scarceller

Also, you can leave the O2 disconnected and drive it some see if you notice anything diffrent. You should not.

scarceller

While your at it check the idle switch and make sure it closes when the throttle plate returns shut. With engine off if you lift ever so slightly on the throttle plate you should hear the microswitch click open and then click closed when you return to closed throttle

Shannon123

Check....i did this and a clear click occurs opening and closing.....getting ready to do the carb spray test.....guess the words extremely flamable on the can means don't do it too long.

scarceller

Also, let's be sure the Idle Control Valve works. A simple test is to turn the key to 'RUN' but do not start engine. Then place your hand on the ICV it should be vibrating and you should hear it humming. This simply tells us that the DME is talking to the ICV and that the coils within the ICV are not burned out. It does not mean the valve is 100% OK but it's a good start to verifying at least it's somewhat functional.

Shannon123

Check....she hums/vibrates nicely.

I may have made some headway.

I started engine and let idle. Started spraying isolated spots and then the rubber boot connecting the air flow meter (AFM), throttle and idle control valve (ICV). Engine settled down and rpms went to 800+. Could the back side of this be cracked or something....the front side looks clean and somewhat fresh. I did tighten the clamps around it (the ones I could see).

scarceller

OK, I suggest you take apart that 90 degree boot that goes from ThrottleBody to AirMeter. There are 2 or 3 hoses on the backside as well. Inspect all these for cracks. The RPM increase is a clear sign of a air leak. Just be sure the spray did not somehow get sucked in the normal intake on the air box. Use a straw on the can to try and pin point the leak. I also use a propane bottle with special attached rubber hose to help pinpoint the issue.

My bet is some hose is cracked or a hose on the back side of the TB or the Black 90 degree boot is disconnected or cracked.

Shannon123

I did feel around the backside and felt the other hose.......if I start taking that boot off and the hose to ICV, will gas leak out (showing my experience level again here)....or is nothing beeing fed through while car is not running ? Thanks for your patience.

Shannon123

I'm letting the car get cold again to double check my carb fluid testing and perhaps isolate things a bit more.....IF this is not the issue, then could the ICV be guped up/need cleaning ? I' ve read a couple links on this and thought I'd throw it out there.

rusnak

It sounds like you have an air leak there somewhere. It's very possible that the rpm increase is due to vacuum suctioning in the carb cleaner, hence the raised idle. The reason that ether is normally used is the same reason propane works. It converts to gaseous form instantly.

You still want to get a strong light, and small mirror and inspect all of those hoses and hose connections. The little hose that connects to the ambient air valve can crack and leak. You should trim the end off, and insure a tight connection.

scarceller

Nothing but air flows via those hoses, easy to take apart.

Shannon123

Well....i may have jumped the gun or hearing things/anxious for a fix. I let the engine cool down (not that it got hot) and tried to simulate my earlier findings. I sprayed on the area of the boot before the AFM and where it connects from the ICV....sprayed front and back (as much as possible) and I'll be damned if I can get her to do what I thought it did earlier.

The only thing I know that I have done....is replace the DME when I got the car. I did not do this for any particular reason, but just wanted to have an extra one and decided to use the new one and old one as backup. This replacement was done 2 months ago, so pretty sure its meaningless as far as the mildly rough/low idle.

This was a CA car and now in Houston....not sure that should or could make a diff.....maybe I should try resetting idle to factory ?

Seafoam anyone ?

flexbert

New guy here too but I suspect you meant DME relay above ? Rebuilt DME on Pelican lists for ~$2677, ~$450 for the DME rebuild service, while a DME relay is $25 for the non-Porsche version and about $95 for the P version.

Lex

Shannon123

I did this procedure....I could not get idle past 750. While the bridge wire was in, the idle was VERY rough....if that indicates anything.

Shannon123

Sorry, yes meant DME relay.

1986 Targa

Shannon,

As per the above posts, what you may have is a leak at the boot interfaces.

Mine developed a leak due to an improperly tightened clamp on the throttle body.

Removing the 90 degree boot is not a big deal, then check it for cracks,
and loose hoses on the back of the boot.

pm me as needed.

Good luck,

Gerry