TOPIC: Update on 1999 Hyundai Accent

The attached photo's... sorry about the quality, are of the MAF sensor.. Mass Air Flow

Rather than hook up some box with a variable resistor and have to guess the effects

I decided to physically reduce the sensitivity of the sensor by adjusting the air flow over it. It is possible to do it with this particular sensor because of its design, newer equipment is less accomodating.

By using 24ga copper transformer wire and a glue gun, started with six turns around the sensor. Ran the engine to check the readings and repeated to get to the final results.


In this particular case it actually lies to the computer about how much air is flowing and (hypothesizing here) allows the computer to compensate for the effects of the groove. Otherwise, the engine idles terribly and will not run properly due to an excess of fuel being dumped into the engine.

Adjusting the MAF, affects the;

'Load_PCT%' - The lower this number the better, it in turn affects these others.

ShrtFt1% which I believe is the low end rpm/idle. you want this to be as close to zero or in the single digit negative numbers as possible. THis may initially report a high numberbut give it a chance it should auto adjust down after some idle time.

LongFt1% which I believe is the higher rpm range, ie; 50-60mph range. You want this to be negative. In my case it went directly to -15.6.


I should also note that the PCV was rerouted to the intake side, the IAC was removed entirely, direct line plugged with a 1/8" hole for idle air. Plugs were re-gapped +20%.

Since I had the "ScanGauge" I also took a reading of the calculated Gallons Per Hour, GPH which is also affected by the above changes. In my case, at idle it reported .14GPH.

and that's how I got 50MPG out of a 1999 Hyundai Accent w/ 1.5L 4cyl that normally got 35mpg highway.

Gotta love the Groove...

Karl Fortner
Tacoma, Wa.
GadgetmanTacoma

Karl what you have done is changed map in the ecu by changing the maf it thinks less air flow less air less fuel. The ecu short trims are NOT the idle only they are instant readings of the inj timing afr they actually train the long it is setting itself by the map the ecu is setting inside. By afr calculation air to fuel per load to baro pressure.Any time the ecu detects sharp change it counter reacts by ect iat 02 mass maf and map to determine if there is a map inside the ecu within tolerance. But as I said your on the money but your idle issue is the small iac hole make it alittle bigger and it should dissapear without affecting the mpg. Dan gadgetman Mo.

Ron, I guess I think that we all know the terms ,sorry. The ecu is the car computer it`s very smart and rely`s on maps set by the manufacture. These maps are like graphs and there are many pre made inside. These maps can, lets call it overlay each other, meaning they can slide ontop one another,this being said they can change the parameters very quickly as to air, load ,air temp,engine temp,barometric pressure outside, this is done with the map sensor ,o2s oxygen sensors, and finally the fuel. All these things will work together in certain maps. As long as you make gradual changes by fooling the computer,maniplating values of the components by resistance change or voltage changes as Karl did on the maf it`ll cut the fuel back to its lowest parameters without tripping codelight. He said he had idle issues and he cut the idle air passage down I think he should make it a little larger and It`ll idle fine. He was thinking the short fuel trims were just controlling at idle they are not as they are the true fuel readings of the o2s immediately. The o2s only give true readings after the vehicles is warmed up then the commputer takes over the o2s readings. This I know is very deep but I think if all the gadgetmen understand what is really happening with the fuel to air to load factors they`ll have alot more success. Thats where the hho group have so much trouble as they try to change to much to quick and computers take over to the dump fuel map. As you know the groove is a very vital part to the equation as if you do any of this without hho or fuel reformer or the GROOVE it`ll be doggy as the fuel to air mixture will not be right. Major power loss also lean burn. Dan gadgetman Mo.

Hi Dan,

Thanks for the Primer, as I qualified my post with "hypothesizing" I was definitely going on what I was seeing and hoping I was close. I have a better idea now of the why behind the ecu actions. It may take a few times reading it through to get it all organized in my head but it makes better sense now.

On the idle, I actually tried a larger diameter bore on the IAC and the ecu did not want anything to to with it. "Grumpy little critter". So I went back to what was working for the engine. Hopefully, I won't come across another like it but will put the info into the bag of tricks going forward. The current configuration acts like it was pre-groove. If it should get grumpy again, I'll play with it some more.

Thanks

Karl Fortner
Tacoma, Wa.
GadgetmanTacoma

Karl,
Superb work. You truly are a Gadgetman as Gadgetfolks are those who are willing to try and try and try until they get the results. Sometimes it doesn't seem like they will come. Great idea to fool the ecu by changing the MAF. Dan is right on the money about keeping an eye on the fuel trims. This is that next level we all need to get to in order to advance our results and process. Very impressive.

Since the last run I filled up and updated the ScanGauge which I knew had to be done. Not only does the engine get tuned but you have to train the scan gauge to reach the correct MPG readings out of it.

So, don't trust the electronic gadgets without validating them, the actual MPG at that point was 25mpg, 10 less than normal for highway, but it ran clean. Came to conclusion that 1) the scangauge still needs some tuning and 2) that detuning the MAF sensor to much can possibly have an adverse effect on what it and the scangauge may think is happening.

Here are the ecu readings after that run prior to my next set of changes
(All of these readings were with engine up to temp. 184F)


Load% 3.9
ShrtFt1 -8.6
LongFt1 -16.4
RPM 1000
MAF .458

This is with one strand of 26ga wire removed .015"dia.

Load% 2.7 / 3.9 (fluctuating)
ShrtFt1 -18.0
LongFt1 -16.4
RPM 840
MAF .504


This is with two strand of 26ga wire removed
Load% 3.9
ShrtFt1 -25.0
LongFt1 -16.4
RPM 800

Here is @2040rpm
Load% 9.8
ShrtFt1 -21.9
LongFt1 -16.4
RPM 2040
MAF 1.078

and back at idle
Load% 3.9
ShrtFt1 -6.3
LongFt1 -16.4
RPM 760
MAF .476 to .513

Took it out for a 60 mile run at this point
60.6 miles, took 1.33gal fuel 45.56MPG (that's 10mpg better than pregroove)
Load% 3.9
ShrtFt1 1.6
LongFt1 -21.1 Check engine light - Long term fuel trim to Rich
RPM 840
MAF .513

Took 2 more strands off the wrap ( Total of 4 strands .060")
Load% 5.5
ShrtFt1 -6.8
LongFt1 -21.1
RPM 800
MAF .630

@2000rpm
Load% 11.4
ShrtFt1 -22.7
LongFt1 -21.1
RPM 2000
MAF 1.217

@3000rpm - equivalent to 60mph in 5th gear.
Load% 16.9
ShrtFt1 -21.1
LongFt1 -21.1
RPM 3000
MAF 1.750


One of my checks is to put a clean white rag over the tailpipe for 30 seconds to check for carbon, etc. During all of this it has come off the tailpipe as clean as it was prior to putting it on. Don't have a microscope... don't ask...

One thing that was obvious on this last check that stood out, the other times there seemed to be a hint of something about the smell being off. This time the dryer vent was obvious.

thoughts... opinions

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma

Good job and yes the ecu is wise!!!!!!