Throttle issue

[Pughney1]

So the issue I’m having is when I’m driving and trying to maintain a certain speed, like 55. The car will stutter and the wideband gauge pegs lean. I took the car to get tuned by a reputable person and he said he can’t figure out what the issue is. I’ve tried different throttle body’s, tps sensors, adjusted valves, triple checked the timing with a light, different injectors and it still does it. If you are accelerating it’s smooth all the way throughout boost and the a/f stays around 14. As soon as you try to drive it like a normal person it just intermittently stutters and goes lean. It’s not the entire time you’re driving 55. It’ll just randomly do it and then go back to being smooth. It’s like the computer doesn’t recognize my foots on the throttle. I know absolutely nothing about tuning a car. He said there’s a spot on the table where if he adds fuel it goes to rich and wants to die and if he takes fuel out it does this stutter. Does anyone have any advice?

[DaX]

Are you running in open loop or closed loop?

Is it possible for you to post your calibration file and a datalog from when the car is having the issue?

[Hondata]

Post your calibration and a datalog.

[Pughney1]

alright I don't know how to do that but I think I attached something.

[Pughney1]

okay I think this is the datalog

[Pughney1]

Are you running in open loop or closed loop?

Is it possible for you to post your calibration file and a datalog from when the car is having the issue?

I posted them below. Thank you for any advice.

[Pughney1]

Post your calibration and a datalog.

I posted them below. Thank you for any advice.

[Pughney1]

So the issue I’m having is when I’m driving and trying to maintain a certain speed, like 55. The car will stutter and the wideband gauge pegs lean. I took the car to get tuned by a reputable person and he said he can’t figure out what the issue is. I’ve tried different throttle body’s, tps sensors, adjusted valves, triple checked the timing with a light, different injectors and it still does it. If you are accelerating it’s smooth all the way throughout boost and the a/f stays around 14. As soon as you try to drive it like a normal person it just intermittently stutters and goes lean. It’s not the entire time you’re driving 55. It’ll just randomly do it and then go back to being smooth. It’s like the computer doesn’t recognize my foots on the throttle. I know absolutely nothing about tuning a car. He said there’s a spot on the table where if he adds fuel it goes to rich and wants to die and if he takes fuel out it does this stutter. Does anyone have any advice?

[DaX]

Thanks for posting the files. First off, I'm not a professional tuner and I don't work for Hondata, so take my advice and analysis with a grain of salt.

I don't want to bash, but your timing maps look terrible, and if a professional tuner set those up, I would look for a new tuner. I'm not sure if those could be the cause of the issue or not.

If you zoom way in on the issue that is happening in the datalog you sent, you can see that just before the AFR spikes, the injector duty and pulse-width drop. This is the cause of the AFR spike. Now you need to find out why your injectors are reducing their duty cycle. Looking further, during these lean spikes your short term fuel trim goes from zero to -29%. Something is telling the ECU to pull fuel.

Which fuel injectors are you using? I see they are 440cc/min, but you have the same dead times loaded as the stock 240cc/min injectors. Did your injectors come with a chart for dead times?

You are running in closed loop - you could try switching to open loop and see if that solves your issue. Or you could try reducing how much your short term fuel trim can adjust your fuel (currently set to -30% min and +47% max). Or we can wait and see what Matt or Doug from Hondata have to say.

[Pughney1]

Thanks for posting the files. First off, I'm not a professional tuner and I don't work for Hondata, so take my advice and analysis with a grain of salt.

I don't want to bash, but your timing maps look terrible, and if a professional tuner set those up, I would look for a new tuner. I'm not sure if those could be the cause of the issue or not.

If you zoom way in on the issue that is happening in the datalog you sent, you can see that just before the AFR spikes, the injector duty and pulse-width drop. This is the cause of the AFR spike. Now you need to find out why your injectors are reducing their duty cycle. Looking further, during these lean spikes your short term fuel trim goes from zero to -29%. Something is telling the ECU to pull fuel.

Which fuel injectors are you using? I see they are 440cc/min, but you have the same dead times loaded as the stock 240cc/min injectors. Did your injectors come with a chart for dead times?

You are running in closed loop - you could try switching to open loop and see if that solves your issue. Or you could try reducing how much your short term fuel trim can adjust your fuel (currently set to -30% min and +47% max). Or we can wait and see what Matt or Doug from Hondata have to say.

I’m running rc440 injectors with jumper harness’s. They did come with a paper I should still have it somewhere. I have zero knowledge of how to change any of the things you mentioned. He doesn’t tune for a living anymore. But he’s supposed to be the “best” in my area. Should the dead times be 440 too? And if I change the short term fuel trim would It need to go up or down? I seriously appreciate your help. I’m going to try and change these things you said. If it doesn’t work I can just re-upload his tune that I have saved on my laptop, right?

[DaX]

Yes, if you have the original calibration file saved on your laptop, you can make the changes to a copy of that file, then revert back to the original one later if you want.

Now that I think about it more, I think that running in open loop may solve your issue. If you run open loop, you won't have to worry about short term fuel trim. If for some reason you really want to run in closed loop, you may need to adjust the "rate of change" settings in the calibration file. Unfortunately I've not played around with this (I run my car in open loop), so I can't give you any direction on how to do that.

If you need to adjust your dead times, reference this chart for RC440's - choose the column to use based on what your base fuel pressure is. Please note that changing dead times will likely require a re-tune, as all your fuel maps will need to change.

http://www.rcfuelinjection.com/Portals/ ... y_Time.pdf

[RAS]

I had a similar issue. Ended up being my TPS. Your TPS reading is all over the place in the datalog, as mine was before replacing.