[Guest]

I have not been really happy with my MPG and I'm wondering if this is a problem with the car or my choice of fuel.

The car is a 95 RMW with tow package. That is a 2.93 gear gear and mechanical fan. I think the factory rating is 22 MPG on the highway. What bothers me is that with every other car I have ever owned I have been able to surpass the factory highway rating when cruising on the interstate at 70-80 MPH.

I went 250 + miles and only got 16.5 MPG. I have been using 89 octane which is 10% ethanol. I am a farmer and prefer to use this fuel, but I wonder how much it is costing me. As a quick experiment I switched to 87 octane for the remaining 60 miles home and got around 18-20 MPG. This is an early test, but has anyone else had any experience with this? Chemically the ethanol should cause a slight decrease in MPG, but nothing that drastic.

We have never gotten over 18-19 MPG. Lately it has been closer to 16-17 and I have been blaming it on the cold weather and more city driving, but now I wonder.

AFAIK the car is all original except for a F-body EGR (that's what I was told when I bought it) and I replaced the plugs with another set of double platinum's. I also have done the TB coolant bypass and homeplate delete, first base delete, and modded air box.

Thanks.

 

[Guest]

rex,. if you have plenty of miles on it,. try some new o2 sensors it worked for me,.

 

[Guest]

I only get 11mpg (if it makes you feel better)

 

[Guest]

I just got done with a 500 mile trip to Selkirk Newyork. My wagon got 25 MPG all the way. Of course my car has the LO5, so your car having more power should get better mileage than mine. As said above, get new O2 sensors and reset that computer. I also only use Prem. gas. My engine also has 168,000 miles and the transmission has 7000 miles. I saw a 1 MPG increase when I had the Transmission rebuilt.

 

[Guest]

I installed a NAPA fan clutch (from the mid 80's Caprice) and got a little more power and maybe a 1/2 MPG. This is quick cheap mod compared to a whole electric fan coversion. (Do a search on "NAPA fan clutch" in the archives and get the part number.)

I would also agree that changing O2 sensors is probably a good move for economy and power. I plan to do mine in the spring.

 

[Guest]

My '94 RMW gets mid-20s @70-75mph w/ std. 2:56 (ugh )....16-18 combined city/highway.

 

[Guest]

I have the same RMw with tow package / 2.93 gears and whatnot. 174k on bone stock original engine (new trans). My mileage is 14-16 in town and maybe 20-21 on the highway. I'm trying AutoRX on my 1200-mile christmas trip this week and then doing a SeaFoam treatment when I get back. I'll let you know what I find.

 

[Guest]

Wagon gets 14 avg. mpg w/wife driving kid around w/3.42's & I did get 22 @ steady 70 mph. As comparison, sedan (350lbs. lighter) w/2.93's gets 25 @ steady 70 mph.

 

[Guest]

Originally posted by Klez:
I only get 11mpg (if it makes you feel better)

I get that when the foot is all the way to the floor too much

 

[Guest]

Thanks bunches guys. Looks like I've got some issues to take care of.

I will try the 87 octane only and if that isn't enough then I'll try the SeaFoam and new O2 sensors from Dal.

 

[Guest]

I think I found something tonight while doing a Seafoam cleanout.

Smoke came from the area of cylinder #8 on the exhaust manifold. I have a broken bolt and I'm pretty sure the manifold must be leaking. If this is true, how does the EGR tube and EGR valve attach. I thought I might have seen the tube back there. If I break the tube what are my options? What if the manifold is cracked? Do stock ported manifolds work very good? I could port them myself while it is off.

Did the EGR tube get messed with while replacing the EGR? Could it be leaking?

Basically any options and advice/ past experience is great.

Thanks

 

[Guest]

I fixed the manifold bolt. It wasn't too bad of a job, but I was very lucky! I was able to wire weld a larger nut on the old bolt and turn it out. I used an air hammer on it before I welded the nut on and that may have helped. The bolt turned right out.

When my wife got to our shop I tried to pinpoint the exhaust leak, but never found it. I guess the warm manifold sealed back up wherever it was leaking. I tore off part of the heat shield sure that I would find a crack somewhere but never did. I was looking between cylinders 6-8 because I read that this was the most common failure point. I couldn't see any signs of a crack anywhere on the manifold so I gave up.

I also found a bad air pump check valve on the drivers side. I removed it and plugged both pipes and just disconnected the rubber elbows for now. The fuse had repeatedly blown for the air pump so I had given up on it months ago.

Could the bad check valve also have caused MPG issues?

Thanks!

 

[Guest]

Another little update...

Last tank of mixed city / highway (mainly highway) was 15 MPG (before repairs).

