OFT - Control Minimum RPMs?
 

I recently had my JDL header installed, and flashed to a stage 2 tune with OFT. On my first test drive, when I stopped at a red light the RPM's went pretty low (~400 RPM) and the engine seemed to bog down and stutter for a second (CEL briefly flashed). It got better with time though, perhaps the engine learning? Either way I figured that I would just edit the minimum idle rev tables in RomRaider. Now the car idles just a bit higher like it should, but only after it first dips down to 500 RPM when I brake to completely stop at a red light, or in the time between going from engaging the brakes at a stop to engaging the throttle. I haven't logged anything yet but that's the next step. I figured some/most of you may have already dealt with a similar situation. Thank you for the input!

TL;DR - within RomRaider can I edit table values so that the RPMs never drop below ~700 RPM?

Its normal for the car to have a low idle after a flash The ecu needs a few miles after every flash to recalibrate itself, the same thing happens when you unplug the battery and reconnect it. Should be normal and more fun with the stage 2 tunes very soon!

Cheers,
-Greg

I have been having this issue come up periodically even after putting hundreds of miles on the car after the flash. I'm running a Tomei UEL header with full catless exhaust on the OFT stage 2 e85 tune. Probably every 3 days it seems my car has trouble finding its idle. While monitoring with the OFT I see that the AFR seems to hunt around going up to mid 15s then jumps down to 13s which is where the car seems to bog down and almost stall sometimes turning off the headlights. I can't seem to find any reason as to why it happens though.

Huh that seems similar to what I'm seeing, although not that extreme...odd.

OFT - Control Minimum RPMs?
 

I have a similar condition. When I clutch in and decelerate to a stop (AFR goes to 15 as rpms drop from ~3000) the rpms drop too much and have to bounce back up to find the idle spot. It doesn't happen all the time and I usually can tell by the excess vibration in the gear lever.


Sent from my iPhone using Tapatalk

Mine does this as well. I forgot to mention it but I'd say it happens every once in a while but when it does it will do it almost every time I come to a stop until I park and turn the car off for a while.

I just wish there was a way to program in a soft stop that says don't let the RPM's dip below some set point. Is this possible?

I don't believe so. The ecu is already told to not let the engine go below the idle point by the tune. If yours is anything like mine with the afr changing then it seems to be more of a problem with keeping a steady afr at idle and it adjusts to compensate resulting in the rpm dip.

This is what the idle should be like. There's nothing that can be done.... Except to improve the idle settings.

Is this a common problem with the OFT tunes? I thought I remembered reading that the tune was supposed to help with the idle problems that existed on the stock tune.

I'm pretty sure that all it does is raise the minimum RPM setpoint.

My idle was a disaster on the stock tune. Idle on OFT is much better, but not quite perfect.


Sent from my iPhone using Tapatalk

Mine stalled several times before learning phase is completed.
From the next drive, everything is ok.

I'm going to edit the PI/DI ratio tables under idle conditions as per this post and see if it helps: http://www.ft86club.com/forums/showp...6&postcount=21.

Curious, how long does a "learning phase" take anyways?

Let the cars idle for a minute stationary
Check the afr and commanded afr both should be pretty close to 14.7 and fairly stable might go to 15 or 14.4 or so but outside that is unusual

Check the long term fuel trims at idle should be less than 10%

If you got unusual values check for intake or exhaust leaks dirty maf sensors clean connectors on maf and o2 sensors.

You can try bumping idle to 750 and setting the overun fuel resume to 1400 from 1300

But fix hardware ussues first
Seen couple if guys with bad front o2 sensors
Bad rear 02 usyally only effect cruise fueling

OFT - Control Minimum RPMs?
 

Edit: nevermind I read it wrong :P



Sent from my iPhone using Tapatalk

I found on petrol the stg 2 OFT tunes to be really good at idle. I am now on e85 stg 2 OFT and the idle is not as consistent. Not terrible but will occasionally bounce around. I have a light flywheel so just figured the e85 tune wasn't as sorted.

Update, changing the PI/DI ratio tables didn't work for me. Might work for you guys with bigger injectors though, definitely worth a shot. It's only been one day but the car is relearning since I reflashed it and dipping as low as ever until it learns not to do that $hit... *sigh*

I did some data logging this morning, I'll take a look tonight. I'm pretty sure the car is just learning how low it can go, I just find it very frustrating haha we'll see if it persists but this is really good input, thanks!

Same thing has been happening to me for months and months. I have a Tomei UEL and have tried several tunes, cleaned my MAF, air filter, bought new o2 sensors, injector orings replaced, new gaskets for my header and exhaust, yet this problem still persists.

