[Mk2] [NA] Low Idle, Temp Guage not Working Properly

[classicjoe]

Hi all,

I went out in my mr2 rev 3 NA today done a 2 hour motorway journey no problems.

I then stopped on my drive, the car (just bought) seemed to be idling lower than it had about 700rpm rather than 900rpm. So i thought try some fuel system cleaner and a tank full of Shell Optimax fuel.

It still seems to run low on idle now and then, but also it seemed to stutter at about 2000rpm when under light/low acceleration. it seems fine when you give it a good bit throttle.

Also the temperature gauge seem to have stopped working correctly, it was staying on low (cold) and now and then it may rise slightly about a 1/3rd or so and then go back down to low.

I can also hear a bubbling noise inside sounds like from behind the dash where the radio is but not sure.

The alternator belt was slipping a bit and squeeking when first started but soon stops after about 20secs.

The car has been fitted with a (IMHO) an awful pipercross cone filter.

Should I be worrying and be prepared to dig deep into my pockets???

I was wondering if the temp gauge could be registering a low temp if there was an air pocket around the sensor??? is that possible.

Worst nightmare could it be the beginning of head gasket failure???


any help appreciate,

Joe

[HighwayStar]

Where are you based mate?.... Can you get it to an affiliate for diagnostics? If it's head gasket I reckon you'll see mayo in the oil filler cap. It could be air in the system effecting the gauge but it would do it fairly regularly on a long run I would have thought not just when sitting. Could be a faulty thermostat.
Somebody else will be about with better info shortly... meanwhile... do your carpets in the front get wet at all? Whip up the mats and feel around. Does the heater work OK and is the coolant at the right level?

R.

PS. Welcome to the site and to 2 ownership.

[classicjoe]

Where are you based mate?.... Can you get it to an affiliate for diagnostics? If it's head gasket I reckon you'll see mayo in the oil filler cap. It could be air in the system effecting the gauge but it would do it fairly regularly on a long run I would have thought not just when sitting. Could be a faulty thermostat.
Somebody else will be about with better info shortly... meanwhile... do your carpets in the front get wet at all? Whip up the mats and feel around. Does the heater work OK and is the coolant at the right level?

R.

PS. Welcome to the site and to 2 ownership.

Hi thanks for the welcome and reply.

I am based in the UK (North east)

Okay here is the latest.

When I got the car the coolant was low so I filled it up with the toyota red stuff...slight overfilled woops.

Ive been out in it this morning and have realised that if I keep the heaters set to cold and turned on then most of the time the temp guage will be normal (mid-way) and idle as normal 900rpm and the car drives smoother. if I turn the heaters off or to warm then the temp guage ceases to work properly and shows low temp, and sets idle high above 1100-1500rpm (not sure exactly) and makes it difficult (bucking) when driving slow (parking etc).

I was thinking could this be a knackered thermostat??? as the car drives well smooth with good power delivery when temp guage reads normal (blowers on cold) but soon as I switch to hot temp or switch them off the temp gauge drops and car idles high again.

If the car thinks it is cold (when it really isnt) will this cause the choke to be on thus causing my problems. and is it likely to be the thermostat and or air in the system . . .gonna go and try to bleed coolant system soon.


cheers

Joe

[HighwayStar]

Do you have wet carpets under your mats... passenger side? Or if not can you get under the car to look for coolant leaks... particularly near the fuel cell.
First thoughts through my head... 1) thermostat... get to an affiliate and swap it for a known good one, run the car and presto, it'll solve it or not.
2) Air in the coolant system... bleed and bleed and bleed again. There's a how to somewhere here.
3) Heater matrix packed up/leaking etc... tell tale is wet passenger footwell. If it is it's dash out and a new/er unit in.
4) Pipes from hell..... age and friction at a poor design point cause coolant leaks from the pipes that run under the car above the tank. Tank off and replace the pipes. Not an easy job as the name impies...

Hope you get it sorted.

[classicjoe]

Do you have wet carpets under your mats... passenger side? Or if not can you get under the car to look for coolant leaks... particularly near the fuel cell.
First thoughts through my head... 1) thermostat... get to an affiliate and swap it for a known good one, run the car and presto, it'll solve it or not.
2) Air in the coolant system... bleed and bleed and bleed again. There's a how to somewhere here.
3) Heater matrix packed up/leaking etc... tell tale is wet passenger footwell. If it is it's dash out and a new/er unit in.
4) Pipes from hell..... age and friction at a poor design point cause coolant leaks from the pipes that run under the car above the tank. Tank off and replace the pipes. Not an easy job as the name impies...

Hope you get it sorted.

Thanks for the advice, I have ordered a thermostat and should get it tomorrow, will let you know the results, fingers crossed.

I will do a full coolant system flush aswell, is there anywhere cheaper than MrT to get a suitable coolant???

thanks again

[DavesMr2turbo]

anyjoy mate?

[classicjoe]

anyjoy mate?

I did not get time to fit thermostat, but also looks like I have knackered the cat by driving it with the stuck open thermostat (constantly running rich/idle fueling)

So I have ordered a stainless decat pipe from flea bay and hopefully get it fitted at the weekend.

Will keep you up to date.

Joe

[classicjoe]

Hi all,

Been busy today I fitted my new JapSpeed Decat pipe, As I believed the cat to be severly blocked an thus causing the loss of power and misfire. I also got round to changing the thermostat, old one was totally goosed.

Even with the new parts fitted the engine still appears to be running very rich??? Is it possible that the lambda sensor or ECU coolant sensor is bust?


If anyone could advise me the best and most economical way to sort this please.


thanks

Joe

[Moo]

Check for ECU error codes. If the lambda sensor is faulty it will produce a code. A knackered ECU temp sensor would cause it to run rich but only until it's reached normal operating temperature. If the ECU temp sensor has failed the car would run like a dog until it was warm.

Does your car reach normal running temp (needle just under half way) with the new thermostat fitted?

[classicjoe]

Check for ECU error codes. If the lambda sensor is faulty it will produce a code. A knackered ECU temp sensor would cause it to run rich but only until it's reached normal operating temperature. If the ECU temp sensor has failed the car would run like a dog until it was warm.

Does your car reach normal running temp (needle just under half way) with the new thermostat fitted?

Gonna do a ECU check, Yeah the car reaches normal temp. I thought the Lambda sensor worked constantly to control the fuel/air mix whether the car is warm or not?

[classicjoe]

Okay managed to do ECU after fourth time thinking my engine check light was bust . . completely forgot about immobiliser, all working now.

I believe I got error code 21 (two flash pause one flash) which is the O2 sensor signal, So I think its a safe bet to buy a new one.