Okay, so like the title says, i recently went through with the purchase of a 1998 CR-V with the 4at in it. I bought it from a used car stealership under the condition of a mechanical inspection. So just driving the vehicle home (30 miles) the CEL came on. Quick inspection and found P0420 Catalyst system efficiency below threshold. Reset the light hoping everything would go away (big hopes) so anyways, the next morning i drive the vehicle to work and sure enough the CEL comes right back. Same code. So i figure more then likely i need a new cat. I am in an area where emission testing is done so not so sure about a spark plug defouler or whatever for the secondary o2 sensor. From what i have read as well is it could just be a lazy secondary o2 but not sure.

Second issue i find.. As i keep driving the vehicle i keep noticing a slight flare in the transmission from 3-4th gear. All other gears seem to shift smooth but from 3-4 almost every time i get a slight flare of a couple hundred rpms. looking around on google and forums i find it could be a possible worn 3rd gear clutch pack. Checked fluid and was right on the top of the fill line. No sure about brand. Driving the vehicle in D3 and manually shifting to D4 once needed it shifts right in with no flare. Also driving freeway or long stretch of road and mashed the peddle and it will upshift to 3rd and smoothly shift back to 4th. Seems to be only from starting at lower vehicle speeds. I assume because it takes longer for fluid to build pressure?

then third issue i find, as it was raining yesterday i took a fairly quick turn and while i was turning i hear a whine in the back that swiftly goes away after the turn is completed. I do it a couple more times in different areas and under hard and light accel and the harder the accel is the worse the whine. So again a quick search of google/forums and find it to be a rear diff going out. Sound right?

Basically this is the big issues im worried about. This rig was bought for my wife who has my 1 year kid with her all the time. I need it to be reliable and trustworthy. Are the issues mentioned above something that should be fairly easy to fix or should i be running the vehicle back to where i bought it?

Cliff notes

1) P0420 Possible cat issue
2) Flare in trans from 3-4th gear
3) whine in rear during turns

Thank you for any and all help.

 

Welcome, the whine in the rear mind be your dif fluid needing to be changed, its pretty commom with our crv's

 

ISSUE I:
P0420 is normally caused by an inefficient TWC (Three Way Catalytic Converter) or an exhaust leak before the secondary O2 sensor. The ECU monitors the O2 levels at the end of the Exhaust manifold before the exhaust gas enters the TWC, and then monitors the output of the TWC as the exhaust is leaving the TWC toward the resonator exhaust pipe. When the TWC and the secondary O2 sensors are working properly the ECU uses those data in order to adjust engine timing and injector "on" duration along with all the other sensor inputs. There are only two tests listed in the Dealer Service Manual for checking this operation.

1) a) Reset the DTC (diagnostic trouble code) and start the engine. b) Run at 3000 RPM until the cooling fans come on. 3) Connect the SCS service connector (short the two pins in the blue connector next to the OBD-II port: right side of the center console), and drive the vehicle between 40-55 mph for at least two minutes, then decelerate for at least 3 seconds with the throttle fully closed (i.e. your foot off the pedal). Hold the speed at about 35 MPH until the check engine light comes on again.
2) If the CEL light does come on again, then you have to check the TWC. I believe you've gotten this far in your original write-up.
3) The image below shows the exhaust system. If you had an exhaust leak you'd probably already know it by the sound, but just in case have a look in the areas circled, and the TWC itself. If you find a leak, you "may" have found your culprit. If not, your O2 sensor could be bad, or the TWC is probably clogged or has failed internally. Using an OBD-II with live data can tell you if you have a bad sensor depending on how the output reads while the engine is up to temperature and running. More likely it's both the TWC and O2 sensors are shot, as far as I have seen. Just my experience and opinion.



If I were in your shoes, I'd check the above items first. If you find that the TWC is faulty, I would suggest you get a TWC and a new secondary O2 Sensor. I just replaced my TWC and Sensor, along with adding a Yonaka cat-back exhaust system. The part numbers are below as well as the links from which I ordered my parts. Since replacing the TWC, Sensor and exhaust I'm getting 2 mpg more than before.

PARTS
Sensor, rr. oxygen, Part Number: 36532-P3F-A01 ($50.00 USD)
Converter, Part Number: 18160-P3F-A20 ($99.00 USD)
Yonaka Cat-Back Exhaust: ($225.00 USD)

SOURCES
TWC - http://www.ebay.com/itm/291593830732?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
O2 Sensor - For 96 01 Acura Integra Honda CRV Civic 2344098 Rear Oxygen Sensor O2 Brand New | eBay

Cat-Back Exhaust - http://www.yonaka.com/Yonaka_1996_20...cb-crv9601.htm

ISSUE #2:
Fix the other issues first, then look at this one if it remains after fixing #1 and #3.



ISSUE 3:
Your CR-V runs in two wheel drive (i.e. Front Wheel Drive) so long as all four tires are rolling at approximately the same speed. When making a hard turn, on the other hand, the outside tires are rolling faster than the inside tires, the drive system "sees" this and engages the rear differential to compensate for wheel "slippage". What you are hearing is the rear differential in operation. The noise can be caused by a faulty differential clutch assembly (inside the rear differential), chipped gears (inside the differential), incorrect lubricant, low fluid level, old and/or worn out fluid, or contaminated fluid. There was a TSB on the breather tube changes/addition, but I don't think that applies to your year. I may be wrong on this. At any rate, I would have the fluid replaced because it is cheap and necessary, making sure to use the Honda CVT Fluid (DO NOT use any other type or brand). One quart required for a fluid change. Inspect the fluid quantity, as well as quality, of what comes out. It usually tells the tale if it's a fluid problem or an internal problem. If there are chips then you know it's an internal issue. If it's low or crappy looking, a change or two might clear it all up for cheap. Fluid part number 08200-9006 is about $15.00 a quart. After at least two fluid changes and the noise remains, then it's time to consider having the rear differential serviced by a transmission shop, or find a replacement.

Good luck! Let us know how it turns out.