TOPIC: 1998 Buick 3.8

I finally did my first groove! I have a 1998 Buick Park Avenue with a 3.8 V-6 and the starting mileage was 20.8mpg. After the groove it has pretty much leveled out at 24.3mpg, however, I have driven a lot less highway miles since I did the groove so I expect it to go a bit higher over time.

On this engine, the PCV valve is built into the intake manifold and is located under the MAP sensor. I tested the mileage without modifying the PCV and only got 23.4mpg. I then plugged the port on the PCV valve and it slowly increased to 24.3mpg. I have not noticed any other changes.

If you ever work on this engine, beware of the exhaust studs. As careful as I was I still broke both studs off and it caused a big delay in the job.

I documented the whole modification and you can see the 8 minute video on Youtube on the following link:

Let me know if you have any tips or comments.

Thanks

IWhen I done my 94 buick I cut thrue in the same places. I dont know what your mileage is but my I went from 24 to 39 after I changed the o2 senser it realy made a diffrence.Unfortnely I do not have the car any more it was in a crashand got wrote off. I did save the throtal body

Thanks orrist, I'll look into changing the 02 sensor and see if that increases the mileage....

To whom it may concern,

This is a very good example of the same cars getting different mileage. So for all you skeptics that cant believe the times when we get big mpg increases think of these two vehicles its been this way for ever as the cars are like humans the basics are the same but they still all act different. Ive had big jumps and small and a couple no increasebut the avg get some increase,but I can assure you if you dont do the mod you wont get an increase.

I know the people are broke as thats what I get here all the time but really they cant not afford to with fuel heading too record levels and if obama gets back in and doesnt let us drill and refine the prices are projected to reach 8.00 by august 2013

Dan gadgetman mo

On this engine it is NOT necessary to remove the exhaust. I have done more than 20 of these, never having had to do this.

All that is necessary is to remove the bolt from the bracket to the throttle assembly and use a screwdriver to pry the bracket out of the way. Now, you will have to reposition it a couple of times to slide the throttle assembly out, but it sure is a labor saver!

Hi Ron,

I tried every applicable tool in my extensive tool box (I have a lot more than was in the bag you used in Hayden) and no wrench or socket would reach the right bottom nut so I felt I had to take off the crossover in order to get that nut off. I'm not big on bending things to get a job done, but I would have tried it had that bracket been the only problem. Do you happen to remember what you used to get to that right bottom nut? In the future I would love to not mess with the exhaust.

You should simply try moving it. Given the direction of the mount bracket, you will find it able to be turned with a little push.

No need to bend it or to get to the bottom bolt at all!

Hope this helps with future mods.

And congratulations on your first mod! Be sure to change out that O2 sensor. The tend to get sluggish after about 50K...

Hi Jmoe, thanks for the xclnt video on your Buick 3.8 groove job. Others can learn from that vid!


I did one of those 3.8's in a 99 Olds 98 awhile back. I had about the same issues as you. I didn't have such a hassle w/ the brackets, I do recall having to Houdini w/ the nuts w/ 1/4" drive ratchet/socket. I always check the TB walls closely first and use epoxy if in doubt.

Pretty decent MPG results ya got, pay attention to Dan's post. Might want to plug in a scantool if avail. check O2 voltage's/cross counts. The whole Groove thing is about learning! Keep on Grooving!

TracyG Gadgetman Reno

Hi Jeff,

You are keeping track of your actual fuel usage right?

Go back and manually confirm the mileage.

The reason I say this is that the computers don't always report the mpg correctly simply because it does not kn ow what is actually happening.

You may find your mpg to be 3-4 mpg better than what the computer is reporting.

Which Ain't a bad Thaing.

Nice job on the car and the video

Karl Fortner
Tacoma, Washington

Hi JMoe!

Yes, while it is true that the "bracket" in question is "in the way", I also have done these before, both for Mods and to simply clean the TB or replace the plastic intake assembly where I work, as GM has problems with the EGR tube distorting the plastic manifold, causing a coolant leak.

As you are looking at the TB from the drivers side, simply remove the small bolt that attaches the bracket to the TB and move the bracket towards the front of the car, just enough to clear the TB. It won't be a straight shot out, but enough wiggle room to do the trick.

Replacing the O2 sensors is also recommended, as others have said - I will testify to that. Just because they don't set a code does not mean they are working at peak performance - vital for optimum MPG.

Keep up the good work!

Scott Castleberg
Pellston, Mi
Gadgetman Michigan

Hi Scott,

Thanks for the info. As others have also mentioned, to move the bracket to the side, on this particular model, the bracket is mounted over a stud with a nut, not a bolt, Next time I will bend it to move it over the stud and out of the way and hope it doesn't break. The real problem was getting to the bottom right nut to get the throttle body off. Apparently there are several configurations of this engine and mine is the hard one.

I will definitely replace the 02 sensors to see if I can gain any more mpg.

I'll update as soon as I know.....