Still having idle issues, help please

[Jinks]

There are a lot of settings that can influence start up time. These include injector priming pulse duration, the amount of by-pass air during cranking and the amount of fuel being injected during cranking and these values are all temperature dependent. See if you can find somebody with a quick starting NSX running AEM and grab their start-up parameters. Compare them to yours and if there are significant differences, try making small changes to one item at a time to see what helps.

One trick, try opening the throttle a little bit while cranking. If that helps start up that could be an indication that you need more by-pass air (the EACV need to be open more) during cranking.

Slow ignition capture (capturing the cam sensor sync pulse) can affect start up. However, if you have stuck with the standard NSX cam and crank position system that shouldn't be a problem.

The system is set for a 3 second fuel pump prime at startup. I’m not sure if that is too long or not but I do not have a fuel pressure gauge yet. So I imagine Shad set it for 3 seconds to build fuel rail pressure in those 3 seconds but I cannot confirm yet. I’ll be buying a fuel pressure gauge to hook up to my ecu and gauge art set up.

 

[Old Guy]

The fuel prime pulse may be different than the injector priming pulse. The injector priming pulse opens the injectors briefly while the pump is priming to wet the intake walls with fuel which provides a little fuel to speed start up. Injector priming can be helpful if the injectors sit farther back from the valves. Fuel pump priming is done to pressurize the fuel system for faster start up and make sure there is fuel available IF the system uses an injector prime pulse. Not all engines use or require injector priming pulses. The AEM ECU may or may not offer an injector priming pulse and it may or may not be configurable.

The OEM ECU provides a 2 second pulse to the fuel pump to pressurize the fuel system. The service manual doesn't say anything about an injector priming pulse. If the OEM system does not use an injector prime pulse then you probably want to make sure that you are not implementing an injector priming pulse (if the AEM ECU even offers that option). The fuel pump prime will be of fixed duration; but, engines that benefit from an injector priming pulse will generally have a temperature dependent prime pulse. They usually benefit from a longer prime pulse at lower temperatures and a shorter prime pulse at higher temperatures.

Injector priming isn't required to get a reliable start. It may help in getting a faster start just because it loads the intake manifold with a little pre start fuel. Too much priming will make the engine harder to start (equivalent of flooding) and not enough priming (if the engine wants some prime fuel) will make it slower to start. People who turn the key immediately to cranking without the fuel prime will never see the benefit of a prime pulse because they are immediately into cranking pulse widths.

There are a pile of parameters related to getting a reliable / fast start up (Oh - did I mention that some ECUs will use a set ignition timing during cranking rather than the timing map - might want to check on that setting). That is why I suggested a comparison to a known good configuration file to try and figure out whether yours has some funny things. The amount of time to do a full throttle tune on an engine is trivial compared to the time required to set up the configuration for starting if doing it from scratch. When doing 'start from cold' tests, you only get one or two tests per day because once the engine has started the intake valve and plenum warm up which completely alters the starting conditions. It can take 1-2 months of once a day testing to get a good 'start from cold' configuration if you don't have a good base configuration as a starting point.

 

[Jinks]

I’m getting a ton of great information here guys. Thank you.

 

[Mac Attack]

I’m getting a ton of great information here guys. Thank you.

The "Idle" parameters are simple compared to the "Starting" parameters. :wink:

Out of curiosity, did you replace your camshaft/crankshaft position sensor during the rebuild? That would have been a good thing on a 25YO engine. Once AEM syncs timing, it should fire immediately. You can verify this by monitoring your connected ECU while cranking. Once "Stat Sync ON" lights the engine should fire up if your start parameters are set correctly. The ~2 seconds it takes for the AEM to verify timing (even with the sync early option enabled) seems to take forever compared to OEM that just assumes it is always correct and fires the injectors and ignition coils immediately.

