Maf?? O2???? Egr??? 94 Rodeo

[lostsoul74]

oK, heres my problem. I've got a 94 isuzu rodeo, v6, 4x4. 174K, runs great running around town, but on a current cross country drive, after long periods of drivingtime, it bucks and kicks, blowing black smoke. It does this after about 3 hours of highway driving. Instead of getting an average of 75 miles per quarter tank, I drop down to about 28. I can find a sweet spot on the accellerater pedal and after a while, the check engine light will come on, and run fine again, no kicking or bucking. but if i deaccellerate, check engine light goes off and same problems again.
I need you guyses guesses on which sensor it is, or general issue in general, pretty sure it's a sensor (at first i thought it was a clogged cat, but been hollowed and same problem)
I also need to know where the sensor is located, so if it is say the maf, exactly where on this vehicle it is, I'm familiar with cars, but not familiar with this vehicle..... price was right.... and recommended cleaning or testing ideas. Thanks guys, you can also email me today direct at [email protected], so that i can view it on my phone while driving and have idea on how to fix. it's costing me nearly 500 in gas to make it back to ny, instead of 180 origianlly, plus major pain tryihng to control the buckling. Thanks again guys Eric

[Cat Fuzz]

You could have bad spark plug wires causing misfiring and arcing. If a plug wire breaks the conductor, there is enough current for it to arc from the top of the coil to ground. Start the truck in the dark and watch for sparking near the coil packs. That would be the first thing I'd check. Also, pull your codes. There should be several posts on the board explaining how to do it, unless the search function is FUBAR.

[lostsoul74]

hey thanks CF, appreciate it, read the email late night while driving, pulled over, checked it out, no arcs, etc. It had a full tune up about a year and half ago.
Now that i've finally made it back to NY, (after wasting 412 dollars in gas which should of only cost 180) (yea, not very cost effective, but main concern was just getting my tools back to NY, didnt feel like sleeping my truck overnight while waiting on a dealership to open and having to wait all day to get a huge bill and have them tell me it was some 400 dollar thing that I knew if I just get to a pc and figure out hte problem, it would be a 10 dollar ebay or junk yard sensor)
Now that i've had a chance to really read up on it and search here (it was your suggestion to pull the search for the code instruction that lead me to the post where guy had exact same problem). It looks like it's just an o2 sensor, beautiful thing, i'll have to grab one and check it out in the next few days, is there a way to clean an o2 sensor???? thanks guys. Hopefully thats the problem, but then again, now that i'm home, it doesnt really effect me, only once i've been on the road for hours at a time, fine for around town. Thanks again CF, I had tried searching the board before (public libraries on the road... oi.....) but didnt find anything matching my exact problems, just could be's, that instructions search led me right to an exact scenario one, thanks man... E.

[highlandlake]

If your problem gets temporarily better when the check engine light comes on, then it could be that the ECM is switching to a default setting mode when an error code is triggered. I don't know enough to suggest which sensor is causing the problem, but thought I'd share this info if it helps narrow down the possibilities. Some sensors such as the Throttle Position sensor will be overridden when in default mode to allow the vehicle to be driven safely for a short time. So maybe the O2 sensors will do the same as suggested above. Let us know what the outcome is.

[rodeo02]

Not sure if the 1994 3.2L has a MAF. It may have a MAP sensor instead. A bad MAP sensor could have some 'dead ranges' like you describe & cause serious fuel trim swings.

G/luck
Joel

[Cat Fuzz]

Originally Posted by rodeo02

Not sure if the 1994 3.2L has a MAF. It may have a MAP sensor instead. A bad MAP sensor could have some 'dead ranges' like you describe & cause serious fuel trim swings.

G/luck
Joel

My 94 has a MAP sensor.

[95.5 Rodeo]

When my Rodeo was blowing black smoke, it turned out to be a bad oxygen sensor:

http://www.automotiveforums.com/vbul...d.php?t=258045

They are not meant to be cleaned, just buy a new one.


Dale

[lostsoul74]

hey thanks guys, really appreciate the help, probobly this weekend i'll get a chance to toy with it more, been out of town for a bit and been stressin over this thing too long, time for a break now that i'm home.

ps. yea, I know that story well, the DC to rochester run, had the same problems from the same place. If yours was a 94, i would of swore I bought it. lol. Rochester

oh yea, where is this Map sensor??? and whats the cleaning suggestions.

Instead of waiting a week for an ebay buy, or digging around junk yards hoping to find a good one, (no, i wont buy new, why waste the money and find it's not the problem, or either way, why waste the money if you can do it yourself), i've read several hits on searching for o2 sensor cleaners as people use QD electronics cleaner for both air sensors and o2 sensors, works great, i'll keep you gents posted. and thanks again guys, if it wasnt for the internet and forumns, I'd have some serious headaches and empty pockets. lol.

[Blue Bowtie]

It could be a MAP. It could also be a TPS, it could be a saturated EVAP canister. It could be a lot of things. You'll only be guessing until you retrieve the stored error codes from the PCM. That should tell you exactly what the ECM doesn't like about what it's seeing for input data. Until then, you're simply guessing. Use the tools that the ECM has to tell you what's wrong.