Garbage gas mileage, 10mpg

87'GTstang · Sep 12, 2004

Cool deal, missed the TW heads. I seriously doubt though you are going to find longer wires for your o2 sensors. Companies are not going to make a special emisions component in case someone wants to run a very non-stock item (in this case - long tubes). It just isn't cost-effective for a company to do so, but if they do, then i'de be impressed - i'm sure some company out there has seen the issue and maybe addresed it by now, who knows. If your search still turns up with no luck however, those extension harnesses are made for a reason and is probably the best way out is that be the case.

Also, while i'm thinking about it, is your speedo calibrated and are you sure you're not running around slower than you really are (the common gear-swap overlook)?

5spd GT · Sep 12, 2004

Grn92LX - About the idle surge...mine has gotten better...I got an idle surge the other day as I was pulling into my driveway and the last time it had did that was about a week earlier...and if I get on the gas a bit it goes away...it really is almost like stock (idle surge wis')...because it did it before...so I wouldn't worry about it...I got my Pro-M from jdsperformance.com for $200 (chrome)...so they aren't to high...but trust me...I know how funds go...

Edit: Yeah I just got a 23 tooth white speedo gear for 3:55's since they don't make one for the 373's with the "stock" internal driven gear... ...I'll replace it when I do my clutch...my speedometer has slowly bounced more and more over the last year...that chewed up gear from last year has barely changed...it bounces just a bit more...

Michael Yount · Sep 12, 2004

Grn92 - sounds like you have an answer for everyone's suggestion - so I'm sure you'll figure it all out. Good luck.

stangbear427 · Sep 13, 2004

87'GTstang said:
...I seriously doubt though you are going to find longer wires for your o2 sensors. Companies are not going to make a special emisions component in case someone wants to run a very non-stock item (in this case - long tubes)...

I've never seen them either, just extensions. Not to be a jerk, but I have to interject a point here even though you probably already know what's wrong with your statement. o2 sensors aren't really a special emissions component, if that were the case then they would be going into the trash alongside smog pumps. On our EFI cars, they are vital to the proper (not the clean) functioning of the computer to read and control engine management parameters (a/f, temp, fuel press, open loop/closed loop, etc). This is why almost every off road mid pipe comes with 02 bungs. Unless you have a carb'd racecar, you probably can't get it to run well without them. If they are working right they will help the engine run efficiently, and it logically follows that it should be running cleaner as well- but it's just a bonus, not a purpose.

Michael Yount · Sep 13, 2004

Actually Stangbear - the O2's perform both functions you describe and were designed to do so. As emissions regs became tougher and tougher, the manufacturers needed ways to meet them - especially the beginning of the testing protocol when the cold-started engine has to run a bit richer. O2 sensors, and eventually heated O2 sensors allowed feedback so the computer could optimize for fuel economy and emissions. Bit of trivia - Volvo pioneered the use of them as a feedback for better control with catalytic converters. The injection system with feedback via O2 sensor was called the Lamba Sond system and was optional on Volvo's (yes, people actually paid more for it) beginning in the late 70's.

From a performance perspective there's really no downside to having them present for most modded motors out there - much like the egr system. They allow the engine to run clean and conserve fuel in part throttle mode, and at full throttle the engine drops out of closed loop anyway and discounts the O2 readings during that time.

Michael Yount · Sep 13, 2004

Another issue to consider is the placement of the sensors further back in the exhaust stream (you've got long tubes right?). This does cause problems sometimes because the amount of Oxygen present changes throughout the length of the exhaust system. Chemical reactions continue in the exhaust pipe, and the sensors are designed to pick up oxygen levels pretty close to the chamber. When you move them back, the oxygen content can change from what the system is expecting. The other issue is related to temperature. They have to be at a certain elevated temperature to function properly. The further back you move them, the lower the exhaust temp at that point is, and that may be negatively impacting the readings as well.

