[Rick]

Ok guys, lets see if we can figure this one out somehow. A few days ago I got a message from a fellow group member located here in the Phoenix area who has a 2000 Insight that refuses to get decent mileage. He said last summer the car was fine, but this summer he's been hard pressed to get more than 50 mpg. So anyways I had to be down on his side of town so we met and I drove his car. We got the car out on the freeway and it just refused to go in to lean burn. I would let up and let up more and more on the pedal all the way to nothing and it wouldn't go much past the 70 mpg instantaneous mark. Now this is where it gets wierd. I turned the air off just to see if it would make any difference and it did not for a few minutes, but on the little return trip I was able to hold a nice lean burn for a few miles without the air before it got too hot. Turned the air back on and was still able to get the car in to lean burn. After a few minutes though the car decided to get stuck back in rich mode again and I didn't see lean burn after that.

Now I know that depending on terrain and load (ie AC) that you won't be able to drive in lean burn, but you should be able to back off the pedal and watch the fcd enter it anyways. His car just wouldn't do it. I'm trying to figure out why it acted the way it did because he said that he played around with it some after my little test drive and he said with the air off the lean burn would return and stay for a little after turning the air back on but then would disappear. There is no check engine light on, although he claims he got one before the ecu got replaced, but that apparently fixed it. I'm trying to figure out what it could possibly be. He's had it in to dealerships several times and they last time attributed the mileage to a low charged battery. He showed me the service reciept. It said something like "customer complained of poor gas mileage. Upon inspection we found the battery pack to be charged to only 32%, the battery was charged to 78% and resulting fuel economy increased from 53 to 56 mpg." Whooptie doo.

But something is deffinitely wrong with the car and I think we're going to try another dealership and we're going to take both cars in and show them what his car is not doing. The best thought I had so far was that possibly the last sensor on the NOX converter might be bad causing the car to think it needs to be in a constant NOX purge. That or potentially the Nox converter itself might have seen better days (I wounder if an emissions gas test would reveal this). The only other thing I can think of which might be causing this being how it acted with and without air conditioning on is maybe the air is causing too much load on the engine, but it felt normal going on and off compared to my car.

The other pecular thing was that his first check engine light was apparently for a oxygen sensor (not sure if it was the nox one or not) which they apparently were not able to prove defective so nothing was done except updating the ECU which apparently had just come out at the time. So I wounder if this seems to be a common problem umong early 2000 models. His vin showed in the first 1500 cars made I believe.

Well if you've read this far thanks. Anyone else have any ideas? Naturally I'll let everyone know what goes on. I doubt anyones actually taken two cars to the dealership before to show them how a car is supposed to act so maybe we can get something done with this one.

 

[Willie Williford]

Lena off, Lean on

Ricky, if you can get an OBD tool, run the car with the tool in the operational mode. You will be able to see if in fact the engine is going into "lean burn" mode. (voltage on the 02 sensor will decrease from a max. of around .550 to much less.) If the second 02 sensor was defective or even acting slow you would get a definate "check engine light." Also, even with the second 02 sensor disconnected, I don't think you would not be able to enter "lean burn". :roll:

 

[Motty82]

I think it has to do with the NOx system and possibly the Catalyctic Converter.

Catalytic Converter Deterioration Detection / Replacement

The Insight uses 2 oxygen sensors to monitor the condition of the 3-way catalyst as required by OBD-II and EU2000 regulations. However, the detection system is not able to directly monitor the condition of the lean NOx catalyst.

My bet is that the lean NOx catalyst has deteriorated and needs to be replaced.

~Martin
Recycled
2000 5 Spd

 

[Rick]

Unfortunately I do not have an OBD tool. Perhaps they will listen to me at the dealership and use theirs and see if that proves true or not. I think the hardest part about this is going to be finding a mechanic that understands the car some and can say that we have a valid problem. I think I should try finding some official documentation that the car has lean burn in the first place to show them.

 

[Willie Williford]

sometimes

If your lean "cat" is bad you should be able to detect it by the "back pressure" test. It will either be cloged up or burnt out. When are you going to the dealer? Maybe I should take a run to Arizona and hook up the OBD tool and see what kind of readings are there.........Willie*

 

[Will M]

Did anybody think to check the tire pressure? Early on, driving my 2000 Insight, I'd forget to check for long periods of time and sometimes the tire pressure got really low. The car handled fine, but gas mileage wasn't very good. Low tires could add enough drag to keep you out of lean burn.

