Lexus082

Ever since I had my starter replaced I have had this problem. I have what seems to be a low idle speed which in turn makes the car shake slightly when sitting in drive or at park with of course the engine running. I have told the Toyota dealer about this and they looked at the car today and told me everything checked out ok. They said they did notice the engine skaking ever so slightly. On the tach at idle the needle reads the engine idle speed is 200-300 rpms. On their tach that they hooked up to the engine it read 615 rpms. Give it a little more gas the shaking goes away. The said they checked for a vacuum leak and didn't find anything. Before this visit to the toyota dealer for the low idle, I have cleaned the mass air flow sensor, changed some vacuum lines, replaced air and fuel filters, and cleaner the iacv. Not sure what else to do other than to take it to a different dealer. They said my tach on the dash isn't getting the proper tach signal. I'm stumped... Also the idle is steady once it levels out. Even the initial cold start idle seems too low and it takes my car alot longer to fully warm up now.

CCC-TT

iTrader: (1)

the shaking comes from it idling too low, i'm not too sure what it could be but i would suggest changing your spark plugs and wires

TheMole

iTrader: (13)

So it started after you replaced your starter or after your cleaned your maf? What did you use to clean your maf?

Lexus082

I have changed the spark plugs (month ago) and the wires are only two years old. Both Lexus oem parts. I changed the plugs about a month ago.

The car hasn't stalled out yet, but the idle seems too low. This wasn't going on until after Toyota replaced the starter. They can't find anything wrong with it. Or don't want to admit there's a problem. I pretended to play dumb and asked him if it was normal for the engine to shake. He said it was ok b/c it was a very slight shake. I said it should shake at all since its a balanced engine and nearly a vibration free engine. I know it wasn't like that before they worked on it. I hate when they look at you with some dumb look on there face and say there's nothing wrong.

When I start my engine from a cold start it idles at 750rpms. It takes forever for it to warm up. (Even when its 70+ degrees outside). I am mostly concerned with increase in engine wear due to the low idle. I guess I'll just have to start replacing all the vacuum lines. I'm not sure if they replaced the intake manifold gasket or not. With winter approaching it will take my car 30 minutes to fully warm-up at idle.

TheMole

iTrader: (13)

The reason I asked about the MAF was because other members have had issues after cleaning it.

Lexus082

Yes, I have read that also. I cleaned that after I started getting the low idle. I ohmed it and it was within spec. I also have no check engine lights.

Lexus082

Anyone? Is there a tool (vacuum gauge?) maybe that will indicate even a small vacuum leak? I'm desperate in trying to fix this issue. Its been going on for five months.

Which would be a better temp. fix?

Option A: Tighten the throttle cable until the idle is correct?

or

Option B: Adjust the factory preset throttle screw on the throttle body allowing the throttle plate to allow the butterfly valve to stay open a little bit more thus allowing more air into the engine thus increasing the idle speed?

or

Option C: Both of those ideas above are bad and I should continue my search into whats wrong with the idle. Meaning: I work on it myself somemore and also take it to a different toyota/lexus dealership?

What do you guys think?

SClean4

I have experienced the same thing before only once, I think. The car shook real bad when I was nearly idle in stop-and-go traffic.

I've had a similar/different problem, though, where the car will occasionally sputter, etc. while I'm driving at low speeds. It might have something to do with the intake or possibly something else. I'm still looking for answers to this problem.

Lexus082

I had another mechanic take a look. We heard like an abnormal "puff" sound of air or something coming from the tail pipe. He said the engine was mis-firing. Say by mistake I for some reason still have the same distributor cap and rotor from the last 75-80,000 miles and haven't changed it. Could that cause a low idle issue/ misfire? The plugs and wires are new. I haven't ordered those caps and rotors yet from Lexus.

TheMole

iTrader: (13)

Its possble if the rotor is so worn that it is not making good contact.

Lexus082

That would be something that I can physically inspect right?

TheMole

iTrader: (13)

Yup, just take off the distributor cap via 3 bolts/screws. Might be kind of stuck if it hasn't been replaced in a while. Just keep trying to pull away from the distributor. The intake is in the way, but there is just enough room to remove the cap. Don't pull up because the force might crack the rotor like when I did it. Fortunately I was going to replace the rotor anyways.

Lexus082

Upon further inspection no thanks to Toyota or Lexus technicians. I found that the car is misfiring due to a damaged spark plug wire. The wire rubbed against the timing belt and it destroyed the wire. So I have been running on 7 cylinders for about five months or so. Hopefully when I replace this wire and reset the ecu the idle will return to normal.

Luke_in_SD

how did the wire come in contact with the belt? isn't there a big space between them?

Lexus082

I guess there was extra slack where the wire wasn't held in place and rubbed against the timing belt/pulley.