I picked up a cherry 1997 Infiniti J30 with 68k miles last week. The first few days she ran like a champ. On Thursday I went to start her and she cranked up like normal, ran for 2-3 seconds, sputtered and died and then wouldn't start again. Cranked fine but wouldn't fire up. Tried the next day, same thing. Giving it some gas didn't help stop the car from dying or in starting the car. There was no CEL.

I scanned her a few minutes ago and found a P0325. For kicks and giggles tried starting again. She cranked up with a little finesse on the throttle but idled somewhat rough. Interestingly, turning the AC on seemed to make her run a little smoother and bring the idle up a little bit (just shy of 1k, w/o AC more like 700-800). Took her around the block and I feel like she was a little sluggish. But it's a new car to me and my daily has much more power so take that with a grain of salt.

FWIW, I do think the car was sitting for a while. I put a fresh tank of gas in immediately after the purchase. Only issue flagged on the PPI was leaking valve covers, which in my book is just old car stuff.

I've read the P0325 is rarely actually the knock sensor, it just tends to throw that with other codes or with misfires. Can anyone speculate as to what might be going on? Going in for diagnosis and timing belt next week, so hoping to have some ideas before they get back to me with their diagnosis. Also kind of hoping a fuel filter and can of seafoam may fix it...

Which leads me to a slightly tangential question. Is there any good way to get the fuel filter off? I was struggling with the lines being basically fused on for near 30 minutes before calling it.

Half the stuff built in the late 90's to early '00's will have a P0325 two minutes after you install a brand new knock sensor. On a car from that era the code is meaningless, the ECM just throws it "because" for reasons that I'm sure only Hitachi understands. The fuel filter is a reasonable suspect, but you can easily rule it in or out by squirting Brakleen or some other combustible down the intake. If it runs great for 5 seconds after a squirt then the problem is fuel starvation, if not then it's something else.

Good info, thanks. I'll make sure the mechanic doesn't insist on the knock sensor.

I'm either half way or 1/10th of the way into changing the fuel filter. That bottom line just won't come loose no matter how much I try to break the bond with a tiny screwdriver. Not enough slack in the line just to cut it, unfortunately.

Usually you can get any frozen hose loose by using a small hook-tool to lift the edge, spray WD40 or PB Blaster on it and then gradually work the hook between the hose and nipple. The WD will follow the tip of the hook and when you get about 1/3 of the way around the diameter, the grip will usually let go.

VStar650CL wrote: ↑

Mon Mar 29, 2021 9:30 am

Usually you can get any frozen hose loose by using a small hook-tool to lift the edge, spray WD40 or PB Blaster on it and then gradually work the hook between the hose and nipple. The WD will follow the tip of the hook and when you get about 1/3 of the way around the diameter, the grip will usually let go.

Thank you. This is going to be pretty helpful generally. I tried prying with a small screwdriver (destroyed the screwdriver in the process) but it didn't occur to me to use PB/WD. Is it a different tool for fuel lines versus like radiator hose (ie: smaller)? I'm assuming this is the same process for any hose that's bonded on.

Side note, I think this fuel line may be too small as well. I got the upper line off by partly cutting it then prying then giving her all my burly (not-so-burly) man might. However, I put it back on after giving up on the bottom and now the upper one is stuck like hell again. On my 300SD which also uses rubber fuel line (all of which is fresh due to me re-routing the fuel lines) it always just slips right off after releasing the clamp. Is that normal or do you think I might be looking at lines that are too small?

Quick update. Went out to test the car and she actually idled normally. So possible the shiny new gas + seafoam did the trick (still didn't get the fuel filter off). FWIW I found out the car has only been driven 400 miles over the past 10 months and the selling dealer had her for 2 months without any driving to speak of. So there was likely quite a few months of just sitting involved. Car has to go in for a timing belt anyway (don't have time to screw with it) so I'll still have the mechanic check it out.

Fingers crossed clean bill of health and she continues to idle normally so my next update will be calling the thread resolved.

Waiting on my precision hook set from Amazon for the fuel filter, but the mechanic pointed out potential issue with the IAC and that the throttle bodies were dirty. They wanted $290 to mist something through the intake. I got CRC Intake Valve and Turbo cleaner and emptied a can of that into the car. It seems to run much better. I haven't had the crank/no-start since and the idle seems better. I was going to take throttle body cleaner to the throttle bodies as well but they seem pretty sparkly after the first treatment.

With the help of the precision hook set the filter was a breeze... sort of. And between the intake cleaner and the filter the car seems to be running great now. Think I'm going to spray that stuff in all my cars.

That said, idle does seems to fluctuate slightly and I really would love to clean up the IAC. So yeah, if anyone has any input on where that is I'd be eternally grateful. I've seen videos on how to disassemble and clean but nothing on physical location. I'd give my first born for a picture about now (but in all fairness I don't have a first born so it's a bit of a one sided deal).

The IACV sits on the back of the engine, against the firewall, in the upper corner, driver side
It attaches with four bolts, hard to get off.....there is a 10mm "bolt" you can turn to adjust the idle.
If I remember correctly, to adjust the idle you have to disconnect throttle positioner switch...