You might look for other factors as well, but this one hasn't been mentioned yet, so...

 

[Rick]

Willie, thankyou very much for your offer. He's had the car to Tempe Honda 3 times so far so I think we're gonna try Arrowhead Honda on my side of town and see if they can get anything done. Lets see what they do first, and then if they can't get anything done perhaps we can call in the cavalry (you).

WillM, I did ask him about tire pressure. He said he had about 40 and 36 in them. I would have gone and checked but he had the valve mender pressure indicators on the stems and they all read ok. I suggested he trys 50 psi after showing him my tires which were at 50 for some 15,000 miles with a much more even tread wear compared to his. Still, the FCD just refused to jump in to it's lean burn. Even if the tires were low it still should have jumped to 100mpg or so even if we were loosing speed.

See the thing is Rich who is having these problems (he's registered here, but hasn't posted) has had the car for a couple years. He said last year it was fine and he had no trouble getting in excess of 70mpg, but suddenly this year the mileage is gone. So this is not a case of a driver that doesn't know whats going on.

Still, I suppose there are a bunch of different things that could cause it to be doing what it's doing. But, it acts like it's trying to be in a constant nox purge so thats why I'm guessing it's something in the exhaust system. Does this sound like a valid guess? Thanks guys.

 

[Willie Williford]

on and off

Rick:
Keep me posted. I'll be available untill 7/28/03 when the "LITLE RED ROCKET" launches for Oregon and parts in between and beyond. :twisted:

 

[rich]

Without AC mileage is good

It's my Insight you guys are discussing, and the Tempe dealer's supposed to call any time after discussing it with Honda.

This morning I put on about 50 miles, about 45 freeway and 5 city. Got 72.5 mpg garage to garage. (The first hwy segment was 76 mpg.) So I don't think it's tires, alignment, etc.

The trick this morning is that it was cloudy. I could run the AC for a few minutes (Econ, AC On, temp at 71, fan on 3 or 4) to cool things down, then shut it off (Econ AC Off, fan on). I'd turn the AC back on when slowing down or going "down" a slight hill (sometimes keeping the lean mixture). So most of the time I was getting lean burn, with instantaneous readings of 75-90-125 mpg.

On the "flat" if the AC was on, it dropped to 50 on the freeway segments, not always instantly, sometimes it would stay lean for a mile or three. And last year, it was doing better.

It's as if the AC loads it up and something triggers the richer mixture where it didn't before. Whether it's a sensor or the AC is loading more heavily, I don't know.

BTW, driving like this is hard work and was definitely uncomfortable and less productive this afternoon in 112 weather.

It was interesting to test the car this way, and reassuring that the higher mileage is still possible with it. I'm a driver, not a mechanic, so I appreciate you guys and the help you're offering. Thanks!

 

[james]

(Light bulb comes on over head) But of course: the A/C is adding just enough additional load to the engine so that it won't go into lean burn. It's like when I go over the freeway overpasses: even though they're only a gentle slope, it still adds enough extra load to drop it out of lean burn on the up side.

I don't use A/C much, but don't often see lean burn when it is on.

Is it hotter this year than last? Or could the A/C filter be getting dirty, so the cooling is less efficient?

 

[rich]

Results this morning

This morning, similar weather, drove same route and left ac on throughout the trip. (Econ, ac on, fan 3, 71 degrees) Got 70.5 mpg. Like it should!

The 15 mile return trip was over 79mpg. With ac.

I took it to the Tempe Honda dealer. He plugged it in to his computer and check the fuel-air reading. 0.98 - ideal is in the 0.95 to 1.05 range, so that loks good. Of course, everything was working.

He thought the ac compressor sounded louder than normal., so he took readings relative to that and will be comparing them to two other Insights on the lot. If necessary, Rick has offered to bring his Insight to Tempe for comparisons.

I'm driving to Anaheim tomorrow, so maybe that trip will give us a new experience. In any case, it will be Monday before I'm back with a trip report. And, so far, this dealer is still trying, not yet saying that's the best it can do.

It didn't hurt that when I pulled in I had him look at the 79mpg indicator. It proves what the car (THIS car) can do.

