TOPIC: Update on 1999 Hyundai Accent

Here's everything I did to this point and the results.

Put the Groove in the throttle body, found a second point where a vacuum leak may have been, JB Weld took care of that.

Suggestion for checking, when you put the light up inside, be in a dark place, it is much easier to spot the holes.

Removed the Idle Air Control from the system, inserted a plug in the hose with a 1/8" hole for the idle.

On the MAF sensor, I put a thin strip around it to reduce the air sensed so it's getting more air than is reported to the computer.

Regapped the plugs from .032" to .045"

and now the other part.

Prior to the Groove modification and other adjustments this vehicle was getting

35mpg on the highway. I have been logging this information since I purchased the vehicle back in January.

I just got back from a 40 mile round trip, mostly highway.

I filled up before I left, reset the trip odometer and went on my way.

Got back to the same gas station and refueled.

Total miles traveled 40.7
Amount of fuel replaced .683 gallons and that is with a little bit top off.

Fuel mileage based on the above numbers 59.590 mpg

I'd call that a win. Only thing left to do is take it down for emissions testing.

Karl,
Please let us all know the mpg over the next 500+ miles if possible. Thank you.

I can do that, it may take some planning as I don't use the vehicle for personal trips usually.

After having a e-mail chat with GadgetmanTC in regard to cold temperatures and IAC modifications I went back to my Hyundai and wondered.. what if, since the IAC was external, I take a 1/8" ID tube and use it as a bypass for the IAC once the engine warms up.

Now, initially I had removed the IAC altogether and put in a plug with a 1/8" venturi for the idle air pathway, which worked fairly well but there were still some low idle issues. (did not keep it from getting some crazy gas mileage though. Had I stopped at the .5 gallons instead of the .683 gallons, the mpg would be more like 80mpg)

So, I put the IAC back into the system and attached a 1/8" ID hose from the plenum side to the manifold side. The idea behind this was the hope that the computer would use the IAC to warm up the engine, reach a point where it would want to idle down and because of the 1/8" line bypassing the IAC it would close the IAC off entirely to reduce the idle/air flow to a normal level.

The results I have seen so far is that the idle at cold startup is better, I can rev the engine and it will idle back down without almost stalling and otherwise the performance of the engine is good. I need to schedule a long trip for this vehicle anyway so I will be interested in seeing the results myself.

I would like to post a photo of the mod but not having much success at this point, I will put them on the Facebook page...




Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma (Youtube)

Karl can you give me an update on what your long and short fuel trims are reading and what did you cover maf with and how much did you leave exposed and did you throw any check engine lts? Dan

Hi Dan
SHRTFT1% -25
LONGFT1% 0.0
Air Intake temp was 54F so the longft may be off
The attached photo is the MAF sensor and I use a piece of double-sided sticky tape that is used for assembling vinyl windows. It has some pretty good stretch to it.

You can use a fine gauge wire and use multiple wraps to get the width you want or some other ridged type of stretch material that will stick to itself. ( Don't want it coming off with the engine running )
The only Check engine Lt was the throttle position sensor.

I'll post all the pic's on Facebook

So, the last test was with the IAC intact with a 1/8" bypass tube, speculating that the IAC would stay closed once the engine was warmed up. Not the case, 63.9 mile run with a 20mpg average. Not what I was looking for.
Current configuration has a restrictor plug ( 1/8" flow orifice) on the plenum side of the IAC with the 1/8" tube still intact.
Running much better and much cleaner exhaust once warmed up.

Ultimately I'm looking for a 12Volt solenoid valve to take the IAC out of the flow once the engine is warmed up.

My ScanGauge unit should be here tomorrow. That shipped out of California on the 27th by way of the USPS sort facility in Kearny (Car-nee), NJ. Now you know why the Postal service is in the dumper. Next week my 5 gas analyzer will be here, then the fun really starts.

This is Dan again read your fuel trims I bet their positive now reset the ecu and nibble the fuel down so the ecu isnt startled and mpg will begin to rise. You took to much fuel away to quick ecu say`s no you don`t. Dont cover to much maf or ecu will wake up to dump fuel mode. Dan

So here is the latest as of 1/11/2012

I took the Hyundai for a 25 mile run, not expecting to much since I hadn't changed anything from the day before. I got to my destination and the mpg was around 35 which was the normal before the mod. When I left, it was like the computer woke up to a new world, by the time I got to my exit on 16W the ScanGauge was reading 46.2MPG with plenty of room for more.

Here are the readings at 'Idle'
Load_PCT% 3.9
ShrtFt1% -1.6
LongFt1% -15.6
MAF .458
ScanGauge GPH .19 (gallons per hour)

I removed the tape I had on the MAF sensor and replaced it with wraps of 24ga single strand copper wire.

This took several tries to get the right number of turns to repeat the above numbers or at least close to them.

Final numbers were
LOAD_PCT% 2.7
ShrtFt1% -3.9 This started at 25 until the computer settled down and adjusted.
LongFt1% -15.6
MAF .380
ScanGauge GPH .15

I also recorded the O2 sensor readings
O2B1S1 .050 (volts)
O2B1S2 .380 (volts)

earlier readings were
O2B1S1 .900 (volts)
O2B1S2 .765 (volts)


I've also found that if the MAF sensor is above .600 it develops low idle issues along with fuel flow issues.

I'll take it for a mileage run and see what the ScanGauge can tell me.

Later

Karl Fortner
Tacoma, Wa.
GadgetmanTacoma

Karl if those fuel trims stay close to what you have youll see increase in mpg while running at 65 to 70 doccument trims and inj time itll be in mil sec if your cutting fuel it`ll be about in the 4`s to 5 watch closely as after the 3`rd start and stop after your long run as long as the trims stay neg youll be on the money the mass and map are very sensitive and the ecu crosses air to temp to o2s for avg, it`ll run lean without as long as it has a chance to change the map inside the ecu gradually. If gradual learn process is accomplished It`ll stay.Big mpg just dont cut power to much as load factor will come into play. Good work Dan gadgetman Mo.

Okay, trip from Tacoma to Olympia and back, approx. 30 miles one way.

Load_PCT% 2.7
ShrtFt1% -1.6 to +1.2
LongFt% -15.6
MAF .356
O2B1S1 .170 to .830 (volts)
O2B1S2 .650 to .745 (volts)

ScanGauge .14 GPH

Average MPG both directions 50mpg + That is a gain of 15mpg.

Karl Fortner
Tacoma, Wa.
GadgetmanTacoma

Now thats what I`m talkin about if we all get on that track we`ll be making history. Can you take a picture of what youve done to let everyone know? The fuel trims tell it all it`ll take some training for some to understand whats going on but you`ve hit it on the money. Keep up the good work and pass the word along alittle groove does make a big diff and it doesnt hurt to add alittle mod of your own. Dan Gadgetman Mo.