http://www.youtube.com/watch?v=ukWHSSIO0H8
For those of you that also experience cold start problem, is it similar to ours?
For those of you that also experience cold start problem, is it similar to ours?
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Video of cold start problem in our CTSC'd NSX...
- Thread starter GhettoRacer
- Start date
What happens if you keep cranking the first time, battery dead, or does it eventually start?
When it runs, is it OK?
I notice gauges on dash, fuel - boost - A/F. Do you know the A/F ratio?
What is the temp outside when you took the vid?
LMK,
LarryB
When it runs, is it OK?
I notice gauges on dash, fuel - boost - A/F. Do you know the A/F ratio?
What is the temp outside when you took the vid?
LMK,
LarryB
We must re-prime. When it fails to catch after the first 2-3 seconds you can crank all you want nothing will happen. I did exactly that when I first took this car home back in Dec. It took me like 2 hours to get it started the first morning after LOL. But now I know the trick.
The temp is not the issue, but the temp in video was probably mid 40's or about 50. It was 11 am already so... This week weather in California is mid 60's and I always have to do at least 2 tries to get it started (which is not bad). Once it fires up everything is perfect. Subsequent restarts are usually 1 shot and immediate. Especially i engine is still warm; so after engine resting for up to 3 hours it will start fire up great.
EMS = AEM Series 1 and fully tuned by Shad @ Driving Ambition so it is about as good as it gets...
The temp is not the issue, but the temp in video was probably mid 40's or about 50. It was 11 am already so... This week weather in California is mid 60's and I always have to do at least 2 tries to get it started (which is not bad). Once it fires up everything is perfect. Subsequent restarts are usually 1 shot and immediate. Especially i engine is still warm; so after engine resting for up to 3 hours it will start fire up great.
EMS = AEM Series 1 and fully tuned by Shad @ Driving Ambition so it is about as good as it gets...
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Thanks for the feedback Ric. On the supra forum (lot of experienced tuner), a fellow name Kurt added this:
Hmm!! I wonder if maybe Shad has a solution of this already?
Hmm!! I wonder if maybe Shad has a solution of this already?
I sent Shad a pm here few days ago... He's probably too busy to sign on the forum yet. I have lot of other projects so NSX isn't currently daily driven anyway... Hope Shad can tell me more... I'm guessing he should have a good cold start tune he can send me...
I have the AEM EMS and it's tricky to tune for cold starts, as internet searches will tell you. What works on an NSX in one state may not work on a similar NSX in another state. Factoring in that you only get one shot at tuning for cold starts every hour (obviously to let the engine get cold again), and it's hard to have a professional tuner set this up for you perfectly.
I think I have mine tuned correctly, but then on a cold engine start when it's in the 40's or below outside, my Odyssey 680 battery voltage sags when cranking and the AEM needs at least 10.5V to work correctly. I also have a few crank sync errors when starting... maybe due to the voltage droop and also due to my old melted crank position sensor.
I have been modifying a base map myself from Autowave, mentioned in my engine build thread here:
http://nsxprime.com/forum/showthread.php?t=154927
Just got to the "Start" tab and read what all of the parameters do. Do your injectors fire in batch mode until your start RPM is reached (OEM does this)? What is your start RPM, start timing, initial crank pulse, fuel pump prime (OEM is 2 sec), and crank injector time?
I'm not an AEM expert, but the guy from the supra forum is incorrect I think - idle tab and fuel/timing maps are not used for starting until your engine RPM exceeds your programmed value. THEN it switches over to the actual engine running parameters factoring in your warmup enrichment, etc.
Unlike Hondata or Megasquirts, AEM info is hard to come by. The other systems have a lot of "DIY" tuners that help each other out. Professional AEM tuners want to protect their training investment and there doesn't seem to be much "free" help on the internet. There's a lot of crap you have to wade through too if you do find some tidbit of info.