87'GTstang · Sep 13, 2004

Didn't think about the operating temperature reading deal with the O2 sensors and all. Due to laws of heat and cold it's only natural for the exhaust to rapidly cool the farther down it moves from the manifold/collector area dictating a cooler than optimal O2 sensor - never thought of that............

Oh and yes, the O2 sensors are considered to aid with both as Mr. Yount said. They help an engine run at its best performance with regards to stoich. but so that the car isn't caught running too lean or rich at times (especially during start-up where emissions are at their worst) and it fine tunes for fuel economy.

stangbear427 · Sep 13, 2004

Leave it to Michael Yount to bring Volvo trivia into a o2 sensor discussion.

You guys are over-analyzing my statement and missing my point. What I was saying quite simply is that even if there were no emissions stations, emissions standards, emissions tests or emissions concerns, our cars would still have o2 sensors. They are necessary for the engine to run right, period. When they start to crap out, emissions readings will get worse. That doesn't make them "emissions equipment" any more than a fuel pressure regulator is- but when a FPR goes postal and starts letting 50% more fuel into the engine than is called for, you can bet it isn't going through the sniffer with flying colors. The statement I was replying to was:

87'GTstang said:
Companies are not going to make a special emissions component in case someone wants to run a very non-stock item

which is erroneous, because
1. companies can and do in fact make items specifically so we can run non stock, non emissions certified parts- that's why we have computer re-flashers, MIL eliminators, smog eliminator pulleys, and oxygen sensor extensions (which nullify the need for o2's with longer tails) and
2. the car will not run right without them regardless of what exhaust component is used, whether it will ever be subjected to an emissions test, or whether or not the car will ever even be driven on a public road... all of which is getting significantly off topic and not doing our noble thread poster any good at all- except in that he may want to get some new o2 sensors and see if his gas mileage improves.

5spd GT · Sep 18, 2004

So Grn92lx...you got the calibrated MAF in yet?

Grn92LX · Sep 18, 2004

5spd GT said:
So Grn92lx...you got the calibrated MAF in yet?

The new 30lb pro m 80mm maf is sitting right next to me. Now i'm just waiting for my accufab 75mm TB to arrive and im gonna install them both at the same time. It should be here monday. I will check my gas mileage before as well. This tank seemed decent actually. I will report back once I have it running good and when I go through a tank of gas with it.

K.C.90gt · Sep 19, 2004

stangbear427 said:
Leave it to Michael Yount to bring Volvo trivia into a o2 sensor discussion.

You guys are over-analyzing my statement and missing my point. What I was saying quite simply is that even if there were no emissions stations, emissions standards, emissions tests or emissions concerns, our cars would still have o2 sensors. They are necessary for the engine to run right, period. When they start to crap out, emissions readings will get worse. That doesn't make them "emissions equipment" any more than a fuel pressure regulator is- but when a FPR goes postal and starts letting 50% more fuel into the engine than is called for, you can bet it isn't going through the sniffer with flying colors. The statement I was replying to was:
which is erroneous, because
1. companies can and do in fact make items specifically so we can run non stock, non emissions certified parts- that's why we have computer re-flashers, MIL eliminators, smog eliminator pulleys, and oxygen sensor extensions (which nullify the need for o2's with longer tails) and
2. the car will not run right without them regardless of what exhaust component is used, whether it will ever be subjected to an emissions test, or whether or not the car will ever even be driven on a public road... all of which is getting significantly off topic and not doing our noble thread poster any good at all- except in that he may want to get some new o2 sensors and see if his gas mileage improves.

not to say your wrong or anything but O2's are not "necessary for the engine to run right, period". They only help aid in giving the computer more information regarding how the engine is running, but they are in no way necessary. My car was tuned as well as many others with the O2's disabled so the computer disregards all input from them and I get around 15MPG around the city. Even if his O2's were bad i dont think that them being the only thing bad would effect his gas mileage that much to where it would be 10MPG. It sounds to me like 92grnlx should look at the tune and verify that the MAF/INJ are working together the way they should. Maybe try swaping out other parts like the others suggested. Did you check the plugs to verify your running rich or not? It could just be a miscalibrated speedo gear or fuel guage, maybe a leak, etc.

