I have a 94 FD with R85, Microtech and a fuel system to handle it. The car is currently running untuned on a map from KDR while I broke it in. Recently, I've had some problems with it idling properly. Infact it doesn't idle correctly at all. I usually have to put my foot on the throttle and hold the RPMs at around 1k, it feels smooth at that point, not really stuttering or backfiring. But if I were to let off, idle would drop to about 700-800 for 3-4 seconds then drop further and eventually stall.

So far I've only tried replacing the plugs which didn't help any. I haven't done anything else although I'm thinking of replacing the fuel filter. Any other ideas on what it could be? I'm scared it could be the engine although that seems hard to beleive when it feels perfectly normal when not idling and I never felt any power loss until around 4k rpms when it gets extremely rich.

I know I need to just call KD and set something up to get the car tuned and I will do that soon but for the timebeing I just feel nervous and am hoping it could be anything except the engine. :P

Any ideas on what the likely culprit could be?

 

there are SO many possibilities...

if it fires up easily, hasn't lost any power in the low rpm/cruise areas, and sounds ok at 1000 rpm, the motor is *probably* ok. so just bring it in and have it tuned. make sure you mention what it's doing, though. it could be as simple as being a bit over-fueled down low.

for now, try raising your idle just a hair and see if keeps it from stalling out.

 

It starts up without any problems and it does feel fine during normal driving ignoring the idle problem. I know what a popped engine sounds/feels like it and its not like that. But would it feel that way if just a seal were cracked?

Also my vaccuum is around 15-17 when I hold it at 1000 rpm. I want to say that seems right? However when I let off and the idle starts to drop the vaccuum is around 4-8 before eventually stalling.

I would like to hopefully think its a fuel problem. I know the car is running VERY rich. The plugs have fouled more than a couple times, hopefully that will go away once its been tuned. Right now its just on a map to break the engine in.

 

if you're pulling 17", i wouldn't worry about the motor.

one thing to check with microtechs is the tps setting. they have the idle map, and the load map. if you let off the gas and your throttle plate doesn't return to exactly zero (which happens a lot befor eyour motor is warmed up due to the fast idle stuff), you'll be in the load map-which is a lot richer than the idle map.

does it kinda chug or go brap brap brap a little? if it does, it's way too rich and there's your problem.

ok, here's the opposite of what i said before... try turning your idle stop DOWN...yes, down. that'll make sure your throttle plates return to zero or below (assuming your tps is calibrated correctly), and make sure you're in the idle map, instead of the load map.


or you can not even bother with any of that and just go have it tuned.

 

what's your base fuel pressure?

I had the same issue with my setup after installing a new FPR. I had the Pressure set to high, (or too low I do not remember which) but the car would not idle right. Once I set the base pressure at idle to the correct level, the problem went away.

I do not recall the correct level, and I do not want to give you bad info, but check to make sure that the base pressure at idle is not too high, or conversely, to low.