Car running badly after power fc
03-13-13, 07:53 PM
#1
Car running badly after power fc
Okay this is going be a long post as I'm having a ton of idle issues. Yeah I decided to get a power fc for those of you that was in my other thread.
I installed the power fc, did the idle learn process and did arghx tweaks. Pulled car into garage and drove it the next day. Everything was completely fine. I didnt go over 4k rpm yet on the power fc.
As I get to my friends house idle starts surging when I come to a stop. I just put all the stock idle adjustments to stock specs on the stock ecu so they should all be fine. I tweaked the ISC from the power fc under F/C idle adjustments. Seemed to work.
We went to lunch afterwards. After lunch I walk into car and start it but its running terrible. Idle surging from 600-the very last tick mark on the rev counter. Also car is popping out of exhaust. I turn on and off car and car has pops everytime starting and still doing that low idle surge.
I just want to get it home which is 5 mins away so I do the full power fc reset to stock. Seemed to work, I let it idle for the idle learn just the first stage since I'm just limping it home. So I take off and I'm getting back fires on decel, excel, shifting u name it.
O2 feedback is on at this time. The only tweaking I did was trailing map p16-18 and more fuel in upper rpm. Should have nothing to do with idle.
1200 miles on rebuild, new silicone vacuum hoses, fuel filter, wires, plugs, full premix with no omp, downpipe, catback, and stock box with k&n filter.
I installed the power fc, did the idle learn process and did arghx tweaks. Pulled car into garage and drove it the next day. Everything was completely fine. I didnt go over 4k rpm yet on the power fc.
As I get to my friends house idle starts surging when I come to a stop. I just put all the stock idle adjustments to stock specs on the stock ecu so they should all be fine. I tweaked the ISC from the power fc under F/C idle adjustments. Seemed to work.
We went to lunch afterwards. After lunch I walk into car and start it but its running terrible. Idle surging from 600-the very last tick mark on the rev counter. Also car is popping out of exhaust. I turn on and off car and car has pops everytime starting and still doing that low idle surge.
I just want to get it home which is 5 mins away so I do the full power fc reset to stock. Seemed to work, I let it idle for the idle learn just the first stage since I'm just limping it home. So I take off and I'm getting back fires on decel, excel, shifting u name it.
O2 feedback is on at this time. The only tweaking I did was trailing map p16-18 and more fuel in upper rpm. Should have nothing to do with idle.
1200 miles on rebuild, new silicone vacuum hoses, fuel filter, wires, plugs, full premix with no omp, downpipe, catback, and stock box with k&n filter.
03-13-13, 09:56 PM
#2
Okay this is going be a long post as I'm having a ton of idle issues. Yeah I decided to get a power fc for those of you that was in my other thread.
I installed the power fc, did the idle learn process and did arghx tweaks. Pulled car into garage and drove it the next day. Everything was completely fine. I didnt go over 4k rpm yet on the power fc.
As I get to my friends house idle starts surging when I come to a stop. I just put all the stock idle adjustments to stock specs on the stock ecu so they should all be fine. I tweaked the ISC from the power fc under F/C idle adjustments. Seemed to work.
We went to lunch afterwards. After lunch I walk into car and start it but its running terrible. Idle surging from 600-the very last tick mark on the rev counter. Also car is popping out of exhaust. I turn on and off car and car has pops everytime starting and still doing that low idle surge.
I just want to get it home which is 5 mins away so I do the full power fc reset to stock. Seemed to work, I let it idle for the idle learn just the first stage since I'm just limping it home. So I take off and I'm getting back fires on decel, excel, shifting u name it.
O2 feedback is on at this time. The only tweaking I did was trailing map p16-18 and more fuel in upper rpm. Should have nothing to do with idle.
1200 miles on rebuild, new silicone vacuum hoses, fuel filter, wires, plugs, full premix with no omp, downpipe, catback, and stock box with k&n filter.