Seems like we need to get an "Unofficial AEM EMS Help/Question" thread going :wink:
Dave
I think I have mine tuned correctly, but then on a cold engine start when it's in the 40's or below outside, my Odyssey 680 battery voltage sags when cranking and the AEM needs at least 10.5V to work correctly. I also have a few crank sync errors when starting... maybe due to the voltage droop and also due to my old melted crank position sensor.
I have been modifying a base map myself from Autowave, mentioned in my engine build thread here:
http://nsxprime.com/forum/showthread.php?t=154927
Just got to the "Start" tab and read what all of the parameters do. Do your injectors fire in batch mode until your start RPM is reached (OEM does this)? What is your start RPM, start timing, initial crank pulse, fuel pump prime (OEM is 2 sec), and crank injector time?
I'm not an AEM expert, but the guy from the supra forum is incorrect I think - idle tab and fuel/timing maps are not used for starting until your engine RPM exceeds your programmed value. THEN it switches over to the actual engine running parameters factoring in your warmup enrichment, etc.
Unlike Hondata or Megasquirts, AEM info is hard to come by. The other systems have a lot of "DIY" tuners that help each other out. Professional AEM tuners want to protect their training investment and there doesn't seem to be much "free" help on the internet. There's a lot of crap you have to wade through too if you do find some tidbit of info.
Seems like we need to get an "Unofficial AEM EMS Help/Question" thread going :wink:
Dave
I know. The more things I do to this car, the more I appreciate it's original design and the compromises the engineers made to have a nice all-around vehicle.
Dave
Dave
Ohh, nice build log Dave. Subscribed and I will read up on it! I think the settings on our car is pretty close... and only needs minor tweaking... since we always have to re prime, I would think adding more fuel would help...
Man, that's disheartening to read.
I don't have this same problem, but I have a different problem where I have extremely rough idle after a long cold start (ie occurs overnight, but doesn't happen even after 6-7 hours otherwise). It often takes several minutes before it suddenly smooths out and can be driven. It's incredibly frustrating to not just turn the key and have it start up.
I've been thinking of going down the AEM route because I figured I would kill two birds with one stone: 1) go for high boost and more usable power across the band and 2) fix the suspected A/F issue causing my rough idle at start.
I didn't realize that cold starts with AEM were a tricky proposition...
Assuming series 1 AEM ECU:
In AEMPro Go to > Engine Start> Advanced Start> Advanced Engine Start> Options - Advanced Start> FuelPumpPrime. Set this value to 5 sec. the default time is min 2 sec. Try adding time untill the start is easier.
You should be able to prime in 2 sec. so there is likely a mechanical issue with the fuel system. Could be pump or connecting hose from pump to fuel hat or could be the regulator. Do you have a fuel gauge on your setup?
Dave
In AEMPro Go to > Engine Start> Advanced Start> Advanced Engine Start> Options - Advanced Start> FuelPumpPrime. Set this value to 5 sec. the default time is min 2 sec. Try adding time untill the start is easier.
You should be able to prime in 2 sec. so there is likely a mechanical issue with the fuel system. Could be pump or connecting hose from pump to fuel hat or could be the regulator. Do you have a fuel gauge on your setup?
Dave
This was surprising to read. Do others with EMS confirm? Seemed to me like you were cranking for a very short period of time for an early 1990s Honda. While the crank seemed quite short, the priming seems excessive. Once primed initially (replace air in lines with fuel, pressurize system) I don't see why subsequent priming is needed before for each attempt.
Maybe waiting until after the 2-second prime finishes is part of the problem. What happens if you try the following?
1. Prime (as much as you want).
2. Turn key to accessory (or off).
3. Turn key to "start" without stopping at "on" and keep it there for like 6 cranks (not one).
Great tip! I will try that and report back!
Starting the car in the AEM ECU is only controlled by maybe three things getting it to start or "pop over" should not be an issue and should happen every time. Most cold start issues are around keeping it running after pop over.