FYI. The OEM NSX ECU start parameters are given in the service manual. There's a nice little paragraph about what the ECU does when starting, down to the fuel pump prime duration, the injector batch fire description, the cranking ignition timing, etc. You can duplicate all those parameters with the AEM system. The rest is trial and error for each cold start temperature parameter. That's what takes so long...

I recommend you change one parameter at a time and test. Keep a log of your changes and sequentially number the files. AEM has a built-in log for your file you can use to keep notes if you're not a paper person.

 

[Jinks]

Bumping this thread. The idle on the car is perfect. However,,,, when building rpms slowly to about 2500 and letting off throttle, the afr’s Go lean as hell and the car almost stalls then it corrects itself. Same issue, same problem. It’s almost as if it cuts fuel on throttle lift in low rpm. Though, Macattack did help me getting the throttle wizard dialed in and I really appreciate the help. The car runs just fine, it is just a nuisance and I want the car perfect. Kings Motorsport does remote tuning. I’m thinking of doing this to get that issue and the long start issue cured. But then again, I wonder if I should just take a day off and drive to Orlando. These guys are one of the only ems 2 trained techs that know the nsx platform in Florida. Yes, really... Everyone drives Mclaren or Bentley’s here... NSX’s are far more rare here than in California.

Dave,
I also tried adjusting the parameters you mentioned and it didn’t resolve anything related to this particular issue. I’m thinking maybe fuel cut of some sort? I know Valhalla had this issue on ems 2 but he is dbw and it was directly related to that.

 

[Jinks]

So I changed out the fast idle valve with a new one and cleaned my idle air control valve. I also inspected the throttle body and cleaned it. It was already pretty clean though. Problem still remains...
I am waiting on a call back from stp motorsports once they get ahold of Lance. I’m going to have Lance tune my car. If you haven’t heard of him, he is a legendary AEM tuner.

 

[Old Guy]

Lance? So the legendary AEM tuners have been elevated into the celebrity one name recognition category like Prince, Bono, .....

One last kick at the can. Both the pre and post drive by wire OEM ECUs require a clutch signal, transmission in neutral signal and a brake signal (not so sure about the pre DBW ECUs). These signals are all part of the OEM idle control system. The service manual does not provide any description of what they do in terms of idle control; but, in the probable cause list for engine stalling the failure of the brake signal is listed as one of the possible causes.

None of the very limited number of after market ECUs that I have some familiarity with use brake, clutch or transmission signals for idle control. They all put the engine into idle control using a mix of RPM, MAP and throttle position. If the AEM is set up to use the brake, clutch or transmission signal as part of its idle control, perhaps check the operation and connection of those switches. An intermittent switch or bad connection could be the cause of your hit and miss idle. If the AEM does not use the brake, clutch or transmission signal, then time to move on and seek an audience with your AEM Zen master.

 

[docjohn]

haha you will have to choose only one name ....old or guy:tongue::biggrin:

 

[Jinks]

Lance? So the legendary AEM tuners have been elevated into the celebrity one name recognition category like Prince, Bono, .....

One last kick at the can. Both the pre and post drive by wire OEM ECUs require a clutch signal, transmission in neutral signal and a brake signal (not so sure about the pre DBW ECUs). These signals are all part of the OEM idle control system. The service manual does not provide any description of what they do in terms of idle control; but, in the probable cause list for engine stalling the failure of the brake signal is listed as one of the possible causes.

None of the very limited number of after market ECUs that I have some familiarity with use brake, clutch or transmission signals for idle control. They all put the engine into idle control using a mix of RPM, MAP and throttle position. If the AEM is set up to use the brake, clutch or transmission signal as part of its idle control, perhaps check the operation and connection of those switches. An intermittent switch or bad connection could be the cause of your hit and miss idle. If the AEM does not use the brake, clutch or transmission signal, then time to move on and seek an audience with your AEM Zen master.

