Air/Fuel Ratio After Mods

[RichD]

After adding an aftermarket intake on my Z125 Pro, the engine ran very lean. I had to remove the O2 sensor, add diodes to the harness to make it run richer. The ECU could not make up for the increased air flow from the more efficient intake. Can the Honda ECU reprogram itself to compensate for exhaust and intake mods?

 

[dmonkey]

With both exhaust and intake mods you'll likely run into the same issue with the CT. The stock ECU has a limited range of adaptability and same as any other modern vehicle that's limited in part for emissions compliance. I've not heard of anyone reflashing the USA market ECUs, but on this forum you'll find details on other modifications to adjust the fueling such as wiring in an EFIE device in reverse, aRacer RC Mini X aftermarket ECU, Kitaco I-MAP, Takegawa/Enigma FI-CON, and other such piggyback fuel controllers.

 

[valntyn82]

I have not tried this myself yet. But I have read, and seen on YouTube, that if you replace the fuel injector with a larger one, like the injector for the PCX 150, the ECM will be able to keep the mixture the ratio. With just the stock injector it is not able to keep up with the increased airflow.

 

[Harley rider]

when i just did intake and exhaust mods i had to move up to a 120 cc per minute injector and then the ecu could keep up just fine but was a little rich, a pcx 150 injector would actually be a bit much for this. a 110 would be perfect . another option would be the EFIE but even that might not be enough. stock injector for these engines runs at 90 cc per minute from what i could find.

now that i have a 145 big bore kit with cam, intake, and exhaust, i had to move up to a 150 cc per min injector and i am right on the money with EFIE device. the EFIE that changes the signal from the 02 sensor to make it a little richer than even the ecu wants, but no other ecu mods on mine and it runs great. i do have a a/f ratio meter mounted and follow it to make sure i am where i need to be. also keep in mind it takes about 60-70 miles for the ecm to adjust perfectly to any and all mods and relearn.

 

[CTExplorer]

when i just did intake and exhaust mods i had to move up to a 120 cc per minute injector and then the ecu could keep up just fine but was a little rich, a pcx 150 injector would actually be a bit much for this. a 110 would be perfect . another option would be the EFIE but even that might not be enough. stock injector for these engines runs at 90 cc per minute from what i could find.

now that i have a 145 big bore kit with cam, intake, and exhaust, i had to move up to a 150 cc per min injector and i am right on the money with EFIE device. the EFIE that changes the signal from the 02 sensor to make it a little richer than even the ecu wants, but no other ecu mods on mine and it runs great. i do have a a/f ratio meter mounted and follow it to make sure i am where i need to be. also keep in mind it takes about 60-70 miles for the ecm to adjust perfectly to any and all mods and relearn.

I'll 2nd this. Mine is a JA55 but with intake, high flow filter, and new exhaust, and Kitaco type 1 cam mine ran too rich with the pcx150 injector even with the efie off. I went with a 1st gen grom injector and efie set pretty low and seems to work good. Worth noting I noticed it had a much more offensive tone to the ears when it was really rich and is much easier on the ears now.

 

[BergyPatty37]

Interesting, I had a Honda parts guy tell me that on his Trail (no longer owns) he was running a hotter spark plug and an injector from the ADV 160 in it. Said it ran much better after ECU relearned. Bought it to try so I guess Ill see how it goes. As far as I know his was also a completely stock motor, as is mine (albeit I have a JA65 whereas his was A JA55). I guess I'll see what happens

 

[CTExplorer]

Interesting, I had a Honda parts guy tell me that on his Trail (no longer owns) he was running a hotter spark plug and an injector from the ADV 160 in it. Said it ran much better after ECU relearned. Bought it to try so I guess Ill see how it goes. As far as I know his was also a completely stock motor, as is mine (albeit I have a JA65 whereas his was A JA55). I guess I'll see what happens

I did forget to mention I'm running a 9 range plug now as well. It still shows really light but was no faster if not slower then stock with the PCX150 injector as rich as it was and I got aignificantly less mileage. Again, JA55.

 

[Harley rider]

its all about the air fuel ratio and the cc per minute flow rate of the injector, get that right and the ecm will cope and give you greater power. i have about 5 injectors now, but i have the benefit of knowing what my air fuel ratio is. your looking for 12.5-13 for the most power, but that does run little warm

 

[BergyPatty37]

@CTExplorer Sounds like it would be even worse than for me with stock motor. Ill try out it for a little bit and see what happens. I would expect same results then. Might have to look for a smaller injector. Don't plan (keyword plan) on doing any other mods to the engine/intake/exhaust so will probably just go back to stock injector or maybe slightly larger.