The AEM ECU by default will use a fixed base timing number (ussually 10 degree) while cranking and a fixed fuel amount based on throttle possition. You adjust the "Crank adjust time (RAW)" untill you get the car to pop over everytime. You can crack the throttle a little like 5% during the initial cranking and see it needs more air to pop over if that does not help then you most likely need more fuel. These two things effect the cars ability to fire the engine then once the engine gets to its "Crank Exit RPM" (default 400rpm) the rest of the idle air, fuel adders for temp, and ignition tables are used untill then it is just raw fuel vs. fixed ignition to pop it off and get things going.
The AEM will require longer crank times than OEM, the ECU has to see something like two complete crank rotations to sync the crank sensor before it will fire. There is no way around this. I personally believe there is a ECU wake up or self test time that the ecu is doing prior to crank sync and if you start cranking while this is happening it will never fire.
I found this to be the best method for start:
1. ign on for fuel prime
2. wait for prime to end
3. start car, wait for two to three seconds while cranking
4. car should pop over around the 2 second mark if not you have not got the "Crank adjust time (RAW)" set right and you need either more or less fuel.
5. once it pops over if it stalls then you need to look at all the other idle tables and adders to keep it running
All of this assumes you do not have a mechanical issue with you engine or fuel system, you cannot fix mechanical issue with a tune, you can cover them up but they are still there.
Dave
The AEM ECU by default will use a fixed base timing number (ussually 10 degree) while cranking and a fixed fuel amount based on throttle possition. You adjust the "Crank adjust time (RAW)" untill you get the car to pop over everytime. You can crack the throttle a little like 5% during the initial cranking and see it needs more air to pop over if that does not help then you most likely need more fuel. These two things effect the cars ability to fire the engine then once the engine gets to its "Crank Exit RPM" (default 400rpm) the rest of the idle air, fuel adders for temp, and ignition tables are used untill then it is just raw fuel vs. fixed ignition to pop it off and get things going.
The AEM will require longer crank times than OEM, the ECU has to see something like two complete crank rotations to sync the crank sensor before it will fire. There is no way around this. I personally believe there is a ECU wake up or self test time that the ecu is doing prior to crank sync and if you start cranking while this is happening it will never fire.
I found this to be the best method for start:
1. ign on for fuel prime
2. wait for prime to end
3. start car, wait for two to three seconds while cranking
4. car should pop over around the 2 second mark if not you have not got the "Crank adjust time (RAW)" set right and you need either more or less fuel.
5. once it pops over if it stalls then you need to look at all the other idle tables and adders to keep it running
All of this assumes you do not have a mechanical issue with you engine or fuel system, you cannot fix mechanical issue with a tune, you can cover them up but they are still there.
Dave
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The problem is that the AEM EMS gives you what it's advertised to do - "Total Control." There's a lot of complicated $hit that you can change to help control your engine, or really screw it up.
The "Starting" tab is just one of the many functions to mess with. From my poor memory, here's what happens when you start the car with an AEM and the things you can change, noted with an *:
Insert key and turn on ignition:
1) AEM ECU reads your sensors and determines if your engine is running or not based on what parameters you give it. If my engine RPM is less than 400*, the AEM goes to the "Start" tab.
2) Fuel pump primes*
3) A single shot of fuel is injected into all cylinders for a certain time period*
Turn key to engage starter:
4) crankshaft rotates, AEM batch fires all injectors* and coils* after certain RPM* is exceeded. Fixed ignition timing for starting is used*
Hopefully this gets your engine started. The reason you dump in a lot of extra fuel when it's cold is to compensate for the fuel that condenses on the cold intake and cylinders. That's why the problem described above is either with the fuel pump not priming correctly, or just not enough fuel is initially dumped into the engine when the injectors fire during cranking at the low coolant temps.
Once a start RPM* has been exceeded, then the injectors no longer fire in batch mode* or with the starting injector time pulse duration*. You switch over to the regular running engine timing* and fuel* maps, but you have warm-up enrichment curves* to play around with too based on coolant temperature, time after start, etc. Also, you can program in engine speed multipliers* based on coolant temp and time after start too.