Lol. He goes by Lance Toyomoto. Famous for tuning the 2JZ’s. He’s factory trained aem guy. I did one last final check on the motor today and found a small hole in a vacuum line between the blower and the intake. I replaced the line but still doesn’t wanna idle right. I guess I’ll have to spend 700$ to see if it’s in the tune. But I have a good suspicion it is.

 

[Mac Attack]

[MENTION=31260]Jinks[/MENTION] I'm glad to hear you found a professional tuner! That $700 will be well worth the peace of mind for your expensive build.

I only saw the original tune you sent me, and just the idle section was a bit concerning.

Per your email, if cleaning the IACV made the idle worse (if anything), then the problem could be exacerbated by an idle adjusting screw being too far closed. Since I'm not there and can't see the IACV duty cycle as you let off the gas, perhaps the IACV is already open too far trying to maintain a base idle and it just can't open further to catch the engine before it dies. Like I mentioned in Post #32 .

If you can, before you take it to the tuner, I recommend running through the idle adjusting screw procedure as described on page 11-84 of the SM.

 

[Mac Attack]

None of the very limited number of after market ECUs that I have some familiarity with use brake, clutch or transmission signals for idle control. They all put the engine into idle control using a mix of RPM, MAP and throttle position. If the AEM is set up to use the brake, clutch or transmission signal as part of its idle control, perhaps check the operation and connection of those switches. An intermittent switch or bad connection could be the cause of your hit and miss idle. If the AEM does not use the brake, clutch or transmission signal, then time to move on and seek an audience with your AEM Zen master.

Good idea, but he does not have those inputs.

 

[Jinks]

@Jinks I'm glad to hear you found a professional tuner! That $700 will be well worth the peace of mind for your expensive build.

I only saw the original tune you sent me, and just the idle section was a bit concerning.

Per your email, if cleaning the IACV made the idle worse (if anything), then the problem could be exacerbated by an idle adjusting screw being too far closed. Since I'm not there and can't see the IACV duty cycle as you let off the gas, perhaps the IACV is already open too far trying to maintain a base idle and it just can't open further to catch the engine before it dies. Like I mentioned in Post #32 .

If you can, before you take it to the tuner, I recommend running through the idle adjusting screw procedure as described on page 11-84 of the SM.

Thanks for the tip and all the help. I readjusted the idle screw and got the car back to where it was before yesterday. I also did some reading up on prime yesterday and found out that a whole slew of people who went FI on ems 2 had similar issues when pulling out of gear and coasting to a stop. Some people just live with it. It drives me nuts. I’m also hoping this new tuner can tune it less rich and get it to start faster. He comes highly recommended. Patricio has his car tuned from Lance. Supposedly, people wait in line for this guy down here. The shop that books the guy is STP motorsports and the awesome thing is, they are a mere few blocks from my new job I start on Monday. I was thinking about taking it to TR3 performance, they do high profile Porsche and Ferrari/Lambo race cars. But the owner doesn’t really know the Honda platforms well.

One last tidbit, I noticed the car running slightly high temp yesterday while sitting in the garage. Oem gauge was 1 tick under halfway but the gauge art read 202 degrees which starts to trigger a red flag in AEM Tuner. I looked at the temp sender on the the coolant passage pipe and the sensor is new but the connector looks rough. Not sure if that connector is available separately or not and maybe it was just because I wasn’t moving but I know that sensor plays a big role in idle control. Radiator fan was on. As per Shad’s recommendation, after changing the fast idle I left the cap off of the expansion tank and ran the car to bleed the air out. The service manual only gives a full bleed process after coolant change. Is there another way I should bleed the air out?

 

[Mac Attack]

I should have clarified what I said before on just the idle section was a bit concerning.... What I meant was I really only looked at the idle section and that alone set off some red flags.

I vacuum fill my NSX these days. Before, however, I would get the rear end of the car as high as possible relative to the front and then let it idle with the cap off. Make sure it's warm enough so the thermostat opens. Also, turn the climate control temp up so the heater circuit is open to coolant bleeding too.

