TOPIC: '02 Subaru Outback EJ25 2.5L 4 CYL 5 Spd AWD IAC mod (and Grooved!)

Man, am I STOKED!
After 6 1/2 years of Grooving my own old rides, plus doing over 35 Gadgetman Groove jobs for others...I finally got to Groove a modern vehicle of my own.

Wow- just Wow!

I will try to restrain myself, but it's gonna be hard. My '02 Outback Groove job and IAC mod combo, along w/ the PCV re-route I posted a few days ago- well...

Holy Personality Change, Batman!

hint: This Stuff Really works.

I'll start with the Idle Air Control Valve (IAC) mod on this cable-drive TB. First, here's the TB:



This TB has the IAC valve mounted in a bore. Incoming air enters a port above the throttle valve, opposite side to the Groove, that connects to the IAC valve bore at it's bottom. IAC black resilient pintle valve extends or retracts to vary the air to the engine, controlling idle RPM via the ECU.



The throttle plate is closed at idle, so Idle RPM is dependent on the IAC system. There's also a hose nipple for the EVAP system hose, this nipple also opens to the IAC valve chamber bore. IAC valve output airflow including EVAP vapor, goes to a separate passage that opens into the intake plenum, downstream from the TB. So there's no concern of this airflow disturbing the air coming past the throttle plate/Groove interface.

This mod is about restricting overall flow allowed to pass the IAC valve, since when the IAC valve is open it acts like a vacuum leak. The IAC must still be allowed to function, we just want to restrict it to an extent.(to control the resulting "vacuum leak"). Note that IAC's are usually not found on Drive By Wire TB's-- only cable drive ones.

My method here is just like how I've done it on several GM TB's First fully clean the TB, IAC passages, and carefully clean the IAC valve and black resilient pintle. Next the round port that goes from the IAC chamber to the downstream passage, is roughed up w/ a drill bit, to give the JB Quick epoxy a better grip.




Then I use a hose that closely fits the bore the IAC goes into, and put several wraps of clear box tape on the end. This will seal the IAC valve bore, and give a base to the epoxy for it to set up on. but the epoxy won't stick to clear box tape.






Shove the wrapped hose into the IAC bore tightly, check it's fit and seal. Then fill the round outlet port w/ JB Quick, to just fill it and no more. After the epoxy sets up I drill a hole thru the epoxy, to connect IAC chamber to the outlet port exit. Resulting decrease in outlet port diameter gives the desired IAC restriction. Worked out well--after Grooved TB was installed, at cold start idle RPM was just over 1000 RPM, down from stock 1200. Idle RPM's decreased to 750 or so as warm up progressed. Closed throttle RPM's remained as before the mods.




I have 2 more pics to show final result, I'll try to add 'em later, seems I hit max pic's allowed.









I'm giving the tiresome details here, so that other G-Men might benefit.

Tracy G

So this past Saturday I grooved the throttle body, reinstalled it and did the ECU re-learn/ test drive.

holy Power Boost Batman!! After all this time, studying and applying all of Ron's lessons to my 2 old carbureted rides. Then performing the Groove and the extra stuff to probably 36 other engines- I now get to experience it on a modern car of my own. I now really know first hand what it's been about all this time!

to wit: I did a nice clean Groove, w/ the large bit. Full width, full depth, no issues or bit breakthru's. Bit fit was checked and found to have minimum side play. Did the ECU memory dump w/ the jumper wire on B+ cable, w/ all the details there.

Right away on the test drive, the first time I tried to get up to just 10 MPH, the throttle blade crossed over the Groove and the car began to "launch". Woah! I found I had to re-learn how to drive it, just as I was "teaching" the ECU about the Groove. With only very moderate throttle this car just wants to GO now. I took it thru all the speed steps, 10, 15, 25, 35 45-50 MPH. I got a short full throttle blast in at the end on a long road section just east of the airport. I probably ought to look for a small Superman cape to fly off the top luggage rack...

The low and mid-range power and torque increases and much sharper throttle response are clear-cut. No doubt at all on those!! When I got back I did the Tailpipe Sniff Test- and it was Much cleaner than before, if not completely gone. I'm getting used to using a much lighter foot on the gas, that will take awhile to adapt to. No Check Engine light, no issues at all so far.

