Video of cold start problem in our CTSC'd NSX...

[GhettoRacer]

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

1. RC injectors not sure what size (have took look it up), there's a adjustable 1:1 FPR but no FP gauge.
2. not sure, originally an old CTSC kit (stock CTSC has booster bump?). then Shad @ DA changed it to AEM EMS... i think there is no on longer a booster bump.
3. ok.

 

[Mac Attack]

Can you just attach your .cal file?

 

[GhettoRacer]

i can't seem to attach .cal nor .rar file as attachments here? those interested please pm me your email and i'll send it. thanks.

 

[Mac Attack]

i can't seem to attach .cal nor .rar file as attachments here? those interested please pm me your email and i'll send it. thanks.

I think you can replace the .cal extension with .txt and try to upload. Sent you a PM anyways.

 

[GhettoRacer]

email sent. thanks Dave & Dave! :biggrin:

 

[Mac Attack]

To change fuel pump prime, go to "Engine Start" -> "Advanced Start" -> "Options - Advanced Start"

A window will pop up... Change "Fuel Pump Prime" to a few more seconds. See DDozier's post below.
Save, upload, and try that single change first.


Also, it looks like your "Start Extra vs Temp" might be a little low. If it's hard to start when cold, try bumping this up slowly for coolant temps less than 104F.


Finally, if anyone sends you a .cal file (me included of course) and says "Here you go, try this" be careful. A REALLY NEAT feature of AEM's software is that you can take that .cal file and compare it to any other .cal file and it will show the differences between them. You have an expensive engine, people make mistakes, so you should know what changes may or may not have been made.

Go to "File" -> "Compare" and look at the differences.

Let us know how it goes!

Dave

 

[GhettoRacer]

I need to borrow a buddy's serial to usb converter before I can play with the cold start. I've gotten used to doing the "procedure" and can always get the NSX fired up with in a minute or two so I haven't gotten eager to try the suggestions...

This weekend I'm busy at Infineon Raceway instructing my students and just really enjoying myself back at the track DE/racing scene. It's my first event in 4.5+ years. Luckily a wet morning turn into a totally awesome sunny day. I have lots of videos, blogs and little stories to share.

Anyway, the car runs great except for the fact the it burns ton of oil and cold start. If the weather stays good I'm going to take it out for a few laps at Infineon this today.

 

[DDozier]

Your calibration file wasn't priming the fuel pump...

Go to "Engine Start" -> "Advanced Start" -> "Options - Advanced Start"

A window will pop up... Change "Fuel Pump Prime" to at least 2-3 seconds.

Save, upload, and try that single change first.

The default value is 0 for "Fuel Pump Prime" but the ECU is hardcoded for a 2 sec. minimum prime, so if there is anything less than two sec. you still get two sec. if you want more than 2 sec. you add it here.

Listen to Dave DO NOT LOAD ANY .cal FROM ANYONE. Do not make a change to your .cal without saving the original. Do not make changes unless you know what the change will do and can measure the change to verify it had the desired effect. If you do not understand exactly what the field and value is doing ask before you change. Cause and Effect, Trial and Error, are not your friends in engine tuning.

Dave

 

[Mac Attack]

Thank you Dave for clarifying that.

I have the newer Series 2 and am using the new AEMTuner. Based on one of Dave's previous suggestions, I downloaded the older AEMPro to look at the older supplied NSX start cal from AEM, as well as read up on a few of their .pdf's. I wasn't aware of the nuances on the older configuration... The new AEMTuner explicitly says how long the fuel pump will prime in the configuration window. Sorry about that. Yet another reason not to believe everything you read on the internet :smile:

I edited my post above to correct the information.

Dave

 

[GhettoRacer]

Still haven't gotten around to tweaking the NSX. It't really not that bad since I do the re-prime trick so... I was having fun at Sears Point over the weekend...

I'll post the videos in a separate thread.

 

[GhettoRacer]

http://www.amazon.com/gp/product/B0006LSIOI/

USB 2.0 to old school RS232 serial adapter came in! Now I can modify AEM EMS to hopefully fix the cold start problem.

