gas mileage

[mitchdakid]

I know this has been posted before but I couldn't find it. Sorry
Anyways 96 Blazer 2 door with flowmaster muffler and I am getting 13 mpg. I was getting 16-17 a couple months ago and since then it has gone down hill. What do I do to gain it back.

[TonyMazz]

13 !?!?!?!

Geez I have 100% stock and routinely get 18-21 mpg on my 99 4.3L...and that's with 160K on her....

Do you still have the stock MAF...??

[mitchdakid]

Originally Posted by TonyMazz

13 !?!?!?!

Geez I have 100% stock and routinely get 18-21 mpg on my 99 4.3L...and that's with 160K on her....

Do you still have the stock MAF...??

K I am a CARB guy so I don't know fuel injection stuff, what is the MAF, and I think I have the stock one, I haven't replaced anythign but the muffler and yes 13 sucks I was getting around 16-17 in town, and 19-20 on hwy just a while back.

[TonyMazz]

Originally Posted by mitchdakid

K I am a CARB guy so I don't know fuel injection stuff, what is the MAF, and I think I have the stock one, I haven't replaced anythign but the muffler and yes 13 sucks I was getting around 16-17 in town, and 19-20 on hwy just a while back.

Well need to know when you ....tuned vehicle up....
Wires, cap , rotor, etc...?
How many miles on the motor ?
What type of motor ?
MAF = Mass Air Flow Sensor......your air intake coming to the throttle body...

Just wondering, is it running smooth ? Did you change anything else ?
I am sure others will pipe in once you tell us more about this motor...?

Did you take off the cat or disconnect an air sensor on the exhaust and it's constantly dumping more fuel in.....??

Tell us more...

[mitchdakid]

Originally Posted by TonyMazz

Well need to know when you ....tuned vehicle up....
Wires, cap , rotor, etc...?
How many miles on the motor ?
What type of motor ?
MAF = Mass Air Flow Sensor......your air intake coming to the throttle body...

Just wondering, is it running smooth ? Did you change anything else ?
I am sure others will pipe in once you tell us more about this motor...?

Did you take off the cat or disconnect an air sensor on the exhaust and it's constantly dumping more fuel in.....??

Tell us more...

84000 on the motor and haven't done wires, or cap, etc. 4.3 motor and the MAF is stock unless it got changed before I bought the vehicle. I am going to put a highflow cat on but havent done anythign yet because I want to know what the problem is first.

[BlazerLT]

You need to do a complete tuneup.

[mitchdakid]

Originally Posted by BlazerLT

You need to do a complete tuneup.

So what is the complete tune-up. Spark plugs, wires, and cap.

[BlazerLT]

AC Delco Platinum Spark plugs gapped 0.060
Cap & Rotor
PCV valve
Air Filter
Fuel Filter
Plug Wires

Important things you should also do:

Transmission flush an fill with a new tranny filter
New transfer case and front and rear differential fluid.

[TonyMazz]

Just in case he means new transfer case FLUID not a new transfer case

[BlazerLT]

Originally Posted by TonyMazz

Just in case he means new transfer case FLUID not a new transfer case

OOPS! Yes, transfer case fluid.

[Fireplug]

Your check engine lite on??? With that low mpg it sounds like it might be on

[mitchdakid]

Originally Posted by Fireplug

Your check engine lite on??? With that low mpg it sounds like it might be on

no check engine light.

[Phillip Cross]

would like to know if tune-up helped. I have never been able to improve mileage on any modern (electrconic ignition) vehicle I have ever owned that was running smoothly by replacing plugs, cap, wires etc. I always do it anyway -- but it never works. I think that especially in the case of wires and distributor cap (which are quite expensive these days), routine replacement might not be the way to go in most cases. Just looking for opinions. I will probably never break the tune-up habit I picked up when a teenager woking on cars with carbs and ignitions with points and lower voltage.

[thomasrn]

Originally Posted by Phillip Cross

would like to know if tune-up helped. I have never been able to improve mileage on any modern (electrconic ignition) vehicle I have ever owned that was running smoothly by replacing plugs, cap, wires etc. I always do it anyway -- but it never works.

Lemme throw out a few options:

Spend the $40.00 bucks, get the computer scanned using a semi-decent scan tool, you want to know:

1. Are the O2 sensors active and not sluggish. You should see values like 0.2 up to 0.8 volts. Bank1 Sensor1 and Bank2 Sensor1 are used to control your fuel mixture if memory serves. The other two are around the CAT. The O2 after the cat should be fairly flat. At 85,000 KMs, your O2s should still be good. They normally last around 100,000 Miles.

2. Are you getting any missfire conditions while driving?

3. Some other item not thought of? Ask whoever is doing the scanning.

Other then this, we come back to the basics:

4. Is the exhaust clear of obstuction? Clogged cat maybe?

5. PCV Valve failed causing a pressure buildup in the engine?

6. Kids stealing gas from the tank!

7. New plugs and wires and cap and rotor. But if you aren't seeing any
missfires, I can't see this helping.

Grasping at straws, we come to

8. U joints starting to Seize up. Are they hot after you go for a drive?

9. Transmission service, bands tightening, new oil, new filter.

10. Flat tire.

11. If you hear 'clicking noises' it could be a lose spark plug wire. Check
for ARCing.

Regards,
----- Robb -----

[BlazerLT]

Would best to first do the proper engine tuneup procedures and maintanence before you start to look into the computer diagnosis.