MPG HELP!

[Meano]

If the exhaust has been messed with, i wouldnt be surprised if you have had your manifolds/headers replaced and you may have lost your o2 sensor along the way. That would be a death sentence for your gas mileage with these CCC controlled cars and your car's computer would be wondering what the hell is going on. is your check engine light on?

Negative the light is not on, I'll look in the light and see if I have one if not i'll pick it up ASAP. I posted another thread but never got an answer maybe you could give one, a guy from my job is offering me a set of headers off a 4.3L s10, will they fit my 4.3L el co?

 

[DRIVEN]

I'm completely confused. How is it possible that your rearend is slipping?

 

[Meano]

I'm completely confused. How is it possible that your rearend is slipping?

The gears in the diff i'm sure, if I accelerate too hard or go up a steep enough incline it starts to "slip", more like the car starts chugging along.

 

[DRIVEN]

Sure it isn't the transmission? I've never seen a rearend "slip". If the rearend is "chugging" -- it's done. Changing the fluid won't save it. Sounds like you need to pull the cover and do an inspection.

 

[Meano]

Sure it isn't the transmission? I've never seen a rearend "slip". If the rearend is "chugging" -- it's done. Changing the fluid won't save it. Sounds like you need to pull the cover and do an inspection.

It could be, I'm not very keen when it comes to mechanics, though i'd like to be. But it doesn't happen often, like I said just if I mash the gas to hard or go up a steep incline. Can't the diff gears slip though? Isn't that why they make anti-slip fluids and additives.

 

[DRIVEN]

Not unless something's seriously wrong. The ring and pinion are meshed together. Friction modifiers (additives) are for limited slip differentials which you are unlikely to have from the factory. Do some studying on how limited slip (positraction) works and it'll make more sense. Automatic transmissions, however, can absolutely slip. If you pull the rear cover from the rearend to drain the fluid you can do a visual inspection. You'll know pretty quick if you need to worry about the rearend anymore or not.

 

[Meano]

Not unless something's seriously wrong. The ring and pinion are meshed together. Friction modifiers (additives) are for limited slip differentials which you are unlikely to have from the factory. Do some studying on how limited slip (positraction) works and it'll make more sense. Automatic transmissions, however, can absolutely slip. If you pull the rear cover from the rearend to drain the fluid you can do a visual inspection. You'll know pretty quick if you need to worry about the rearend anymore or not.

Okay cool, so hopefully nothing is seriously wrong. I had a buddy who works at Jiffy Lube check it out and he just said that the fluid was a little dirty, told me I need to replace it but know better than spending $100 there when I can do it for $30 and 30 minutes at home. So if the transmission is the problem, what steps would I take to fix the problem?

 

[pencero]

You can keep using that trans and replacing the fluid for thousands of miles but it's still going to deliver crappy fuel mileage most likely based on what you're saying. You can't get very good mileage with 3 gears so might as well upgrade. The 700r4 is compatible w/ those performance chips you're talking about but they're considered obsolete I think you have to buy them used now. I had one on my blazer, it didn't deliver better fuel mileage but performance improved significantly. I'd stay away from the chip if you're serious about mileage, get the 700r4 trashed and have it rebuilt by someone who knows what they're talking about. Having a 7 second 0-60 and 16 second qtr miles is nice, but you'd still be looking at 15mpg best w/ a chip and those numbers are hardly in contention w/ other cars at the track so spend money to save money. The 2 years I had my $1,500 blazer I probably spent nearly $5 grand in fuel costs w/ that stupid *ss chip but I used to have money like that - now that I dont I look back and wonder wtf I was thinking w/ that truck. Sure it was faster than a regular blazer and I even beat some stock mustangs in it, but it wasn't 'fast' compared to cars that are actually fast though 😛

 

[RITTER]

I have never understood this discussion ... I understand the concept that is being discussed, just not the reality of it :|

These cars were built with these 3spd automatic setups with highway gears and they didn't get horrible fuel mileage then :idea: Your "slip" that you are describing is more than likely your transmission getting ready to retire.

 

[DRIVEN]

I absolutely agree. The manufactures were mainly focused on fuel economy and the combinations were well thought out. Your best bet is to stay as stock as possible. If MPG is your goal please resist the temptation to deviate from the factory combination. No headers. No chips. No gearing changes. No overdrive swaps.
1. Compression test to determine mechanical condition of the engine.
2. PROPER tuneup using quality parts and setting the timing with an actual light.
3. Replace air and oil filters.
4. Check O2 sensor for proper operation.
5. Check tire pressure.
6. Make sure brakes aren't dragging.
7. Obviously, you'll need a non-slipping transmission with a functioning lock-up.
8. Burn the best fuel you can find. Ethanol kills MPG.
I would expect that you should be able to get 18mpg if everything is in proper working order.