First, a disclaimer -- complete newcomer to the boards. A search for relevant posts left me thinking a general, "what-to-do," question was in order. Also, found myself at a complete loss when the more technical members of the forums were discussing their mods. That said, this post is a request in hopes you can help guide the decision on what to do with this vehicle. At the moment, it is parked in a non-driving state and the goal would be to return it to status as a daily driver.

• 2004 Infiniti G35x (3.5L, VQ35) with 140,000 miles (Gray/Black Interior) - 100% factory/No after-market mods
• Back-pressure indicates failed catalytic converters on both sides per third-party shop.
  • Service Engine lamp flashes while driving. ("catalytic converter damaging condition")
  • Runs VERY rough with intermittent surges; Occasional stall.
  • Occasional Fuel Smell perhaps related to poor combustion.
• Loud squeal during starting - Most likely failed bearing on power-steering pump that started after new belt installation.
• AWD Control Board has failed per Infiniti (Nothing on OBDII; Guess it isn't included.)
• Interior Condition - Good - New radio needed; Everything else works.
• Exterior Condition - Poor - Needs Xenon headlight replacement; Multiple bumper dents; Small rust spots.

That's the gist of it. The question is, what's to be done? It's been a great car, and it'd be a shame to let it go like this. But, the prices on cats (>$1,800) and the power-steering pump ($>400) seem to be the death-knell for a car with 140k and a street value of roughly $2,500, in good condition. While the desire to improve performance isn't too great - she isn't headed to a track anytime soon - it's very likely that the engine maintenance and exhaust work would offer opportunities. The other consideration is any damage the failed cats may have caused to valves/pistons - just because the lamp was blinking doesn't necessarily mean we haven't been on the edge for some time.

The questions:

1. Should there be any effort to save a car in this condition with the anticipated costs and limited ability to perform DIY repairs?
2. Purchasing after-market catalytic converters is easy; who do you get to install them? Midas wants $2,400, for their own gear and that's absurd. In the same vein, other shops will only use their own cats for liability purposes. (The exhaust system hasn't been touched since it was manufactured; this will most likely require a torch.)
3. The power-steering pump and Xenon headlight must be replaced. The AWD board does not. (Car defaults to 25/75 per documentation and we're not around snow.) What else should be done if this were to return to status as a daily driver?

Thanks for taking the time to read this and I'm looking forward to your thoughts.

 

I can't comment on much more than the cats in depth, but IIRC a flashing SES is more serious than a simply lit one; get codes pulled at an auto store pronto.

As for cats, you can always go with High Flow Catalytic Converters. With stock exhaust they'll make the car a bit louder (speaking from experience with a coupe and Berk HFC, some of the loudest ones), but ones by Fast Intentions or any other reputable brand are very solid. They are also much cheaper than OEM, costing $650 at the highest; various shops quoted me $100-150 to swap them, but if you have jacks and some extended hex wrenches/extended patience, it's a completely do-able change yourself. You'll also pick up some power at the wheels; easily beats OEM for me. If you want a shop to install them, try to find a smaller mechanic/exhaust shop; installing cats isn't something that is easy to mess up, and prices should be better.

140k is fairly average mileage for the year, but the various problems range from easy (new headlights) to more complex (you mentioned the power steering pump and other engine troubles) give me some pause. Getting codes will help you narrow down the cause easily; my first guess is crankshaft sensor, but the symptoms you described could be a whole host of problems (camshaft/crankshaft sensors are a very easy fix if you DIY).

If I were you, consider the cost of the car plus the cost of repairs, and see if that is more than the amount it would take to get the same car/similar car that you want in good condition, even if it has higher mileage. If it's a higher cost to repair your car than purchase a new G (I got my 2005 Coupe 5AT for $6000; granted, I had to replace every tire and eventually the entire transmission, but that was partially my fault), I'd sell your current G and get a different car. A well taken of G with anywhere from 130k-160k should be findeable for anywhere from $5000-7000 (manuals carry a premium and it's getting harder to find a clean car, though). Even if the engine in your G is toast, you can find clean VQ35DE's online for less than $1000; if you have a mechanically inclined friend a swap can be done over a weekend, or a shop may charge around $1000, from what I've heard.

Best of luck with the G.

 

If you will turn the wrenches yourself then replace the cats with a used set from eBay or the marketplace here on G35Driver if any are for sale. The HICAS controller can't be read via OBD2 because it's not an engine control system. Dealership Consult-II can pinpoint the exact problem for a diagnostic fee. eBay the components that need replacing.

Personally I'd just fix the issues but it would only cost me about $500-$750, if you are paying someone to work then you're probably better off just selling the vehicle as a "mechanics special'.