rice a roni

iTrader: (1)

Just picked up a 98 HX for a winter beater. For 800, I'm not going to complain, but the 5 wire o2 sensor is out so I'm contemplating converting from obd2a to obd1, running a chipped and converted p06, and tuning for the MPGs.

Looking for input. Can't decide if I should just run it as is, buy a replacement 5wire o2 off of ebay, or chipping and tuning would be better. I have a wideband, crome pro, datalogging, burner, etc, and I've tuned before.

Caoboy

No.

Whatever you are thinking, forget it.

Just replace the o2 sensor, leave it as is, look up cleaning out the egr system, and learn how to drive it as is, and learn how to improve your driving to raise the mpg.

Otherwise you are going to completely ruin the gem that is the HX.

spAdam

iTrader: (1)

x2.


You're not going to bet the factory cal on this one, especially since you'll lose the lean burn strategy in the process. Better off to spend some time catching it up on maintenance and fixing any other small issues, the thing should net you well into the 40's if driven properly. Is it a manual or a CVT, btw?

rice a roni

iTrader: (1)

5 speed and thanks for the input.

I'm gonna drive it around and see what kind of MPG's I'm getting before I purchase a 5 wire o2 sensor. If I get 30+ without an o2 sensor I'm just going to leave it.

Caoboy

You need the proper o2 sensor to get the better mpg.

The car goes into a lean burn mode and it needs the right o2 readings to do that....

rice a roni

iTrader: (1)

I got a disappointing 32mpg highway.

Put in an order for a 5wire o2 sensor.

spAdam

iTrader: (1)

Yeah. It's just running along in open loop. Not sure what you were expecting.

blackeg

i agree to leave it stock. rather than mess with the calibration i would swap a y8 in there.
i had an hx in the mid 2000's. the ecu was stock, stock motor but it had a y8 trans which pretty much made it perform both mpg and acceleration like a y8. overall that damn thing is a different animal from the ecu to the head/vtec setup to the wiring in the chassis.

ThE HeLLRaZoR

Tune it!! Don't tune for best MPG's. Tune it for best combustion efficiency...

I purchased a Flash System and new Bosch3 Injectors for my 88 Corvette and I picked up a real good chunk of power(could feel this improvement) and +8mpg when tuning was completed.

My 88 had pos old tired stock Multec Injectors. My fuel injection went from a faucet to a fine mist.

spAdam

iTrader: (1)

Upgrading to modern injectors will make a big difference, when and where you can. Unfortunately, to tune on the HX, you're going to lose all of the factory features that make it such a good gas sipper... Lean burn, EGR, etc etc.

rice a roni

iTrader: (1)

I originally ran it without an o2 sensor to see what kind of mpgs I would get in open loop. I've picked up a 5 wire o2 sensor and it seems to be working well. I'll report back once I gas up. Had 50 miles on the trip odometer when I installed the o2 sensor.

Caoboy

Did you reset your ecu when you changed out your o2 sensor?

rice a roni

iTrader: (1)

So far so good. Took 2.5 hour trip to buy some winter tires and one tank of gas, I managed 397 miles.

I was waiting for the gas light to come on, but it never did. I was sitting on the red mark so I decided to gas up and not get stranded.

I managed 38mpg if I calculate for tire size and odometer reading, otherwise I would have gotten 39.xx mpg.

VegasInvasion

I have a knack for hypermileage tunes, and I've tuned a few of these. The EGR is actually useless, it just fouls up the engine. The Y5 is pretty easy to tune compared to the D15B dual-Vtec engine, albeit a better suitor for hypermileage.
I would advise against trying to tune this yourself though, unless you're experienced and have a dyno at your disposal. Lean tuning is dangerous without adequate load and knock monitoring.

S2K Yellow

I have done some reading about the Lean Burn mode that the HX is suppose to do under certain speed & load conditions, however I cannot determine if my 2000 HX (manual trans) will engage lean burn. I have read than when it goes there it will do over 20:1 AFR and that excites me since Stoichiometric is 14.7 . I am thinking about buying a wide band AFR gauge unit and plumb it into my exhaust manifold and see what I am getting. The car does not break into the 40MPG in the two years I have had it. I have done the tune up with timing belt, water pump, valve adjustment, ignition timing, spark plugs, plug wires, both O-2 sensors, and MAP sensor about a year ago. The odometer is at 217K burns a little bit of oil but not enough for a tear down. The exhaust pipe never does go to a grey color.
Is there a sure fire method of knowing this car goes into the lean burn mode ? If I am missing some basic thoughts, please let me know. I have not looked into the distributor other than changing the rotor as I recall. Does it have some significant function for promoting Lean Burn ?
Mileage is why I bought the car in the first place. Once I see improvement I plan to do some HHO gas augmentation for greater MPG.
Appreciate any comments from other HX owners/experimenters. Rob

Caoboy

Get a scangauge, s2kyellow.

Clean out your EGR.

Leanburn initiates at something like 62mph? or a certain RPM, and mph combined.

You have to be very 'smooth' and keep your mph/rpm constant so that the leanburn will kick in and start working. Some say you can feel it initiating. I have no personal experience.

