mikeloc24

Well poop, my car is at it again. When the engine is engaged I feel a vibrating and studdering while idling. It's not just isolated to idling as I can feel it (it's just less noticable) while driving. My engine is also a lot louder than it was a couple of weeks ago. These are the things that have happened recently that "may" or may not have something to do with this issue:

1. I replaced my water pump and thermostat a month or so ago. I've noticed some coolant around the pump now, the mechanic says it's normal as the pump was new (as well as the gasket). Since I don't know much about water pumps I just let it go. The fan clutch was also replaced around the same time along with the timing belt tensioner.
2. I inadvertedly put some 87 octane gas in my car, I have since run that crap out of my car and filled up with 91 octane, still the stumbling is there.
3. I had a full tune-up done within the last year so I know it's not that. I also just checked my tranny fluid as I read that the fluid may be toast and that causes the issues I'm experiencing. Nope, fluid still nice and clean (reddish color).
4. My check emgine light is on and I believe I may have a bad sensor somewhere...would this make the car shake and rumble like that? I didn't think so as it wasn't driving like this during that first week when the CEL was on.
5. Brakes and all that are fine, my issue seems to be a stumper as I'm now out of ideas as to what's causing my car to ride so roughly.

Anyone with ideas please chime in. Don't waste your breath telling me to "search" because I've been reading and searching for the past 6 hours, no joke. WTF is wrong with my car now?!?!! I swear I want to kick it...*&^%$#@$(&^#!!!!!

-one pist-off Locsta

DaveGS4

iTrader: (2)

Mike - when's the last time you ran some quality fuel injector cleaner through your car? Either Techron or Redline (my preferences)?

It sounds like you might have a dirty throttle position sensor (TPS) or maybe a clogged fuel filter.

Have you had your CEL code diagnosed?

BLK13X

Mike, try cleaning the injectors as Dave said, but also have you checked your car to see if it's misfiring at all? My car was doing the exact thing when I brought it down to the mechanic to see wtf was wrong with it and it came down to a misfiring problem (finally fixed though). The ignitor isn't usually a suspect but get it checked out too... bad ignition wires as well maybe?

Jose

mikeloc24

Dave, last time I had my injectors cleaned was perhaps about a year or so ago. I had a shop professionally do it for $75 and then like maybe every other month I'd run some Gumout or something similiar through the gas tank to help keep it clean. Someone told me not to keep doing that if I'm using quality gas (which I do). I usually get Chevron gas (with Techron) or I get gas from 76, those are my 2 places. I changed the fuel filter about 30k ago so hopefully that's not it either, I read that the Toyota ones are supposed to be "lifetime" filters but I didn't buy into that and replaced it anyway about a year after I initially got the car. I haven't checked the code yet but I was wondering what code it could throw that would have a sympton such as the ones I'm experiencing? A bad o2 sensor wouldn't cause this shaking/vibrating would it? I'll check the TPS, I've never messed with that before. Thanks for the tips, guys/gals please keep 'em coming...my head hurts from reading, wondering, worrying, and stressing over the unknown

Jose, how did you fix your misfiring issue? I don't even know how to "check" for a misfire on this car...it just seems like my car is choking for lack of a better term. Stumbling, burping and stuttering...not bad but bad enough for me (or one of us) to notice it.

edit: I'm beginning to think it IS the TPS after reading threads for another hour!!! still not positive though...will have to check the CEL code tonite.

THE_CEO

hey mike has it been raining out there lately?...water could have slipped in there...but that should go away after a few drives...

CEO

BLK13X

Mike, get down to your mechanic and get him to do a diagnostics check (I can't remember the terminals off the top off my head)... it should come up with something

Now, my case seemed to be a very isolated case, as the coil on cylinder 5 was not firing (very minute spark at the most) when all the rest were sparking fine. This could've been caused by a number of different factors (how often the previous owner in Japan took care of the car etc etc.), but part of the reason was the dodgy alarm install (that I cannot sue over anymore... there was $1800 worth of damage done to my Soarer by them *********!!!). At first the diagnostics shown up to be the ignitor (ECT14), but most of the electrical parts were tested, replaced where needed etc... things like the ignitor were alright, but the engine ECU was replaced, and the wiring was botched... guess it was pure bad luck for me (as my turbos crapped out at the same time too) and I had to hit up the bill.

Also, you might wanna try a compression test to check that the car's running on all cylinders properly (you never know... happened to a guy I know... lost compression in 2 cylinders from memory).

Jose

RalAegidius

Low flow rate through the oil filter???

When I was just starting to do oil changes myself, I discovered that some brands of filter don't have an adequate flow rate and this makes the car shudder and idle roughly, like it's going to stall.

