Tune.....you need a tune.


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The reason I want to avoid a tune is the local tune shop quoted me $1000(600 for tuner and 300 for tune). I feel like that is way too much to throw into a high mileage car.. and why would the car just now suddenly require a tune after almost a year without issue?

 

You've most likely always been lean and the new o2 is reacting to it.

Just get a flash pro it has preloaded settings for the r18 with intakes etc.


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Ok... So what are the chances of getting flash pro used at a good price? Or is my best bet to fork over $600?

 

If you can't afford to fix it then put the stock parts back on.

 

Search craigslist or the forums.

But if you don't want to get a tune either go stock or prepare for the consequences of a too hot burn


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Forgive my harshness but I am kinda surprised at the lack of any meaningful insight. Its so easy to say just throw a tune on it, and ignore the entire point of my post. I believe there have been reasonable arguments made on other threads as to whether a tune is actually needed with such minor modifications.

So, I would like some knowledgeable insight into possible causes of running lean.

It is not a matter of affording a tune, its a matter of is it worth it on such a high mileage car that MAY be near end of life. Convince me of why a tune would be worth it.

 

Try other local shops or reputable ones you trust 1000 seems too high

 

Dude, take off the intake and TB spacer. They aren't doing much for you anyways. Go back to stock = headache resolved.

 

It's not rocket science.. More air with the same amount of fuel=lean

 

Wow, you clearly know nothing about the car. What the hell is the point of the MAF sensor? You all clearly have the "I don't know whats wrong but if you undo what you did last that should take care of it" logic. That's ridiculous. The intake is not the problem, that's proven. The o2 sensor was intermittent, it was not completely dead. I would have had a constant CEL if that were the case.

I came here for some knowledgeable insight into the issue but no one seems to know what their talking about. Not even the obvious was suggested...clean the sensor, check the filter...is it oiled too much..check for a leak. I guess this is too complicated for you guys that tout around on forums devoted to the 8th generation civic trying to look smart and give advice. You probably own Si's anyways which means you shouldn't even be responding to a post about an R18. Sorry my expectations were so high, I'll go elsewhere.

 

The MAF sensor was calibrated to the stock intake... You no longer have the stock intake, the MAF reading is wrong, you get the wrong amount of fuel. Put the stock airbox back on and I bet the CEL will not come back.

 

A lot of useless posts here - oh, interwebs, how typical. The MAF sensor *IS* reading off - that's 100% fact.

You *SHOULD* tune for all mods, even minor bolt-ons.

With that said, it doesn't make sense that the ECU was able to keep fuel trim in check (even if not ideal or even good) and then go out of tolerance. The car was running well until recently, right?

What brand did you replace the O2 sensor with? Did you splice it or did it come pre-connectorized?

Did you inspect all connections and wiring for issues?

 

Yes, the car was running fine until recently. I replaced the o2 with Denso pre-connectorized (I believe it is OEM direct replacement).

I agree with you, a tune should be used to take full advantage of these mods. However, the MAF and ECU are a lot more sophisticated than these other people are giving credit. It is my understanding that the MAF is the same one used in the accord V6's that make twice the power, it can handle the change in variables in the r18. Furthermore, the ECU compensates for barometric and temperature changes at extremes which can usurp the increased performance of bolt-ons. That is why the ECU was able to keep the fuel trim in check for the past 6 months of daily use without issue. I'm in a bit of a warm cycle weather wise, so I'll double check everything again in the next few days.

It won't be long before I hit 300K with this car. I have reasoned with myself and will probably end up getting FP (no thanks to any meaningful advice from these other people). I figure I can sell the tuner later and get some money back. But I do not want to cover up the problem with a tune. That may be sufficient for some people, but not for me. With as many miles as this engine has seen, I can't help but think there is something else faulting that not many people have seen.

 

Even if it is the same MAF sensor, the calibration for flow vs. voltage in the ECU will be different to account for the different intake design. If you don't believe me, check the attached spreadsheet. I copied the MAF transfer table from the R18 stock calibration along with the 2013 V6 Accord stock calibration out of FlashPro. Returning to the stock airbox for now would be your best bet to correct the fueling.

If your O2 sensor was marginal, that would explain why it didn't throw the lean code earlier. There are many times where the O2 goes bad but no CEL; the only way to tell is by checking the datalogs (e.g. In Soviet Russia Factory Wideband Tunes You | FlashPro Tuning).

 

Thank you for the info and resources. Sounds like I can't rely on what the car is telling me as much as I thought.