 

[peiserg]

My NSX with the FIC always started up quickly, like stock.

With the AEM, there has always been a cold or warm start "issue" where it takes about twice as long as you were cranking. I.e. I get into the car, let the fuel pump prime for 3 seconds, and then crank the motor for about 3-4 seconds. It will always fire up on the first try, BUT takes that extra 3 seconds of cranking to fire. If i cranked it quickly like you do, it would NEVER start.

 

[GhettoRacer]

I couldn't get the serial to work yesterday when I first tried it. It turns out there's a specific order AEM ask us to do when USB to serial is used. Basically, fire up AEM software, select serial port, go offline, click connect, and then finally turn ignition on to give AEM EMS power. Now it works fine. I had thought maybe the USB to serial adapter I bought isn't compatible.

Anyway, I'm very happy to report that after change fuel prime value from 0 to 5:


Go to "Engine Start" -> "Advanced Start" -> "Options - Advanced Start"

A window will pop up... Change "Fuel Pump Prime" from 0 to 5.

And then under:

"Engine Start" -> "Advanced Start" -> "Initial Crank Pulse Table"

I selected the entire row and added 10% (input 110).

Uploaded the new calibration file, and then I tried it. It fired up after about 2 turns over!!! On FIRST TRY! AWESOME.

However, today's temp is pretty good in Union City, California. About mid 50's and the sun is out. The real test will be on a colder morning... But I'm positive it's now solved. AEM UEGO meter has arrived as well. Now I can street and dyno tune the car further. I'm excited. Thanks to everyone that helped!!

 

[L_RAO]

Good stuff. Congrats on getting rid of that problem.

Looking forward to the UEGO install & the tuning capacity it will afford you.

 

[DDozier]

I couldn't get the serial to work yesterday when I first tried it. It turns out there's a specific order AEM ask us to do when USB to serial is used. Basically, fire up AEM software, select serial port, go offline, click connect, and then finally turn ignition on to give AEM EMS power. Now it works fine. I had thought maybe the USB to serial adapter I bought isn't compatible.

Anyway, I'm very happy to report that after change fuel prime value from 0 to 5:


Go to "Engine Start" -> "Advanced Start" -> "Options - Advanced Start"

A window will pop up... Change "Fuel Pump Prime" from 0 to 5.

And then under:

"Engine Start" -> "Advanced Start" -> "Initial Crank Pulse Table"

I selected the entire row and added 10% (input 110).

Uploaded the new calibration file, and then I tried it. It fired up after about 2 turns over!!! On FIRST TRY! AWESOME.

However, today's temp is pretty good in Union City, California. About mid 50's and the sun is out. The real test will be on a colder morning... But I'm positive it's now solved. AEM UEGO meter has arrived as well. Now I can street and dyno tune the car further. I'm excited. Thanks to everyone that helped!!

Good to hear now set the fuel prime back to zero and check again, there should be no reason if the fuel system is working correctly to prime for 5 sec. This is a safety issue. You want the least amount of prime to get the car to start as possible in case there is ever a leak in the fuel lines.

Dave

 

[Mac Attack]

Also in the AEMTuner software, the pump prime time is the time it runs when ignition is turned on before start, and also the time the pump runs after ignition is turned off.

I could never tell that my pump even runs after ignition is turned off.

Dave

 

[GhettoRacer]

the car sat for 2+ weeks and i didn't drive it. this morning i decided to take it out for a spin. it's a wet morning and not particularly cold. maybe 60's. i had to prime it like 3 times before it starts. i'm not really quite sure if it's the priming or if i should bump up the initial crank pulse width some more.

i think i'm going to add more fuel at initial crank. another 10% and see...

comments? for you guys that have AEM what value are your initial crank pulse width set at? thanks.

 

[Mac Attack]

Do you have an aftermarket FPR on it?

I've been reading a lot about fuel components for my planned setup and it seems aftermarket FPR's don't hold fuel line pressure very well after they sit for awhile (unlike OEM FPR's).