I installed the power fc, did the idle learn process and did arghx tweaks. Pulled car into garage and drove it the next day. Everything was completely fine. I didnt go over 4k rpm yet on the power fc.
As I get to my friends house idle starts surging when I come to a stop. I just put all the stock idle adjustments to stock specs on the stock ecu so they should all be fine. I tweaked the ISC from the power fc under F/C idle adjustments. Seemed to work.
We went to lunch afterwards. After lunch I walk into car and start it but its running terrible. Idle surging from 600-the very last tick mark on the rev counter. Also car is popping out of exhaust. I turn on and off car and car has pops everytime starting and still doing that low idle surge.
I just want to get it home which is 5 mins away so I do the full power fc reset to stock. Seemed to work, I let it idle for the idle learn just the first stage since I'm just limping it home. So I take off and I'm getting back fires on decel, excel, shifting u name it.
O2 feedback is on at this time. The only tweaking I did was trailing map p16-18 and more fuel in upper rpm. Should have nothing to do with idle.
1200 miles on rebuild, new silicone vacuum hoses, fuel filter, wires, plugs, full premix with no omp, downpipe, catback, and stock box with k&n filter.
did you try adjusting the idle screw under the intake elbow?
and also you should invest in a wideband the backfires normally mean you are running rich and the excess fuel is igniting after its in the hot exhaust . that idle surging is either a vacume hose that got loose or something needs adjusting , check all the vacume hoses just incase.
Last edited by Tem120; 03-13-13 at 10:02 PM.
03-13-13, 10:20 PM
#4
take your time , use the AC , , defroster , everything
so the car records the loads and what rpm it should have . seems like something was out of whack
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03-14-13, 01:02 PM
#15
try the stock ECU then as suggested, if the result is the same then something has worked itself out versus in.
also if this is a used PFC try disconnecting the commander, the wires on the commander may be the culprit for the issue(some people move it around a bit and the wires end up breaking, fraying or the board on the commander breaks the solder joints causing the ECU to freak out).
also if this is a used PFC try disconnecting the commander, the wires on the commander may be the culprit for the issue(some people move it around a bit and the wires end up breaking, fraying or the board on the commander breaks the solder joints causing the ECU to freak out).
03-14-13, 03:19 PM
#16
Hi Jay,
When I put the ECU that you have now into my FD I first adjusted the idle screw per the FSM. Basically you jumper two pins in the diagnostic connector to stop the ECU (do this with the factory ECU) from attempting to adjust the idle speed. Once this is done, the car is fully warmed up and with no electrical load on the motor (fans, lights, etc.) you set the idle screw such that the car idles at 720 RPM. That's it, the car should idle flawlessly after this ... assuming that there isn't another issue.
This should help to give you a good baseline. That is, is the car running correctly on the stock ECU.
One other thought, check the clutch switch under the dash. Just look under there with a flashlight while a friend pushes the clutch in. I seem to remember that there are two switches that move in and out with the clutch. If either of them aren't moving out or are only moving partially this may be part of your issue. It's a cheap fix if it's broken ... check the link below ... did this on my own car.
https://www.rx7club.com/3rd-generati...switch-423749/
When I put the ECU that you have now into my FD I first adjusted the idle screw per the FSM. Basically you jumper two pins in the diagnostic connector to stop the ECU (do this with the factory ECU) from attempting to adjust the idle speed. Once this is done, the car is fully warmed up and with no electrical load on the motor (fans, lights, etc.) you set the idle screw such that the car idles at 720 RPM. That's it, the car should idle flawlessly after this ... assuming that there isn't another issue.
This should help to give you a good baseline. That is, is the car running correctly on the stock ECU.
