REALLY bad gas miliage - REFERENCE
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Post by ES_97Sport on Oct 7, 2014 18:54:14 GMT -5
Ahh emission control systems. Good times. Guess I'll see about taking it off to try that. Do you still have the weight for the old one and is there is a size weight difference from the 97-99 and 00 and up. Oh, good God, no. That's too scientific. They handed me the old one, then handed me the new one and said, see, you can tell this one weighs more. PFM, I swear. But, they were right, I could tell a difference. I don't know how much but it was definitely enough that there was no imagining it. So, I suppose you could buy a brand new one and weigh it. Then go dig my old one out of whatever landfill it ended up in or find one in similar bad shape and weight it. But, I don't know what that will tell you, because there's no threshold to judge 'good' from 'bad'. See, this is the kind of crap I hate about IT that's leaking into automotive. Its broke. How do you know? I don't know. Then how do you tell if its broke? Well, you just know. HOW do you know? You just know, you know? Sigh. That's why I like base mechanical and electrical engineering. Everything is quantifiable, there is no guessing and there's no making stuff up. It is what it is. Dang, I AM old. Edward
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Post by jkdv8 on Oct 7, 2014 21:14:07 GMT -5
Ah ok I got it. I'm sure some of it has to do with trade secrets maybe, possibly?!? If they let everything out the bag then mechanics would lose money. Also, the high probability of it being the way you said. I suppose once you work with it for awhile you kinda get use to knowing what's good and bad. Like an acquired skill so to speak (charcoal canister sense) lol. But you're right it can be rather aggravating.
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Post by ES_97Sport on Oct 8, 2014 13:08:01 GMT -5
Ah ok I got it. I'm sure some of it has to do with trade secrets maybe, possibly?!? If they let everything out the bag then mechanics would lose money. Also, the high probability of it being the way you said. I suppose once you work with it for awhile you kinda get use to knowing what's good and bad. Like an acquired skill so to speak (charcoal canister sense) lol. But you're right it can be rather aggravating. 'Aggravating'. Yes. No, I don't think so. I can't find anything in the FSMs and the techs I've worked with are friends for years and years and they have to info that isn't in the FSMs that tells them either. They honestly don't know. I've never run across how you tell even with other manufacturers. Even going back to the beginnings of having charcoal canisters in vehicles. I imagine the engineers could tell you but I get the impression this just ain't anyone priority. I mean, most vehicles never last long enough to have the canister replaced. The techs only just barely consider this to be a service part. Its like O2 sensors. You're supposed to replace them every 80K miles or therein abouts, but no one ever does. They wait until they die. Edward
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Post by jkdv8 on Oct 8, 2014 18:39:37 GMT -5
Ah ok I got you. That makes sense. Suppose it will remain a mystery That is really odd though.
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Post by ES_97Sport on Oct 16, 2014 16:39:19 GMT -5
Fun with "#6 Mass Airflow Sensor (MAF)" ...
I purchased a new OEM Mitsu MAF a couple months ago. I was pretty sure mine was approaching EOL. Sluggish throttle response off idle, some strange highway speed behavior in the transition between light decel to light accel. I also had a very intermittent 'miss' during warm up and while driving. And all of this is itermitant but has been getting steadily worse of the last 4-5 years. I had some similar behavior on my little '97 3.0L. I decided to swap MAFs between the vehicles - the only thing that changed is that the few things happening on my big Sport now were happening on my little Sport. Ahhh, so, ....
For the last 7-8 months its been replace one part, test and diagnose, then move onto the next, and so on. Last weekend I was down to the IAC and the MAF. My new IAC isn't here yet (and there really isn't anything wrong with the one that's in there now), so I replaced the MAF in my big Sport with the brand new MAF.
Amazing! All the previously mentioned behavior disappeared. Throttle is very responsive and glass smooth. Acceleration is very solid and rock-solid consistent. No off idle surging, high speed acceleration/deceleration stumbling. Absolutely no misbehaving at all, now.
