Power FC trouble tuning at idle
Thread Starter
Joined: Aug 2004
Posts: 4,785
Likes: 145
From: Colorado Springs, CO
trouble tuning at idle
Turbo8 was doing some street tuning on my car yesterday (until we can get on a dyno in a week or two) and we're having some trouble getting it to idle correctly. I have two problems actually.
1. When I let off the throttle, usually as I'm driving, I can't get it to stop hunting for idle afterwards. I counted yesterday and it actually got up to 17 times that it wandered and if I hadn't blipped the throttle I imagine it would have kept going. Most of the time it only varies about 4 times at the most and then it settles around 1000RPMs. Anyway, I'd say about half the times it will get so low in RPMs that it will die, even if I'm moving down the road or highway. It seemed like he had fixed it at one point but then it came back.
2. The car will idle at different RPMs for no reason, and it will change on it's own. A couple times yesterday we got it to idle down around 800-850, it would stay there for a minute and then get up to around 950 and stay there for a minute or so and then it would jump up to 1100 and 1200. We have the AFRs set at around 14-15 while it's idling around 800-900 and they go to 11s when it's idling around 1100-1200.
We also checked TPS settings in the Commander and they were good.
Mods...(not sure how many of these are applicable)
Injector Dynamics 725cc primary and 2000cc secondary injectors
CJ Motorsports fuel kit with Aeromotive FPR
Supra pump with Kenne Bell BAP
HKS twin power
stock coils
large streetport
GZ LIM wrapped with heat reflective tape
1/8" aluminum spacer for the LIM to keep the fuel rails from touching
I don't remember anything else that might apply.
Also, I just changed the injectors from 1000cc primaries and 1600cc secondaries not long ago, and I also stripped my wiring harness down to a single turbo harness (I kept ISC btw).
The car drives just fine, it's just idle that's having problems.
Any ideas?
1. When I let off the throttle, usually as I'm driving, I can't get it to stop hunting for idle afterwards. I counted yesterday and it actually got up to 17 times that it wandered and if I hadn't blipped the throttle I imagine it would have kept going. Most of the time it only varies about 4 times at the most and then it settles around 1000RPMs. Anyway, I'd say about half the times it will get so low in RPMs that it will die, even if I'm moving down the road or highway. It seemed like he had fixed it at one point but then it came back.
2. The car will idle at different RPMs for no reason, and it will change on it's own. A couple times yesterday we got it to idle down around 800-850, it would stay there for a minute and then get up to around 950 and stay there for a minute or so and then it would jump up to 1100 and 1200. We have the AFRs set at around 14-15 while it's idling around 800-900 and they go to 11s when it's idling around 1100-1200.
We also checked TPS settings in the Commander and they were good.
Mods...(not sure how many of these are applicable)
Injector Dynamics 725cc primary and 2000cc secondary injectors
CJ Motorsports fuel kit with Aeromotive FPR
Supra pump with Kenne Bell BAP
HKS twin power
stock coils
large streetport
GZ LIM wrapped with heat reflective tape
1/8" aluminum spacer for the LIM to keep the fuel rails from touching
I don't remember anything else that might apply.
Also, I just changed the injectors from 1000cc primaries and 1600cc secondaries not long ago, and I also stripped my wiring harness down to a single turbo harness (I kept ISC btw).
The car drives just fine, it's just idle that's having problems.
Any ideas?
I'll just copy and paste what I've been saying to Turbo8 to avoid being repetitive... Maybe upload your map as well and I'll take a look.
Well fuel pressure definitely isn't low, it should 38-40 PSi with the vacuum line unplugged on the FPR. Also, FD's idle best between 12.5 and 13.0 AFR (depending on the ports), its not like an RX-8 that will sit at 15 afr without issue. I'm also assuming their is no air pump hooked up, if there is you need to unplug it while tuning.
Other then that it could be a TPS and throttle body setup issue or other settings in the map itself.
thewird
38-40psi fuel pressure is with the vacuum line hooked up the FPR and the engine idling pulling 14-16" of vacuum. So if anything it might be high.
I did forget to mention the motor has a good size street port so you are correct it will want to idle a little richer than normal due to the overlap. The Renesis is a zero overlap rotary so it can idle wherever you want it to. Even a street ported 13B-REW should still be able to idle in the high 13.6-13.8 AFRs.
