ok guys heres another damned idle problem question. when i start up my 87 t2 to warm her up. she starts hesitating at 1.5 rpm goes down 1.4 and then back up for around a minute, then she idles normally till the normal 750rpm. also some times when im stopped in neutral the idle out of no where just drops down almost stallin the car but it never does, does this every once in a while quite annoying freaks me out.

thanks!

 

The idle is controlled by the BAC valve, so I would look into that

When at idle, you say that sometimes the idle drops, does it happen when you hit the brake pedal or turn on something electrical

if it does, then it's pretty normal. the bac is supposed to compensate for any load on engine at idle although the drop should not be too big unless u turn on a lot of electrical at once

see http://www.geocities.com/huguesdc1

under 'idle'
for bac valve operation

 

Sounds like your car is not doing the three grand for seventeen seconds as described in the HUGHES writeup. You might check the neutral switch on the gearbox for a fix. If the ground is not being passed thru the neutral switch to the ECU, then that act/non act will keep the three grand for 17seconds from happening. You probably don't want the three grand when cold but its supposed to happen on a functional car. Sounds like the cold start thermowax, fast idle cam etc is working though.

I have no training of any sort, but in my opinion......if the idle is set to approx 750 with the initial set coupler installed, you will eliminate most of your stopped at a lite problem. I'm definetly not saying the initial set coupler being installed *is programming the computer*. It ain't. The initial set coupler puts the BAC in a hold position while you set the idle. That way the bac isn't trying to influence the idle as you screw up and down with the various screws. Once the idle is set to 750 this way, in the future the bac won't have to work so hard to maintain the 750rpm idle. Also when you pull the bac plug off, you will notice very little change in the idle rpm because the idle mixture is already set to seven fifty. If the idle was set below seven fifty with the initial set coupler in, then in that case if you pulled the bac plug while idling the rpm's would fall down considerably i.e. large change in rpm's.

I'm betting if you warm your car up right now, and pull the bac's plug, the idle will fall considerably. If so, set the idle.

P.S. I like HUGUES site.

 

thanks guys nice site by the way!

 

If your 3000 RPM startup is not working, be happy. If you want it working for some morbid reason, check the small thermal switch on the bottom drivers side of the rad.

Your idle problem is most likely related to the BAC valve. Either clean or replace the valve.