Anyway, I wanted to bring this up because this is the only 'sensor' where there are actually three sensors incorporated the same device. Mass Air Flow (MAF), Intake Air Temperature (IAT), and Barometric Pressure (BARO).
After replacing everything except the MAF and IAC and having the TPS readjusted, I was pretty much sure that the MAF part was misbehaving. There isn't any way to test the MAF with any commonly available diagnostic tools and the MAF can be in pretty bad shape before it will trigger CEL and produce any code(s), but I've driven motorcycles, cars and trucks with known airflow issues and they're pretty easy to recognize if you know what you're looking for.
That did not explain, however, other incorrect behavior. These I misdiagnosed as a conflict between the '97 3.0L ECM and my 3.5L engine and the reason it was misdiagnosed is because the information isn't available without a MUT. BARO is the current barometric pressure and is used in the adjustment of various parameters to correct for altitude. I think the most commonly known parameter is timing - higher altitude = more timing and less altitude = less timing. After replacing the MAF assembly and removing the AEM F/IC piggy-back computer it was VERY obvious that BARO wasn't working right anymore.
IAT doesn't have as big an impact as the other two on NA vehicles and the data can be access via OBD and its easy to check and make sure it's reading correctly with a simple thermometer. Mine appeared to be fine - in that it always read what I expected it to.
Anyway, this is actually a little off topic, because even though neither MAF or BARO were working right - in fact they were both pretty horked up - fixing the problem had a minimal impact on fuel mileage. But, while MPG didn't go up much, fuel usage evened out considerably. Behavior and usage are now much more consistent - like they used to be for years and years after I first bought it.
Oh, and one last thing. The exhaust for the last 3-4 years has been stinking badly. Even after replacing everything, over the last three weeks I'd noticed it'd improved, but still smelled pretty strong. It started out intermittent but a couple years ago it went to being that way 100% of the time. Idle was very slightly ragged. Very slight. Both went away within a few minutes of starting it with the new MAF assembly.
Edward
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Post by 91clipseDOHC on Jun 14, 2016 19:38:18 GMT -5
I'm going to start diving into this with my 2000. I just got back from a 1000+ mile trip and was averaging 14-15 MPG's on the highway. The highest I recorded was 15.8. Granted I was driving 75-80 MPH, but I still feel like it should be better. (Its an all stock 3.0 4WD, by the way).
I know that I am getting oil into the exhaust, which I assume is bad valve stem seals. I plan on replacing them even though its a lot of work. I also suspect that my converter is jacked up from the oil leaking into the exhaust. I get a bad smell at the back of the car while it idles and occasional smoke out the back. I'm hoping replacing the seals and converter will help. I will also be replacing the factory muffler with a Magnaflow unit and inspecting the pre-cat portion for any exhaust leaks.
In the meantime I guess I will also start replacing the emissions control items and see if I can get my fuel economy up. How many miles can you guys make it on a single tank? If I'm lucky I can go 225 a tank on the highway and around 200 in the city. ****EDIT**** I actually just priced out replacing those items and DANG! That's a lot of money. Has anyone disabled/removed the EGR/emissions system rather then replacing it?
