Okay, here's the details:

Mostly stock '93 R1
PFS intercooler / intake combo
Downpipe
PowerFC - idle set a little higher than stock - 900rpm


The car idles fine during warm-up, drives nice, but after the engine's warm, when i come to a stop or push the clutch in and take load off the engine, it will idle fine for about 1-2 seconds, and then stumble and stall.

I checked my clutch switch, and it seemed to be working fine. I replaced it with a different clutch switch to double check, and it made no difference. I've pulled the UIM off and checked my vacuum lines, and there doesn't seem to be any leaking or loose.

I'm at a loss. The only thing I can think of is a bad IACS at this point, and juding by what i've read. Any other thoughts by someone that knows more than me?

 

bump for some help!

 

im having the same issues but it goes away after a while, I have a single setup and no longer run the IACS but I noticed when my idle was set higher I never had this problem. does your car keep dying even after you've been driving for a while or does it normally dies everytime you stop?

 

I had the same problem too. I would start my car and let it warm up a bit, drive down the road and come to a stop, it would die. But then at the next stop it wouldn't, and wouldn't for the rest of the trip. I raised my idle slightly and it seemed to fix the problem for me.

 

Your deceleration fuel cut recovery setting may be too low.typically it should be set about 300rpm higher than your idle rpm setting.See p33 in the PFC instruction manual.

 

I'll check on that, is that on the same screen as the idle setting per PFC monitor?

 

Has it always done that or did it start after instaling the PFC?

factors that can affect your idle in the manner you mentioned are:
- mechanical settings on the throttle body (which affect TPS settings)
- TPS adjustment
- needs some tuning of the idle areas (most likely one of the above unless it was recently tuned for your car).

 

Yes

 

well, the TPS seems to be functioning properly. reading .497 volts at idle, and about 4.5v at WOT

I'll have to double check the throttle body settings. I'm pretty sure that the bleed screw was set as per startup specs with the pfc manual

I never really had the car running after the rebuild on anything other than the PFC. The stock ecu kept on throwing knock codes and going into limp mode. I think my knock sensor is bad. right now the knock monitor is turned off in the PFC.

I'll have to check the idle recovery setting in the PFC. Hopefully that does the trick. Thanks for the ideas. Let me know if you have any others that come to mind! Much obliged!

 

For what it is worth I strongly advise that you download a copy of the FSM and check your idle speed adjustment as in SectF,p16-17.To make the proper adjustment you need to jumper the Ten pin connector to Ground at the Test Connector box.(Assuming you do not own a Mazda System Selector)

Note that that the LAST item to be adjusted is the Throttle Adjusting Screw.In fact this screw if it is as set at the factory very rarely needs adjusting unless the backyard specialists have messed with the car.

 

isnt that only for the stock ecu? i thought you didnt need to ground the pins for the PFC?

 

I'll double check everything in that regard... it's entirely possible, but i don't think it likely as I just got it back from a rebuild. It's got about 2500 miles on a rebuilt engine, and I would have thought those things would be double checked on reassembly, but then again, who knows.

 

I posted about this earlier, as I had the same problem. Turned out my diagnosis came back with a bad water temp sensor, which helps the ecu regulate the air/fuel mixture. Once warm, the car was stalling and dying and hesitating if I got it on the road. It was replaced, along with the O2 sensor for good measure, and now runs like a champ. But now it doesn't pass emissions.......that's another thread.

 

I've already changed my thermosensor when my car was flooding so that's not it

 

True.