96 Isuzu Rodeo Gas Mileage Problems

Ok, I moved to Iowa in April of this year. Since then I put some 18" chrome rims. These rims were really heavy and I realized that my mileage was going down. Well about a month ago, I took off the rims and put on the regualr ones wtih new tires. My mileage was good for about a day or two when I went to chicago and then it was bad again. I would say that I'm getting about 12.5 mpg on my rodeo.

I do know what I could do to make it better like it was before (15 city, 17 hwy). I hardly get on the hwy and use my car in city and I figured that was the reason why, but it still sucks.

Now I did change the timing belt In April, when I moved here, and I was getting crazy gas mileage from Texas to Iowa (21 mpg!), and I changed my spark plugs last June. so i wouldn't say they are the issue.

What should I check or do differently to make my car run better?

My suggestion would be oxygen sensors.

Ok, so how do the oxygen synsors work exactly? Do they need to be calibrated or replaced? How much would they cost me and I can I install in myself?

Thanks,

Ivan

check the tire pressure

Also winter gas will give you lower MPG, and colder weather will too.

I went from about 18 mpg city this summer to about 14 city on my current tank due to the cold weather.

I was about to post on this topic. My rig has gone from 17-18 mpg down to 14-15 mpg. I thought maybe I'd swap the 2 upstream sensors...

Ok, so how do the oxygen synsors work exactly? Do they need to be calibrated or replaced? How much would they cost me and I can I install in myself?

Thanks,

Ivan

To the best of my knowledge the O2's cannot be cleaned/repaired/calibrated/replaced with better used ones. They are purely a swap for new event. The cost varies from what you can find on E-Bay if you know what to look for - to the high cost of going to a dealer. The challenge to replacing them is that there are as many as four on your vehicle. They can be tested while in the vehicle using a high-end scan tool in the diagnostics port. But you have to know what to look for in voltage range. Also these sensors are a bi*ch to remove since they tend to get rusted in place, and are in hard to reach places sometimes. A special socket is available at parts stores. Put some penetrating lube on them in advance.
I just purchased one for my Chevy truck and it was only $20 with shipping - but I got lucky I think. Some sensors cost nearly $100 each plus labor if you take it to a shop.
Has anyone here had experience with whether the front or rear ones on a Rodeo are common to degrade?
Tom

Its not uncommon on any vehicle for o2 sensors to start reading low without throwing a CEL. I had it happen on my mitsu before. Not sure how many the 96 has (my '99 has 4) but you would only need to change the ones before the cat converter. The ones after the cats really only tell the computer if the cat converter is working. I'm going to replace mine next spring simply to make sure the system is working right. As far as I know mine are all original and now have 96k miles on them.

Same here, have the '97 Rodeo, 2 O2's went bad at around 150k; changed out all 4. Paid $45/each - installed myself.

Don't know how many the '96 year has, but they're not worth cleaning/recalibrating, at 100k+ miles they've done their job.

Definitely, on the 96 yr, bring your tire psi up to at least 34-35 on all 4's.

Agree to the change in gas mileage recently too; just a short 2-3 weeks ago, I was getting 18-19 city; I'm now down to 15 or so.

I actually cringed when winter comes around for this reason, find myself spending more $$ on gas alone.

Other then that, keep your breathers clean; i.e air, fuel filter, pvc, egr, etc.

Some sensors cost nearly $100 each plus labor if you take it to a shop.
Has anyone here had experience with whether the front or rear ones on a Rodeo are common to degrade?
Tom

My 4 sensors - Bosch brand, I paid $45/sensor; installed them myself. Fairly simple job, as long as you have small/medium-sized hands.

When you're removing the old sensors, start with a 1-2min idle on a cold engine, shut it off, then wiggle them out. Be careful to not allow the engine to run too long, exhaust/manifold get hot quick!

My 2 front ones were the ones that went.

Did you get those sensors at NAPA? I'm heading over there today...

Did you have to splice, or was it plug and play? Thanks!

Got them at AutoZone - cheaper then Napa.

Plug and play; no splicing with the Bosch anyway.

Thanks!

Anytime.

