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Hi, happy to be in the ETCG garage. Been trying to diagnose this problem at ToyotaNation for a while, so I thought I’d try my luck here. I love my 98 Camry V6, it’s always been reliable and I try to do all the work to it myself. Recently it has developed its first engine performance issue (at 207K), which is a rough idle/engine lope that occurs only when the engine is cold. If I let it warm up 10 minutes it is fine, although I think I feel some slight jerking when I hit the gas sometimes as well.
I’ve replaced the air filter and a very old PCV valve as attempts at an easy fix, but to no avail. I’ve done due diligence reading everything I can find, so I know there are LOTS of potential causes of a rough idle :(, but the thing I don’t see very much is common causes of a rough idle that ONLY occurs while the engine is cold. In fact the loping is noticeably worse when the outside temperature is very cold. This is the only real clue I have, but I’m not sure where it should point me to.
For reference, the engine starts cold at around 1800 RPM. After 5-10 minutes it drops to about 800 and then all is well. If I put it in gear cold it goes to about 1000 and lopes hard. It only lopes in park/neutral if it is very cold out. After I drive the car a good bit, even if I let it sit for a while afterward, it starts at only 1200RPM and then I can put it in gear right away and all is well.
Vacuum leak is next on my mind, but I find it a hard test to do, so many places to look. And of course the question that keeps bothering me – why would a vacuum leak (or any problem) only cause an issue while the engine is cold? What do you think, these conditions point to anything in your mind?
Thanks all
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Thanks Barney, please see the pics below. You can see the good vs the bad. The bad spark plug obviously had some issues going on and is blackened and caked with gunk. Even on the outside of the valve cover there is a clear oily discoloration.
I’m thinking I was right about the spark plug seals that I posted a couple weeks ago, what do you think? Only thing I can’t figure out is – how does the oil go down the spark tube and get past the washer and threads where the spark is screwed into the cylinder head?
Thanks, it does seem clear by looking at the valve cover that the oil leak is coming from the tube seals, no? I’ve been wondering if the problem could have been coming from the combustion chamber side, but it can’t be a coincidence that the valve cover has that oily stain around the tube of the bad spark plug…
Something I forgot to mention – when I took the bad plug out I could see all that nasty carbon gunk down on the top of the piston. You can almost see it in the pictures above.
First question of course, is why am I getting this buildup? And then can I clean it out somehow without taking the cylinder head off the block? I was pulling out little chunks of it with a telescoping magnet tool.
One time I had an engine that was no start. I checked for spark – no spark. I also checked for fuel – no fuel. This car was running fine before. Coincidences do happen.
Oil on the outside and oil on the inside of the plug seal could be separate issues. Anyway, I suggest doing compression, dry and wet, as a first test of the engine’s health.
Let us know the results.
Thanks, I’m picking up a compression gauge shortly.
In researching the condition of the bad plug, I found out that the velvet-like carbon coating is mostly indicative of running rich. Obviously the plug wasn’t sparking quite right with one of its electrodes gone, so isn’t is plausible that the carbon gunk just built up as a result of all the non-combusted gas that was going into the chamber? Then in a best case scenario, the new plug will burn a lot of that crap out, yes/no/maybe?
I’m also starting to think that the plug was actually not screwed in tight at all when I took it out. I actually didn’t think that particuar plug was seated in the spark socket for the longest time before I finally realized pulled it up. Plus the the plug washer didn’t come out with the plug and I had to fish it out. None of the other plugs were like this.
Maybe I’m being optimistic here but I’m starting to think that a new plug and some seafoam may be all I need. Also just remembered that some knuckleheads pulled one of my plugs a few months ago to look at it, and somehow I just imagine that it was this one…
Well after all that…the problem is still there. Starts up rough, misfiring maybe, then gradually evens out when it gets warm. I can’t believe there was a broken spark plug in the engine, and it WASN’T the source of the problem. Pretty discouraged at this point, been at this for more than a month now. What the heck could be going on?
Well, when I see a missing electrode red flags start waving. Anyway, I suggest doing a dry and wet compression test.
Don’t scare me. I mean, it runs fine after it warms up a few minutes, would seem to rule out catastrophic cylinder damage wouldn’t it? :unsure:
When you do a compression test, do you have to take out all the sparks just to check one cylinder? Haynes seemed to indicate it but I can’t see why you would. What is a wet compression test? Is that when you add a little oil to it to see if the compression goes up?
Ordinarily you don’t encounter a missing electrode on a spark plug. Something has to have knocked it off. What that something generally is – is detonation – an explosion in the combustion chamber. The explosion can damage rings and piston lands too. So, I don’t think this is something to be scared about – a car is just a hunk of metal – but something to be aware of.
There’s also the question of what happened to the piece of metal that came off of the spark plug. It could have scored the cylinder.
Maybe everything is fine but I’d think you’d want to find out. If you can’t do the necessary testing then I’d suggest taking it somewhere.
Since the plug seemed to be loose I was hoping this – http://www.ngk-sparkplugs.jp/english/techinfo/troubleshooting/10/index.html
I wish there was a place in Brooklyn I thought I could trust, if I had any of them do the compression test I wouldn’t trust them to even screw the spark plug back in.
I have a compression test, Seafoam application, and listening to injectors ahead of me. Just what I wanted in the middle of the worst snow of the year…
Thanks though
[quote=”numbeforty1″ post=87459]Don’t scare me. I mean, it runs fine after it warms up a few minutes, would seem to rule out catastrophic cylinder damage wouldn’t it? :unsure:
When you do a compression test, do you have to take out all the sparks just to check one cylinder? Haynes seemed to indicate it but I can’t see why you would. What is a wet compression test? Is that when you add a little oil to it to see if the compression goes up?[/quote]
Detailed info and videos on compression and leak down testing can be found here.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
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