Benny had all the diagnostic equipment but he always seemed to have a pretty good idea of where to look first by the time the car was inside the shop. He fixed it so fast he did not want to charge me for it. But I insisted he take $10 for a hamburger. Benny passed away. He trained a successor who is also good.
Sorry to bug you again. I just have one more question. When you drove to the mechanic, did the vibration continue throughout the trip? Or was it only present when you were idling or at low speeds?
Thanks!
With one cylinder misfiring, naturally, the vibration amplitude would be worse at low engine speeds and at a rate proportional to the engine speed. Also acceleration would be slower and high speed might not be possible. . The cylinders fire one at a time, in regular sequence. The pulsations of energy are absorbed and smoothed out somewhat by the mass of the flywheel, rotating parts, drive train, and the rest of the vehicle, as engaged at any particular time.
So thatās a yes, you only felt them at low speeds?
It is normal for a fouled plug to only cause vibrations at low speed. Any regular misfire will be felt only at idle or low speed because as the engine RPM build up, the inertia of the rotating parts will smooth out the vibrations.
But if you have a misfire, you will also have a check engine light with a code of P03xx. The xx is the cylinder number, I.e P0301 would be the number one cylinder. A P0300 means a random cylinder misfire.
You can have a vibration but not show a misfire because all the plugs are firing. You can find the errant cylinder by pulling a plug wire, one at a time to find the cylinder that is least affected but with todayās modern epoxy coils, that can damage them. You could however just disconnect the firing signal from the computer by disconnecting the plug from the computer at the coil end.
OK, thanks.
My old physics book is about one and one half inches thick. You canāt transfer that information with a question and answer conversation.
OK, thatās fine. But, I mean, it was a simple question. But I assume, based on your answer, that the answer is āyes.ā So thatās fine. No need to discuss further. Thanks for your info. Iāll relay that to the guy whoās going to take a look at it.
Just wanted to give an update here.
So I had to wait a few weeks for the guy who was going to look at my car to be available. Turns out he wasnāt working on cars out of his house anymore, but had taken a full-time job, and was working some overtime. So it was a couple of weeks until he was available.
That was fine with me, as I was kind of burnt out from all the going back and forth to the other shop, and needed a break from dealing with the car.
So I dropped it off at his house the other day, but he didnāt do much. He looked at one of the spark plugs and said it looked fine, and he cleaned the throttle body, but thatās about it. Other than that, he said he didnāt know what the problem was. So that was kind of a bust.
But my neighbor recommended a nearby shop that he said does great work at a reasonable cost. On google maps they have a 4.7 star rating, with almost all the reviews being 5 star, along with a few ones and a few fours. So Iām going to drop it off there on Monday. Iām hoping, hoping, hoping that theyāll be able to figure out what the problem is.
So, thatās the latest.
Hereās an update on the situation.
So I took it to the shop mentioned in my last post. But he didnāt seem to have a handle on what it could be. Still, I left it with him. But after three days he still hadnāt gotten around to looking at it. So I picked up it.
I found another shop through Google Maps thatās been around for a few decades and has rave reviews and a 4.9 rating. So I took it there.
I explained to them that Iād had the car for 17 years, but never had those strong vibrations when at idle or under 5 MPH before, but that right after the other shop replaced the valve cover gaskets, the exhaust manifold gasket, and the catalytic converter, the strong vibrations started.
After looking at it, he said they couldnāt anything wrong with it that they would recommend to repair. He said he looked at the engine mounts and pulled or pushed on them or something (donāt remember exactly what he said), and he said they seemed fine. Said all the work they did looked fine. Didnāt see anything wrong with the new pipe to the catalytic converter (originally he thought the pipe might be a misfit).
I asked him if he tested the spark plugs or whatever. He said they didnāt do that because he didnāt see any misfires. (Indeed, when the car is over 5 MPH the engine feels very smooth. No hesitation or misfires. And the other shop said that air to fuel ratio was spot on.) So he said he didnāt see any need to run those tests and charge me for it.
So he said he didnāt know what it could be. I picked up the car and he didnāt charge me for looking at it.
However, a strange thing happened after I picked up the car. I noticed that the under 5 MPH vibrations were not as strong as they had been. Previously they had been extremely strong to the point of it being uncomfortable, and you could even feel the vibrations on the door panels by the windows. But now the vibrations were about half as strong as they had been, and you no longer could feel the vibrations on the door panels.
