I have a 90 NA that has a flucuating idle once it is warmed up. With no accesories on it is fine. The more things you turn on the worse it gets. The AC or blower on high will kill it. The BAC valve is fine, 12.6 ohms. I have even swapped it out and no change. I have the idle setting tool and that is fine.

Any ideas?

Brian

 

TPS, or a vacuume leak or the next culprits. If you can't find any loose hoses check around your manifold to make sure it's seated well and the gasket isn't leaking. You might need to replace it. I spent about 2 hours adjusting my TPS and idle and finally got the pulsing to stop for the most part. Sometimes it will do that during idle, but nowhere near as bad.

 

I do have the tps adjustment tool and have adjusted. I know, it does act like a vacuum leak, but I haven't been able to find one. However, it has been like this since I rebuilt the motor. I will check for vacuum leaks around the manifold. What are the tell-tale signs?

Brian

 

While running, spray carb cleaner, some use starting fluid, around manifold/hoses to see if you see a change in engine idle. Check both BAC valves. Blow through the metal tube to see if inner seal is leaking. It should not allow any air to pass when the inner seal is closed. Or, pull the rubber hose off the bac. Cover both open ends (rubber hose and bac tube) and start and see what the idle is like.