NunoFil3

Lexus Is200 Misfire Cylinder One When Warm

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Hi, i'm new on this forum and i have a misfire problem on my beloved Lexus is200 sport V6 2001, that is making me going crazy and desperate.

When i first drive the car in the morning (cold engine) the car drives fine with no misfire problems, soon as i stop and turn it of, with the engine already warm, and turn it on back again few minutes after starts the misfire.

I read the codes with a obdII and is always the code 1301 ( misfire cylinder 1) and sometimes the code 1171 as well (bank 1 to lean).

I've changed the spark plugs, coil packs, check the air pipes and still not sorted.

Please any one can help me???

Thanks in advance.

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It sounds like you've covered most possible ignition related causes but there could be a problem with the trigger pulse to the coil pack from the ECU. Try waggling the coil pack connection when the fault happens and make sure the contacts are all clean. If this checks out you may need to investigate possible mechanical causes like a damaged/burnt valve. This may show up on a compression test or better still a cylinder leakage test.

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Thank you very much for your reply Steve, today i just read the resistance(ohms) of the injectors with a digital multimeter and all showed 18ohms apart from the number one that showed 0ohms so i recon i had to change it because is the cause of this my nightmare.

Do i have to drain the coolant to to remove the throttle body or can i go around this in order to remove the odd injector?

Thanks

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Good diagnosis I forgot about the injectors, it helps nowdays if you can use a digital multimeter. Not sure if there is a water feed to the TB on the IS (can't see one on the exploded diagram) but if so just drain it partly so the level is below the TB connection.

You will probably have to remove the fuel rail which will pass under the TB to get the injector out.

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Ok Thanks for the advise Steve, i order a second hand injector because a new one from Lexus was a ridiculous price(£209), and i will do the job myself, i just hope that is not to hard because i never done it before.

Can i still use the same TB gasket and the fuel rail once removed how do i stop the fuel coming out and will i have any problems like air in the cooling system once i put everything back?

Sorry for all this questions but i just don't want to messed up.

Thanks for all.

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No problem, from what I can see the TB is not water heated, look under it for any rubber hoses before removal.

I would replace the TB gasket but according to Lexus they cost around £40.00 so must be a bit more than a normal gasket, if you remove the TB carefully you may get away with reusing the original.

Also make sure you fit new injector O ring seal where it fits nto the fuel rail, part number is 90301-07024 only a couple of pounds.

There will be some fuel in the rail but the pressure will be low without the pump on. Release the fuel filler cap and then loosen the banjo connection onto the fuel rail pipework,use a piece of rag to soak up any drips, be careful not to lose the 2 washers either side of the banjo connection.

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Many thanks again, this O-rings where can i buy it here in UK apart from Lexus dealer?

Thanks again for all.

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Hi, forum just to say that finally my misfire problem is sorted, it was the fuel injector in the cylinder number 1, when cold the multimeter showed "15" Ohms and when warm showed "0" Ohms, so i changed the injector and so far so good.

I've never had done nothing like this but it wasn't very hard just need to be careful and patient.

Happy days.

Thanks to Steve for all the advice.

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Great result! Glad to be able to help.

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Hi guys ive also run into this problem! after reading lots of members problems about this and hours on google! im still no further forward :eerrrmm: i had the car on diagnostics which pointed out misfire on cylinder 2 & 6

Ive replaced all 6 spark plugs, and both coils that were giving of misfire readings.... turns out the coils i replaced with the new coils were fine!.... so back again to drawing board! after pulling each coil in turn with the car running i noticed cyliner 6 spark plug was dry! no fuel was being injected to the cylinder and spark plug..... ive had a replacement injector fitted and car serviced new timing belt and oil change and still the problems there!!!! car runs fine when cold for few miles until the engine heats then the misfire and loss of power is there again! a local mechanic has said i may need to consider changing the ECU but i dont really want to pay for more parts that are not going to solve the problem! any help would be well appreciated!

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So after finding there was no fuel getting to No. 6 cylinder you have replaced the injector with a new one?

Before the ECU is condemmed have you checked for the presence of the injector pulse for that cylinder?

Your garage will need an Oscilloscope to be able to perform this test, if there is no pulse present then it needs to be checked for at the ECU and then go from there, it could quite easily be damaged wiring between the ECU and the injector which is making/breaking contact dependent on the temperature.

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Hi steve thanks for the reply.

the injector was takin from a donar is200 that was running so the injector should not be a dudd. The garage ive been to has said the voltage is dropping way low to 3v and should be at 12v as the engine bay warms.....am guessing thats the lead going into injector 6 thats dropping to 3volts..... ive heard of this problem so it may well in deed be the wiring! ..... Il be taking it back for another look.

thanks for the input steve.

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