rexhvn

Hi guys,

My engine was recently rebuilt with a run in tune. Ever since i've got it back, it always shuts off when its cold. If I hold the RPM's hight (3k RPM) it's fine, but you can also feel it almost cutting out and waiting to stall. When the engine is warm, its fine and idles fine. It could well be the tune but wanted some input incase it could be something else.

Mod: Street port, PFC, FMIC, PFC, full exhaust - Break in tune

Any help is appreciated.

Thanks,

IRPerformance

iTrader: (41)

Tune. Start with the water temperature correction maps.

nguybao

iTrader: (6)

^ I had the same issue and it was just the water temp correction settings.

rexhvn

Is this something I could adjust via the PFC or best to take it back to the tuner?

DaleClark

iTrader: (55)

I'm pretty sure you can tweak these using the Commander. It's easy to do and you won't break anything, just document what your starting values are.

I know the stock PFC maps have problems with the cold values, I can't remember if they need to be richer or leaner. They're really bad when it's cold out.

Dale

rexhvn

So i've played around with the water correction maps but the cars still dies out under if I don't hold the revs up.

Old values:
-30c 1.29 1.29
-10c 1.26 1.25
+30c 1.14 1.44
+50c 1.07 1.07

New Values
-30c 1.20 120
-10c 1.17 1.17
+30c 1.10 1.10
+50c 1.00 1.00

Can someone post up their figures so I can compare? I can continue to play with them but i'm doubtful it will resolve it.

wstrohm

Are you familiar with the cold-idle setting as described in the workshop manual? This is a mechanical setting of two screws on the firewall-side of the throttle body. One sets the fast-idle speed and the other sets the coolant temperature at which the butterfly flange drops off the idle cam.

Although the problem could be per the discussion above, you might want to try the mechanical settings.

arghx

iTrader: (3)

Read my pfc commander tuning thread in this 3rd Gen section and set water temp values back to default for now.

wstrohm

Link to ^
https://www.rx7club.com/3rd-generati...needed-841706/

rexhvn

I'm going to bring this back to life. I took my FD to a rotary mechanic who looked at this. He found it was a faulty cold choke... nonetheless it was fixed for a while, started up fine and idled fine however just recently it started stalling again but no where near as bad as before.

Any ideas?

IRPerformance

iTrader: (41)

Faulty cold choke? This is an fd?

wstrohm

Well... "choke," maybe not. But 1993 - 1995 RX-7 fast idle control is set with two screws. See the attached picture of the throttle body from the "1993 Service Highlights Manual," and notice the illustration at the lower left. The screw pointing upwards contacting the wax rod sets the coolant temperature at which the fast idle cam leaves the throttle shaft, and the leftward facing screw at its right sets the fast idle speed.

breakfast

iTrader: (4)

Just my two cents, when I was tuning my idle I had a similar issue, and I went in the other direction with my water temp correction values. The way you changed them before you decreased the amount of extra fuel the engine got when cold.