There is no air pump or cat, sorry I forgot to mention it.
He has bypassed the coolant hoses into the thermowax into the TB but he said he screwed it down so it isn't holding the throttle plates open at all...I'm not 100% convinced but his TPS voltage was low at idle. He may have just improperly adjusted the TPS with the thermowax active.
He also posted a thread up in the PFC sub forum today...
Thank you,
-Dave
Set the fuel pressure correctly to 40 PSi with the car running and the vacuum line to the FPR unplugged. This is how its setup from the factory (36 or 38, cant remember) and helps stress the pump less if you don't need more fuel.
While it may seem like it idles with AFR that high, but it will cause issues exactly like the ones you describe. A stock port FD can idle in the low 13's if setup right but when the weather changes or some other circumstance, it will change. I wouldn't even consider idling leaner then 13 on a street port, I usually target 12.5-13 and make sure its mostly within that range after driving it around some. I've tuned a lot of FD's and have never have had anyone complain about idle (or anything really) after it leaves my hands. On another note, a street port should idle between 1000-1100 RPM depending on how aggressive the street port is. In a hot climate area you might be able to get away with a slightly lower RPM.
Also, verify your using the correct injector dead times for those injectors at 40 PSi with zero lag. I have some info on how I setup the ID injectors on one of the ID threads somewhere.
thewird
thewird
Originally Posted by thewird
Originally Posted by Turbo8
Originally Posted by thewird
Originally Posted by Turbo8
Hey man, I've seen you around on the forums and you seem to know your stuff. So I wondering if you could help me out...
First off, I've tuned rotaries before (mostly RX-8's) but I have tuned my fair share of FD's (I own one as well), so talk to me like a real tuner
I'm not asking "Should I run X Ignition timing at X PSI with X Split" so don't worry!
I am currently tuning a friend A-Sec 500R single FD with a PFC and Datalogit. Mods:
- A-Spec 500R single turbo kit
- PowerFC with Commander and FC Datalogit
- ID 725cc primary and 2000cc secondary injectors in CJ Rails, SARD FPR
- No A/C, emissions, etc only has PS.
OK, problem is his car will randomly die. His car had a rough tune done by someone else prior to swapping his injectors. I convinced him to dump his old school Bosch 1680s and huge 1000cc primaries with an FJO driver and get the ID's. He swapped them in and the car would start and almost instantly die, he did change injector settings.
I made further changes to the map for him and and the car would start and stay running. But now it will randomly die or the RPM will surge/hunt. It can happen anytime...during downshifts, whenever the clutch is pushed in, etc. But usually if he clutches and comes to a stop and it doesn't die, it won't, meaning it won't idle for 2 min and then die. Once it's idling it will idle all day.
That is another issue...I had his idle all dialed in at 850rpm pulling 14.2-14.5AFR and rock solid. Sometimes, and seemingly randomly without touching anything or coolant temps/IATs soaring, the idle will bump up to 1100rpm and run 11.5AFR. I believe there is a direct relationship between this "high idle" and the engine randomly stalling out.
Thus far, I have changed everything I can think of and nothing. His fuel pressure at idle is a little low (38-40psi IIRC). I'm wondering if this is more of a mechanical issue than a tune problem? Or my other hunch is, for some reason, the PFC is getting held in a non-idle cell on the fuel/timing maps and not coming back down because some setting is preventing it...I just can't find it!
Thank you for any/all help and sorry for the longish PM.
-Dave
First off, I've tuned rotaries before (mostly RX-8's) but I have tuned my fair share of FD's (I own one as well), so talk to me like a real tuner
I'm not asking "Should I run X Ignition timing at X PSI with X Split" so don't worry!I am currently tuning a friend A-Sec 500R single FD with a PFC and Datalogit. Mods:
- A-Spec 500R single turbo kit
- PowerFC with Commander and FC Datalogit
- ID 725cc primary and 2000cc secondary injectors in CJ Rails, SARD FPR
- No A/C, emissions, etc only has PS.
OK, problem is his car will randomly die. His car had a rough tune done by someone else prior to swapping his injectors. I convinced him to dump his old school Bosch 1680s and huge 1000cc primaries with an FJO driver and get the ID's. He swapped them in and the car would start and almost instantly die, he did change injector settings.
