1999 3RZ Misfire Codes P0300, P0303 NEED HELP - Page 2 - Toyota 4Runner Forum

SDsurfx · 04-12-2019, 02:31 AM

Final reply, mostly in case someone has this problem in the future.

Leak down test indicates cylinder #3 intake valves are leaking. It needs to have the cylinder head removed and sent into a machine shop for a valve job. The shop actually recommended NOT doing this, as something will likely soon go wrong in the bottom end @ 300,000+ miles, and it would be a wasted investment.

Gonna keep driving it as is and start looking for another 4Runner. Thanks for the help y’all.

davidch · 04-12-2019, 11:19 AM

Consider this: obtain two of the thinnest valve shims, the 2.50mm size. Install those in the #3 exhaust. These shims will guarantee you have clearance and that those valves are fully closed. Absolutely don't start the engine with the engine, as they might pop out, but I'm sure they'd stay in at cranking speeds.

Re-run the compression test. If the psi rating climbs back to match the others, you may have the situation where those valves were at or just a hair under zero clearance, and the valves havn't burned yet.

Then, get all the valves adjusted properly.

Kanoe · 04-12-2019, 09:26 PM

Quote:

Originally Posted by SDsurfx

Leak down test indicates cylinder #3 intake valves are leaking. It needs to have the cylinder head removed and sent into a machine shop for a valve job. The shop actually recommended NOT doing this, as something will likely soon go wrong in the bottom end @ 300,000+ miles, and it would be a wasted investment.

How do you know it needs a valve job? You still have not checked your valve clearances. A $10 dollar shim MAY be all you need to get it running right again. Especially if it is an intake valve, maybe it's not cooked. It hasn't been doing it long you say.

Park that thing and crack it open and check your valves! It'll take you less time than you spent on the injectors. Don't ruin a 3rz. This is craziness, madness, insanity. Trash an engine rather service it? It's not a difficult procedure, what have you got to loose?

MaineRunna · 04-12-2019, 10:50 PM

Quote:

Originally Posted by SDsurfx

Took it in for the valve adjustment. They ran a compression test first just to see what’s going on:
1- 180 psi
2- 180 psi
3- 80 psi
4- 180 psi

Doing a leak down test tomorrow to see if it’s valves or piston rings.

Look at your other three cylinder's compression, your engine is still strong! Get the valves adjusted or or the head rebuilt, Toyota bottom ends last forever if taken care of. This isn't some old big three small block, it's a Toyota engine. I gotta say it, I saw a guy years ago put rebuilt heads on a 70 Buick 455 and it smoked like a bastard and oil literally poured out of the tail pipes, but it had 155k on it and the rings were cooked, which is like a fuel injected Toyota having a having 4-500k on it. If you were running strong and not using oil and don't have other major problems, get it fixed.

SDsurfx · 04-13-2019, 12:26 AM

Got a ton of time off starting next week. I already have the valve feeler gauges. Gonna give the valve adjustment a try. Just sucks that I’ll have to crack it open twice to complete the job, but good point guys. I can measure one day, order all the parts and finish fit a few days later when I get the shims in. No dealer seems to stock them.

The shop kinda made me feel like it was a lost cause. I also found a machine shop in town, maybe I can just have the head checked out. Found another thread where a guy did it all for less than $500.

Thanks for getting me back in the fight on this!

SDsurfx · 04-14-2019, 02:27 PM

Gonna start ordering parts for this job, anticipating having to send the head off to a machine shop.

I’m not sure if a simple valve adjustment will fix the problem as the intake valves on #3 are leaking (must be the valve and/or valve seats worn).

Anything I’m missing here?

Toyota 4Runner,T100,Tacoma 2.4L 2RZ, 2.7L 3RZ (95-04) Full Gasket Set - FGS9039 (head, intake, exhaust)
Toyota 4Runner,Tacoma 2.4L 2RZ / 2.7L 3RZ,2TR,2TZ Engine Cylinder Head Bolt Set HBK957Head bolts
Fresh coolant (though it’s only got 5k on it)
Fresh oil/filter (due for change anyway)
New Plugs (old ones fouled due to misfire)

MaineRunna · 04-14-2019, 05:10 PM

Quote:

Originally Posted by SDsurfx

Gonna start ordering parts for this job, anticipating having to send the head off to a machine shop.

I’m not sure if a simple valve adjustment will fix the problem as the intake valves on #3 are leaking (must be the valve and/or valve seats worn).

Anything I’m missing here?

Toyota 4Runner,T100,Tacoma 2.4L 2RZ, 2.7L 3RZ (95-04) Full Gasket Set - FGS9039 (head, intake, exhaust)
Toyota 4Runner,Tacoma 2.4L 2RZ / 2.7L 3RZ,2TR,2TZ Engine Cylinder Head Bolt Set HBK957Head bolts
Fresh coolant (though it’s only got 5k on it)
Fresh oil/filter (due for change anyway)
New Plugs (old ones fouled due to misfire)

Maybe a timing chain and guides if you feel like it.

SDsurfx · 05-03-2019, 10:28 PM

Well she’s back on the road. Got to a point where I was running into problems I hadn’t anticipated (broken timing chain guide), and was using my vacation wrenching when I’d rather be surfing.

Had a shop finish it off:
1. Cylinder head rebuilt (#3 intake valves were in fact BAD)
2. New timing chain and guides
3. Fresh oil, coolant, and gaskets

Runs great. The intake manifold was filthy, can’t believe it was even running much less getting 20ish mpg on only 3 cylinders!

No more P0300/0303, CEL, or rough idle.

Alan in Alabama · 07-04-2022, 12:48 PM

SDsurfx, Thank you for your last follow-up post where you told the final outcome of finding the problem and having it repaired. I've followed on various forums through the years and the worst threads are where someone asks for advice, gets it, and then disappears, making the thread much less useful for future people who have the same problem. And many times not even a thank you for expert, free help.

I did a search for 3RZ problems and found this thread,

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