I still think the ECU compensates for the different intake the same way it compensates for a cold winter morning. In simple terms, its a piece of pipe with a filter being replaced by another pipe with a filter. The scenario that was explained to me was the CAI presents the same change that a fresh filter and very cold morning would effect on a stock system. With that being said, I can see it faulting out because the effect is doubled now that it is colder out.

I believe that explains why a lot of people get away with intakes because i also hear them switching to a short or ram air during the winter months.

 

Yes, as long as the airflow across the MAF remains the same as stock, the ECU can compensate for any changes that alter the volumetric efficiency of the engine. The problem with most aftermarket intakes is that they don't account for this. Changing the piping diameter or disrupting the laminar flow across the sensor will alter the MAF reading. Also, the MAF is measuring the mass of air entering the engine, so no compensation is needed for temperature. Cold air will be more dense and the MAF will read a higher mass of air.

Take the R18 and Accord tables I posted before. Say you were theoretically able to put the Accord intake on your R18. The actual mass of air entering the engine would now be more than double what the MAF thinks it is seeing based on the sensor calibration in the ECU.

On older Hondas that were tuned via MAP (speed/density), you could basically slap on any intake you wanted and not throw a code, since the ECU is estimating the amount of air based on the manifold pressure, RPM, and temperature, instead of trying to measure the air at the intake.

The FlashPro help file has some information about the difference between MAF and MAP tuning: https://www.hondata.com/help/flashpro/index.html?tuning_mass_flow.htm

 

Volumetric efficiency? I'd appreciate it if you could elaborate.

1. MAF sensor: unless the Honda MAF is different than Subaru's, it will compensate for air temperature based on the intake air temperature, which will effect how the ECU calculates intake mass flow of air (typically in grams of air per second.)

The MAF sensor input to the ECU is based on the intake GEOMETRY - the diameter and flow type. Only a VERY small percentage of the actual air being sucked through the intake passes the MAF sensor, a sample, if you will, of the total air flowing through the intake. The ECU takes the MAF signal and looks up in a set table what the related air flow is.

If the intake diameter and shape around the MAF are changed, then the lookup table is WRONG.

The result for a larger CAI, for instance, will most likely be a larger flow rate of air than what the MAF is reporting. Why? Because the MAF is NOT smart. It literally senses what flows past it and sends that to the ECU. The ECU is what does the calculation of airflow based on this.

How do we know how off the reading for the MAF is? Great question!

Well, the O2 sensor input is what the ECU uses to maintain the required AFR. If the MAF sensor is reading 10% less flow than is actually flowing past it, the O2 sensor will sense that in the exhaust and the ECU will add more fuel to maintain target AFR.

If the 02 sensor is bad AND you're not tuned for a non-stock intake, the ECU will compensate wrongly and the ECU will either be way off and not know it or will think it's way off and actually be close to where it is supposed to be.

It sounds like your new O2 sensor may not be reading correctly.

 

I appreciate your knowledgeable posts and insight. I was getting a bit frustrated in the beginning for the thoughtless replies, for which I apologize. You have definitely made things clear pepperdanky.

Thanks again mate!

 

The volumetric efficiency is the volume of air the engine can move over a period of time. If you add a header and/or exhaust, the volumetric efficiency of the engine will increase. With the MAF in the stock housing, it will compensate for this as it will measure the increased mass of air entering the engine.

The MAF used in our cars is the hot wire type, so by nature it does not need to apply IAT compensation to the signal. The signal generated by the MAF is already sensitive to changes in temperature, humidity, pressure, etc.
https://www.hondata.com/forum/viewtopic.php?t=13894#p60405

 

I'm going to put this to you in terms you can understand.

The MAF is calibrated around the diameter, shapes and distance from the throttle body to show voltages as specific grams per second of airflow. When you put an intake on the car, you MUST recalibrate the MAF to get proper readings. Otherwise it's generally right at higher rpms, but wrong at lower rpms or at light throttle readings.

If you cannot afford tuning, remove the intake and reset your ecu by removing the battery connection and replacing it. Car will not throw the lean code again. Just because it may have been fine before doesn't mean it will stay fine.

 

The mass airflow sensor is a wire that is heated and based on how it cools reads different voltages as different masses of air. When turbulence is put into the mix the airflow can make it read incorrectly since it gets different velocity air than it was used to, and it will read incorrect voltages at air masses that are not actually very different than before.

 

Get yourself a used fp , and put that thing on a base map , it will be good for you. You can get a used fp for 450-550.