Aron9000

So the car is a 1992 SC300, completely stock 2JZ-GE, 5 speed manual, 99,700 miles, I'm the 2nd owner, always impeccably maintained, I have every single damn service receipt since this car was new.

Anyways, I don't drive this car every day(I have a Tacoma truck as well), but I do drive it a bit, especially on long trips. Anyways, I started driving it again this past week, after it had sat for about 3 weeks, maybe a month. Well what the hell, in 2nd gear, between 2-3k, it starts developing a random misfire, like the engine is cutting out. Almost like it isn't getting fuel, the feel of the "miss" is very similar to an old Cadillac I had with a bad ground. But hell, maybe it is spark or fuel related, to my records this car has never had the spark plugs changed, I really didn't want to do them because its kind of a PITA to do them on this motor.

Anyways, its a very random sort of thing, it only happens very occasionally, in 2nd gear, going up a hill, mid throttle, pulling 1800-3k rpms. I'm thinking maybe spark plugs, since it is so random and happening when the engine is under a good damn load. Otherwise it runs great. BTW it is summer so I am running the car with the A/C, which works perfectly. I don't think its the A/C compressor locking up, because I've had that happen in another car and it it just siezed, then destroyed the serpentine belt.

Any ideas on the diagnosis would be appreciated. I have a trip planned to Atlanta in July, and I'm not taking the Lexus if its running funny. That reg cab Tacoma is a penalty box on wheels if you're doing a long trip, very noisy, no cruise control, fart in it and it becomes a **** gas chamber.

Brennen01

I would suggest looking at your ECU to see it has any leaking capacitors and do the 12V fuel mod to see if that helps.

https://www.clublexus.com/forums/per...tures-faq.html

jimbosr1

you might want to change those 25 year old spark plugs,LOL
before you do any other trouble shooting.

Bdub215

iTrader: (1)

Wtf is the 12V mod going to do on a car with bad plugs??????

1997Soarer

iTrader: (1)

This. The spark plugs that came with this car from the factory were only rated to last 60k miles. You've managed to go 40k miles past that. Until you swap them out, there's no way to tell if you have any other problems until you rule out the plugs by replacing them.

Aron9000

Spark plugs might have been changed, maybe not, I just don't know. If this were like changing plugs on my Tacoma 4 cylinder(ie super easy), I'd have done it A LONG time ago. Been driving it a bit more, the miss has gone away, maybe it was a case of bad gas, as it had been sitting for like 4-6 weeks with half a tank of fuel in it. Going to fill it up tommorrow with GOOD shell gas(not the crap Kroger/Thortons gas) tommorrow and report back in a couple of days. Kind of pisses me off how much of a premium "premium gas" goes for, its 80 cents more than regular at shell, 40 to 50 cents more at Kroger/Thortons/discount gas stations, I've been using the cheap 92/93 octane at the discount stations, I kind of wonder if this would make a difference(all the stations I buy gas from are fairly new and VERY BUSY, thus the gas wouldn't have water in it coming from the station, hopefully).

Also if I change the plugs, should I change out the plug wires??? The look fine, the parts I can see anyways. All the vacuum lines, radiator hoses, and rubber bits on this engine look brand new IMO.

KahnBB6

iTrader: (5)

Changing spark plugs on a non-VVT 2JZ-GE is a minor PITA but it's not entirely horrible.

It can't hurt to have a little extra vacuum line on hand in case you might need it. Gates brand hose is the best.

Yes, you should change the plug wires with a Denso OEM spec if they are very old. I usually give them 120k miles or so from new at most.

Plugs... I don't know the part number for our engines off the top of my head but I think they should be NGK Iridiums for the best plug life.

Distributor cap and rotor -- get both from Denso.

The most annoying parts of this is the dismantling of many of the sensors on the throttle body, putting absorbent blue disposable shop towels and a rag underneath the awfully placed coolant bypass pipe on the the throttle body and getting the throttle body off without getting coolant into the spark plug galley. Once I started using a special type of very long needle-nosed pliers with a 120-degree bend near the tip I've always had a much easier time getting that bypass hose unclamped and reattached.

There is no good way to do the spark plugs on a 2JZ-GE non-VVT without the engine being totally cold, as in leaving it overnight before doing the plugs the following day. That is, unless you follow the TSRM's advice of draining all the coolant and refilling it later.

Aron, if you haven't had the ECU rebuilt with new capacitors yet I would also consider that as a priority in addition to the plugs.

Also, if your plugs really are this old and worn out your two front O2 sensors might have been affected from over-fueling also. It's not a given and should not be addressed before doing the plugs and rebuilding the ECU but it is also possible in addition.

Aron9000

^ Thanks for all the great advice. Guess I'm finally going to have to roll my sleeves up and get dirty, been putting off spark plugs for a while now(hell it ran great until a couple weeks ago). Might as well fix the leaky valve covers while I'm in there as well.

Also with the ECU, is the case easy to take apart(ie a couple of screws)??? I didn't see a thread in the FAQ section about the ECU. Figured I'd take it apart, if the board and capacitors look good, put it back together and not worry about it. I've read about this problem with the LS400's, the capacitors bulge or leak, causing you random weird issues like the car sputtering.

Aron9000

UPDATE:

Car has been running great the past couple of weeks, I think it might have been bad gas from it sitting for a month with half a tank.

Anyways, I changed the oil today, while I was at it, I pullled the #1 spark plug for inspection(or maybe its #6, its the one at the front of the motor that's easy to get at). What do you think? I'd say they're due for a change lol . . .

RXRodger

iTrader: (2)

Looks ok, I don't see anything there to be concerned about, maybe get a set and have on hand for when you have something else going on with the car and have time to change them. By the way, the Denso plug is PK20R11 and NGK is BKR5EIX-11, I would stick with which ever of those two is available/cheaper since they both work equally well. You are right, it's a PIA to change these. Edit: You can order them from Amazon for about $35 or $40 no tax free shipping.

As far as the O2 sensor comment by Kahn, he says the front 2 but he must be thinking later models because in the 92 the front 2 are the only 2. Also, your plugs have been changed because what you have in your hand is an NGK which didn't come in the car, at least I don't think they ever did, Denso would have been in the car originally unless I am totally wrong on that which would not be the first time.

Another edit, listen to what the rest of these guys are saying on the ECU, get it serviced or you run the risk of damage to your ECU board from the leaking capacitors and then you will be trying to find one of the early ones used and still may need the service. Money well spent.

Aron9000

Yeah they don't look bad, but they aren't great either. When I had the cover off the engine, man the timing belt looked great, which tells me that sticker on the air cleaner, that it was done in 2010 at 58k miles is spot on.
I'm pretty sure that running rough was bad gas, I drove it hard on the tail of the dragon back in April, last time I really drove it until mid June, hell it might have sat two months with a half a tank of gas in it.

I'm thinking some major work at 120k, when the next timing belt is due, car is at 100,500 right now. Complete timing belt service, new spark plugs, new plug wires, new distrubitor cap and rotor, fix the leaky valve cover, fix the leaky distributor o-ring. Any other work you guys recommend while I have the engine apart in a year or two???

Right now I'm going to keep driving it, as it is running strong, just as good as when I took it up the Tail of the Dragon back in early April.