This is just the basic stuff. Then you have ignition timing feedback, O2 feedback, IACV settings for idle offset when suddenly letting off the gas pedal, deceleration fuel cutoff, and other stuff. Extra fuel injected based on TPS rate of change and other parameters (when you stomp on the gas), knock control, VTEC control, and oh yeah, your base fuel and timing curves.
Learning this stuff from scratch is why I took so long to begin tearing my motor apart. I was curious to try and learn something new, and I wanted to do it with my old engine.
Now, I didn't start from scratch, Autowave sent me an excellent start-up calibration file to get going when I bought my EMS, that also had good baseline fuel and timing curves. It may sound a little overwhelming, but just make small changes and observe the effects. Log data and scrutinize it, then make small changes based on your desired results, and then repeat the process.
Dave
Oh, the NSX OEM ECU fires the injectors in batch mode during startup, sets ignition timing at 15 degrees BTDC during cranking (page 23-87 of the SM), and primes the fuel pump for 2 seconds (page 11-24 of the SM), and sets DCFCO at 1500 RPM (page 11-24 of the SM).
Dave
Dave
I would try and let it crank a little longer. Your first attempts to start in the video sounded like the cranking time was a little short. The nsx has 2 crank sensors and two cams sensors. The Oem ECU see all four of these sensors and is why the stock ECU will tend to start more quickly where the aem only references 1 crank and 1 cam sensor so crank time is slightly longer. When I say slightly longer maybe around .5 to 1 second longer. like dozier said adjust the crank adjust time raw until you get it to fire. You can also play with the warm up enrichment table as well. Watch stat sync in the channels and as soon as this turns to on the car should start. If you find yourself having continuous cranking while this stat sync is on something is not right and you run risk of flooding the engine. I also noticed that when your car fired and died right away there may not be enough fuel in the main fuel map at low rpm. As soon as the engine fires up and goes past 400Rpm cranking exit Rpm it references the main fueling map.
I am hearing something that sounds like the doors unlocking when you turn the key to accessory and then locking shortly after turning to on. ???
Aftermarket alarm system is my guess. Locks/unlocks on ignition.
It must be one of the coolant-temperature-dependent multipliers on your base crank injector time table if this is the case.
First, I would bump up your "Start Extra vs Temp" for coolant temps less than 100F by about 5% or so at a time.
Once it starts quickly and consistently, if it still dies right after starting, then increase the "Start Extra Decay" table values a few seconds for the low coolant temps.
Like Mike said, let her crank a few extra seconds.
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Thanks for the tips guys. Letting it crank longer does not work. I did a lot of that the first night I took her home. The first morning it took me over 2 hours to get her started and that was a lot of extended cranking... 
I'll try to see if I can make the adjustments you guys suggested today.
I'll try to see if I can make the adjustments you guys suggested today.http://www.youtube.com/watch?v=vRAOfWRNLkY
For an example of a semi warm start up, check out this new walk around video I made. You can skip to the start up by going to 7:30.
The car was fired up for and ran for about 2 minutes in duration when I was washing the car. Notice the stock coolant temp gauge still all the way at the bottom so the engine is not even warmed up.
It was just one re-prime, and you can see it fires up immediately... This was about 5:30 pm and the weather is excellent mid-high 60's all day.
For an example of a semi warm start up, check out this new walk around video I made. You can skip to the start up by going to 7:30.
The car was fired up for and ran for about 2 minutes in duration when I was washing the car. Notice the stock coolant temp gauge still all the way at the bottom so the engine is not even warmed up.
It was just one re-prime, and you can see it fires up immediately... This was about 5:30 pm and the weather is excellent mid-high 60's all day.
I understand it doesn't now, but as you start changing your startup settings, just let her crank over another second or two.
Before you start changing things to much:
1. What injectors are you using? and static fuel pressure ?
2. No boost a pump is in use with your system right?
3. With the laptop connected to the car and the key on NOT running, click the Start Icon and let me know what the throttle position % is without your foot on the pedal and what the RAW value is at 0% in the "Crank Injector Time Table"
This will help in getting you going the right direction first on your changes.
Dave
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