The tuner will be able to check out the temperature issue for you. If you're sitting still in a hot FL garage, then yes, a healthy engine and coolant system may very well get to a coolant temp of 202 F. Yes, that sensor plays a huge role in idle control. It tells the engine what speed to idle at.

The thermostat is fully open at 194F, and the OEM low speed radiator fan kicks on at 183F. High speed should kick on at 194F. Did you go to an aftermarket thermostat? Hopefully Shad didn't change the fan settings in the AEM from what Honda recommends, but I haven't seen his latest file and I don't have access to my computers with AEMTuner loaded right now.

Just make a list of issues for the tuner to check or answer! It's possible to fix all of these issues. You don't have to live with an engine that almost stalls every time you let off the gas.

 

[Jinks]

We put in an oem thermostat brand new. I’ll try the bleeding process today with the car jacked up from the rear. I know the tune needs work but I just want to get all the air bubbles out.

 

[Jinks]

FWIW, @Old Guy and @Mac Attack, even though the time you have spent here trying to help with my issue has not resolved my problems, I think threads like these are extremely valuable to everyone and I just wanted to express my gratitude to you both for taking your free time offering to help for nothing... Look at all the idle issue threads popping up! If there is ever anything I am selling, or something you need, please ask me. I will contribute to the cause and pay it forward.:smile:

 

[Mac Attack]

Just happy to help! I know how disappointing it can be after a major rebuild and then it's not 100% right.

This is a little more complicated to diagnose over the internet unfortunately. I'm pretty confident this tuner will fix your problems.

 

[Old Guy]

Even though it didn't resolve the problem, I hope the information might be of some use in the future. For me, its like working on a crossword puzzle as I have my morning coffee. It think my wife might say that if I didn't have somebody else's problem to work on I would go out and make my own.

 

[(/O^O\)]

[MENTION=31260]Jinks[/MENTION] et al.Lurker now registered - not an NSX owner. Hey y'all.I'm the Legend owner who installed MDX injectors w/o ECU mod - posted as a DIY here.http://forums.acuralegend.org/mdx-injector-swap-mpg-t26181.html?This mod has operated well and passed NMexico smog test for 6 years.I'll never need to undo this mod, main benefit being better droplet atomization followed by better burn within existing ECU design.I post today to note an issue at low revs that combines with alternator output which matters now that you are putting greater current to your new injectors.Current output drop at low alternator revs reduces injector output and results in engine rev drop and stop at the extreme.Matt once claimed it also leaned out as it reduced injector pulses so that may initiate a cascade of events. It is easy to offset with about 100RPM idle increase above my alternator cutout level.It is such a minor matter that it seems insignificant to me - but I deal with it with knowledge, experience, and after all, it's my Frankenstein.I have considered a hi-po alternator to re-curve the current for improved idle range output.I have also wondered if your 100watt regulator control module would plug into my OEM 70watt alternator and give a small increase in current at low revs.Since you already have the larger 100W alternator, I suggest mapping its idle output and consider whether a hi-po unit from a stereo supplier who deals in these upgrades might solve your idle cutout.FWIWGLTA

 

[Jinks]

Okay, we made big progress today on the car with Chris from SOS checking and changing some base maps. I’m still on a waiting list for a full tune but the car runs better. A night and day difference. The car also starts on the 4th crank.Some things we calibrated were injector battery offset, calibrated tps, at rest it was reading 2%, and dfco was not set at throttle off.

 

[Mac Attack]

Your deceleration fuel cut off (DFCO) was previously enabled above 2k RPM, the TPS was below 3.1%, low engine load of 12.7 psig, and a coolant temp above 32F.

DFCO would not have functioned correctly if your TPS wasn't calibrated like I said to do back in post #32 !!! Hopefully your professional tuner will also sync the engine timing with the AEM later too.

Regardless, glad to hear you took the time to go over it and fix some of these basic mistakes.

 

[(/O^O\)]

@Jinks et al.
Lurker now registered - not an NSX owner.