I made further changes to the map for him and and the car would start and stay running. But now it will randomly die or the RPM will surge/hunt. It can happen anytime...during downshifts, whenever the clutch is pushed in, etc. But usually if he clutches and comes to a stop and it doesn't die, it won't, meaning it won't idle for 2 min and then die. Once it's idling it will idle all day.
That is another issue...I had his idle all dialed in at 850rpm pulling 14.2-14.5AFR and rock solid. Sometimes, and seemingly randomly without touching anything or coolant temps/IATs soaring, the idle will bump up to 1100rpm and run 11.5AFR. I believe there is a direct relationship between this "high idle" and the engine randomly stalling out.
Thus far, I have changed everything I can think of and nothing. His fuel pressure at idle is a little low (38-40psi IIRC). I'm wondering if this is more of a mechanical issue than a tune problem? Or my other hunch is, for some reason, the PFC is getting held in a non-idle cell on the fuel/timing maps and not coming back down because some setting is preventing it...I just can't find it!
Thank you for any/all help and sorry for the longish PM.
-Dave
Other then that it could be a TPS and throttle body setup issue or other settings in the map itself.
thewird
I did forget to mention the motor has a good size street port so you are correct it will want to idle a little richer than normal due to the overlap. The Renesis is a zero overlap rotary so it can idle wherever you want it to. Even a street ported 13B-REW should still be able to idle in the high 13.6-13.8 AFRs.
There is no air pump or cat, sorry I forgot to mention it.
He has bypassed the coolant hoses into the thermowax into the TB but he said he screwed it down so it isn't holding the throttle plates open at all...I'm not 100% convinced but his TPS voltage was low at idle. He may have just improperly adjusted the TPS with the thermowax active.
He also posted a thread up in the PFC sub forum today...
Thank you,
-Dave
While it may seem like it idles with AFR that high, but it will cause issues exactly like the ones you describe. A stock port FD can idle in the low 13's if setup right but when the weather changes or some other circumstance, it will change. I wouldn't even consider idling leaner then 13 on a street port, I usually target 12.5-13 and make sure its mostly within that range after driving it around some. I've tuned a lot of FD's and have never have had anyone complain about idle (or anything really) after it leaves my hands. On another note, a street port should idle between 1000-1100 RPM depending on how aggressive the street port is. In a hot climate area you might be able to get away with a slightly lower RPM.
Also, verify your using the correct injector dead times for those injectors at 40 PSi with zero lag. I have some info on how I setup the ID injectors on one of the ID threads somewhere.
thewird
Thank you wird for your help
I think we have it either narrowed down to the ISC or we just need to tweak the fuel injector settings more. The most random part is the motor will be idling happily and then all of a sudden RPMs will surge to 1100-1200 and it will go rich.
Once we get the injectors dialed in it should be good to go
I think we have it either narrowed down to the ISC or we just need to tweak the fuel injector settings more. The most random part is the motor will be idling happily and then all of a sudden RPMs will surge to 1100-1200 and it will go rich.
Once we get the injectors dialed in it should be good to go
Do the fans come on when that happens? You might have to reset the PowerFC and have it relearn idle in the different states. I've had to do that on a car before and then everything was fine.
thewird
thewird
Thread Starter
Joined: Aug 2004
Posts: 4,785
Likes: 145
From: Colorado Springs, CO
I'm currently working on the car and need to get back to it but I wanted to say that when I set the fuel pressure before, I did set it to 40psi with the vacuum line disconnected, so that's already good to go.
I don't know for sure if the fans come on and then it dies. I don't think they do though because it happens all the time, when it reaches the low RPMs when it's hunting for idle. It doesn't just die at any time, like when the RPMs are higher, only when it hits the low point when it's hunting.
I'm going to disconnect the ISC when I get the coils reconnected again and see if that does anything. I have a feeling it's just the map but I could be wrong.
Thanks for your help! I'm gonna get back to work now so I can get this thing running again.
I don't know for sure if the fans come on and then it dies. I don't think they do though because it happens all the time, when it reaches the low RPMs when it's hunting for idle. It doesn't just die at any time, like when the RPMs are higher, only when it hits the low point when it's hunting.
I'm going to disconnect the ISC when I get the coils reconnected again and see if that does anything. I have a feeling it's just the map but I could be wrong.
Thanks for your help! I'm gonna get back to work now so I can get this thing running again.