So I donāt know if when they were prodding around in there, pushing and pulling things, something fell back into place more. Or maybe because itās warmer out right now (70F) that made a difference.
But I know for a fact that when I brought it there this morning, the vibrations were extremely strong. But it was also much colder (about 40F).
So thatās good news, anyway! The vibrations also previously started up again at around 45-55 MPH, and I havenāt taken it on the freeway yet to test that. But so far, based on just feeling it at idle, it seems a lot better than before ā at least in the little bit that I rode it back to my house.
So thatās the latest.
I wonder if it could be a problem w/the EGR system or the PCV system? Have any of your shops taken a look at those two? Probably worth the time for a look-see.
The EGR valve shouldnāt be allowing any exhaust gasses into the intake manifold at idle or low speed driving. If it did, that could cause this symptom. The PCV system should limit the amount of flow from the crankcase into the engine to a very small amount at idle. If it was allowing too much, again that could cause this sort of symptom.
I diyāer test my vehicleās PCV & EGR systems as part of routine maintenance. For the PCV I isnpect all the associated hoses are in good condition and their connections are air-tight. I also test the PCV valve itself, first that I can feel a strong suction with the engine idling, and that the valve inside rattles around freely with the engine off. I test the EGR by activating it at idle with a hand-held vacuum pump. If that stalls the engine or makes it severely shake, that means the EGR valve isnāt stuck in the closed position. With the engine off I also look at the valve to see if the valveās pintle linkage moves freely in response to the hand-held vacuum pump.
Disclaimer: diyāer only, no experience w/OPās specific vehicle.
I kind of suspect the shop prying on the mounts to inspect them affected the vibrations . . . or lack thereof
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Well, I just took it for a drive while itās cold out (40F) and it was the same ā vibrations are about half of what they used to be. So itās definitely not temperature-related.
No, i donāt believe they have. I looked up the maintenance on those two valves, and I see itās recommended to clean them every 50K miles. I donāt believe Iāve ever done that. I bought the car with 43K miles on it, and it currently has 107K miles. So that might be a good thing to do anyway.
Thanks for the tip. I may just bring it to another place and see if they can figure out the vibrations, and have them do maintenance on those two systems at the same time.
That seems very possible. Not sure what else could have caused the change.
I didnāt reread the whole post but, Iām thinking the vibration might be coming from the exhaust system. maybe it is hitting under the vehicle somewhere. and while they were looking under the vehicle feeling around, they might have tugged on the exhaust a little and the vibration lessened.
That could be. And it would make sense, since the vibrations started right after they changed the catalytic converter and the pipe. Still, they said they checked the cat and pipe and said that everything seemed correct.
Well, the vibrations are back at full strength. I havenāt done anything with the car or had anyone else look at it since the last post here. However, I did replace my hitch-mounted bike rack with a new one. After installing the new hitch-mounted bike rack, I noticed a loud screeching sound when I made a turn. I figured that was from the weight of the bike rack shifting something.
After that first initial screeching sound, it never happened again. So I figured, it must have shifted something, and whatever it shifted must now be in a stable position.
Previously we were thinking the vibrations might be due to the new catalytic converter and exhaust pipe that were installed. But the hitch is mounted to the frame, not to the exhaust. So, I donāt know.
Also, new thing which may be related. I noticed tonight when the car was in Park, but the engine was running, that I heard a click from the engine about every 30 seconds, like clockwork. Donāt recall ever hearing that before. But, sitting there, I would hear a click about every 30 seconds.
When the car was in Drive, but standing still, the click didnāt happen. Only if it was in Park.
But then tonight, several hours later, I went back to the car and tested it again, letting the engine run while in Park, and waiting for it to warm up, but the clicking sound never returned. So, I donāt know.
Plan on taking it to another mechanic after the new year, but Iām not very hopeful.
One idea thatās pretty easy to do, use a length of old garden hose as a stethoscope to see if that click seems to be coming from the area near the cat .
Only problem is that it hasnāt happened again since. Maybe Iāll check for it after Iāve driven for a while. I only tested it with getting the engine to full temperature.
Turn on the defroster, see if the a/c clutch cycles every 30 seconds.
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Sorry for not getting back sooner. Iāve tried several times to reproduce the problem, but havenāt been able to. So I guess it was just āone of those things.ā