I have noticed that when I have the A/C on, the problem becomes MUCH worse than when I turn the A/C completely off.

It's not this. There are other settings other than the Target Idle RPM. Correct MAF settings help, it seems having slightly negative trims help. Try increasing the Idle Airflow and Load maps (if they are there).

Idle stability tables may help as well

This tends to be more when blipping the throttle or revs dropping and less so if the idle is unstable, unless the stability tables are jacked up and ends up in oscillation.

Is this only happening on aftermarket headers? Specifically UEL headers? I ask because if that's the case, then the folks with this problem might be running into a peculiarity with the idle control loop. Other than the Target Idle, are there other parameters we can adjust that have been defined? Haven't checked out the "idle stability tables" Steve mentioned, but those sound promising by title.

Maintaining a consistent idle might sound easy, but getting a machine to balance consistently is surprisingly complex. There are likely damping functions built in to the control loop to keep it from oscillating back and forth. Part of setting that up is adjusting for things like intake length, intake resonance, exhaust resistance, exhaust resonance, angular acceleration, etc. Making a change to ANY of these would mess with that control loop. If you change the header to a completely different design, you will have to adjust how the ECU maintains idle, or more likely than not deal with transient effects like this.

arh ok
well try the overrun fuel resume table maybe bump it to 1400 from 1300

I have UEL header


have my base idle at 650
modded idle stability tables
full DI at idle


no stalls coming to stop
dips slightly on a/c cycling
and on rear demister turn on
but no stall or shaking just dips to say 550 then recovers

Wasn't trying to suggest your setup or methodology is incorrect. I actually agree with you on the stability tables if they are what I think they are.

I was just attempting to point out that the shape of the header is a part of the idle control loop. Changing that is the same as messing with the ECU regarding idle stability.

Can you elaborate on your idle stability tables?


Sent from my iPhone using Tapatalk

The Tables are under Timing compensation in romraider called Idle Target error range A and B

You've changed those? Any idea what that does? I thought you meant the actual large idle stability tables....

Afaik and it a bit hazy, amount of ignition retard\advance applied to control idle speed as it deviates from the base setting

Using Kodename's defs in romraider, I have larger tables. Just looked at them today, and this definitely looks like it controls the damping function I was talking about. How it does it is related to either timing or airflow targets. Steve99, why are you thinking its timing? Numeric values seem like it could be, but do you have any other information on it?



Disclaimer: I have not messed with this yet as I do not have any idle problems. The following suggestion is based on theory, but I cannot vouch for safety or functionality of the resulting tune. I haven't been doing this as long as some of the other folks on here.

My guess is the OP is going to want to very gently increase the entries around the center top of the table. This should begin correcting the drop in RPMs more aggressively at a higher rpm.



While I am here...
Why are there so many 'idle speed target [letter]' tables? I have 9 of them and they are all different.

I think you have the wrong tables mate :-)
They are under Ignition timing Compensation, not under the logical place you look, Idle control

but both lots of tables will likely effect idle stability/compensation
Theirs just so much going on at idle, so many compensations, and they are just the ones the ecu reverse engineers have found

I use the ones @Spuds posted and not the ones you suggested as they're more logical IMO

@Spuds

idle stability #1 and #2 tables Map

For me it's gotten better. It'll dip to 500 RPM sometimes but no longer to the point where the lights dim...either some of the tune changes I made worked, or the engine learned but either way it's no manageable. Your posts have all been very informative and it's interesting to see how many other people have had similar issues.

So I decided to have a play, I changed:
Idle stability (from MY17)
Idle ignition timing (increased a little)
Idle MAF Targets (increased a little)
Ensured idle fuel was slightly rich (negative trims)
Overrun tables (increase throttle at lower RPM to get close to Idle MAF Targets)

Best idle yet....

I think the overrun tables might make the most difference for me, but it's gotten so much better now that it's barely noticeable any more haha

Hi Steve,

Your idle stability tables are good for fixing stall issue just after flashing.
Thx.

Hey guys... I've been getting the dreaded p000b code recently. We had a cold spell down into the negatives recently, and I found that when I had to stop abruptly in traffic, the engine would start shuddering really hard. Either turning the car off then on, or giving it gas fixed the problem. Now when I get these ugly shudders at stop lights, a couple minutes later I get the p000b code and the car goes into limp mode. I reflashed the OFT Stage 2 tune today for the first time in many months, so maybe this helps? My factory warranty just ended yesterday :bonk:

I'm probably going to have to put the stock header back on, reflash to stock, and drive it several hours back the dealership I bought it from. I called them up today and they seemed willing to work with me on it. This sucks so much a$$...