 

[Willie Williford]

on and off

If you are geting those kind of mileage figures, I don't think anything is malfunctioning. What sensor was he reading?........or was it a gas analyzer at the tail pipe?

 

[Rick]

Willie, it seems wierd with his car. With the air off it was fine. Turn the air on and the mileage took a much larger dive than it should have. You could back off and back off more on the pedal and you couldn't get the car to lean burn. Now why air has anything to do with it I don't know, but it seems to be playing a factor so perhaps my theories were not correct.

Now it's sounding like it's in and out.

 

[Willie Williford]

On and Off

Rick, Once the AC reaches the required temp. per the climate control, it goes into a "percent cycle". Sometimes on, sometimes off. I have an "AC compressor on" light in my vehicle and when the light comes on I can back off the throttle a little trying to compensate for the extra load on the engine. It doesn't seem to change the mpg much during that cycle. Intermittent malfunctions in the system will not be registered by the MIL light. Lean burn normally happens in the higher gears at between 2200 and 2500 rpm, (I think.) Don't quiet understand how the dealer got the AF ratio.

 

[james]

"Now why air has anything to do with it I don't know..."

Again, the simple thing to check/replace is the filter in the AC system. If it's clogged, the system has to do more work to produce the same amount of cooling, so more load on the engine, so less lean burn and lower mileage.

Also might be something like a bad bearing in the AC compressor itself, so that it takes markedly more effort to turn it. It still works, just uses more power, and the same thing happens.

 

[rich]

Results of CA road trip

Well, the thing is intermittent. About half the time, I'd guess. Sometimes, like today, I'll drive a stretch of freeway and it's okay for a bit, then acts up, then okay again. Other times it stays good or bad for an hour, or even several hours.

My trip from Phoenix to California was interesting. 52mpg again from here to San Bernardino, then 84 mpg from there into Anaheim.

The return, Anaheim to San Bernardino, was 76 mpg. Anaheim to Indio, 72 mpg. (Beaumont to Indio, which must be more downhill, was 91 mpg -- over about 50 miles). Then it got bad, 48 to 52 mpg, until I reached Phoenix. The last 35 miles, running 75 to 62 mph while the sun was still out, plenty hot, was 81 mpg. All of this was with ac running fulltime, set at 74, auto, with the fan at 3.

Another interesting note: When the car is doing it's "bad" thing, I even get the rare "Down" shift indicator. Today when I was driving at 45mph on Baseline Road, a mostly flat road, I started up a gentle hill and got the down indicator. I've noticed this behavior before in other locations. Yet, as I'm sure you've experienced, a down indicator never shows up except on a long highway mountain climb.

The folks at Tempe Honda? They've given up. Well, not exactly, but the Shop Foreman walked me back out to my car telling me, "I think your car is running real well."

The service manager says "Keep bringing it back until they get it right." But the shop foreman, who says he has "never" been able to get any better than 55 to 61 out of an Insight, keeps telling me Honda is "happy" if it's getting 48 to 50. He's amazed that I can get such good mileage (when it's working right). He's no longer any help.

So I have an appointment at Arrowhead Friday morning.

 

[Rick]

:twisted: Hehe, Go Time! :twisted:

 

[Rick]

Well, I met Rich up at the new dealership this morning and unfortunately the car was acting just fine all the way up to this side of town. They test drove it and it was fine. We spoke with the shop foreman for a little while and he said he had an idea of what it could possibly be, he wouldn't tell us, but he said he needed a screen shot from the OBD when the car is doing it's bad thing. Well, looks like this is going to get more interesting now.

 

[geriolala]

:idea: THe quality of gas .....?

As i check the best average are made with high grade fuel ???

Just an idea . It would explain why it is quiet different for time to time .

octane ???
Geriolala

 

[Rick]

No, gas wouldn't make this quantum of a leap in difference. We're talking about less than 50 mpg on the highway cruising at a speed where you should get 70 to 80. It's in and out, sometimes it runs fine, then it'll go in to it's bad mode. We're woundering if maybe something isn't connecting completely somewhere. Rich also mentioned seeing the down shift light a lot when the cars in it's bad mode. And this change happens on the same tank.

Again, Rich is not crazy, I drove his car and I experienced it go from it's bad mode to a normal mode. Really wierd. Ohh, I might also mention, we ruled out anything having to do with the air as a possible culprit, it was just coincidense that one time, Rich says it'll do it with the air on or off.