Grn92LX · Sep 20, 2004

5spdGT, I got my pro m 80mm mass air installed along with my accufab 75mm throttle body. Just before I put them on, I went and filled up on gas and I got 15mpg this tank and that was with mostly highway driving and some around town. We'll see if it improves.

My speedo is as good as its gonna get, 7t drive in my tremec with a 21t speedo for 373's. It reads a little faster than im really going which actually makes my gas mileage worse in reality.

My spark plugs are maybe 4-5 months old and they have a nitrous gap from when I has spray. I wanna get a new cap and rotor and new plugs and set the gap back to normal.

Does autozone sell brass terminal cap and rotors kits for our cars???

5spd GT · Sep 20, 2004

Grn92LX said:
5spdGT, I got my pro m 80mm mass air installed along with my accufab 75mm throttle body. Just before I put them on, I went and filled up on gas and I got 15mpg this tank and that was with mostly highway driving and some around town. We'll see if it improves.

My speedo is as good as its gonna get, 7t drive in my tremec with a 21t speedo for 373's. It reads a little faster than im really going which actually makes my gas mileage worse in reality.

My spark plugs are maybe 4-5 months old and they have a nitrous gap from when I has spray. I wanna get a new cap and rotor and new plugs and set the gap back to normal.

Does autozone sell brass terminal cap and rotors kits for our cars???

Nice... ...can you tell if it runs better (smoother)...and did you notice any power gains...

How about try the OEM cap and rotors...that is what I'm going to get along with some new wires...but if the brass terminal cap and rotor are better...go for it...what are going to set the gap at...I have mine at .045 (Autolite 3924's)...the TW's might be different (you would know)...

Grn92LX · Sep 20, 2004

I just checked autozones site and they do sell a brass terminal cap and rotor kit for $19.99. Im gonna go for it and its red. Im gonna get a new set of autolite 3924's and gap then around .050, maye a touch less. Right now their about .037 for when I had the nitrous.

No, honestly, I cant really tell any power gains. If I gain 5-10, I doubt i'd feel it. The car runs and idles very good though and I dont have the optimizer hooked up either. It does seem to idle better and seems to idle 'healthier'. hard to explain but I notice it. I'll probaly hook that optimizer back up tomorrow and dial in the idle so its better. No surging really, maybe a little minor one here and there and warm starts are fine, no surge there. Though, I never had any surging issues with the old meter and optimizer except when it was first started for the day. I will see how it does tomorrow on its first start of the day dead cold. I'd like to dyno it again when I get a chance. Hopefully my mileage improves

I also took a side by side shot of the 65mm accufab and my new 75mm accufab. I measured then both too and the 75mm is about 3/4" bigger. It matches my TFS inlet perfect and my c&l tube too. Im VERY happy about that!

5spd GT · Sep 20, 2004

Grn92LX said:
I just checked autozones site and they do sell a brass terminal cap and rotor kit for $19.99. Im gonna go for it and its red. Im gonna get a new set of autolite 3924's and gap then around .050, maye a touch less. Right now their about .037 for when I had the nitrous.

No, honestly, I cant really tell any power gains. If I gain 5-10, I doubt i'd feel it. The car runs and idles very good though and I dont have the optimizer hooked up either. It does seem to idle better and seems to idle 'healthier'. hard to explain but I notice it. I'll probaly hook that optimizer back up tomorrow and dial in the idle so its better. No surging really, maybe a little minor one here and there and warm starts are fine, no surge there. Though, I never had any surging issues with the old meter and optimizer except when it was first started for the day. I will see how it does tomorrow on its first start of the day dead cold. I'd like to dyno it again when I get a chance. Hopefully my mileage improves

I also took a side by side shot of the 65mm accufab and my new 75mm accufab. I measured then both too and the 75mm is about 3/4" bigger. It matches my TFS inlet perfect and my c&l tube too. Im VERY happy about that!

