Lexus082

I have a misfire that occurs I think just at idle. So basically to sum it up, I have replaced the plugs, caps, rotors, and the wires are only two years old. I pulled each wire (One by One) to make sure I didn't have a dead cylinder.

So heres the symptoms:

--The idle speed is within spec. approx. 700 rpms in park and 583 in gear.
--Tachometer is not getting the proper tach. signal.
--Have a random misfire.
--Car shakes slightly after it warms up when the idle comes down to 700 rpms.
--Engine mounts have never been replaced.

Any thoughts after reading those symptoms?

I have read that a misfire can be caused by a vacuum leak, leaky egr valve, weak fuel pump or fuel pressure regulator, dirty injectors, water in the gas...

Bryan858

iTrader: (1)

Tachometer is not getting the proper tach. signal. - ecu may try to correct this which can cause poor idleing.

I have read that a misfire can be caused by a vacuum leak, leaky egr valve, weak fuel pump or fuel pressure regulator, dirty injectors, water in the gas...

I'd start by checking vacume leaks if your ignition sys is all good... Bad gas and dirty injectors next. Pre cat exhaust leaks can also cause misfire so you may want to check there as well.. Good luck in finding the problem.,.,

Lexus082

Can anyone name some more causes of an engine misfire at idle?

gserep1

You didn't say how it ran above idle. Does it miss at high speed or only at idle?

it is very unusual to have a miss at idle and not at speeds above idle. That sounds like a burned valve in that scenario, which is not likely.

How is your throttle response in park? Does it rev freely like oour engines do all the time? How did it run prior to changing all the parts? Did you have any driveability problems?

The part about the tachometer not getting the proper signal is disturbing. How do you know that? What does it indicate?

That should set a malfunction code. Do you have a check engine light with the engine running? If so, try to get that diagnosed.

Please keep in touch.

JamesN

iTrader: (5)

Try checking the Ignition coils, cap, rotors, sparks plug and wires. But I would check the ignition coil first.

Lexus082

I'm not sure how to identify whether or not its missing at high speeds. I know its missing at idle though. Throttle response in park is fine. Car drives great, only at idle the car starts to shake. It was shaking/missing before changing out all the parts. So I changed out all the parts and its still missing. The toyota tech and a guy from advanced auto both hooked up separate tachs and both said the engine was idling at 700 rpms in park. Maybe is not throwing a cel due to a mechanical failure within the tach itself in the speedo cluster. No check engine lights, I wish it would throw a code at me. I plan to replace both ignition coils. I have replaced the caps, rotors, plugs, and wires.

Lexus082

OK, well the idle is fine. Its just misfiring. I have replaced the plugs, caps, and rotors. The wires have about 60,000 miles on them. I checked for spark and also checked the resistance on all the wires and found them to be within spec. Less than 25k ohms. Fuel filter has been changed, ecu reset, Toyota said I didn't have a vacuum leak. I've had it missing for a while, so I know its not bad gas. I've put fuel injection cleaner in and gas treatment also. Still is misfiring.

Also, I thought if a coil was bad I'd only be running on 4 cylinders?

robunicu

iTrader: (1)

I have the same problem. it started yesturday. i floored the car a bit then came home and next morning i had almost no gas. as i was backin up the car started sputering a bit. and sounds like its missfiring. shakes every5 sec or so. first thing i did is use the injector/gar cleaner. and it didnt work. i cleaned the air filter and didnt work. now i took spark plug out and its kinda black. im guessing my timing is off. im so desperate. had so many problems with my lex. someone help us.

Lexus082

I just changed out the fuel pump today and that did not solve the misfire either. Running out of things myself to check. I'm not so sure its a random miss anymore though. I think I can feel it while driving around. And I definetely feel it at idle. The entire cars shakes..


Robunicu: If you think its missing pull each wire off the distributor cap one by one. Putting back each plug wire as you go along. If there is no change when you pull a wire off thats the bad cylinder (problem area) ie: spark plug, wire, injector. When's the last time you plug wires were replaced? Along with the caps & rotors, and plugs??

Also thats the very first time when I noticed it, when I started backing up into my garage one day it started happening and hasn't stopped since.

robunicu

iTrader: (1)

i just bought the car, so i have no clue, the reason i think mine started to misfire is because i did a dougnut and i might have jumped a tooth. it might be timing? it kinda stoped missfiring now. or maybe i got used to it, idk

ddr_6

damn my car does the same exact thing so if u ever figure out whats wrong with it and how 2 fix it send me a email at conantgymnast@gmail.com

Lexus082

I think mine is either a problem with the injectors or a plug wire is bad.

sc250tt

Probably a faulty coil . when coils get heat they tend to start acting crazy .the only thing that i dont understand is you said the car dont do it while your driving ,so that might rule out the coils. Inspect the engine harness wires coming from the firewall .maby a wire is grounding .

Lexus082

Discovered it was a vacuum leak at the intake manifold. I guess the Toyota mechanic didn't replace the gaskets and/or double check his work after replacing the starter.

Lex99

Guys, I have the same issue. Just started out of no where. Scanned it at a local autozone. Read misfire in 2&3 cyclinders. Changed all of the plugs (they were pretty bad). Did not solve the problem although it's slightly better at idle. Then I pulled each coil pack clip, the car ran like **** each time I pulled one so it's not the ignition. Is there a history of bad injectors with Lexus vehicles? I'm at my wits end.. My car won't even switch into OD on the highway b/c of the misfire... Somebody help!!!