I'm the Legend owner who installed MDX injectors w/o ECU mod - posted as a DIY here.
http://forums.acuralegend.org/mdx-injector-swap-mpg-t26181.html?

I post today to note an issue - corrected - at low revs that combines with alternator output which matters now that you are putting greater current to your new injectors.
Current output drop at low alternator revs reduces injector output and results in engine rev drop and stop at the extreme.
Matt once claimed it also leaned out as it reduced injector pulses so that may initiate a cascade of events. It is easy to offset with about 100RPM idle increase above my alternator cutout level.

A change in fuel pulses will only enrichen the mix until the point the injectors stop due to current drop. You'll have a little better resistance to engine stall and lower mileage - the OEM ECU can 'learn' this on its own as it has a tiny stall resistance built into it.

Since you already have the larger 100W alternator, I suggest mapping its idle output and consider whether a hi-po unit from a stereo supplier who deals in these upgrades or a pulley diameter change might solve your idle cutout in addition to the work done by SOS.

Mr. Jinks, I recognize from your earlier post that you were dealing with it by an idle adjustment as I referred to - which apparently wasn't all that was needed as my situation allows.
Hope this helps.
FWIW
GLTA

 

[Jinks]

Your deceleration fuel cut off (DFCO) was previously enabled above 2k RPM, the TPS was below 3.1%, low engine load of 12.7 psig, and a coolant temp above 32F.

DFCO would not have functioned correctly if your TPS wasn't calibrated like I said to do back in post #32 !!! Hopefully your professional tuner will also sync the engine timing with the AEM later too.

Regardless, glad to hear you took the time to go over it and fix some of these basic mistakes.

Thats correct. Most of the stuff you told me was wrong really was. I just didn’t want to touch it. I’ve never tuned a car before or played with engine management. So everything looks good for now so far. If I had to do this all again, I’d have listened to Shad and gone fic but I really wanted the gauge art.:redface: I suppose everything can be adjusted infinitely with the Aem but when you’re not the guy doing it, it’s not really a good financial decision.

 

[Jinks]

@Jinks et al.
Lurker now registered - not an NSX owner.

I'm the Legend owner who installed MDX injectors w/o ECU mod - posted as a DIY here.
http://forums.acuralegend.org/mdx-injector-swap-mpg-t26181.html?

I post today to note an issue - corrected - at low revs that combines with alternator output which matters now that you are putting greater current to your new injectors.
Current output drop at low alternator revs reduces injector output and results in engine rev drop and stop at the extreme.
Matt once claimed it also leaned out as it reduced injector pulses so that may initiate a cascade of events. It is easy to offset with about 100RPM idle increase above my alternator cutout level.

A change in fuel pulses will only enrichen the mix until the point the injectors stop due to current drop. You'll have a little better resistance to engine stall and lower mileage - the OEM ECU can 'learn' this on its own as it has a tiny stall resistance built into it.

Since you already have the larger 100W alternator, I suggest mapping its idle output and consider whether a hi-po unit from a stereo supplier who deals in these upgrades or a pulley diameter change might solve your idle cutout in addition to the work done by SOS.

Mr. Jinks, I recognize from your earlier post that you were dealing with it by an idle adjustment as I referred to - which apparently wasn't all that was needed as my situation allows.
Hope this helps.
FWIW
GLTA

Oh yeah, I followed that thread a while back. I was looking forward to you putting out a tunable oem platform. What ever happened with that?

 

[Jinks]

Videos to follow soon on my new calibrations. Out of town this weekend though. But boy it feels good to get behind the wheel again for an engine I bled for.... :biggrin:
A BIg thank you to anyone here offering help. I really do appreciate everything...

 

[Nsxrookie]

Damn bro wish I could help. Usually it’s an air or fuel related issue. I see you tuned it to the rich side which may mean you need more air coming in. Oh crap it’s old. It just popped up in taptalk lol.


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