philip77o

Hi,

Tomorow I'll be doing the idle ajusment on my 86 951 in order to fix a small idle problem (tiny ups and downs on idle and strong fuel smell off the exhaust) I just need to be sure of a few things. First, when I jump the terminal B and C do I need to keep it jumping while I adjust the RPM or touch the terminals a few seconds then I remove the jump wire ?

Another thing is that I think I may have a small vacuum leak, When I disconect the small vacuum line on the top of the bypass valve, I blow air into the line while pressing on the bypass valve nozzle with my thumb, and air can circulate into the system. Is this normal or I'm not suppose to be able to blow air into the line ? Is this the right way to test for an air leak ? (I own the car for about 4 months, the vacuum line looks like they have been replaced with blue silicone line so it's not the factory old lines.

thank you

mahoney944

If they were replaced I doubt they are leaking I would just inspect for cracks in the hoses if they look newer. I know Ive seen people pressure test their system by removing the air box and meter and making a plastic cap with a shop hose attachment and securing it with a hose clamp in the j boot and pumping 15psi of shop pressure into the motor and inspecting for leaks. Also which idle adjustment process are you using to do this? ive notice my car at idle doing this, its very minor but if theirs a solution post it here.

Cyberpunky

You need to keep the jumper there. Procedure is on clarks garage.

philip77o

Another thing, when they say "performed while the car is not running" does that mean whit ignition on or off ?

http://www.lindseyracing.com/LR/Parts/IDLE944T.html

Tedro951

Ign off until it says to start the car.

fejjj

If the vacuum lines were replaced and you still have a an idle fluctuation then likely it is your throttle body seals.

Many people overlook these when they replace vac lines.

philip77o

I did everything they say on the DIY, the adjusment screw is set 1/2 turn from fully seat, idle is smooth at at around 850 rpm. As soon as I remove the jump wire, the idle start the bounce a little again... same thing if I shut the engine and remove the jump wire then re start the engine... Am I missing something ?

URG8RB8

You have opened a giant can of worms! If you want to get to the bottom of this it most likely will not be easy. I just went through a similar issue. As mentioned earlier, take the time and pressurise your system. You will find leaks, I am sure of that. If your TB is original all seals are shot, again guaranteed. Kit is cheap from Paragon and has good instructions. Even after fixing all these issues, idle still might not be stable, as your sounds like an ISV issue to me. This piece is expensive. I cheaped out and bought a rebuilt one from Paragon at first. It did not work, so I bought an original and that one did work. There are many "procedures" on how to test your ISV, but this is only misleading. It will tell you if it is opening and closing, but this is only 2 of 255 different positions the ISV goes too. This is quite a complex device for the 80's. Then you have the DME and KLR board issues to deal with and/or look into. I would save these for last. Hopefully Josh's new DME's will be ready soon which will solve the board and solder joint issues. Good luck in your quest!

eman930

Id start with check all vac lines and leaks as a basic rule. I was able to remove my IAV and clean/lube it, its been working great ever since.

philip77o

I'm currently testing for vacuum leak, I put 15psi into the j-boot and I get a leak at the banjo bolt on the intercooler pipe, I replaced the two o-ring and put a hose clamp and still have a leak

odb812

You have a problem with your idle stabilizer valve(the thing you electronically disable when you put the jumper in the diagnostic port). The valve sits directly below the intake manifold and regulates how much air passes by the throttle body under idle to compensate for a cold engine.

You can try to clean it out. I've heard some people try spraying some sort of penetrant in the line that goes from the IC->TB pipe to the ISV and that frees things up.

When mine went I left the jumper in the diagnostic port and disabled it until the next time I took my turbo out. The next time I took my turbo out I put a rebuilt one in and it worked fine. The next time I had the turbo out after that, the ISV was in way of where I wanted to run some new wiring and vac lines, so I pulled it out again, disabled it on the diagnostic port, and I don't miss it a bit.

URG8RB8

There should not be O-Rings on the banjo bolt, there should be copper or aluminum crush washers.

philip77o

Yeah I meant copper washer sorry. Luckily I found a similar banjo bolt in my garage, I also replaced the small section of silicone hose. Looks like there is no more leak, except under the manifold which I believe is normal ( positive crankcase ventilation) I'm gonna start the car, let it warm up and see if I still get the jumping idle.

URG8RB8

No, not normal! There is no PCV on our engine. You should be able to hold 15psi for at least 5 minutes with the compressor shut off. See my post of this for the proper procedure. Search for my alias last month.

philip77o

I started the car, let it warmed up until the coolant temp was to 1/4, idle was very smooth but at 1000 rpm... shut the engine, jump the terminal B and C, re start the engine and it ran like crap, gave the adjusment scew a couple of counter clockwise turn to hit 850 rpm, removed the jumper wire. 20 seconds later the jumping idle came back ( less worst than before but still some up and down)

Update Retried the idle ajusment with engine temp to 1/2. Idle is smoth but I cant get it lower than 1000rpm, sometimes it drops to 850/900rpms, I give a small tap on the gas pedal and then idle comes back to 1000 rpm.. no jumping in rpm, vac/boost gauge and afr. I can't go take a ride right now because it's snowing outside