 

[CTExplorer]

@CTExplorer Sounds like it would be even worse than for me with stock motor. Ill try out it for a little bit and see what happens. I would expect same results then. Might have to look for a smaller injector. Don't plan (keyword plan) on doing any other mods to the engine/intake/exhaust so will probably just go back to stock injector or maybe slightly larger.

I found the 1st gen used Grom injector on ebay. Plenty there for a cheap option if you decide to try that route.

 

[CTExplorer]

Interesting, I had a Honda parts guy tell me that on his Trail (no longer owns) he was running a hotter spark plug and an injector from the ADV 160 in it. Said it ran much better after ECU relearned. Bought it to try so I guess Ill see how it goes. As far as I know his was also a completely stock motor, as is mine (albeit I have a JA65 whereas his was A JA55). I guess I'll see what happens

I never thought of going with the hotter plug with the 150 injector but it was so rich I doubt it would of done enough. I went down to like 90 miles on a full tank before the gas light would start flashing.

 

[BergyPatty37]

@CTExplorer What mods have you on your bike with regards to intake, exhaust and engine?
Did you notice the grom injector to be better than stock and the 150? I have a feeling it will be running rich but this guy put almost 20k on his bike so im not sure. I don't mind trying for a couple hundred miles to see if it runs any better once ECU attempts a relearn

 

[CTExplorer]

I have a Takegawa high flow foam filter, intake (I can't remember the name but it was from webike, looks 3d printed, and probably similar performance to any upgraded intake), Kitaco type 1 cam, Takegawa sport exhaust ( the one that reuses the stock guards and looks like stock), and the 1st gen Grom injector, and EFIE (I believe set to 200mv) and 9 range colder plug.

Stock injector would run too lean for my comfort even with the EFIE and gave me reason for concern when really pushing it for longer periods. The pcx 150 with no EFIE you could smell the richness, was really harsh on the ears, was slower, blackened the exhaust, and was getting about 90 miles before the gas light would start flashing. With the Grom injector and efie it runs really good (for a CT 125, lol) with the best power and I'm back up to 120+ miles before the gas light flashes and the exhaust tone doesn't hurt my ears like it did with the 150 injector.

 

[dmonkey]

I have a Takegawa high flow foam filter, intake (I can't remember the name but it was from webike, looks 3d printed

"KSPP Highflow" is one like what you describe, so it might be that.

 

[BergyPatty37]

@CTExplorer Thanks. Do you know what years the 1st gen groms run from? 2013-15?

 

[SLO]

After adding an aftermarket intake on my Z125 Pro, the engine ran very lean. I had to remove the O2 sensor, add diodes to the harness to make it run richer. The ECU could not make up for the increased air flow from the more efficient intake. Can the Honda ECU reprogram itself to compensate for exhaust and intake mods?

I did a Yuminashi 143cc BBK,High air flow air filter,removed snorkel,high flow ,de cat exhaust to head. Put a Honda 150cc scooter injector in,as per Yuminashi BBK instruction.Actually they recommend a 140 injector. It runs rich,and I keep new plug ready,NGK CPR6EA9. NGK lower number=hotter. Answer to question yes,but change injector. If it backfires after letting off throttle on full throttle wide open run,it is too lean.BBK came with 238 cam,and I may have over gapped rings,is why it runs rich. But that might be why it hasn't blown apart. 13 tooth in front,Shinko 3/0 front rear. 60 mph plus on flat ground.

 

[SLO]

I did a Yuminashi 143cc BBK,High air flow air filter,removed snorkel,high flow ,de cat exhaust to head. Put a Honda 150cc scooter injector in,as per Yuminashi BBK instruction.Actually they recommend a 140 injector. It runs rich,and I keep new plug ready,NGK CPR6EA9. NGK lower number=hotter. Answer to question yes,but change injector. If it backfires after letting off throttle on full throttle wide open run,it is too lean.BBK came with 238 cam,and I may have over gapped rings,is why it runs rich. But that might be why it hasn't blown apart. 13 tooth in front,Shinko 3/0 front rear. 60 mph plus on flat ground.

I forgot,all my rides are at 2500 ft and up to about 6000 ft above sea level with rapid changes. Might be why plug gets(dirty).

 

[CTExplorer]

@CTExplorer Thanks. Do you know what years the 1st gen groms run from? 2013-15?

Sorry, was at Windrock for the weekend enjoying my other hobby

 

[CTExplorer]

@CTExplorer Thanks. Do you know what years the 1st gen groms run from? 2013-15?

Here's the item I won on ebay

 

[BergyPatty37]

@CTExplorer Thank You! Looks like a great time. Miss my WJ!