I know you guys in the rust belt don't want to hear this, but that was the easiest repair I've done on any vehicle. The old ones popped out with little effort with an adjustable wrench (supposed to be 7/8", I think, but I don't have one in the toolbox!) after disconnecting the connector. And the new ones plugged right in. The ones I took out were marked AC, like the fuel filter I swapped a couple of months ago, and the Bosch were a direct fit. I paid $52.99 each at AutoZone for these Bosch 4 wire precat sensors. They were "O.E. type" versus the "universal type," which were the same price. I got nearly 158K out of the first ones. I'll let you know if mileage improves. The truck ran great on the first trip around the neighborhood.

don't forget to reset your system, by undoing the battery for a bit.

Thanks for the reminder!

I know you guys in the rust belt don't want to hear this, but that was the easiest repair I've done on any vehicle. The old ones popped out with little effort with an adjustable wrench...

Easy?!!??
Grrr...:banghead: I'm glad someone doesn't have to curse the universe and remove knuckle skin every time an under-body repair is done.
Today I spent two hours breaking free rusted exhaust pipes from the Chevy truck. Wrung off five of the six manifold flange studs. (rust of course) I liberally doused them with AeroKroil penetrant lube three times before I embarked on this project. Then there was the task of loosening the pipes from the catalytic converter. Saved the cat ($140) but had to whale the snot out of it and used nearly every tool and persuasion implement to get them to separate. (rust again). I was flinging tools and hurling curses all over the land. And it was only 25 degrees in the garage. That floor gets cold. I had to stop an hour ago cause NAPA gave me the wrong intermediate pipe. (10" too long???) And the new oxygen sensor I got from E-Bay didn't make it in today's mail. So the truck will sit in the driveway disassembled for a few more days. If it wasn't for rust I wouldn't have had to replace the Y-pipe.......So again I'm glad everyone doesn't have to go through this crap - it gets expensive and time consuming.
Spider - still interested in fixing yours yourself?:evillol:

highlandlake - I'd have to move, seriously.

Starting to consider that ourselves here in Colorado - getting tired of the cold.

I dont think moving is worth it. I'm finally mostly unpacked, and only moved a 1 bdrm apt a few miles.

Rust is what made it take so long to do my starter. Couldnt get the bolt out for the flange between the cat and y-pipe. Would have been easy if some genious at the factory hadn't decided it was a good idea to weld the nuts to the flange. Could have used a nut splitter otherwise. Couldn't get the bolts to snap off either with easy out sockets and a 2 ft breaker bar. Finally had to give up and brought home my sawzall the next day and cut the heads off. Glad my truck didnt spend any more time in wisconsin then it did.

As for o2 sensors, I've never had much trouble getting them out as long as there is room to turn a wrench or get the o2 socket in there.

...As for o2 sensors, I've never had much trouble getting them out as long as there is room to turn a wrench or get the o2 socket in there.

i don't know if this has been mentioned in this thread yet, or not.

don't try to remove the O2 sensor with the exhaust stone cold. it will probably be practically impossible. unlike the normal advice about removing sparkplugs, warm it up a few minutes and then do remove the O2 sensor, (and you will probably want to use one of the special O2 socket wrenches, but it often not necessary). you want it warm enough, but not so hot you get burned under there.


//bc

Well, a bit of improvement with the new upstream sensors. We took a ride to Busch Gardens in Tampa today. Including a little driving around town yesterday and the 2 hour trip to Tampa and back today, with the A/C on the entire way and a heavy foot, we took the truck 298 miles on 17.947 gallons which works out to 16.6 mpg. The last half tank before the swap was less than 12 mpg. I'll keep an eye on it.

Well, a bit of improvement with the new upstream sensors. We took a ride to Busch Gardens in Tampa today. Including a little driving around town yesterday and the 2 hour trip to Tampa and back today, with the A/C on the entire way and a heavy foot, we took the truck 298 miles on 17.947 gallons which works out to 16.6 mpg. The last half tank before the swap was less than 12 mpg. I'll keep an eye on it.


I replaced mine today with the same Bosch. The idle seems smoother. The sensor was hard to remove from that bracket w/o jacking up the truck.

... Iowa ... I went to chicago and then it was bad again. I would say that I'm getting about 12.5 mpg on my rodeo...I have the same situation here. The gas mileage in Ohio is wonderful 20mpg, but once I come to Chicago I get 12-14mpg.
The reason is the gas formula in IL.

Isuzu Rodeo 99, 4WD

Update: Last tankful was 16.9 mpg. Looks like it's back to normal.

how many miles did your old O2 sensors have on them?

