Smart Car of America Forum banner

1 - 20 of 38 Posts

·
Registered
Joined
·
318 Posts
Discussion Starter #1
Does anyone, know (100%) what the stock fuel injectors are rated at?

Evilution site says 120.9cc/min but their description of the fuel injector is not what the US models use. They use a EV6 style connector and the US version uses a Denso style connector.

Next question...

What is normal operating fuel pressure?

Evilution site shows a fuel pressure regulator on the fuel rail that could easily give me an answer but... The US models don't use a FPR on the fuel rail, instead fuel pressures are controlled in the pump.

Thanks in advance!

-Ian
 

·
Registered
Joined
·
318 Posts
Discussion Starter #2
Found a post stating that 46PSI is the operating fuel pressure... Can someone confirm this?
 

·
Registered
Joined
·
4,297 Posts
Thank you sir...

Now, what size are the stock injectors?
One of 2 ways to get a possible answer: call Tim @ SFR
or punch up the part number of the stock injector on the net and see where the search engine takes ya..:wink:
 

·
Registered
Joined
·
318 Posts
Discussion Starter #6
C'mon Barney... You think I'd ask a question without doing research? :p

Tim didn't have an exact answer ("I think it's a bit higher than 120cc/min") and the part# on the internet is very elusive. I can find the injector but no specs.

If you've found an internet source that tells the spec of the injector please tell me and I will have all the info I need.
 

·
Registered
Joined
·
4,297 Posts
Give the number to an injector distributor (rebuilder)... :p

Keep in mind I'm using 101's and 100's with smaller turbos and having no issues...
 

·
Registered
Joined
·
318 Posts
Discussion Starter #8
What do you mean your running 100's and 101's? I called my local injector guy and they didn't have any info on the injectors.

-Ian
 

·
Registered
Joined
·
318 Posts
Discussion Starter #10
Maybe I'm just tuning incorrectly...
Tomorrow and/or Friday I will take another stab at it...
Having more information is never a bad thing.
If no one can verify the stock injector size I will get a stock one tested... I feel it will be $10 spent well.
 

·
Registered
Joined
·
4,297 Posts
Until you get a aux. wideband with data logging capacity installed I wouldn't do much of anything...
What happened with the tuner guy at the dealership that was going to help you out???
 

·
Registered
Joined
·
318 Posts
Discussion Starter #12 (Edited)
A wideband is not needed to tune the vacuum side of the map because you are trying to mimic the factory ecu's fuel trims.
If your fuel trims are correct then your AFR should be 14.7:1 up to boost and the ECU will be happy

In the boost section of the map you are 100% correct about needing a wideband because the controller will alter the O2 sensor reaing (sending a leaner signal) in order to add additional fuel.
If you watch the fuel trims in boost, you'll probably see it leaning out but don't get scared because you have your wideband to tell you your air/fuel ratio.

I thought he knew what he was doing but that wasn't correct... Now that I've spent coutless hours reading and figuring out the system I feel comfortable doin' this.

Just need tuning time and my last couple questions answered.
 

·
Registered
Joined
·
318 Posts
Discussion Starter #13
DR. INJECTOR of Portland gave me the answers I needed.

Tested a stock 2012 Smart Fortwo fuel injector...

Here are the specs....

100cc/min with a fuel pressure of 43 psi

With a fuel pressure of 46 psi the fuel injector is rated at +/- 110cc/min.

The injector size Split Second recommends for 7psi of boost is a 50% increase over stock... resulting in the need for a 150cc/min to 160cc/min injector.

Split Second does not recommend using anything above a 100% increase over the stock fuel injector size.

So... If I wanted to hit 14psi of boost I would need a 200cc/min to 210cc/min injector.

With all of this said, using a larger 266cc/min injector like SFR uses in their kits will still work but makes tuning the Split Second controller much more difficult than if you were to use a 200cc/min injector.

Repeat... Tuning with an injector size that is over 100% larger than stock will work and has been proven to work, but will result in a difficult tuning experience.

I also feel that using to big of an injector is the potential cause of the annoying P2227 code. The code can be tuned out with relentless tuning (as Barney has expressed) because you have to find the PERFECT cell value for each Fuel map cell in order to stay within the MAP voltage range the ECU wants to see.

The Split Second controller is actually a very simple system and very effective... if you stay within the parameters they built the controller around.

Now... The hunt for 200cc/min injectors!
 

·
Registered
Joined
·
318 Posts
Discussion Starter #14
After some schooling from gearhead, I understand that the larger fuel injector is needed because of the lack of a raising fuel pressure regulator (I'm assuming this is a return-less system). I'm guessing this is the reason why SFR uses a 266cc/min injector that is a bit more than 150% bigger than stock.

I'm still a little confused by SS's recommendation of not using anything larger than 100% over stock. If this controller was built for this car, why is everyone using a larger than recommended fuel injector?
Makes me think there was some confusion in the development of the controller.

Vacation day tomorrow = tuning time!
I'm determined to beat this challenge of tuning.
I hope to get the non-boost area tuned decently or at least get an understanding of what needs to happen.
Fortunately I live next to a good stretch of 45+ MPH road, some very long parking lots, a LONG hill and stop/go driving.
 