Ral

SC4Million

Bad coolant sensor?

If the car cannot get a read from that sensor it will try to run in cold startup mode all the time (eg: super rich) effectivley "choking" your engine.

after running the car a bit turn it off see if you smell gas.

WestOne

I wouldn't rule out a fouled spark plug, especially after accidently running the 87 octane. An engine not firing on all cylinders will be roughest at idle and smooth out as you increase RPM. Plugs are pretty cheap anyway so give it a try.

qtb33

Another easy check it to pull the throttle body off and inspect for massive "coking". This is very common and will plug up idle passages and make the car stummble off idle and idle lower giving a rough shaking sensation. If there is a bunch of carbon build up an easy fix is to just spray it down with some carb cleaner and give a good wipe. Repeat untill clean. It won't hurt to spray alittle down the runners as well to help clean them up. When you start the car the first time back together it may rev quickly or idle bizzare for a second or two but its perfectly fine.

If your plugs are of concern replace them too but don't just run out and buy some. Take a look and see if they are bad. There are places online (try google) that will show you what your plugs should look like and not look like as well as tell you what is wrong if they are discolored. Ideal is a light tanish color. Anything else you should look up; this will also aid in your diagnosis of the problem.

Hope this helps. In either case if you haven't done this and you have 100K miles or more on your car it will only help.

mikeloc24

Thanks for the replies guys, I think I may have moved closer to figuring out what the problem is with my car. Last night I got two pieces of wire and retrieved the check engne light code. I got back a code 25, "lean air to fuel mixture"...looks like it's pointing to bad o2 sensors or perhaps a faulty injector. I guess I'll know more once I dig into it tonite. Anyone else ever have this problem of know how to fix it? I definitely am getting a code 25. Thanks for the help.

-Mike

WhiteTiger

Mike

You noted that the car is louder which suggests an exhaust leak to me. Sometimes header bolts will come loose or a flange or tube will crack allowing added air in before it crosses the O2 which will make the O2 sensor read leaner than it actually is at the cylinder. The computer will use the O2 to adjust the mixture since it thinks it is lean, making it more rich when it really doesn't need to be, which would cause you to stumble and idle rough throughout the RPM range depending and how deep you are digging into the throttle (more noticable under lower acceleration as greater acceleration will use the fuel before the computer can re-adjust).

On some of the other items suggested.

To test the spark at each cylinders you can pull each plug wire (one at a time) while the car is running, if there is no change in the operation then you are not getting spark to that cylinder and the wire or plug is bad.

Same process with the injectors. You can pull the injector plugs one at a time to see which cylinder, if any is having an issue. If there is no change, then there is a problem with the fuel delivery at that point.

With the lean O2 code it probably isn't the temp gauge since a car runs richer during warm up and leans out the mixture once the car is at operating temp. Which is opposite of your lean O2 code.

The O2's could be shot, but you can remove and test them I do believe.

Just a few ideas, hope you find it soon!

mikeloc24

Thanks Ed, an exhaust leak huh? That also may be the case. Now, how does one go about determining if there is indeed an exhaust leak? I mean short of taking it to an exhaust shop, unless that's the only way. Yes, the car is noticibly louder. You can really feel the vibrations and hear the stumbling during idle and low acceleration. Like you said, when I'm on the freeway I don't notice it as much unless I turn off the radio, roll up all the windows, and specifically listen and feel for the stumble. When I do step on the throttle lightly I hear a fluttering sound, like my car is a Ford or something. Hopefully "fluttering" is the best word to describe the sound I'm hearing when I lightly step on the gas, but at stop lights it feels like the car wants to turn off due to lack of gas. I'd hate to go about replacing things without knowing specifically what the issue it. Whatever the case I guess I better not go on any dates anytime soon until I fix this issue!

Ya know, I'm actually starting to think I have a faulty injector. All the symptoms are pointing towards that. I'll test it out and see if my injectors are working properly.

mikeloc24

problem found, bad o2 sensor(s)...just gotta change them...never thought an o2 sensor would have this much of an effect on how the car drives/performs/idles...

SPORTcoupe

iTrader: (2)

It's funny how O2 sensors work.
They calculate AFR based on Oxygen content in the exhaust.
Problem with this is that the O2 sensor assumes that combustion has taken place.
Now imagine this: You car is running so rich that a few plugs are fouled and not igniting.
Because there is no detonation, the air does not get burned and gets passed right into the exhaust where the O2 sensor picks it up and shows a lean condition.
The lean reading to the ECU makes the ECU add yet more fuel and drown your plugs even more.
It's a ****ty loop.

~Alan