In trying to fix the intermittent dying when letting off the gas I seem to have introduced a new annoyance.

The idle pulses three times and then it smooths out.

Always three times. And then smooth. Doesn't seem like a vacuum leak though one is theoretically possible because I also had a blown exhaust manifold gasket and to remove and replace the turbo I had to pull the ACV and the intake assembly. But I dont understand how a vacuum leak could "self-repair" after three pulses.

Any ideas?

 

3 pulses, explain this a bit more. Is it when you star the car, 3 pulses, and then its fine for the whole day? Maybe misfiring is what you mean by 3 pulses?

 

I've seen/heard something similar and it might be what your seeing/hearing.

If my car is fully warmed up/hot, and idling, I can pull the plug off the BAC for a moment or two, then reinstall the BAC plug. More times than not, the engine will cycle up/down several times before returning to a normal 750-800 rpm idle.

So, maybe check and make sure your BAC elect plug is on good and if it's on good, then pull it off and look at the contacts inside the elect plug to see if one of them is being *pushed back* when you intall that elect plug. Like.....gently pull on one or both wires while looking at the contacts inside the plug, and see if one or both move out of place when the wires are gently pulled on. If the contacts are not locking in the plug, you MIGHT be getting a intermittent contact causing the rolling/cycling idle that happens three times in your case.

Also when the engine is hot and idling and you pull the BAC plug off, see how far the idle drops down. If it drops down well below 500rpm, you might consider resetting your idle speed closer to 750rpm with the BAC plug off. That should help eliminate the rolling idle that happens three times in your case.

 

JJ, it's just like the normal "Frak I have a vacuum leak" idle pulse. But it goes away.

Thanks, Hailers. I did disconnect the BAC plug when putting in the new turbo/exhaust gaskets. We'll check it out.