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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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Is the intake setup all stock? Are you (or did you) use an oil impregnated air filter? Is your check engine light on? If so, what are the codes?
Try cleaning the MAF (remove it for cleaning as well)…… use only MAF cleaner and spray down on the wires, not just the Intake Air Temperature sensor (the red bulb that is easy to see)… Sometimes cleaning them does not work and they need to be replaced…
When was the last time you cleaned/replaced the spark plugs? (many times on 3.0 Toyotas, people neglect the rear bank due to the plenum being in the way and thus not the easiest job to do)…. Additionally, when have the spark plug wires to the rear cylinder bank been replaced (you should have the waste spark version I believe).. Also, only use NGK spark plugs on Toyotas 🙂
Are you experiencing Oil Gelling? Removing the front valve cover can tell you this….
Additionally, you can’t rule out a vacuum or air leak (look for air leak after MAF Sensor)…
Unfortunately, the best way of finding a vacuum leak is with a smoke machine… Some people use cigars and blow the smoke through lines, or they rig up a homemade smoke machine out of an inexpensive party smoke machine….
A good thing would be to hook up a scanner to it and see what the IAT is reading as well as the 02 sensors and fuel trims…
Keep us posted…
Karl
If you say the biggest clue is that when the engine is cold it has the issue, it could be due to the metal/plastic expending when it’s warm. So if it’s a vacuum leak– once things warm up and expend– the leak gets sealed. There could be other issues 😉
Thanks Karl, let me clarify-
The intake is all stock, no CEL (I wish I did), don’t believe I have an oil preggo air filter, just using a standard STP.
I really think I’m dealing with a vacuum leak now – if it were the MAF, sparks, wires, or oil gelling, I would still have rough performance while the engine was warm, correct? The car has had oil changes every 3000K since it was made. The sparks have about 55K on them (platinum) and the wires are original but look good.
Are there any good videos on how to do a smoke test?
I’ve recently been reading up on the AICS system, which has no sensors and hence does not trigger codes. The only problem is I don’t see any leaks in it and I’m not sure how to find any. I’ve gone through the “solving idle problems” page on this site, and I understand Eric’s method of spraying the engine to find leaks, but I don’t have a garage so I’m not keen on spraying flammables or water into the engine.
Thanks all
Defiantly start with engine performance as you have but my guess would be the engine mounts. You do have some miles on there and you spoke of other issues that might be engine mount related. I usually do what I can to eliminate any engine performance problems first and then look to the mounts but you might want to check them for damage, especially if they’re covered in oil.
Good luck and keep us posted.
Thanks Eric. I replaced the rear and top engine mounts this summer, the mechanic who did the rear one said the front and tranny mounts seemed alright, even when I was just going to replace them. Do you think a cold engine could somehow put more strain on the mounts than a warm one?
My thought now is that I have a relatively small vacuum leak, which causes the engine to buck the way it does while in open loop, and once the sensors warm up they compensate for the extra air that is going in, thus smoothing out the engine. I’d love to hear if there are any vacuum leaks in that theory though.
When it’s really cold, I can feel the engine lope even in park, and when I lift the hood I can see the engine jumping sporadically, and it looks like it is moving the most around the intake manifold, which is the top rear of this 1MZ-FE engine. That could in theory point to the rear engine mount, but it is brand new and OEM. So my thought is that air is seeping into the intake somewhere, and maybe very likely the Acoustic Control Induction System, since there are no error codes for that system and my OBD is not throwing any. I’m going to test the VSV for that system with a multimeter and poke around those hoses some more. Don’t have a vacuum gauge…might be about time to get one.
Since there are so many 98 Camry’s on the road, I usually find cases online where people have had my same issue, but I haven’t seen anything on this yet. Open to suggestions!
Ok, so the only bad hose I found was this one, which is a vacuum hose to the intake air control valve. This hose connects the vacuum tank to the actuator for the valve. But even after reading about it, I’m not entirely sure how it works. I can’t tell if the hose would actually allow air into the intake or not, could anyone shed some light on it? This system appears to be a Toyota thing – anyone think it could be the cause of rough engine idling, only when the engine is cold?
Also, its actually a few hoses connected by little plastic connectors – why did Toyota opt for that instead of just a single long hose? This design looks like it’s been begging to fail for a while.
Thanks all
If memory serves correct, most 3.0 models have two metal intermediate tubes attached on the valve cover right where you are holding those hoses (a hose went in each end). Strange how I don’t see them on yours… I believe they were involved with the evap system (memory is a little fuzzy…) Haven’t worked on a 3.0 in about 6 months. It is a vacuum hose and does need to be leak free and hooked up.
If you look you can see the tubes (pic from my last 3.0 engine swap)….The tubes are just below the top right valve cover bolt…. Also this pic was a 98 engine going in a 95 Lexus (had to switch back to all 6 COPs)…
-Karl
Thanks for the reference picks. I think I see the metal tubes you were talking about, looks like slightly different design, maybe between the Japan and USA models. That kind of explains the strange plastic connectors on my engine.
I’m thinking I’ll try electric taping this first, but anyone have suggestions on where to get a replacement hose without spending dealer prices?
Yea, at this point it doesn’t sound like engine mounts. I would stay focused on engine performance as you seem to be doing. I’m with Toyotakarl on just replacing the hose with stock. You don’t need to spend dealer money on something like that.
Since it only happens when it’s cold, or in open loop, I suppose there could also be a fuel delivery issue. I know on some older Toyotas they use a cold start injector in the intake. I also remember them having trouble from time to time. I don’t think they were using those in 98 however. Perhaps clean the IAC if you haven’t already just to see if there’s a change in the symptom.
Keep us posted.
Hey ETCG, I think I’m on to something!
The hose wasn’t the issue, but I think I may have found it. Here is a video of my issue – http://www.youtube.com/watch?v=4lrhJWsvSuQ
Now compare that to this one, where someone had leaking spark plug seals causing identical symptoms –
Eric you seem to have Subaru’s in a lot of your videos, guess they’re good for showing folks what problems look like, ha.
I already ordered spark plugs and wires, wish I had got spark seals at the same time. I’ll do the top plug seals along with all sparks and wires, then we’ll see. Really hope I don’t have to take off the back valve cover.
The battle rages on…
A spark plug electrode broke off! This is what I found when I pulled the center plug on the front valve cover. This explains the rattling noise that I heard when the problem first started!!
But what to do now? Obviously need a new plug, but what do I do about the piece that broke off inside the combustion chamber? And this plug and the plug tube are all grimy and black, definitely some kind of leak issue, would that have contributed to the electrode breaking off?
Man, didn’t expect to find this…
Get the electrode out…. It may not be in there anymore though, it could have exited through your valves and be in the cat now…
It may have damaged the valves, maybe not…. A compression/leak down tester would help determine if any damage was done..
As for the color, if your plug seals were bad, there you go…
As far as why… wrong plug, a defect, just plain worn and had enough…
As for the sparkplug electrode, it is most likely long gone – into the exhaust although I’ve heard of where they occasionally like to visit other cylinders and exit to the intake manifold.
I’d suggest seeing what the other plugs look like. It could be a fluke since the plugs are old but especially watch for any with closed gaps because a broken electrode is often a sign of detonation. If the other plugs look good, I would suspect the fuel injector although if that cylinder has developed a ring problem it could be due to oil.
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