Do you have a fuel pressure gauge?

Instead of temperature-related, this may be time and fuel pressure-related... or both.

Dave

 

[CK_SB]

My 93 (turbo), running the 1st gen. AEM EMS, has the exact same starting symptoms. I had the symptom with the OE fuel pressure regulator, as well as with an Aeromotive 1:1 regulator. I have a fuel gauge monitoring the line pressure, and once the inititial prime occurs there is no difference in the starting symptoms with either FPR. Changing the priming duration does not seem to have an affect. Changing the fuel pressure does not seem to have an affect. When I get some time I will run some additional tests and post my results.

 

[DDozier]

My 93 (turbo), running the 1st gen. AEM EMS, has the exact same starting symptoms. I had the symptom with the OE fuel pressure regulator, as well as with an Aeromotive 1:1 regulator. I have a fuel gauge monitoring the line pressure, and once the inititial prime occurs there is no difference in the starting symptoms with either FPR. Changing the priming duration does not seem to have an affect. Changing the fuel pressure does not seem to have an affect. When I get some time I will run some additional tests and post my results.

Getting a car to start is really a matter of fuel to air ratio while cranking. Even if the fuel pressure is not the same as when the car is running as long as you have some fuel pressure and the injector is squirting fuel you can adjust the crank fuel raw pulse width and get the fuel correct for starting. If you have fuel and spark then the only other thing to adjust is AIR. In most cases this is the last thing you want to try and adjust as 95% of the time the crank fuel will solve most starting issues. Once you get it starting everytime, you can play with the start crank timing to see what the motor likes to light off quicker while cranking.

Dave

 

[CK_SB]

Thanks Dave. I was using the fuel pressure to effectively/mechanically adjust the A/F ratio during cranking. I will play around with the injector pulse width during cranking as well. I am curious if anyone has the timing (during cranking) set differently then the default values. Dave, if your car lights off normally can you post your initial settings found in the Advance Start windows and include your timing during cranking setting? Our elevations appear to be very similar so your settings may be a good baseline to compare mine too. Feel free to pm a screenshot of the settings.

Your contribution to the discussion is appreciated.

 

[Mac Attack]

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

I've changed crank timing anywhere between 5 and 20 degrees BTDC and didn't really notice any difference when cold starting. So I left it at the OEM 15. Also, make sure you run the timing sync wizard in the AEM to ensure it's set correctly to begin with.

If it starts fine when warm, it sounds like you need to change your "Start Extra vs Temp" parameters as these are multipliers on your crank fuel table that are based on coolant temperature.

 

[CK_SB]

Thanks for posting the results of your timing adjustments. I too concluded to set it at the 15 degree BTDC during cranking based on the same logic. The car does start great on any occasion other then the first cold start of the day. Do you have your car starting well in all circumstances?

 

[GhettoRacer]

Under "Engine Start" > "Engine Start" the "Crank Adv value is at 10.07 degree currently. Are you guys advising to set this to 15?

Here are my current initial crank pulse width values:

it is 17920 all the way across. the original values were 15360 across as done by Shad @ Driving Ambition. Upping it 15% to 17920 helped a bit. I guess I'll up it another 10% to 19200 and see if that helps. that's only 17.92 ms vs. 19.2 ms... probably not flooding the chambers with fuel any time soon with that. ;-)

In regards to priming value, you would think that by extending it from stock 2 second to 4 second would be the same as manually priming it twice at stock value of 2 seconds. But it seems different...

 

[GhettoRacer]

I implemented the suggestions that Cody Guldstrand made and this morning I tested the cold start. I first tried increasing initial crank pulse width to 25 ms, then to 35, 45, finally 50 ms. I can tell it was getting easier and easier. Will test again later tonight. Notice I set the fuel pump prime back down to 2 seconds as it really made no difference in cold start. My engine crank advance is currently set at 16 now. Might advance it another 2 and see if it makes any more difference.

Cody works at TriPoint and he has lot of experience with Motec and AEM's. His tips have been VERY helpful.