I've recently imported a 1995 FD. It's pretty much stock standard apart from a blow off valve and the the air pump electrical plug being cabled tied undone - so that it's not working.

In the last week I've taken out the old adjustible suspension (it was badly rusted) and replaced with standard shocks and springs. I've rebuilt the whole braking system, cleaned the injectors and also replaced every vacuum line, so I'm well on the way to having it up to my standard. It's running well, a little rough on idle, but the main concern is the amount of time it takes to 'decelerate' from any revs above 4k which is my issue.

If I give the throttle a quick punch it surges up the rpms very fast but takes about 3-4 seconds to get back to idle. It gurgles and sort of sounds like there is air getting stuck in the system as it slowly drops back to idle.

My first thoughts is that it is related to the Air control valve and those other parts that are connected with the manifold to the air pump.

Love to have the advice of anyone here (and related threads...but I couldn't find any) if you've come across this before.

Cheers

 

Sounds more like the throttle cable getting more than typical friction to retract on its own. If this happens in neutral as well so you can watch the cable movements upon release of the pedal by a third party perhaps?

If it only happens under load while driving you could possibly put a GoPro camera to watch it's action while driving.you may have to rig up a light as well to get clear video.

Another option would be to put it on a dyno and you will have the hood of the car up and someone can watch the mechanicals around the throttle body and throttle cable for hang ups.

I would take the throttle body elbow off and manually work the fulcrum the throttle cable usually works and see if it's hanging up a bit. It might be in need of some cleaning and lubrication, possible replacement as a worst case.

 

Or dash pot sticking. Back it off and see if it makes a difference.

 

Also, is it running the stock cat converter? They can begin to clog up over the years, and this can affect throttle response and engine response in a bad way.

But first stop is the throttle cable and the dashpot plunger. I simply lube my dashpot plunger every so often and make sure the small white nylon plunger is moving freely.

 

Awesome, thanks everyone. I've had a look at the throttle cable and can see that it is slightly sticky and lubing it up has helped heaps. The vehicle is running rich as the airpump has been disconnected so I'll check the cat in the next short while.

I'll lube the dashpot up as well. But that will be in about a weeks time, after essays are due!!

Cheers again!

 

Thanks for following up and letting everyone know the solution. This helps the community at large when it happens to the next bloke and makes things easier to track down. Cheers and good luck on the essays!