TOPIC: no mileage or performance gains from grooved car

For starters, you don't have enough manifold vacuum to get the proper effect.

Either there is a leak and it's being elusive, your rings are worn (compression test will identify that one) or the Idle Air Control port has not been restricted. That would be my choices presuming the PCV has been moved and the port on the manifold plugged.

Short term fuel trim should fluctuate, that is the effect of maintaining a proper air/fuel mix to keep the O2 levels (temperatures) consistent.

The long term fuel trim should be stable. If this is fluctuating as much as the short term fuel trims then you need to check the above items more closely.

Also, you can pull a few of your plugs out and see what kind of burn you are getting. If the plugs are clean then you know the burn is good. You could still have worn rings but the groove is working.

Something to keep in mind, was this vehicle burning clean before you had the TB grooved?
If not, then there is a fair chance that there are other issues to be resolved on the engine.

Things that make ya go... hmmm


Karl Fortner
Tacoma, Washington

What should the vacuum be at an idle & what rpm ?When I give it some throttle it does go up.I could possibly have worn rings, since it does smoke some, maybe I will put some Lucas in & see if that helps.The long term fuel trim does not fluctuate as much as the short term does.I will see what the plugs are like.I did not pull any plugs before the groove, but it was running nice & smooth, so I don't know if it was burning clean.This has been making me go hmmm from the start.

Thanks,
Gordy

Hi Gordy,


You should see 20" to 21" of vacuum at idle, anywhere in the vicinity of 600rpm.

You may want to check the spec's for idle on that engine but you should be able to get
the vacuum up in that range. Keep in mind the throttle plate is near closed so the vacuum should be high.

If the PCV, IAC and any leaks have been dealt with it should be there.

Also, I wouldn't be concerned with fuel trims at 1,700 rpm's in the driveway. The loading effect when driving changes that drastically.

That's why Dan asks about fuel trim readings at 65mph, if your at speed and maintaining
will be one set, if you having your foot into it is totally different.

Karl Fortner
Tacoma, Washington
If you read Ron's post if may give you some idea's of where to look.

I took a plug out & it had a nice clean burn, so maybe I will borrow another more accurate vacuum gauge and turn the idle down to 600 and see what I get.

Gordy

Always go back to the basics.

1. Cap PCV.
2. Clear ECU.
3. Check your work!
4. Check vac leaks.

I'm building a new site dedicated to diagnosing. It's at Diagnostics.GadgetmanGroove.com . Go there, leave comments, make suggestions.

Sleepy time!

Ron

I read thru this whole thread, couple things come to mind...

Idle vacuum readings: Gordy what altitude are you at? Ive noticed it seems most all Gadgetfolk are in places below 3000 ft. altitude. Reno is 4500-5000 ft. Idle vacuum drops some as altitude increases.

Vacuum leaks- my Subaru taught me to be militant/fanatical in hunting them down, I think every engine has little ones that the Groove magnifies, ya gotta go Hunting for them:evil:

I treated the Subie w/ Seafoam in gas tank, in engine oil shortly before oil change, and 3oz thru carb at fast idle as per Seafoams instructions. Car loved it. 2 yrs. ago I treated engine w/ Xado engine metal conditioner, found it on ebay. Car loved that too. This Subaru engine is known for short life after rebuild, that's reason for "Miracle in a Bottle" tricks.

W/ all the discussion about the O2's and fuel trims- Gordy how fast does the upstream O2 switch up/down voltage? Dan could give the definition here, but I know too slow a switching rate can indicate a worn O2.

Just a few thoughts from someone with much to learn...

Happy Thanksgiving!

TracyG Gadgetman Reno

Hi Tracy,
My altitude is around 400, so I don't think this is an issue.

I borrowed a snap-on vacuum gauge & the vacuum is 19 at an idle at around 750 with or without the pcv plugged and re-routed, so I don't know if that gives us any clues.I am going to do a compression test on the front 3 cylinders since you have to remove the intake for the back 3.

I used seafoam through a vacuum line & it took a lifter tap away, this is great stuff!I used 3 tubes of xado and did not notice any difference.

My short fuel trims change every second & I just did a check tonight on the long fuel trims at 70mph at 2600rpm and it hangs around 5, so I don't know if thats bad or good.

Hope you had a nice Thanksgiving,

Gordy

Hey, Gordy!
Have you been getting the site emails? No matter. You will find great benefit in visiting .

Please share with me your opinions, but PLEASE go there and read, starting at 'Diagnostics A to ZED'. Your method of checking vacuum is NOT checking for vacuum leaks. It is only checking vacuum LEVEL. WAY not what we're looking at.

Ron