But I do use a scangauge, and you can see stuff like engine load, realtime mpg etc, which can help you deduce when leanburn is kicking in. Also, it shows your O2 sensor, but only if it's open loop/closed loop.

spAdam

iTrader: (1)

If you have any mils or other issues (like the typical cracked exhaust manifold between the 2nd and 3rd runners), it won't lean burn. If you drive aggressively, it won't lean burn. If it was originally sold in California, it doesn't ever lean burn.

A wideband will read out to lambdas of around 1.36. The Honda lean burn strategy runs out to lambdas past 1.5 iirc, so your gauge would show pegged lean if you had it working.

S2K Yellow

Adam,,,, No MILs, no cracked exhaust as I would hear it, and sensible driving with caution to throttle movement and speed. If the Lambda did read out 1.36 it would still be gratifying seeing the AFR at 20:1 pegged or not. That would be conclusive Lean Burn mode.
By the way, have been schooled "old-school" - - - is it necessary that I adopt the lambda terminology rather than AFR. I trained on a Clayton water dyno and AutoScan Scope back in the late 60's and AFR is my default nomenclature. Indeed lambda is here to stay since OBD2 arrived, but I prefer the AFR as it is already in the mind program. :<)

spAdam

iTrader: (1)

Honestly, I gave up on AFR a while back. Lambda is easier and smarter. AFR doesn't communicate well, and the number you're reading from the gauge is probably wrong anyway. I was pretty programmed to AFR too, but now that I've gotten away from it things are a lot clearer.

The wideband/LAF/HO2S/whatever-you-care-to-call-it can only read one thing, and that is lambda based on oxygen demand. any AFR output is there because a conversion factor has been applied to the lambda reading based on an assumption that you know what fuel is in the engine (if it's pump gas, you don't).

For example, a lambda of 1 (stoich) = 14.7:1 for gasoline, but only if it's pure ethanol/additive free gasoline. E10 (what most of us are using, or at least close to it) stoich comes in at ~14.1:1. But guess what? The ecu only sees lambda, so if it's correcting to stoich it's actually running 14.1:1! If it's open loop and you've tuned the car 14.7:1, you're probably actually somewhere closer to 14.1:1...which is fine but not as efficient. But you might begin to see now why cars are having a harder time making mileage on these newer blended/oxygenated fuels that we are being told are greener or cheaper or whatever (and perhaps one of the reasons for your mileage shortcomings).

The other reason I stopped with AFR is because it doesn't communicate well. All hydrocarbon based fuels, save for nitromethane, make best power at .9. Period. I can talk to an E85 guy or an IMSA100 guy about my California 91 pee water cal, and as long as we all speak in lambda there is zero need for translation.

(Assuming NA) If you put your wideband on a properly tuned gas car at WOT, it would read somewhere around .9. If you did the same on a properly tuned gasoline car, you would still see right around .9. Get it?

turbohatch96y7

iTrader: (15)

What you said makes sense and might make me switch to lambda

But the last paragraph

I think you used the same word twice

Gas and gasoline

Maybe tace fuel and gasoline is what you meant?

spAdam

iTrader: (1)

Possibly. I typed it on my phone while waiting for my plane this morning.

Yep. I meant to type E85 for the first one, specifically.

Flr Power

That is incorrect. Research it if you do not believe me. If you tune to 14.7AFR regardless of the amount of Ethanol you will always be back running at lambda 1 or 14.7AFR.

spAdam

iTrader: (1)

You missed my point. Lambda for E10 isn't 14.7:1.

Basically, lambda doesn't change from fuel to fuel, but the AFR at which lambda = 1 is achieved does change from fuel to fuel. Get it?

Lambda is simply Actual AFR / Stoich AFR, so as you can see the fuel specific AFR cancels out and you end up with a nice, tidy, unitless number that translates regardless of fuel.


Kind of keeping with that and (I think) circling back to what you were alluding to, you can still tune to AFR if you wish. Tell your wideband that you're running pure gasoline (you're probably not!), tune your WOT line to 13.2 and your cruise to 14.7 (or whatever works for you), and let it rip. Even is you have pure methanol in there your AFR will still be correct. Just know that the displayed AFR number is not the actual AFR number.

S2K Yellow

I have an appreciation for the level of information being exchanged here regarding the Lambda and AFR readings, however my present pursuit is in wanting to determine the actual LEAN BURN mode.
IF, my HX is going into Lean Burn I would like to know when so I can watch the parameters on the Scan Gauge. I am certain the ECU has a specific number of arguments that need to be met before that condition goes into effect such as; load, speed, coolant temp, ambient air temp, and O-2 signal. I can drive the car to meet those requirements but still don't know if I have achieved Learn Burn mode. IF, the system is not going into Lean Burn, then I want to check out the variables that are not being met to initiate it. My mental process takes on a flowchart process to determine which component or parameter is not functioning. If all of the components are working as necessary and Lean Burn is not engaging then I will need to graduate into a higher level of understanding.
Bottom line to this; Is LEAN BURN WORKING OR NOT. If I need to install an AFR gauge in the exhaust manifold to measure then I will. Thanks for all who choose to engage in this. Rob
If interested, more on the subject can be found >>> Civic HX Lean Burn Monitoring via ScanGauge (Video + Info) - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

spAdam

iTrader: (1)

Sorry about the off topic, you asked a question that I've spent a lot of time discussing and thinking about. I think a wideband is probably going to be the most direct way for you to monitor what's going on.