1 Evaportive canister $104.89 (Rock Auto) 2 Purge Valve $37.99 (Rock Auto) 3 EGR Valve $51.89 (Rock Auto) 4 EGR Solenoid $31.79 (Rock Auto) 5 MAP $98.79 (Rock Auto) 6 MAF $140.99 (AutoZone) 7 O2 sensors $35.79 + 26.79 (Rock Auto) 8 Convertor (single) $126.79 (Rock Auto)
Total $655.71 (plus shipping of course)
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Post by ES_97Sport on Jun 15, 2016 14:13:12 GMT -5
I'm going to start diving into this with my 2000. I just got back from a 1000+ mile trip and was averaging 14-15 MPG's on the highway. The highest I recorded was 15.8. Granted I was driving 75-80 MPH, but I still feel like it should be better. (Its an all stock 3.0 4WD, by the way). Everyone in the US, please KIM, that fuel formulations have changed significantly nationwide during the Obama administration and even further in certain more populous regions of the country. The information on fuel mileage on my web site (4x4 Extreme Sports) and previous posts on various forms dating back to the end of the '90s and beginnings of the 2000s isn't all that accurate anymore. Gasoline does not yield the BTUs it once did only a few years ago. The misguided and environmentally damaging dumping of massive amounts of ethanol into gasoline is probably the most blatant causes of this. Fuel Comparison Chart - Alternative Fuels Data Center - Department of Energy USIts interesting to note that they try to lump straight gasoline in with E10 gasoline - which is 10% ethanol - (like its the same thing or the difference is insignificant) and they misrepresent the BTU output by reversing the label and BTU output of the fuel. Gasoline - 116,090 (lower), 124,340 (higher) E10 Gasoline - 112,114 (lower), 120,388 (higher) ... is how it should read. Given a 300 mile average range on a tank of pure gasoline, the range would be 290 miles with E10, 219-249 miles with E85 and 204 miles with E100. (calculating from the lower heating values on the document above) If you could instantly transport a brand new gasoline vehicle from 2000 off the dealership lot to the present, it wouldn't get the fuel mileage it would have in 2000 simply because of the fuel. So, at least for my big Sport 15-16 MPG is the new 17-18 and 17-18 MPG is the new 19-21. And before everyone jumps on the Obama bashing bandwagon - a lot of this has nothing to do with him and everything to do with the allegedly conservative agricultural industry which gets massive government subsidies to grow corn for fuel ethanol. So, yes, we subsidize an entire industry just to make things worse. We increase total fuel burned (increasing vehicle emissions overall), decrease vehicle emissions (at the tail pipe) negligibly and destroy millions of acres of farm land.And replace all the O2 sensors, 'cause they'll be horked too. I USED to get a consistent average of 290-310 on a tank in the summer and 260-290 in the winter - Gen 1 17.5G tank - on my big Sport with the SAS and 35" tires. Now I average about 240 miles on a tank with the same driving in the summer and around 220-230 in the winter - on Denver fuel which is pushing 15% ethanol now even thought the pumps still say "no more than 10%". Before you run off and spend a lot of money on a lot of Chinese half working knock-off parts - you might want to consider spending the extra cash for the OEM parts. Most of the stuff you have listed is precision electronics - if it doesn't work EXACTLY the same as the OEM part, it will cause problems. Problems you'll never be able to fine, either. The reason CATs and O2 sensors are so expensive is be cause of the platinum content - which is what makes them work. If you decrease the content, you decrease the effectiveness of the sensor or CAT. Those two are the VERY LAST parts you should consider buying cheap replacements of - they CHEAP because they're NOT BUILT THE SAME. To answer your question: Nope. Because if you do it will hork up the ECM/PCM and cause driveability issues. AND it will trigger OBD codes that will prevent the vehicle from passing emissions in at least CA and CO. Edward
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Post by 91clipseDOHC on Jun 15, 2016 14:51:48 GMT -5
Good points on the ethanol content. I run E85 in my Eclipse and used to run it in my Evo too (with the appropriate larger pump, injectors, and tuning). Great for power but horrible for fuel economy (uses about 33% more fuel).
But even accounting for 10% ethanol in the gasoline, I feel like my gas mileage is very sad (especially since my truck is stock). Perhaps it's just as simple as replacing the valve stem seals (to fix the root cause) and then replacing the (most likely) jacked up cat and O2 sensors.
