Hey all,
I have an intermittent CEL 25; I have replaced the cap, rotor, plugs, wires, my temperature gauge seems to be working ok, had the head gasket done not too long ago, my cylinder pressures are all 71, with the exception of one that is 64; I replaced the o2 sensor with one I already had that was good, still, intermittent problem. Any one deal with this problem already? I understand it could be the following,

1) Engine ground bolt loose.
2) open in E1 circuit
3) Open in injector circuit
4) fuel line pressure (injector blockage, ect.)
5) open or short in oxygen sensor circuit
6) oxygen sensor
7) ignition system
8) engine coolant temp. sensor
9) volume air flow meter (air intake)
10) ECM

but what is the most common failure.

 

i'm experiencing the exact problem too. intermittent code 25 and my head gasket was just replaced back in Jan. hope someone could help out.

 

fuel filter, fuel pressure regulator, leak in intake system, plugged airfilter . . .

 

Must be something simple, I replaced the fuel filter recently, pressure was ok, air filter of course is ok, am thinking it may be a burnt valve. How could I check that out, or would the symptoms be different?

 

your cylinder psi is only 71??? Either you have a bad gauge, didnt do it right or have way low compression in all cylinders. A code 25 will most likey be from a faulty #1 o2 sensor or low compression from a burnt exhaust valve which is very common on 3.0's. If your is a 4cyl check your valve clearences. Factory specs are .008 for intakes and .012 for exhaust. Run a better comp test or have someone with a better gauge run one

 

its a 6 cylinder, I googled it and that what most people say it should be. I read that on a repair guide someone put together. So, it seems, that the pressure is ok; I did replace the O2, if it was the O2 am not sure why it wouldnt just pop up with an O2 failure code. Anyway, the truck also runs rough, I also replaced the EGR valve, it was bad, but car still runs rough, and code 25 ( I already reset the ECU).

 

who did your comp test? I think you need to do another one with correct numbers. Im willing to bet you have a burnt exhaust valve and thats what is giving you code 25

 

A buddy who is a mechanic measured it, he compared it to another 3vz 3.0 side by side, one that had < 100K miles, they were about the same. Am I done if I have a burnt exhaust valve?

Now that I think about it, I could be wrong, it may have been 171.....as a matter of fact, it was, just looked at the numbers that I wrote down.

 

that sounds better. You arnt done if you have a burnt valve. This is a common thing. You just need a valve grind done. A shop will charge you about 2400-2800 for a complete, correct valve grind with toyota parts

 

Yeah, but wont doing a valve job create more pressure, and possibly creat problems with the piston rings? I was thinking of looking into one of those 30,000 mile japanese motors, can get one installed for about 2,000; everything already included (heads etc).

Is there any way to test for burnt valve? When I had the head gasket done about two years ago, they recommended not having a valve job done because it could cause more pressure and create problems with the rings. I there any short term, temp fix?

 

if all cylinders were at 171 psi then i highly doubt you have a burnt valve. if it did your pressure would be slightly low on that cylinder. if the code is intermintant then i would try an injector cleaning if everything else is good.

 

He did say he had one cyl that was lower than the others. That would do it. How often do you ever see injectors causing a code 25? In 11 years I havent ever seen one. Doesnt mean it isnt possible but if he has already replaced his O2 sensor, has 1 low cylinder, eng runs rough, I would look at my valves first

 

Yeah, Code went off yesterday, but it is only a matter of time before it returns. Car does run rough, one cylinder was about, 161 or so, the rest were 171 psi.

Like I mentioned, is it worth putting that much into it when for approx 3k I can get a rebuit, or for 2 k installed, I can get one of those used japanese motors? With 250,000 miles, I wouldnt be suprised if it was a valve, They check them when they did the head job (I guess some kind of test while the heads were off); they were ok then, but that was a couple of years ago.

 

yes but again, you never know what shape the used motor is in. You know how yours has been treated so best to repair what you have

 

Is it true that having a valve job done can create other problems with the rings?

you guys know of anyone who has done a valve job with that many miles and worked out ok?

 

You wont have any ring or lower end problems. I have done ALOT of V/G's with that many and more miles and everything was fine. Yours will be just fine

 

Thanks for all your input, its been very informative; just wish I lived up north so I could drop it in your shop!
Thanks again.

 

I've finally fixed my code 25 by replacing the AFM with a used one from ebay. CEL has been off for a week so far...so good! *knocks on wood*

 

Hello again,
I bought a 94 4R 3.0 5sp with 172k on it and drove it for about 1k before I decided to clean the throttle intake with a 1/3 bottle of Seafoam (that was lying around since I couldn't get a throttle body cleaner), a rag, screwdriver and a toothbrush.

I've done this before on my 93 22RE and I noticed a postive difference. While at it, I checked the plug wires to notice one snapped in correctly at the plug.

Fired it up to a little than higher idle (2k) and proceeded to drive when the CEL came on. Checked clamps and connections again of the rubber boots and cleaned it again with throttle body cleaner this time, but still the CEL comes on after I accelerate a bit. Weird because it doesn't come on right after I fire it up or drive up to 3rd gear (without too much on the pedal), in some cases.

It runs fine (tho idle is at 1.2k) but the CEL is bugging me. I noticed that there is small tinging (grinding) sound right under the air filter. Could it be the MAF? Always seems to be the case, I think to do something good for the truck and I screw it up. I don't want to retard the timing (or anything) because I like the 20mpg. Please help. Thanks. DJ

 

Sorry Rene, I thought I started a new post...didn't mean to rip yours off. Ooops