So what does the .050 gap do compared to the .045...I need to mess with that to...I just figured .045 was the "given" gap...just curious? I know there is more of a spark gap...but what does it do for the performance and driveablility?

Thats good that it runs better and smoother ...and has a healthier idle...again...come back with a report on the mileage...it might take a few miles (could make your "readings" inaccurate slightly) to get the car to get the mileage that it deserves...I know my gas mileage seems to have gotten better as I go...but still worse...I need a tune...no "mustang tuners" in the area...

Yeah my car bucks at low rpms (really in 1st gear)...but I figure that is more the cam than anything...trying to cruise smoothly at 700rpm is kind of out of the question in 1st for me...everynow and then it will behave...but if I coast it on up just over 1k it runs nice...

10mm should be about 2/5's of an inch...25.4? millimeters per inch...sorry I had to do it

Grn92LX · Sep 20, 2004

If I remember, the 65mm measured 2.75" and the 75mm was 3.50". The 65mm fits inside of the 75mm haha. I will measure again in the afternoon because now im curious. I have a side by side pic if you wanna see it, gimme your email.

As for the gap, I really dont know. I just know that you gap it less for power adder cars so they dont blow out the spark I guess?

Your bucking sounds normal and why are you trying to cruise at 700rpm?? Are you riding the clutch out in first and not giving it any gas and letting it start out like that?

5spd GT · Sep 20, 2004

Grn92LX said:
If I remember, the 65mm measured 2.75" and the 75mm was 3.50". The 65mm fits inside of the 75mm haha. I will measure again in the afternoon because now im curious. I have a side by side pic if you wanna see it, gimme your email.

As for the gap, I really dont know. I just know that you gap it less for power adder cars so they dont blow out the spark I guess?

Your bucking sounds normal and why are you trying to cruise at 700rpm?? Are you riding the clutch out in first and not giving it any gas and letting it start out like that?

I was just messing with you on the measurements ...even though technically I should be right if the mm's are measured from the same reference point on the TB's...

Yeah I knew about the power adder (lower gap) so it doesn't blow out...just wondering what makes it different...

Yeah I know it is normal...it did it before (just not as bad) with the boltons, gears, and full exhaust...I "cruise" that low because I live down an almost 1/5th mile long dirt road and I try to go as slow as I can so the car doesn't get as dirty or dusty (even though were in the dryest spell we have had since 54'...no rain )...it will stay at that rpm but it bucks pretty badly...

88gtvertboy · Sep 22, 2004

Grn92LX said:
Well, my gas mileage blows. My speedometer hasn't worked in about a year but it works now so I checked my gas mileage last night and got 10mpg. Thats with around town and highway driving. I guess i'll give the car a code test and see if any sensors come up. I kinda think the problem is since i'm running a 24lb pro m 80mm mass air with 30lb injectors and a pro m remote optimizer that the 'tune' might be off. Im thinking of buying a 30lb mass air. I remember my car used to get around 16mpg with mixed driving and beating on it. My O2 sesnors are about 4 years old.

One quick thing about the O2 sensors, does it matter which harness they get plugged into? Is there a left and a right for them or it doesnt matter?

You should not need 30lb injectors for your mods. You should only need 30lbers for forced induction.

5spd GT · Sep 22, 2004

88gtvertboy said:
You should not need 30lb injectors for your mods. You should only need 30lbers for forced induction.

There is nothing wrong with 30's or 24's...I'm fine with my 30's...

Grn92LX · Sep 22, 2004

88gtvertboy said:
You should not need 30lb injectors for your mods. You should only need 30lbers for forced induction.

100% WRONG and thats all i'm saying You never saw my a/f dyno chart huh

Garbage gas mileage, 10mpg

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