Manager Forum

Not quite sure what is happening on this one.

Car has 138K miles, we have been performing maintenance since 95K just bought at 80K. We had been advising him to replace his spark plugs since 120k. At 136K he had us replace the plugs stating at the time it was hesitating. It had codes for misfires on cyl1 and 4. When we replaced the plugs we noted that the diodes on the plugs from cyl. #'s 1 and 4 were bent over. We scoped the pistons and found no marks and made notes then replaced the plugs making sure to use the correct oem plugs which were the same plugs we took out. Six weeks later the customer was returning from a middling long road trip and noticed the hesitation return. We reexamined the plugs and found that cyl#1 plug had been bent again and the porcelain was cracked, but not 4. Customer states no head job ever done. Carfax doesn't show any history of it. Never had this issue before 136k. There is no unusual noise from engine when running, plug is not crushed, no marks on piston head. Obviously there could have been headwork done prior to his purchasing the car but I am surprised if that is the case that this problem waited so long to show up. I am at a loss as to how to proceed. Pull the heads and send them to a machine shop? Can they measure how much if any has been milled? Is there an adequate way to measure piston stretch? Suggest engine replacement? How do I advise my customer? As a temporary fix we have added a washer to the plugs in question and have advised him that we will research the problem. T

hanks in advance for any input.

Never ran accross this but im curious

This is a common problem with Nissan. The power valve comes apart on these. The screws that hold it on fall out and are passed through the engine, often engaging the spark plug on the way. There is a recall and this may be fixed still under warranty.

I have seen those little screws come off but never damage the spark plugs. I cant remember but I believe I found the screws in one once. Ill try to remember were they were at.

ricmorin wrote:This is a common problem with Nissan. The power valve comes apart on these. The screws that hold it on fall out and are passed through the engine, often engaging the spark plug on the way. There is a recall and this may be fixed still under warranty.

can this happen twice on the same cylinder? that is definately a 3rd possibility i had'nt thought of

For those who don't know, the power valve is actually the VIAS system on these engines. It's a variable induction system with a little flapper in the intake stream. It has a solenoid and an actuator, along with a position sensor. The screws come loose on these. Usually you get some type of drivability symptom prior to them coming off, but not always. I have seen them damage spark plugs, but are usually too small to do any further damage. You can use a borescope and look down into the intake runner. If any are missing, there's your problem. The campaign (not actually a recall per se) number is 05-058B.

Of course, this is only a possibility. It could very well be something else.

It looks like ours was a 05 altima and the gap was closed ont he # 1 plug It looks like we did find the screws in the cylinders. oct of 2010 cant believe I didnt remember the issue better. Thats sounds like your solution.

The plate # is 14513-8J000 we needed one, the screw # is 14511-8J00B youll need 8 and we used autolight plugs with no issues and a felpro manifold gasket set . I thought we found the screw in the cat but maybe im wrong im getting to old

Hmm, just checked with dealer. No outstanding campains on this car. Will get him back in here and take a look at those screws. Will post later.

It may have been already done. But that doesn't mean they can't loosen again.

Let us know what you find.

Got the vehicle back and looked down intake with boroscope. Couldn't see screws but did see the blade and while looking at it, worked the actuator with no blade movement, stuck about 3/4 open. Customer will return soon for some exploratory surgery. Thanks for the help, I think we're (your) onto something. I will post results when customer returns

Cool. Likely the screws are gone and the blade is jammed. Shaft is turning by itself.

Part numbers provided above. Don't forget the loctitie! LOL! Good luck.

Ric were have you found the screws? I noted on the inv we found them in cylinders but I swear we found one in cat or maybe I didnt find one I cannot remember.

brianp87 wrote:Ric were have you found the screws? I noted on the inv we found them in cylinders but I swear we found one in cat or maybe I didnt find one I cannot remember.

We didn't. Assumed they made it to the cat because they weren't in the cylinder. Customer did not want to spend anything to find them. They're probably still there.

hmm I wish I remembered better

What's this post about ? Sometimes i feel i start each day with a clean screen.

My guess is the screws are also in the cat. I'm going to look when customer returns. Hope it didn't "screw" up the cat. Pretty "screwed" up how it happened. If it wasn't so early i could go on and on, however, i suspect that someone here on this forum will run with it and hijack the thread!! Off to work. Have an awesome day gentlemen and ladies.