The above repairs, plus a MAF "tinys" cleaning and ECM fuse pull and half tank 87 octane netted 21-22 MPG tonight on a 80 mile trip of highway miles at 65-70 MPH.

That's much better. We'll see what happens on some other trips coming up in the next weeks.

 

[Guest]

Rex!! Your from Shelbina, I live in Columbia, but I am from Hannibal originally. Glad to hear from someone on here that is somewhat local.
When was the last time you changed your fuel filter, spark plugs, and plug wires and I'd ask about you 02 sensors but I think somone mentioned that already. Hope you got your milage issue fixed.

 

[Guest]

I'll be in Columbia tomorrow with the wagon and family. My cell phone # is 660-384-2380 if you want to meet or something. Then we go STL and back on Saturday. I have had mixed results since the fixes. From home to Columbia and city driving I got 16.5 again. Then from Columbia to home to Moberly (backroads and a 100 MPH blast) and home was 18 MPG.

I'll be doing quite a bit of interstate style traveling in the next few days and we'll see how things go. My goal is to beat the 22 EPA MPG rating. I may need new O2's to do that.

I put in new AC double platinum plugs (factory plug) about 10K ago. I think the car is still on the factory opti and wires, but runs well when pushed hard and does not otherwise miss. I think my issues are ECM related. I just have to figure out what is causing the issue.

You don't have a scanner do you?

I also found that my intake between the TB and MAF was a little loose and could have been causing a leak.

 

[Guest]

Man I wish I had read this yesterday. I might have looked you up. I don't think the original opti will have much to do with your mpg issue since the car runs fine, but the original wires might have wore down over time and not be suppling the plugs with enough spark.

And I do have a scanner but it only does OBDII-96 and newer, it's not complient with OBDI-95 and older. Bummer.

Have you replaced the pcv valve? I think that plays a part in fuel economy too and its a cheap part to replace $5-6. Have you checked your tire pressure? That plays a part of fuel milage too. Hope yo get it resolved.
My car had kinda been slacking in the fuel milage dept.a little lately too. About 18-19 mpg vs. its usual 21 mpg. Although I think it might be because it has 88k miles and the plugs/wires/& O2's are origonal has something to do with it.
Josh

 

[Guest]

wow beezed right thru columbia to and from kentucky at christmas guys! nice bandanas barbecue over by the red roof inn! my 93 "B" caprice wagon got nothing under 20 driving 75 all day long, even oddly got close to 25 a couple of times, car is a 5.7 with 3:23's and a G-80 limited slip so something is amiss with yours rex, although i seem to recall hearing more than once the older tbi cars do tend to do a little better mpg wise, bear in mind i run mine on mid grade (mostly ethanol blend at most stations)( i run holiday brand gas with ethanol here and average 15-16 around town all day long) but i seem to get my best mileage on the road with bp amoco silver grade and my worst seems to be on conoco from the flying "j"'s which is annoying as i like thier stops for a lot of reasons! anyone else peeking at this thread let us know if you experience similar differences in gas brands!!!. john

 

[Guest]

Originally posted by rweatherford:
You don't have a scanner do you?

I have one and am in the STL area. Are you going to stop by the GRAIL meeting? I'll be there and will bring it just in case. Hope to catch you there.

Dana

Cell 314-265-1660

 

[Guest]

Originally posted by rweatherford:
....The above repairs, plus....netted 21-22 MPG tonight on a 80 mile trip of highway miles at 65-70 MPH.....

Yeah....The manifold leak from the broken bolt allows 'fresh' air to get sucked into the exhaust stream.
When the 'diluted' exhaust gets to the O2 sensor(s), they read a lean A/F mixture.
The O2's sends a signal to PCM to dump more fuel through the injectors which, in turn...drives you MPG to crap!

Good jub in tracking your problem.

BTW, ported stock manifolds really aren't worth the trouble....as in no real performance value.

KW

 

[Guest]

Originally posted by CHV_FRK:
</font><blockquote>quote:</font><hr />Originally posted by rweatherford:
You don't have a scanner do you?

I have one and am in the STL area. Are you going to stop by the GRAIL meeting? I'll be there and will bring it just in case. Hope to catch you there.

Dana

Cell 314-265-1660 </font>[/QUOTE]Dana,

I'll try calling you around meeting time. I may come if I can. I will be in Ballwin, which is close. If I come I will have a wife and 3 small children with me. Is Growlers fine for the kids?

Again. I'll call. We won't stay for the whole meeting, but probably will need some lunch. I've been wanting to meet some more people. Rick is the only one I have met. I met him at MIR.

Thanks.