MPG tests will be reported when done. I've told customers before that if the power and response go up, and tailpipe smell goes down, then the Groove job is a Success.

And this '02 Outback Groove job is a definite Success judging by those!

Here's the obligatory pics of this Groove, and the last 2 of the IAC mod.

Tracy G

So last night I took the Outback on about a 60 mile test drive. Up north out of Reno on US 395 into California to the gas station at Hallelujah Junction. I'm getting accustomed to using a very light foot esp. at lower speeds in the low gears. This is a run that features 2 major hill climbs, the first up from Reno past Stead, then up out of the valley that Stead is in to the next valley past cold Springs and Bordertown.

On earlier runs on this route, I've set cruise control to 65 MPH and just watched/listened to how she runs. The Outback had enough power pre-mods to climb the hills while maintaining speed in 5th gear. Pre-mods, on Anderson Hill, the second steeper one out of Stead, I heard/felt the cruise cont. opening the throttle far enough to cause the low-frequency droning sound in the inlet air ducting. Meaning it had to go to a large throttle angle %. Then, on the run after the PCV re-route but before the Groove, it did the same, but less so.

Last night, with the Groove, I only heard a small increase in intake droning- so small that if I hadn't been listening and paying attention I wouldn't have noticed it. Power feels like it's always available, like it really doesn't have to strain. It also seems like there is some combination of both me and the ECU are learning to adapt to the Groove's effect's. I'm reminded of comments a customer gave me about his Ford Ranger (I think it was) saying that his 5-speed truck had "gained a Gear". Meaning he could accelerate or pass a car without downshifting like he had to before.

On the initial test ECU-relearn drive right after the Groove, I was startled by the huge power "hit" that happened at lowest speeds in 1st gear. I was wondering if this would mean I would need to fill in and re-Groove the TB, w/ a business card spacer. But now that I'm aware of it, I'm having an easier time managing that throttle/gear combination. I'll still need to pay attention like in School Zones or backing up in parking lots. Just use a Very light throttle...

This Groove mod is SOO unlike other big elaborate engine mods. There's nothing visible on the engine...No shiny red or chrome obvious parts. IF you weren't in the know enough to look real close at the PCV hose, you wouldn't see ANYTHING Stealthy!!

Oh, I almost forgot to mention- When I got back home, I left it idling in neutral and set the parking brake, and re-did the tailpipe sniff test.

result: No SMELL at ALL, just hot air

This, with factory original O2 sensors, cats and muffler with nearly 140 K miles...!

..."and the crowd goes Wild!"



Tracy G

Congrats, buddy. Sounds like you got the same result as when I grooved my Wendy.
Ignition stuff next?

The latest on my 02 Subaru Outback- As I posted before, although the first Groove gave a big power boost, the power came on too fast. Making shifting at low speeds, esp. into reverse, hectic. I filled in the original large bit Groove, and tried adding the dimples in the TB bore walls. This eliminated the too-soon power (and all the power boost from that first Groove.)

I ordered a used TB from ebay. Filled in the IAC port as in the original. I drilled the hole in the epoxy larger this time, to 7/32". Then I held the plate open with a thin and thicker piece of paper on opposite side of the Groove, and cut a Large bit Groove. This put the Groove far enough off idle in operation to avoid the previous trouble. Power is back close to the first Groove's, but not quite.

Overall it's a good compromise

Cold start fast idle is back in the 1200+ RPM range dropping w/ warmup as it should. This tells me I made the IAC hole the right size. Driveability is smooth. When I ask for more power it's there for sure.

On the re-learn drive, I connected the scantool. At start, ST and LT trims were zero. In succeeding re-starts ST dropped into the -7 range. Once I was up over 30 MPH, I used WOT whenever possible/reasonable. Once I got onto a long boulevard I punched it and held it 5-8 seconds. On a back industrial street I punched it and held WOT 8 seconds. On the return, I got onto the long boulevard street behind my place, and did WOT about 10 seconds. As I came off that street and slowed, I glanced at the scantool, LTFT was at -10.7. So, this re-learn drive took LT from zero to -10.7.

MPG numbers will have to wait for road testing. Overall I like the results on this, the Outback Shiela's Second Groove!

