My 1994 Automatic Camry 4-cyl with 162K miles has developed a studder. While stopped at a traffic light I can feel a noticeable studder/shutter and see a slight drop in RPM. It is not rhythmic and feels like the engine is just barely stalling most of the stopped-idle time. When shifted into neutral the engine runs very smoothly. Same symptoms if in R, 1 and 2 but not in park or neutral. When pulling away from the stop the engine shutters some more but smooths out at 2nd gear.
Last summer I changed out the spark plugs and ignition wires and oil change. The described problem has developed since then but not, in my opinion due to that.
I thought it might be needing a transmission fluid change so I purchased a new gasket and filter/strainer. Drained the fluid and replaced said parts. Also, drained and refilled the differential fluid. I topped off the transmission fluid fill with a 1/2 quart of Slick 50 transmission reconditioner.
I must have assumed wrong because the symptoms still persist. What else should I be looking at?
Well it didn't hurt anything to put the new fluids in. Always good to keep up on those some of the time forgotten routine maintenance. The erratic idle could be caused by a number of things. A leaking intake manifold gasket is one but usually is a steady higher racing idle. Could be clogged injector/s, not sure if you have a throttle body which would house a single injector or a fuel rail which would house 4, one by each cylinder. The other possibilities are any of the sensors that feed the information needed to the brain/on board computer to control the air and fuel to the engine under all conditions for optimal performance, and the emission control system.
Trouble shooting comes with several options. Fortunately most vehicles since the start of the electronic fuel injection systems, that would be everything since the end of the carburetor, comes with some description of an on board diagnostic system for trouble shooting the sensors and such.You can purchase a diagnostic tool, and you will need to purchase a Haynes or Chiltons Manual for your year make and model which will tell you what all of the different codes mean. You can find these at any of the auto part chains such as Auto Zone, Discount Auto Parts, Pep Boys etc. Most of these stores will test your on board diagnostics with their tool free of charge. The Manual never hurts to have in your possession as it covers mostly everything from A to Z for mechanical and electrical repair and troubleshooting. Some vehicles have a way of giving you error msg's by a series of turning the ignition key on and off a certain number of times, and giving a code by a series of an in dash light blinking and pausing, this would also be covered in the manual for your make and model.
Hope this helps,
Matt
hi raynor_schei,, that's great ! Thanks for the information. I've seen oil get on plugs before and not cause any issues, or noticeble ones at that. The fact that it is kind of enclosed may have something to do with makeing more of an effect.
Sometimes you assume, or I assume rather as in this case with new plugs and wires I ruled them out first. Though is always good to take notice of what you see and find when performing routine maintenence, such as excessive oil or a rubbed spot on a wire due to vibration so preventive measures can be taken.
The emission control system is made up of many sensors, components and such to feed information to the computer to feed the engine the proper amount of fuel/air mixture, even took over controling the timing and the idle for instance, both of which at one time were adjusted manually, now is controlled by the onboard computer. So trying to keep up with checking those periodically is a plus. Some states require a yearly inspection of the emission control system and my understanding is more states will incorporate it.
Happy Holidays
Matt
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Thanks hdpanama, the Camry is in the shop right now having the CV axles and boots replaced (both shot and grinding). I asked that they diagnose the rough idle. The shop called within an hour and said it could be spark-plugs and or wires. As mentioned, I have just replaced those items, plus, if that, then it would have a rough idle all the time.?.? Right? I asked them to check the engine mounts, somewhere I read that loose or broken mounts can cause this problem, they have not called back on this yet. If all that fails I'll do as you suggested and get the diag codes read...humm maybe this shop will do that for me while it is on the rack? They didn't offer or mention it...wonder why?
Anyway, thanks again, if I get a fix I'll post back here and give a rating (so far; helpful). If you can think of something else, I'm all ears.
Update:
I checked/changed/cleaned the following: battery, alternator, voltage regulator, PCV, intake manifold (cleaned with Deep Creep). When I got to the spark plugs I found oil on the outside of the #3 spark plug wire down and along the connector at the plug (no oil on the electrode side). Cleaned it up and it ran smooth for about a day. It then started in on the rough idle again...only worse. The guys at Toyotanation dot com suggested cleaning or changing out the spark plug wire again and tightening down the spark plug tube upper grommet (30mm nut at the top valve cover where each spark plug wire feeds down to the spark plug). All four grommets were loose but #3 was the loosest. One week now and no more oil or rough idle.
Who would have thought that a little (maybe a lot during driving, I don't know) down in the spark plug tube would cause the rough idle??? I guess it was shorting out that plug when the oil got worse??? Side benefit, I now have a good idea where my oil was going, cuz it wasn't dripping or smoking but I had to put a quart in every 1-2 months.
Just thought I'd pass this along here in this forum. All is well now. Thanks.
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