88 Bonnie LE... shotty MPG

[mdvonte]

88 bonneville LE real bad on gas. i say about 13-15 miles per gallon.

how would i go about making it better? I know its a OBDI and i dont recall being able to tune OBDI cars.

help me out!!

[RJolly87]

What kind of driving do you do? Short tripping? Stop and go? What kind of gas do you run? What mantenence have you done lately? What needs doing?

[MattStrike]

My old '89 PA (same engine) would get 24-26 fwy, 20-22 city depending on traffic, how many stop-go I dealt with and depending on if I ran regular (87) or midgrade (89).

But 15 is way too low. Like, misfire low. We'll need more info on maintenance, how it runs, service engine light status, etc...

[Jrs3800]

Thats agreed... How does it run? any serious missing or the like?

As well is this a Vin 3 88 LE or a 3800 Vin C ...

[mdvonte]

runs like a T

i drive to school to home and to work a total of 10 per day on the days i work or have school. i go through a tank every week and a half

new spark plugs(ACDelco), plug wires coilpack (ACDelco) and icm(BWD[magnovox type])

new miss just a continuous exhaust flow

3800 series 1 150000 miles

fresh oil change and tranny fluid
205/75/r14 tires

thats all i know off hand
i drive like an everyday person and its right in town i do these milages and i dont do a mph over 40

[MattStrike]

No service engine soon light then?

These cars get their best MPG at around 65, in 4th gear with the torque converter locked. At under 40, you're not moving fast enough to even get to 4th gear. If you could make your daily drive just fast enough to get 4th gear (maybe 45?) you should see a mpg increase. Also, I've consistently gotten better mileage (1-2mpg) on midgrade 89 octane gas. And don't be afraid to make brisk or spirited accelerations - it helps prevent carbon buildup.

There are a few things that will need to be cleaned or replaced at your mileage though. Mass airflow sensor, with the specific cleaner for it and a hobby paint brush to lightly brush the wire to help dislodge any buildup. Also the O2 sensors don't normally last more than 100k miles (replace with an AC Delco part, check out RockAuto if you haven't already). A fresh air filter, and a throttle body cleaning (with the mass airflow sensor removed), if it's never been done run a can of seafoam in the gas on your next fill up (don't use it all the time, just a one-time deal is all that's ever really needed).

Also I recommend ditching the magnavox coil setup and converting to the type-2 AC Delco ICM and coils. They are more reliable, and it's a lot cheaper to replace a coil if it goes bad. But it's a preference

[SSEBonne4evr]

Like others have said this is way low.

Check your tps setting.

[mdvonte]

Theres no check Egine light on

So check 02 tps try upgrading my octane.

someone told me to try and run trans fluid (about a quart) threw on my next oil change and tank fill... yey or ney?

[MattStrike]

I wouldn't bother with trans fluid, the seafoam will do better.

And don't forget the MAF sensor cleaning.

[SSEBonne4evr]

Theres no check Egine light on

So check 02 tps try upgrading my octane.

someone told me to try and run trans fluid (about a quart) threw on my next oil change and tank fill... yey or ney?

You will not pull a CEL on these cars with a TPS slightly out of adjustment.
I would check it and add fuel injector cleaner.

[mdvonte]

i filled with 89octane no e10. cleaned the MAF sensor and will mess with the O2 sensor and TPS here soon. and i heard Seafoam could negatively affect engine performance.

and this is off topic but where can i get a quality deck lid luggage rack?

[MattStrike]

If you had a LeSabre, I'd say me but the LeSabre rack is different.

[SSEBonne4evr]

i filled with 89octane no e10. cleaned the MAF sensor and will mess with the O2 sensor and TPS here soon. and i heard Seafoam could negatively affect engine performance.

and this is off topic but where can i get a quality deck lid luggage rack?

Pull the 02 and check the color, should be light grey, if it is dark charcoal color change it.
I have a new one in the box.

[mdvonte]

will do

and how much for the rack?

i filled with 89octane no e10. cleaned the MAF sensor and will mess with the O2 sensor and TPS here soon. and i heard Seafoam could negatively affect engine performance.

and this is off topic but where can i get a quality deck lid luggage rack?

Pull the 02 and check the color, should be light grey, if it is dark charcoal color change it.
I have a new one in the box.