·
Registered
Joined
·
1,635 Posts
After some schooling from gearhead, I understand that the larger fuel injector is needed because of the lack of a raising fuel pressure regulator (I'm assuming this is a return-less system). I'm guessing this is the reason why SFR uses a 266cc/min injector that is a bit more than 150% bigger than stock.

I'm still a little confused by SS's recommendation of not using anything larger than 100% over stock. If this controller was built for this car, why is everyone using a larger than recommended fuel injector?
Makes me think there was some confusion in the development of the controller.

Vacation day tomorrow = tuning time!
I'm determined to beat this challenge of tuning.
I hope to get the non-boost area tuned decently or at least get an understanding of what needs to happen.
Fortunately I live next to a good stretch of 45+ MPH road, some very long parking lots, a LONG hill and stop/go driving.
Fuel delivery is determined by injector flow rate, fuel pressure and injector on-time. If too large a flow rate injector is used you can get over-fueling at low engine speeds. The injector on-time can only be decreased to a certain point. The whole set-up is a compromise of all the variables. You need enough fuel delivery capability to prevent going lean on acceleration at high boost levels yet not over-fuel at low speeds. Tricky.
 

·
Registered
Joined
·
318 Posts
Discussion Starter #16
After two hours of; driving, stopping, clearing codes and adjusting the fuel map... I need a beer break.

My driving fuel trims look good, I've adjusted the long term fuel trim to +3 and the short term fuel trim jumps between -3/+3, right about where the factory ecu likes to sit.

Current issues:
1) At idle the closest I can get to a zero long term fuel trim is -14% without the idle starting to fluctuate up and down... Symptom of injector size being to large according to Mark at Split Second.

2) I can drive normal down the highway at 2500-3500 rpm (about 45mph) and everything looks good and drives well, but when I let off the throttle and slow down in open loop deceleration, the ECU throws a "B1S1 O2 sensor stuck lean" or a "B1S1 Pumping current trim circut open" code...
I believe these to be false codes because my fuel trims function properly.

Any input?

-Ian
 

·
Registered
Joined
·
318 Posts
Discussion Starter #17
After some e-mail conversation I'm still on the fence about using an injector that is over 100% larger than stock with the SS controller.

I am still interested in using an injector in the 200cc/min range.

The reasoning behind the larger injector is because of the higher injector duty cycle in boost. Simply, the smaller injector will produce more heat from electrical resistance in the boost range, potentially causing to little fuel or poor spray patter (Atomization).

I'm wondering if SFR used a Nissan 350z injector because of ease or because a thorough research. The 266cc/min injectors are closer to the requirements of the SS controller but still to large according to their recommendation.

-Ian
 

·
Registered
Joined
·
1,635 Posts
After two hours of; driving, stopping, clearing codes and adjusting the fuel map... I need a beer break.

My driving fuel trims look good, I've adjusted the long term fuel trim to +3 and the short term fuel trim jumps between -3/+3, right about where the factory ecu likes to sit.

Current issues:
1) At idle the closest I can get to a zero long term fuel trim is -14% without the idle starting to fluctuate up and down... Symptom of injector size being to large according to Mark at Split Second.

2) I can drive normal down the highway at 2500-3500 rpm (about 45mph) and everything looks good and drives well, but when I let off the throttle and slow down in open loop deceleration, the ECU throws a "B1S1 O2 sensor stuck lean" or a "B1S1 Pumping current trim circut open" code...
I believe these to be false codes because my fuel trims function properly.

Any input?

-Ian
If those codes are correct they indicate the engine control module is attempting to correct for a lean fuel mixture. The problem is, on closed-throttle deceleration the fuel injectors are disabled until the throttle is opened again or idle speed is reached. As such, the control module should not be attempting a correction.

The first thing I would do is look at scan data to verify the control module knows the throttle is closed when it is closed. Next, make sure nobody has disturbed the minimum air rate setting (throttle stop) on the throttle body.

If all else fails, try a different scan tool to see if you get the same codes. Aftermarket scan tools sometimes translate fault codes incorrectly and send you down a rabbit hole.
 

·
Registered
Joined
·
318 Posts
Discussion Starter #19
If those codes are correct they indicate the engine control module is attempting to correct for a lean fuel mixture. The problem is, on closed-throttle deceleration the fuel injectors are disabled until the throttle is opened again or idle speed is reached. As such, the control module should not be attempting a correction.

The first thing I would do is look at scan data to verify the control module knows the throttle is closed when it is closed. Next, make sure nobody has disturbed the minimum air rate setting (throttle stop) on the throttle body.

If all else fails, try a different scan tool to see if you get the same codes. Aftermarket scan tools sometimes translate fault codes incorrectly and send you down a rabbit hole.
I thought it was a bit strange to be throwing that code during deceleration because the ECU is in open loop, therefore the ECU is not looking for an o2 sensor reading.

I'll check out the throttle percentage.

Throttle stop should be good, I haven't touched it and no one else has worked on the car.

After having the battery disconnected for a long period of time (3-4 days), could the throttle body need to relearn it's positions?
I know from working on Volkswagens and Audis that a throttle body adaptation is sometimes needed.

-Ian
 

·
Registered
Joined
·
1,752 Posts
WOW! Just WOW!

ILOMAX, you rock. I love it when someone gets lemons and makes LEMONADE. I'm not even sure that reference applies ... but you certainly are making the best of the situation.

Regards,

Dan
 
1 - 20 of 38 Posts
Top