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.

ok ,

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.

I was going to get a datalogic before a wideband. Yeah when I did the idle learn process I closed the air screw to 1/2 a turn from closed.

do the full learning again , and you wont be able to use the datalogit to its full potential until after you get a wideband .


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

I did notice that in sensor check VTA1 was fluctuating .10V, Doubt it has anything to do with it.

do you have the stock air pump ? do you have the secondary throttle still connected?

Secondary throttle and air pump is still in there. Everythings still in there. Havent removed anything yet since I got the Power FC.

ok , well go into the PFC forums , and do an idle surging search , there are tons of them . I never had the issue . Mostly becauseI eliminated the air pump , the secondary throttle , and the idle air control LOL

Didnt know you can remove all of those lol.

try reconnecting your stock ecu and see how your car runs?

remove the 4 pins from the ECU connectors in the PFC FAQ by Dale.

4 pins are already removed.

Raise the decel fuel cut in the idle settings.

thewird

I did that before I went to lunch. Idle started sticking at 1300. Then after lunch is when she starting running so bad.

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).

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/

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.

The screw that's under the elbow is the one.

Dig up the FSM on the web ... maybe someone here remembers where you can download a copy. Check F17. This has the instructions. You'll then need to read F16 to see what pins to jumper.

100% gone with stock ecu. Although idle is a little low. It's weird. When the fans come in the idle drops. But idle goes up with headlights.

Mazda RX-7 Reference Materials

bit late now but here is the FSM download.

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.

When I dropped the engine in I made sure everything was good. PVC valve was fine, replaced all vacuum lines. New LIM gaskets. Should be pretty solid. When she idles right the power fc said 17 inches of vacuum. So seems good.

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.

Yeah time to sleep for me too, This is taking a lot of attention instead of my career. Impossible to juggle both.

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 :)

Yeah I converted it so I know what I should be seeing on the Power FC. The way it reads boost however sucks.

I have the Power FC out at the moment. VTA is for TPS? because that was just adjusted into spec a week ago. I couldn't say anything about ISC though. I just don't understand how the Power FC was running my car perfectly for the first day then all of a sudden goes bad. I was having a ton of backfire over every little throttle change. I still get some on stock ECU but their hardly noticeable.

What would be the best way for me to setup the power fc to run my car correctly? Since I had a negative experience the first time. If only we had tuners in the Bay Area.

initialize it and see if it runs correctly. also try disconnecting the commander as i mentioned to see if it helps, it's caused problems in the past. second hand units can be sketchy but i have never seen a PFC fail so far, not to say that they won't if it was previously installed on a car with a wiring issue that backfed through the PFC.

The commander is a possibility. I certainly can't hurt to try.

You might also try disconnecting the power break booster at the manifold and plugging the port. I'm wondering if running without a check valve has damaged it. A broken booster can pass a lot of air. I've never seen this on a 7 but have on other cars.

Take a picture of the voltage screen.

thewird

I'll try those out. Good thing I hardly drive the 7 lol. Would it also help if I deleted some idle controls? Less things to cause issues and I believe the power fc doesn't need all of them to run the car?

if you delete the idle controls then it will be more difficult to pass emissions, the car will want to stall at idle when cold and only idle below 1k when warm.

I wouldnt I'd try reinitializing it if you havent before . and give it another go .

Haven't had time to install power fc but I drove it to work today. Now while driving my idle is 1100 but if I shut her down and start her again idle is at like 600.

Could be that your IAC is dirty or bad but I think that there's either a vacuum leak, the idle screw under the elbow needs adjusting per the fsm or both.

I know ... Lots of opinions / ideas ... Just start eliminating things one by one.

What a headache. I'll be working on it tomorrow. It's just so weird how the car idle completely fine before I installed the power fc. Everything was in spec.

The PFC is out to get you it knows that the Adaptronic is taking over! :lol:

Couldn't resist that.

It felt like I was dealing with a hunting idle forever until I replaced my clutch switch. There are so many possibilities it can be a serious headache.

Seriously lol. The adaptronic movement is getting too advanced. It's taking over power fc!

Yeah it's a major pain. Can I see the clutch switch on sensor check? Maybe it'll help me see if mines bad.

Clutch switch should definitely be on the commander.


Could also test it with a $5 Harbor Freight meter.

Looks like ill be removing the mechanical dashpot because of this thread.

https://www.rx7club.com/3rd-generati...talled-853278/

Then after initializing ill take a pic of my sensor voltages.

Does the ECU need to be grounded through the bracket? My car is missing it and I just thought the ground on the harness is enough to ground the ECU. Maybe thats partly my problem and I hope it didnt kill the ECU. Although my stock one has been working like that.

The PFC? No, not to my Knowledge. It was always held in by a bracket from my stock ecu. The bracket was held on by double sided tape so there was no ground there.

The only thing im thinking is with the ECU touching the bracket and the bracket bolted to the car it is grounding.

the ecu does not require grounding through its chassis.

This is at full warmed up Idle during Idle learn process. Idleing 850.

Attachment 678396

So I went to drive around after idle learn. Wow super heat soaked idling for 30 mins. Was just at 3k and saw knock skyrocket. Scared me a bit.

Although the ecu bracket does need to be grounded. A few months ago I observed first hand just how "possessed" an FD ran without the ecu grounded. https://www.rx7club.com/3rd-generati...ttent-1021661/

Guess ill run a ground wire to the case as a extra.

the harness should have a local ground that you bolt onto the car and connect near the ECU . with that wire grounded it should be enough , the case itself does not need grounding just that wire .

after reinitializing it how is the car running?

As for heatsoak make one of your things to view your intake air temp . I know my car never likes intake air temps above 45.