One other thought, check the clutch switch under the dash. Just look under there with a flashlight while a friend pushes the clutch in. I seem to remember that there are two switches that move in and out with the clutch. If either of them aren't moving out or are only moving partially this may be part of your issue. It's a cheap fix if it's broken ... check the link below ... did this on my own car.
https://www.rx7club.com/3rd-generati...switch-423749/
03-14-13, 04:50 PM
#17
Hey James, ill try that. Your talking about adjusting the top screw? Not the one under the elbow? Which ports need to be jumped?
Also that screw was perfect before power fc. Idle perfectly.
Also that screw was perfect before power fc. Idle perfectly.
Last edited by jayscoobs; 03-14-13 at 04:55 PM.
03-14-13, 10:15 PM
#21
So, I did a quick search in this forum on "pfc idle", titles only:
RX7Club.com - Search Results (did I post this link correctly? You might have to re-do the search)
Unstable idle seems to be common. The issue is broadly "too much air" making it into the engine and that the stock ECU is very forgiving of this / the PFC isn't.
I'm running an original factory 20 year old engine. When I first received the car I tore the uim, lim, turbos, etc. off. I did this so that I could solve oil leaks, check all the solenoids in the rat's nest, replace the coolant hoses etc.
Anyway, in the process of replacing everything that was 20 years worn out I found cracked vacuum hoses, a busted pcv valve, canister purge solenoid that was stuck open and a lim gasket that was blown out. All of these things didn't seem to affect the stock ECU and were replaced before my PFC. Don't know how much maintenance has been done on your FD but it sounds like air is getting in somewhere.
RX7Club.com - Search Results (did I post this link correctly? You might have to re-do the search)
Unstable idle seems to be common. The issue is broadly "too much air" making it into the engine and that the stock ECU is very forgiving of this / the PFC isn't.
I'm running an original factory 20 year old engine. When I first received the car I tore the uim, lim, turbos, etc. off. I did this so that I could solve oil leaks, check all the solenoids in the rat's nest, replace the coolant hoses etc.
Anyway, in the process of replacing everything that was 20 years worn out I found cracked vacuum hoses, a busted pcv valve, canister purge solenoid that was stuck open and a lim gasket that was blown out. All of these things didn't seem to affect the stock ECU and were replaced before my PFC. Don't know how much maintenance has been done on your FD but it sounds like air is getting in somewhere.
03-14-13, 10:56 PM
#23
I was going to ask if your brake booster was damaged from running without a check valve but 17 inches isn't bad.
It's hard to say if the car is or isn't leaking air based on vacuum unless it's a gross leak. The stock ECU (PFC too) can vary the air going into the engine to maintain the idle speed so it can make up for a bit too much air and maintain a decent vacuum in the process.
Just thinking out loud ... time to sleep and see if someone else has an idea.
It's hard to say if the car is or isn't leaking air based on vacuum unless it's a gross leak. The stock ECU (PFC too) can vary the air going into the engine to maintain the idle speed so it can make up for a bit too much air and maintain a decent vacuum in the process.
Just thinking out loud ... time to sleep and see if someone else has an idea.
03-14-13, 11:27 PM
#25
Original Gangster/Rotary!
iTrader: (213)
The PFC doesn't read vacuum in inches of mercury 
What are the VTA1 and VTA2 voltage readings at idle? If they're jumping by a tenth of a volt, that doesn't seem right.
Have you tweaked the screw in the front of the TB with the 8mm jam nut on it? Takes a flatblade screwdriver. Try adjusting the idle with that..... you may have to reclock your TPS however. If memory serves, at idle VTA1 should be between 0.1 and 0.7 and VTA2 between 0.75 and 1.25. Or vice versa
What are the VTA1 and VTA2 voltage readings at idle? If they're jumping by a tenth of a volt, that doesn't seem right.
Have you tweaked the screw in the front of the TB with the 8mm jam nut on it? Takes a flatblade screwdriver. Try adjusting the idle with that..... you may have to reclock your TPS however. If memory serves, at idle VTA1 should be between 0.1 and 0.7 and VTA2 between 0.75 and 1.25. Or vice versa