Bought 97 Q45 in California. Drove it about 300 miles back to Vegas. Check engine came on somewhere in the middle of the trip. Car drove fine on the freeway, but once I got in town the car started jumping on accelleration as if something with the fuel delivery system was choking.

Codes that came up with Knock Sensors.

Following this forums instructions on changing the KS, we did just that.

Off the topic of this thread, but trying to be thorough with what I've done, I also replaced the AC compressor, and Cabin Air Filters.

Also replaced my rear two O2 sensors and cleaner the front O2 sensors.

Following the KS sensor changing, check engine lights went off, car drove good for the short trips I used it for since it was not registered. Drove it, had it smogged, got it registered and on the road I went.

About 2 weeks ago while driving it, after about 30 minutes, on a right turn after slowing down, the car lost power on accelleration on two different occasions.

Later that week, the girlfriend driving the car, called me and stated that it was extremely sluggish on accelleration but drove fine after reaching a higher speed. She also stated check engine light was on.

Checked it out, and I got a P0430 (Cat Bank 2) and a P0307 (Cyl 7 misfire).

Knowing that I have to change my cats, I've been trying to take it easy driving the car, but after about 30 minutes of driving (or 15 minutes in this vegas midday heat) the car runs pretty sluggish and at times feals like it might not accellerate at all. Ran the codes again, and this time I also received the P0420 (Cat Bank 1).

Questions are as follows.

1. I read on another site that the codes P0420 and P0430 are definately the cats, and based on the order of system checking, there is no way this would be O2s or any other part of the exhuast system. Is this accurate? I'd hate to spend the money and time replacing something that didn't need it.

2. Could the bad cats be responsible for the KS failure?

3. Has anyone heard of Catalytic Converter Cleaner? Does it work? Does anyone endorse it? I've heard a few good things about it, but I'm skeptic the comments are written by those that sell it.

4. I found the cats & pipes on Ebay manufactured by Davico. Anyone heard of Davico?

5. I found the cats & pipes on parts.com for twice the cost of that on ebay, and am considering spending the money, but I'm curious if these are dealer parts, or another manufacturer. Any one have experience with parts.com?

6. Anyone have any money saving solutions to finding reasonable priced Cats?

7. I'm skeptic about trying the salvage yard route, but I'm curious if I were to find a low mileage Y33, it may save me some time before spending the money. Any input?

8. Is there any maintenance I should do to the vehicle prior to changing the cats to prolong the next cats life span?

I'm already too far invested in this car to turn back, and besides, short of the struggles of getting it to run good, it's by far my favorite car that I've ever owned.

Any input is greatly appreciated.

Secondly, I would replace primary O2 sensors first as if you don't know (maintenance history?) they are probably shot. Cleaning is not a fix.

You can buy after market catalytic converters adn replace them every two or threee years. The reason they so cheap besides inferior construction materials, is they have less precious metals (platinum).

I would take a trip to Jerry Tucker's to get a better diagnostic handle. OBD II doesn't think nor analyze. It just yields moreinformation.

OEM Sparkplugs were changed when?

Discover the power of the button!

Everything appeared to be original when I purchased it. Spark plugs appeared they were the original. I replaced them with bosch platinum from autozone. I know that's frowned on here, and I have already purchased the prescribed spark plugs, but I'm more focused on fixing the possible problems with the cats.

I will change the front O2s, but would this be a likely cause for throwing a cat code?

The "Jerry Tucker's" you're referring to is in San Diego? I'd hate to take that long of a drive with these problems not resolved (live in Vegas).

cylinder misfire is likely a coil, replace the #7 coil to be safe but there may be other coils that are failing but haven't thrown a code yet (common on 97+).

As for cats (assuming they are gone), I'm not sure what kind of emission laws that Nevada has but I would get a OEM from a junkyard first and after that I would pull off the downpipe and have aftermarket cats (like magnaflows) welded on by a muffler shop. Again, emission laws vary but you may even be able to use two big cats to replace the OEM four.

Good luck

Good luck!

Competent Q45 technicians (Senior Infiniti Tehcnicians) few and far between.

Test the KS through their harness.

Modified by maxnix at 8:08 AM 7/11/2009

At least you are beyond the 10 year tampering limits.

Aftermarket replacement cats are of low quality and minimum cat plating to just make it thru 1 year of testing [see warranty if any]. While oem must last 80-100k minimum per Federal Law.

Actually by buying in California you can sue [with help from CA] the previous owner who obviously committed emission fraud by selling you an emission defective vehicle..............presenting a passing emission certificate is emission fraud via documentation when it can be proven that cats were bad at time of sale.

But then again with 97 only being worth $2,000 > $3,000 max it is usually not worth the hassles in time.

We warn every buyer of 10+ year old vehicles to have $3,000 available to fix the minor problems not dislosed by previous owners.