just picked up my first riv-'96 supercharged-but need help.

first off, ab, eldo and albertj, thank you for taking the time to reply and share your opinions. i talked to the mechanic yesterday again and he suggests that the front o2 sensor is giving "erratic readings"----"reading from 0 to 1000 and back down to 0" and " the computer is giving false readings to the o2 sensor. " this guy hasnt gotten a price from his friend at another shop to "program the computer to talk to the car" but i think that as i'm at work right now i'll just get the car back tomorrow, get a scanner and start to troubleshoot on my own and taking adv of the knowledge on this board.

albertj: the reason i replaced the cat is because it was leaking due to a crack in it and several holes. i replaced it with a magnaflow i got from zzperformance. i did not know about the 80 core charge-thank you for telling me luckily i retained the old cat. i will post the pcm number tomorrow when i get the car back.

i forgot to mention the riv needs a left front hub which is making noise and periodically throws the abs and anti lock lights on. i intend to replace the hub myself. this maybe signifigant as the mechanic also said he tried to gain access to the abs and suspension system to check for codes and said his computer could not connect with those systems to get codes.

smoooth225 wrote:

"reading from 0 to 1000 and back down to 0"

that's exactly how an O2 sensor works. I suggest you look for a new mechanic if he doesn't understand that. Based on this statment plus the other comments he's made about the computer, I would strongly suggest looking for a new mechanic.

Just a suggestion after reading your post. Check to make sure your air cleaner components are all attached properly. If the air intake is allowing air to leak in then your computer will try to compensate and richen air / fuel ratio. Also making o2 sensor act irradicly. Other culprit could be a faulty or dirty mass air flow sensor(maf).I have scene these problems trip PO171 code. As for P0300. may be a bi-product of same problem. Just a suggestin before some mechanic sells you anecm and every sensor under your hood.

As for your fuel tank. Is the tank bad or is the pump retaining ring just missing?

smoooth225 wrote:

i talked to the mechanic yesterday again and he suggests that the front o2 sensor is giving "erratic readings"----"reading from 0 to 1000 and back down to 0" and " the computer is giving false readings to the o2 sensor. "

smoooth225 wrote:

i forgot to mention the riv needs a left front hub which is making noise and periodically throws the abs and anti lock lights on. i intend to replace the hub myself. this maybe significant as the mechanic also said he tried to gain access to the abs and suspension system to check for codes and said his computer could not connect with those systems to get codes.

Albert and I are in agreement... This mechanic doesn't sound like a proper 'technician'.

First of all, "the computer giving false readings to the sensor" is totally backwards. Secondly, once it is warm, the #1 (upstream) sensor is supposed to change rapidly... When they become sluggish is when they need to be changed! Finally, in actual reality, the O2 sensors generally read from 0 volts up to 8 or 9 volts. It could well reach a full volt, which we'll assume is what he means by "zero-to-1000", but it doesn't sound like he really knows what his scanner is telling him - especially if he is unable to access the ABS subsystem... With my own scanner, I'm using a 2001 cartridge and I can still access everything in the computer.

You're probably right to get your own scanner and work this out yourself...

i got the car back yesterday and the mechanic supposedly had his friend at another shop take a look at the computer and advised the computer is not getting along with the sensors (o2). he advised to get a computer particular to the 96 riv and 1) disconnect the negative battery connection 20 install the new computer and 3) reconnect the negative battery cable. yes you guys are right (as always) the mechanic i was dealing with doesnt seem to be competent in his chosen field. i thank you cats for telling me that. deek and eldo, thanks for the info on the o2 sensors. big dave ill check for leaks at the air intake and ck the maf sensor today if possible. albertj-- i have some bad news. i took the white tag off the computer which had the numbers and brought them to the computer last night. i wrote a earlier version of this post and i listed the numbers in the post. i ck back a couple of hrs later and saw that my post was not there! (i probably hit preview instead of send) then i looked for the white tag and I CANT FIND IT (doh!) i'm going to continue to look for it. but i do remember this--it contained a partial sequence of numbers as follows: 96bsky. i was wondering if that was just a coincidence or maybe it had to do with a skylark. in any case i will search for that tag.