In the pics, the original TB#1, you can see the dark epoxy fill against the closed plate.
TB#2 the new one, note the gap between the plate and Groove.

It's funny, Ron always seems right in the end. After driving it, I probably could have used only the piece of card stock, and forgone the second thin paper piece, when I was spacing the plate open. I went w/ caution, trying to avoid the bad off-idle issue on Groove #1.

So now I know. Ron's advice to just use a business card is best.

Tracy G

Update on my '02 Subaru Outback:
Well, Shiela has been out of service for almost 3 months now. I just picked her up from a Subaru specialist shop here, yesterday. After major work done, and a severely lightened wallet, she's back home.

back in mid January, I had installed an Ultra Gauge OBDII monitor, and was out on a drive to test the effect on fuel trim #'s using near and full WOT under load. I was going up the hill on US 395 up out of Reno proper. Was watching the traffic, and the Ultra gauge FT #'s. After 3-4 minutes at or near WOT, going uphill, the Ultra Gauge readout suddenly changed to an engine over-temp warning...one look at the regular temp gauge...OH Crapola!! IT was pegged full hot! Still ran OK, but a trail of steam out back in the rear-view mirror...like a wounded B-17 over Schweinfurt!!

Instantly backed out of the throttle, and realized it was still most of a mile to the next offramp, all uphill...Got to a gas station, popped the hood, let it cool. Bought and added antifreeze to the cooled radiator, limped it home. Subsequent observation confirmed that a head gasket was failing, letting combustion pressure into the coolling jacket, which pushed coolant into and out of the radiator overflow reservoir.

Then almost a 2 month wait to get Sheila into the shop. Head/block resurfacing, new improved head gaskets, and most every other engine seal/gasket. New radiator, full timing belt/ pulley set, new clutch, spark plugs, and etc . etc. stuff.

These Subaru's are great popular cars, but the 4 cyl. engines are well known for doing this. This shop is ex-Dealer Factory trained tech's w/ years of exp. in this scenario. Really good, thorough, sharp...but Not Cheap!!

Well, at least I won't have to worry about this car now. It runs Very Well now: The shop removed my PCV re-route hose and man. vacuum port cap, and replaced with new OEM PCV valve and even the factory PCV valve-to-intake man hose. I just re-installed my PCV re-route hose/cap set.

So that's where she stands right now. Interestingly, with all the work done (engine R/R) the exhaust insulation looks OK, undamaged. This engine and engine bay was already pretty sanitary. With close inspection I can see a couple signs that this work was done, but it's subtle.

When there's more to say, I'll be back!

Tracy G

Yikes and Ouch, but good save!

I had a head gasket blow recently, too, Tracy!

Loreta used the truck one afternoon, and when I went to start moving some more furniture, checked the oil before leaving. It was about 1.5 Gals over full.

ARGH!

Everything stopped.

I got a ride to the parts house, grabbed a package of Bar's Leak Head Gasket Repair (100% GUARANTEED to fix head gaskets!) and it WORKED!!!

A few hours later, along with an oil change, and I took her out for a spin. I had lost two cylinders completely (I didn't check any more after that) and she came ALIVE!!!

Yee-HA!

And I've got that 1999 Dakota with the V-6 running at over 21 MPG's when it started around 13!!!

Damn RIGHT "Yee-HA!!!"

Ron

Well, Ron, Good for you and the Dakota!
Unfortunately for Shiela and me ( and my wallet, too!), Miracle ina bottle wasn't gonna work for me this time. I too have used a similar product in Subie's cooling system, to cure a slow head gasket leak. Subie was loosing a small bit of coolant INTO one cylinder. And the stuff I used (a mix of fine copper particles in I think Water Glass suspension) did the trick. It's been in there over 4 years now.

but Shiela the Outback, her problem was the reverse of Subie. Combustion pressure had blown the head gasket INTO the cooling system. The big downside to most 4 cyl Subaru's of the past 30+ years is head gasket failures, and I will attest to that. So, I used a local Subaru specialist shop I've used before. Fixed the head gaskets with upgrades, plus a new clutch kit, and complete timing belt set

Cost a LOT! but at least it's all fixed now. I think I can rely on this ride for some time to come now ( I hope).

Tracy G