I have been chasing some minor issues on my 1992 RRC

The vacuum advance dies not appear to work correctly, the vacuum diaphragm does not leak, the advance plate in the distributor works smoothly and freely. Mechanical advance works fine.

The question I have is how much advance should it pull in at idle? On other engines, I normally see a lot of advance, like 30 deg or so. On this setup I'm only seeing about 2 deg with the vac line connected. if I tee into another vacuum port, I get a few more deg of advance, but still not what I expect.

I have search and cannot find a spec for this value, any help would be appreciated. I'm guessing that my vac diaphragm is old and hardened and not pulling the plate far enough. The rig runs fine, just a bit sluggish, and a little unstable at idle.

Thanks

Mike

 

My RAVE has a page for a 94 Defender 3.9, it says 5 degrees (+/- 1 degree), BTDC, at idle, with vac line disconnected. In the shop manual write up it says set to six degrees initially.

 

My shop manual says:

 

I have the initial advance set as stated in the RAVE. I'm just really surprised that the vacuum doesn't pull a lot more advance at idle.

I guess it is working normal

I am encountering an intermittent code 48. I installed a new IAC valve, checked extensively for vacuum leaks, set the base idle according to RAVE, installed a new coolant temp sensor, Verified the PCV system is good, clean and free flowing with no leaks, I still get an intermittent fast idle when I hot start the motor. Occasionally the idle will hunt about 50rpm, but for the most part the motor runs smooth and idles good and strong. It does whistle through the intake something fierce though!

Maybe my new IAC is faulty?

I think this is pointing me toward O2 sensors, but I think it would throw a relevant code if one of them were failing. The rig has 128K on it, so I'm not too concerned about wasting my money on expensive components, they are old and I don't mind replacing them anyway. I do prefer to diagnose as opposed to parts swap though.


Thanks

Mike

 

Is it safe to assume you cleared the code?

Anarchist!!!

 

Indeed!

I have cleared it numerous times..

My suspicion is that I have a vacuum leak that is being a booger to find. I have sprayed everything with ether many times, tried process of elimination, pulled and blocked ports, etc.

I am going to swap out the injector o-rings, i noticed the original ones are really hardened, that could be the culprit (no fuel leaks, but possibly air leaks that I cant seem to detect)

Of course i have cleaned the MAF and the throttle body, they are both immaculate. I used MAF cleaner on the MAF and carb cleaner on the throttle body.

I have not done a proper leak down test yet, and i haven't done a compression check yet (I know that's bad, but a just installed new head gaskets and the top end looked fantastic, valve guides and seals look really good too, but still, could be something going on there, it's on my list).

Ill get there, It is totally drivable, just not quite 100%, I'll keep poking away at it until it's right.

Such a cool old rig to drive around...next week it goes in for a new headliner and some minor upholstery repair. Then it is almost tip-top..

Thanks all..


Mike