Could temperature/ a temperature sensor cause a misfire?

[mk2too]

Hi,

Bit of a random one here. I have been trying to cure a misfire on my mk2 na mr2 for a while. I have changed dizzy, rotor, plugs and leads.

It's only on light throttle and below 3k, full throttle seems OK (although not a ball of fire)

However today in the absolute pouring rain I noticed the temperature gauge was sitting imbetween half way and the middle and that the misfire had gone completely which I thought was odd considering it was tipping it down.

Just thinking could the temperature sensor be affected by the rain or malfunction and then cause the car to actually run ok?

I know that is an odd post but thought I'd check it out there.

Thanks!

[abovetherim]

The cat has 2 separate temp sensors. One for the ecu and one for the gauge.

If the gauge was only reading a third and the car had been driven enough to warm it up then there is a problem there. Most likely to be thermostat. That is assuming that temp sensor is working properly.

Your theory has some merit. If the engine is running too rich when warmed up properly it will run poorly. So if the stat stays open and let's the engine run cool the rich mixture has less of a detrimental effect.

Now the reason for rich running could be ecu temp sensor or O2 sensor.

The bgb has procedures to test temp sensors. If you don't have it Google it and you will find places to download the pdf

[mk2too]

Thanks for the reply i know its a bit of a far-fetched explanation but i am 100% sure it wasn't a placebo effect the car run noticeably smoother.

I quite enjoyed driving her and not worrying about pulling away from roundabouts!

Thanks

George

[Poker Face]

I'd check your coil pack as these can crack and be affected by the cold and moisture.

[mk2too]

Just to update this post as I take an awful lot from the forum and threads with no endings are always a shame!

I changed the knackered thermostat with a new one and also swapped out the water temp ecu sensor (green one) and the old girl runs so much better.

The misfire isn't completely gone (even though my dad keeps saying 'well its a 24 yr old motor give her a break') but it is considerably better; especially when cold. The bogging down and lurching has gone as has the missing idle.

So if people are having running problems and you've done the usual of plugs,dizzy,leads etc and your temperature is a bit up and down then it may be worth trying a thermostat and/or a water temp sensor.

Thanks for everyone's replies and help

[abovetherim]

Do you have access to a timing light.
Adjusting the timing is easy and can vastly improve things if it is out a few degrees

[mk2too]

I don't myself but have had a very kind offer from a local forum member to check the ignition timing for me so that will be my next port of call

Good things all around!

Thanks