bigdave wrote:

Just a suggestion after reading your post. Check to make sure your air cleaner components are all attached properly. If the air intake is allowing air to leak in then your computer will try to compensate and richen air / fuel ratio. Also making o2 sensor act irradicly. Other culprit could be a faulty or dirty mass air flow sensor(maf).I have scene these problems trip PO171 code. As for P0300. may be a bi-product of same problem. Just a suggestin before some mechanic sells you anecm and every sensor under your hood.

As for your fuel tank. Is the tank bad or is the pump retaining ring just missing?

bigDave is EXACTLY correct on this. An upstream O2 should NEVER read 0mV or 1000mV when running. An O2 reading 0mV periodically means you have an air leak behind the throttle plate. This also holds true for the 1000mV, as the PCM will add fuel to try and compensate for the increased air reading. P0171 and P0174 may set (lean codes) due to this. Yes, it's possible a faulty O2 can cause this, but unlikely. As stated, I'd start checking for air leaks. A can of carb cleaner can help out. You can spray it around the engine compartment and listen to see if the idle changes. Also, if you have a scan tool, monitor the O2 and Fuel Trims to see if they change (go rich) while spraying around.

smoooth225 wrote:

i got the car back yesterday and the mechanic supposedly had his friend at another shop take a look at the computer and advised the computer is not getting along with the sensors (o2). he advised to get a computer particular to the 96 riv...

Unless you're leaving something out, he either mangled the translation or else his friend isn't any brighter than he is. That's like telling you to buy the right year & model of any part... Did either of them say that they think someone has replaced the PCM with the wrong unit somewhere along the way? BTW, rebuilt PCM's are actually pretty cheap compared to the more esoteric modules, like the LCM & Seat Memory Module. RockAuto has several brands, topping out at $149 for the Delco/Delphi PCM.

[[ Come to think of it: Scott, shouldn't the PCM identify itself on one of the first screens in the scanner? ]]

Abaddon wrote:

bigDave is EXACTLY correct on this. An upstream O2 should NEVER read 0mV or 1000mV when running. An O2 reading 0mV periodically means you have an air leak behind the throttle plate. This also holds true for the 1000mV, as the PCM will add fuel to try and compensate for the increased air reading. P0171 and P0174 may set (lean codes) due to this. Yes, it's possible a faulty O2 can cause this, but unlikely. As stated, I'd start checking for air leaks. A can of carb cleaner can help out. You can spray it around the engine compartment and listen to see if the idle changes.

I don't know if I'd say "never", but it depends how many decimal places we're talking about. On my Cadillac with the built-in diagnostics, I'd sometimes see the O2 voltage drop to zero-point-something on the dash readout. On the other hand, what brand of sensor did you install? If it's Bosch, on these cars that's almost defective by definition...

Also, just to be specific and safe, Abaddon doesn't really mean to spray carb cleaner "around the engine compartment". He means to spritz it on the various gasket areas and vacuum connections around the throttle body and intake manifold.

As for the PCM identifying itself, it depends on the scanner. On the Solus Pro, there is a certain screen you can go into to read the PCM and calibration #'s.

For the O2 reading 0mV, I meant absolute 0. Usually anything below 50mV (in real time data streams) indicates a lean condition. Eldo, just for your own piece of mind (and I know you'll do this ), disconnect a vacuum line or something and create an air leak. Monitor your O2's and fuel trims. With an intake leak, the O2 will read 0mV for about 1-2 seconds, and then spike up really high when the PCM tries to correct it.

And yes, I meant spritz the carb cleaner, not soak the entire engine in it. Sorry for the translation error