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Post by ES_97Sport on Jun 15, 2016 16:02:53 GMT -5
Good points on the ethanol content. I run E85 in my Eclipse and used to run it in my Evo too (with the appropriate larger pump, injectors, and tuning). Great for power but horrible for fuel economy (uses about 33% more fuel). If it contains 30% less BTUs per gallon, you will use 30% more fuel to accomplish the same thing. I'm not saying that's your problem. I was just pointing out to everyone something that has never been mentioned before and needs to be taken into consideration. There is pretty much no way to get 20-22 MPG out of a Sport anymore no matter what you do to it because the energy content of gasoline in the US has degraded. My stock, my '99 Limited 3.5L and '03 Limited 3.5L, get about 18 MPG on average pretty consistently. That's pretty much exactly a 50/50 city/highway mix. My little '97 does a little worse or a little better depending. Its got an ARB bull bar and winch and its a 5-speed M/T, so .... But my stock ones never get 15-16 no matter what fuel or where I'm driving them. Otherwise, I think you're heading the right direction. If you have oil blowing though the exhaust, that's going to seriously degrade the functionality of the O2 sensors - the primary source of metering for the fuel system. Degraded CAT(s) will just make that problem worse. So, IMHO, valve stem seals are #1. There isn't any point in doing anything to the CAT(s) and O2 sensors until then. Edward
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Post by colted on Jun 15, 2016 22:36:56 GMT -5
My 02 XLS 2WD was hovering around 17MPG +/- 0.1 (w/ or w/o AC; mixed city-hiway) based on my Ultragauge.
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Post by dirk on Jun 16, 2016 14:44:05 GMT -5
Since switching to the 33s, and having the throttle position sensor adjusted, I've been seeing 19.3 and 19.5. That is with AC alot, mixed driving about 50/50. I'm running 92 octane ethanol free gas though.
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Post by ES_97Sport on Jun 16, 2016 15:45:46 GMT -5
... I'm running 92 octane ethanol free gas though. The last station on my side of town stopped about two years ago. You are lucky. I wish I could still get it here. Sigh. It was nice to go out to southern UT a couple times a year. Mileage went back to 'normal' after I drained out the last of the CO crud gasoline. But, about a year and a half ago I noticed that now there's no difference between there and CO. About the time emissions/environmental regulations changed for UT. This is one where I absolutely agree with jkdv8 re: regulations. My family farms back east and the whole ethanol thing is a joke. Corn is one of the most destructive things farmers can grow and now they're incented to do nothing but grow corn year after year which destroys the ground and pollutes the water. And all dumping all that ethanol into gasoline does is make vehicles burn 10-40% more fuel to accomplish the same thing. Edward
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Post by jkdv8 on Jun 16, 2016 16:44:03 GMT -5
The ethanol bit makes sense but the levels at the pump around me haven't changed in the time I've had mine. When I first got it I could get upwards of 25mpg on road trips and it slowly decreased from there which is typical as a car ages. I have not taken it on a road trip recently to compare but the last time, a few years back, it was around 21.
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Post by 91clipseDOHC on Jun 16, 2016 16:55:53 GMT -5
As I recall only the front o2 sensor effects the fuel trims and the rear is just there to verify that the converter is working, correct? Assuming that is the case I would only really need to replace the front sensor once my valve stem seals are replaced (at least from a fuel economy standpoint).
I agree with all your points on ethonal, but I've got to say I'm a huge fan of E85. When I switched to e85 on my Evo I gained 40 whp and 60 ft lbs of torque over gasoline at the same boost level. The much higher octane equivalent in E85 allowed for significant advances in timing without inducing knock/detonation.
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Post by jkdv8 on Jun 16, 2016 17:06:45 GMT -5
Yes on the sensors.
Yea ethanol, from a fuel standpoint, isn't bad but the engine needs to be tuned for it, however it's not very practical. Some aftermarket setups have a switch in the glove box to change the mapping and some have a controller that can switch between a few different blends. These trucks inparticular were not designed to run on e85 or anything above 10% ethanol. I have tried the ethanol free stuff and it loved it.
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