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Mysterious Misfire


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Hello, I'm new here and looking for some advice on a strange problem I'm having with my 2003 IS200 SE.

At the same time as I had my car in for a service, it developed a misfire on cylinders 1 and 5. The garage initially checked over all of their work, checking plugs and leads etc. Everything seemed to be fine, then it came back again. This time the garage checked everything over again, including coil packs. They even suggested it could possibly be a faulty/dirty injector so gave the engine a dose of injector cleaner to be sure. Once again everything seemed fine and I took my car home. However it has started again.

Starting the engine from cold seems to produce no misfire at all. Even once it is to temperature from cold there appears to be no misfire. However if I stop the engine once its at temperature and leave it for even a short while the misfire will appear.

I have had my OBD reader on twice I got one set of codes then cleared them to see what I got the next time the fault started.

First set of codes:

P0300 - Random/Multiple Misfire Detected

P0301 - Cylinder 1 Misfire Detected

P0302- Cylinder 2 Misfire Detected

P0305- Cylinder 5 Misfire Detected

P0174 - System Too Lean Bank 2

Second set of codes:

P0305- Cylinder 5 Misfire Detected

P0174 - System Too Lean Bank 2

I'm not too technical so after speaking to the amateur mechanic at work, he suggested checking my O2/Lambda sensors. I have disconnected the one sensor I can see in the engine bay (pre cat), with no luck up to now. The misfire still remains with the O2 sensor connected or disconnected.

I would like to pinpoint the problem before spending money I don't need to changing parts and relying on guesswork.

So in short, when starting from cold the engine runs perfectly even once reaching temperature. Once turned off and started again at temperature (or warm) it misfires and runs rough. Garage have ruled out, spark plugs and coil packs.

Fingers crossed someone can help. This is driving me crazy.

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I had the same symptoms on my 52 sportx would misfire after starting when hot but fine from cold it was a bad injector. Injector cleaner made no difference at all. I managed to find a company on eBay I think it was that sold refurbed/tested injectors for a good price and that sorted it.

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Thanks for the replies. I've got it booked in for a diagnostic on Tuesday morning. Hopefully they will get right to the bottom of it.

Today I had the car out and all was running fine. I left the car parked up when I came back to start it up it acted like it was over heating (had the problem before), no power when pressing pedal and juddering engine then stalling.

After letting the engine cool for a while I tried to start again but the only way I could get it running was to rev as soon as I turned the key. Got it home and that's where it's staying until Tuesday.

I hope this diagnostic can give me answers to solve all this or my IS200 may be going to the big garage in the sky.

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