For Surferfletch - probably over 160k miles. Your mpg should slightly improve even more after a week or so of resetting the system.

I changed them at 158K. They had AC stamped on them. Don't know for sure if they were factory originals, but since I got the truck with 30K or so, I'm guessing they were.

Come on Surfer; send your daughter out on some more missions, you have to keep up with me (mileage wise), I'm pushing 166k!

I was thinking the same! You're just running away from me! The truck is running great as I near 160K. I have no oil leaking now since I changed the oil cooler o-ring and drained of some oil overfill. I think I was measuring the oil level while some oil was still up in the passages and getting inaccurate low readings. Could explain why it was blowing out the valve cover gasket, no? The Dueler Alenzas are great in wet and dry conditions. We found out how well they perform in wet weather when that front blew through here Christmas Day (F2 tornados near Tampa) as we drove up to Sarasota. I have a rear ABS sensor on the way from St. Charles. I'll get that in next week and see if I can get rid of the intermittent ABS light. It's all good....knock on wood.

Hey, speaking of that Rear ABS sensor - can you tell the difference with or without the system working?

Reason I ask, is this truck was blowing that sensor out about every 1 1/2yrs - finally 2yrs ago, when it went out for the 3 or 4th time, I never replaced it.

But now I can't remember if I ever noticed a difference or not; how much IS the sensor?

And, IIRC, it's mounted on the rear axle?

Almost forgot to answer your ?? - yes, I would think if you were overfull in your crankcase that it would leak out the valve covers - they seem to be our weakest gaskets, which is ok, cheap to replace and inexpensive repair.

I haven't attempted to see if there is a difference in the braking with the lights on. It's the same for normal braking obviously. The part listed for $125 on the NAPA site. I think it was $75 at St. Charles. I'll check. The parts guy at St. Charles wanted to call it the speed sensor instead of the ABS sensor. As far as I know, the sensor in the top of the rear pumpkin is the ABS sensor. Early ABS was only in the rear. There are no wheel sensors. Whatever. I'm hoping it comes out easily. I read here once that the end inside the housing can become swollen and difficult to remove without taking the cover off. If that's not a problem, it should be super easy. I got motivated to do it coming back from that trip to Sarasota. Seems the light came on a little more frequently. May have been the highway speeds or the moisture from the heavy rain. I'll see if it solves it.

$76.35. I forgot to ask about the internet discount, but I'm sure I didn't get charged shipping...

Yeah, it's the ABS sensor that's out on mine. So is it inside the pumpkin?

It's right on top. There is one screw holding it to the pumpkin. There is a short wire to a plug. There is an o-ring sealing the hole in the pumpkin. I'm hoping it's a 5 minute job.
http://partimages2.genpt.com/partimages/265368.jpg

Well the lights are back, but the mileage contimues to creep up. The daughter reports 22 mpg at today's fill up. I'll have to double check the math, though!

Sorry, but what lights? The CEL light? What code do you show?

Just the RrABS and BRAKE lights I was hoping to get rid of by changing the sensor. I've never had a CEL with the Rodeo...knock on wood...

Check your brake fluid level.

Also, on the 4x2 Rodeo's this can be a signal for your alternator.

Just the RrABS and BRAKE lights....

according to smiley in a 4x4 wire post:
In my experience: Glowing 'ABS' + 'Brake' lights = A Bad Ground - or a Loose Battery Terminal.

Also: Glowing 'Brake' + 'Battery' + '4x4' lights = A Bad Alternator.


at this thread
http://www.4x4wire.com/forums/showflat.php?Cat=&Number=956651&page=2&view=collapsed&sb=5&o=14&fpart=1


maybe it's a lead you can follow


hth


//bc

I topped up the brake fluid several weeks ago. I think the rear pads are getting thin again. No battery light. I hope it's not the alternator acting up again.

I will check all of my electrical connections, too. Thanks!

You know just stating my experiences with the alternator, my battery light never came on when my alternator croaked either time.

It only came on when the battery itself was really weak, which was 2 days after the alternator croaked the last time. No one had an alternator in stock, so I had to run the truck solely on the battery alone for 2 days - it ran too, just needed help starting from a jump-starter.

Course the battery croaked that same week as well - but they were both over 5yrs old anyway.

Wonder if you picked up a bad Rr abs sensor.

I suppose that's a possibility, too. I'm going to let it ride for awhile and see what happens.