I've got a 94 FD

3" downpipe, 3" catback
All sensors & electronics intact...
Fluidyne radiator
Stock turbos @ stock boost (ported wastegate)
8-10k on rebuild


Here's the problem. I've found that with my A/C on, when my water temps get up to above 195F if I cruise in the 2-4k rpm range and keep my foot really steady, my Air / Fuel ratios slowly creep to full lean which make the car start hucking and buckin. As it's creeping towards lean, the car looses power, but with any minor throttle movement, it forgets it was about to have a stroke and continues like nothing happened.

NOW... if I notice the creep towards lean and I turn off the A/C it starts to richen up and cruise at 14.5 in just moments.


I disconnected the O2 sensor and it ran about 2points richer at cruise (12.2 -12.5) than before so I replaced it. The problem still occurs.

Any ideas?

 

stock ecu cuts fuel to one rotor at low rpm/throttle or when coasting in gear it can initiate full fuel cut. are you sure it has anything to do with your AC?
edit; and my car does similar when i need to change down gear or need to go faster

 

Haah, I'm dumb.

Rear trailing plug wire had popped off the plug... occasionally with the right vibration, it would completely disconnect from the plug and not fire, leaving me with low power and lean condition...

 

So refitting the plug wire solved your problem?

 

Yah

 

No... it didn't fix it. The problem just didn't resurface immediately. I'll check my plugs this weekend. I wonder if I may have burnt out a coil.

 

Is your airpump and ACV working like stock?

 

Yep, they're mooooing away!

That's stock, right?

 

Ummm, im pretty sure if your ignition was not working properly, you would run rich - not lean?

If the mixture was not burnt properly because of your ignition/coils/plugs or whatever - that would lead to a rich reading..due to un-burnt fuel..

(I don't actually have an AFR gauge, the above is just my logic..)