stretching here cause i dont know how else to explain it.... any insightful theorys would be great!!

to make a long story short, the car still has the high fluctuating idle as before , so the smog stations here wont pass me..... what else could it be?? the good news is that i didnt f*ck up the vacuum lines and the engine now runs as it was meant to. this is the first time ive ever heard the BOV's and the car seems like its much faster now that the turbos are actually working properly. also the efini y-pipe seems to help but i dont have a good reference point for comparison. so if you havent done your vacuum lines, consider it! -heath

 

anyone?? sorry its so long

 

There are a few possiblities for having a high idle.

1. Throttle body isn't closing properly. This can be caused by a throttle cable that's too tight, a throttle stop that's been messed with, or a stuck thermowax.

2. Vacuuml leak. ANY air leak after the throttle body is a vaccum leak. Vacuum leak doesn't mean vacuum *hose* - it can be at the gasket surface between intake manifolds, a loose fuel injector seal, you name it. One common leak is the lower intake manifold gasket - the early cars had a paper gasket that was prone to blowing out. I *think* they fixed that by '94 - the new gasket is metal.

Finding a vacuum leak can be tricky. I recommend using starting fluid. Slowly and carefully spray it around where you think the leak might be. If there's a leak, the car will suck in the starting fluid and "rev up" a bit. I prefer starting fluid since it evaporates VERY quickly and doesn't leave a residue, but don't hose it all over everything - it *is* flammable. Just use common sense and it's an invaluable tool.

I've also heard of a case where something was jammed in the ISC making it stuck open a bit. Could be another possibility.

Good luck!
Dale

 

thanks