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Hi everyone....I'm new here. I have spent a great deal of time researching on the Web and here in this forum about some issues I'm having with my Infiniti so I thought I would post about what I'm doing in case any of you helpful .org members can lend some help/advice.

I own a 2000 Infiniti I30t. The car just rolled over 200,000 so she's got a few miles on her. I didn't let the mileage bother me because the original owner put a whole bunch of new parts on the car (shocks, struts, tie rods, suspension, ball joints, etc.). He always put Midgrade fuel in it so I kept up that habit. Aside from the radiator support and the driver side caliper freezing up I haven't had any major issues with the car. The thing that really surprises me is how good it is on tranny and oil; I've had the car now for about a year and haven't had to add any fluid (the levels remain constant on the sticks).

When I first purchased the car I had my mechanic look the whole thing over and he said she was in awesome shape. He pointed out that the check engine light was on because of some fault with the catalytic convector. He said the cat was too expensive for me to replace on that year car so he advised just ignoring it.

Well, I'm **** retentive so I couldn't ignore it. I went to AutoZone yesterday and had the guy put the scanner on so I could get the code number for the problem and he came up with three codes.....

Code P0420
OEM Brand: Infiniti

Definition-
Catalyst system efficiency below threshold-bank 1

Probable cause-
1. Large vacuum leak
2. Rich AF ratio-fuel system faulty
3. Ignition system malfunction
4. Faulty catalytic convertor

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Code P0430
OEM Brand: Infiniti

Definition-
Catalyst system efficiency below threshold-bank 2

Probable cause-
1. Large vacuum leak
2. Rich AF ratio-fuel system faulty
3. Ignition system malfunction
4. Faulty catalytic convertor

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Code P1440
OEM Brand: Infiniti

Definition-
EVAP control system (small leak) (positive pressure)

Probable cause-
1. Gas cap loose
2. Failed canister purge or vent solenoid
3. Failed EVAP control hose or fuel tank
4. Faulty EVAP pressure sensor

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A couple months ago I had went to O'Reilly's and had them scan my car and he only came up with one code (P0420). Now I have another CAT code and the EVAP one. Slamrod was kind enough to give me some info on this and he even suggested a theory about the codes...

"A thought just occurred to me, it may be possible that the EVAP code problem is the root cause of the precat codes. The EVAP system is a part of the fuel delivery system that "evaporates" the gas in your tank so it can be sprayed from your fuel injectors. I'm not sure what specific symptoms this would cause, however i would heavily assume that a fault in the system would cause the car to use more fuel than normal to compensate for the faulty sensors (more fuel is safer for the car and has no bad side effects, while less fuel = more air = engine goes boom). The extra fuel being dumped would cause your air/fuel ratio to be very rich (rich - more fuel, as compared to lean - not enough fuel/too much air). This rich AFR would make your exhaust emissions extra heavy with emissions gases, to the point where the cats can no longer keep up with them, causing the secondary o2 sensors to detect abnormally high amounts and give you your precat codes."

I'm no big knowledgeable car expert, but from what I have read in these forums about the EVAP that sounds like a fairly reasonable assumption.

I checked the gas cap first because that's what a few people have mentioned in the threads when it comes to this type of code. The cap seemed fine and so does the gasket. It even hissed when I took it off so there must be pressure in the tank. Other users have recommended buying a new OEM gas cap, or just cleaning up around the cap and making sure to close it for "3 or 4 clicks". I'm going to try cleaning it up first before I buy a new one, then clearing the codes and driving for a bit to see if the EVAP code comes back.

If it does then I know to move on to the EVAP system causes. I like Slamrod's theory so I would like to start with the EVAP and get that cleared up and then see if it also clears up the CAT codes. I'm going to climb under the car and get some pics of the rear EVAP setup, because in threads like this one I've read that's usually where the problems start occurring (vapor canister, purge valve, hoses, etc.). I'll post the pics when I get them.

I also found links in the forum to the FSM for my car and I downloaded all of them and then made one PDF out of the whole thing so I could easily find what I need. I located the sections on the EVAP components and printed them out so I could find them on my car.

Slamrod was very kind in helping out this n00b when I was posting about my lower radiator support problem and he said, "If you do end up getting involved in the .org, be sure to pass it forward as well for the next guy." Well, this is my way of "passing it along." Hopefully all this will help another n00b whose having similar problems.

I'll post more as I continue to dig into this thing.....

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So, Step 1...the gas cap. The OEM ones I've looked at look just like mine and I don't see anything wrong with mine so I'll wait on buying another one.










Now that it's clean I'm going clear the codes and do some driving around. I've read in my research here on the .org that people recommend not topping off the tank because there could be some overspill that would effect the EVAP system (the charcoal EVAP canister, I believe). They suggest driving around to build up pressure back into the system and then rechecking to see if the code comes back.

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Here are some pics of the rear EVAP system on my car (it's located on the rear driver side of the gas tank).....











They certainly cram enough crap in there, don't they? Got some rust going on, but it doesn't look like anything serious.

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Well, I filled the tank, made sure the gas cap was on tight (3-4 clicks), drove around for a couple days and the CES came on again. I got the P0430 code again, but this time instead of the EVAP code I got a P0325. I've read about this notorious KS so I know it's a real pain in the ****. Made me start thinking about how much I want to spend on this car, especially with the money I'm already shucking out for the front end work. The car runs fine—no pinging, misfiring or stalling issues.

The only other issue I need to address is the weird hesitating when it starts. I think that's just the starter.

boondoxmax

iTrader: (1)

I had the p0430 and p1456 codes on my 03. Replaced the front precat and the evap canister and vent valve. Codes gone. Need to do the knock sensor next.

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I've been thinking about this whole rad support job. Even though I love my Infiniti (I call her Gorgeous, heh), at 14 years old I can't justify spending $650 on the front end. Somewhere on this forum I've seen a thread where a guy welded a beam under his radiator and it was all good and cost a lot less. I'm not sure yet what I'm going to do, but there has to be a different solution that costs less than $650.....

Also, right now I can definitely tell my gas mileage stinks compared to right before I got all these codes. So if anyone knows if mileage can be effected by O2 sensors (the CAT codes) please let me know. I'm not sure if the KS code would effect gas mileage or not, but something sure is.