Eric,
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-make-your-untuned-pfc-basemap-safer-idle-better-no-datalogit-needed-841706/ post #1, #27, #28
Are you running with idle ignition control ON or OFF?
I also agree on the idle AFR. 12.5:1 - 13.5:1 at the leanest. High rpm idles tolerate leaner mixtures. 99% chance your ISC valve is not bad. I've never seen one fail on an Rx-7, although people like to blame them when they can't get the idle figured out.
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-make-your-untuned-pfc-basemap-safer-idle-better-no-datalogit-needed-841706/ post #1, #27, #28
Are you running with idle ignition control ON or OFF?
I also agree on the idle AFR. 12.5:1 - 13.5:1 at the leanest. High rpm idles tolerate leaner mixtures. 99% chance your ISC valve is not bad. I've never seen one fail on an Rx-7, although people like to blame them when they can't get the idle figured out.
Idle ignition control is ON.
And I've personally seen at least two ISC valves fail on FD's. No point is chasing out tail when it's a simple procedure to unplug it and test it out.
And I've personally seen at least two ISC valves fail on FD's. No point is chasing out tail when it's a simple procedure to unplug it and test it out.
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Disconnecting the ISC would drop the idle and you would have to adjust the throttlebody to compensate. I also agree its probably not the ISC as that extremely rarely is the case.
If you post the map I(we) could take a look.
thewird
If you post the map I(we) could take a look.
thewird
Couple things that stand out:
You say "We also checked TPS settings in the Commander and they were good."
What are the readings not running? When it is hunting?
also "1/8" aluminum spacer for the LIM to keep the fuel rails from touching"
Did you use double gaskets on this spacer. Are you sure it is flat and not causing a vacuum leak?
You say "We also checked TPS settings in the Commander and they were good."
What are the readings not running? When it is hunting?
also "1/8" aluminum spacer for the LIM to keep the fuel rails from touching"
Did you use double gaskets on this spacer. Are you sure it is flat and not causing a vacuum leak?
Thread Starter
Joined: Aug 2004
Posts: 4,785
Likes: 145
From: Colorado Springs, CO
IIRC I think we checked the TPS readings when it was off and he had me press the gas pedal to watch the readings change, but I don't remember what they were exactly. I can check and post up.
Yeah I used a gasket on each side of the spacer, and I'm 99% sure I don't have a leak. I had a leak with the Gizzmo phenolic gasket and it definitely doesn't sound like that now, it sounds normal like it used to.
I forgot to mention, I started it the last two mornings and let it run for a few minutes and it would hunt for idle, but it was a bit different. This time it would hold around 1300 or 1400 for about 5 to 10 seconds and it would drop down to about 900 for just a second and then back up to 1300/1400.
Yeah I used a gasket on each side of the spacer, and I'm 99% sure I don't have a leak. I had a leak with the Gizzmo phenolic gasket and it definitely doesn't sound like that now, it sounds normal like it used to.
I forgot to mention, I started it the last two mornings and let it run for a few minutes and it would hunt for idle, but it was a bit different. This time it would hold around 1300 or 1400 for about 5 to 10 seconds and it would drop down to about 900 for just a second and then back up to 1300/1400.
Thread Starter
Joined: Aug 2004
Posts: 4,785
Likes: 145
From: Colorado Springs, CO
It will also die sometimes at the lower RPMs too if I don't give it some gas first. So I'll start it, give it some gas so it doesn't keep dying, then after I let off it will still hunt for idle between 1300/1400 and 900.
The Sleeve
Joined: Apr 2006
Posts: 268
Likes: 0
From: merseyside
Even when i unpluugged my ISC i had idle problems.
my solution
you need to change your idle settings in your ECU all to 0 rpm and make all your timing in the top left 9 cells 12 leading and -12 split trailing.
my solution
you need to change your idle settings in your ECU all to 0 rpm and make all your timing in the top left 9 cells 12 leading and -12 split trailing.
Thread Starter
Joined: Aug 2004
Posts: 4,785
Likes: 145
From: Colorado Springs, CO
Dave sent me a map and I tried it out last night. After adjusting a couple cells on the inj map it idles fine now. I revved it and it went back to normal. It's idling in the 900s at around 13-13.5 AFRs. I'm going to drive it tomorrow night and see how it acts coming to a stop light. So far it seems good though. I'm not sure what Dave did to the map so he'll have to tell you that, but it's working haha.
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