Missfire #3 - Possible sticky exhaust vavle?

[homerobitaille]

I'm so excited that I found this forum - I hope you guys can help!!

I have a 1998 SR5 4X4, 3.4 L 5VZ-FE (130K miles ) with an intermittent misfiring problem. The engine sometimes runs rough (misfires) when I start it after parking with a warm engine. After a few minutes of driving the CEL will blink and at one point (after accelerating onto the freeway) it stayed lit.

My mechanic found an error code for 'misfire #3' and traced the problem to a shorted spark plug wire. He replaced all the wires, the coils, and the spark plugs and it seemed to fix it. But on the way home I stopped at the store (5-minutes of driving) and when I came out - it began misfiring (with the blinking CEL) again! Of course when I started it to take it back to him in the morning it ran just fine and the CEL was off. :rant:

My mechanic now suspects a sticking exhaust valve and is trying to re-create the problem so he can check the compression.

Has anyone else had this problem?

Is there a quick fix other than a (very expensive) valve job?

 

[theizzardking]

I'm so excited that I found this forum - I hope you guys can help!!

I have a 1998 SR5 4X4, 3.4 L 5VZ-FE (130K miles ) with an intermittent misfiring problem. The engine sometimes runs rough (misfires) when I start it after parking with a warm engine. After a few minutes of driving the CEL will blink and at one point (after accelerating onto the freeway) it stayed lit.

My mechanic found an error code for 'misfire #3' and traced the problem to a shorted spark plug wire. He replaced all the wires, the coils, and the spark plugs and it seemed to fix it. But on the way home I stopped at the store (5-minutes of driving) and when I came out - it began misfiring (with the blinking CEL) again! Of course when I started it to take it back to him in the morning it ran just fine and the CEL was off. :rant:

My mechanic now suspects a sticking exhaust valve and is trying to re-create the problem so he can check the compression.

Has anyone else had this problem?

Is there a quick fix other than a (very expensive) valve job?

not sure on these motors a but a leak down test would be far more beneficial than a compression test as all that does is tell you the compression on each cylinder at the p and c's a leak down test actually tells you about your lifters from previous expince with other motors i've built these are different beasts though so it maybe no good also make sure you don't have a vacuum leak as it can also cuase the problems your having as well.

there are a few things you can do to fix a sticky lifter but to get to that point you might as well just replace them on these engines as they are harder to get to.

 

[homerobitaille]

Thanks Mr. King - I'll mention the leak-down test to my mechanic.

 

[toytech76]

A leak down test wont tell you much unless its acting up on you. I honestly doubt its a sticking valve. I have never seen/experienced this on these engines. I would be more suspect to a intermittantly failing injector. Also #3 is under a coil pack. If the plug had a carbon track down the side, it would of transfered to the coil boot and would cause the same problem fairly quickly again. Have him remove #3 plug, check for carbon tracking, and if present, replace the plug and coil. If all is well, have him check the injector when it is misfiring

 

[homerobitaille]

Thank you Mr. 76 - Glad to hear that vavle problems are rare in this engine. He already replaced the the wires, boots, coil packs and plugs (he had seen a burn on the #3 boot). But it didn't do the trick! I like the intermittent injector failure idea... I have a standing offer with him to bring it immedietely when it starts acting up.

It's running fine right now but I am just waiting for it to act up again. Any bets it will happen on my trip to the high Sierra next weekend??

 

[Charlee78]

Look like to me you have a leaking injector. Looses pressure in the cylinder when you stop the engine. You wait a couple of hours then you start it and misfires, give you a blinking check engine light because you are damaging you cat. If you wait 'till the next morning, the gaz evaporates in the cylinder so it start up just fine.

I may be wrong, but it looks just like an injector to me...

 

[toytech76]

The injectors dont leak down usually. They stop firing completely. I havent replaced any injector on these that had been leaking down. its possible but unlikely.

homerobitaille, Where in norcal are you? Who is your mech?

 

[homerobitaille]

Thanks guys. The mystery continues - I'm on day 3 and its still running great! I'm sure it's waiting for me to go on a long trip... I'm debating replacing the #3 injector just as cheap insurance against ruining my cat - but it's still just a shot in the dark.

Mr. 76 - I live in Martinez and use a local shop. Martinez Automotive, located downtown on Green St. Son is the head mechanic. His prices are fair and he's really great at explaining what he finds, what he thinks should be done next and why.

 

[PossumJenkins]

I have the same problem on my 2000 only its a #2 cyl misfire on cold starts that throws a CEL on my truck. I had a shop clear the system to see if it was a one time thing and it took about a week then it happened again. I am hoping my problem is a bad plug or wire possibly because I only have 65k miles on it.

 

[homerobitaille]

Good luck with your problem Mr. Jenkins - I'll be sure to post any resolution I find. So far it hasn't happened again so... I'll have to wait and see!!

 

[cyclenut]

. If the plug had a carbon track down the side, it would of transfered to the coil boot and would cause the same problem fairly quickly again. Have him remove #3 plug, check for carbon tracking, and if present, replace the plug and coil. If all is well, have him check the injector when it is misfiring

I just had the #3 plug get this exact carbon track down the side, leading to misfire. I changed out the coil pack, wires and plugs. Its healthy again...thanks for the tip!

The plugs were eroded more than I expected after 50K ( I know... I should've done them sooner.) Anyways, the gap on #3 was about 0.055", more than the 0.043 spec. I'm wondering if this extra gap didn't help kill the coil pack. The coil pack was nicely discolored to a brownish/black color.

Hopefully I'm good for another 230,000 miles on this 99.

 

[jsulen]

Check the compression of each of your car's cylinders. If you don't have any compression on a cylinder, this means that you have a burnt-out or bad exhaust valve. If there is no compression on a cylinder, the car is running on less cylinders than it should, which can cause the engine to run slower and become damaged easier. Compression can be checked using a compression gauge or engine analyzer.

 

[tjaguilar]

I had this misfire cyl 3 and i got my injector changed and problem solved but it may be different for from what im reading. Good luck!