Car failed MOT on emissions - Rev3 Turbo

[Frank Grimes]

My car has just failed its MOT on emissions. Its fine at high tickover (when the tester is pressing the throttle and its at about 2500rpm) but when it goes back to its normal tickover it 850ish rpm the emissions go through the roof.

When the car is started from cold, I don't get the high tickover (1500rpm). It struggles a bit just under 1000rpm, then suddenly after a few minutes the revs start climbing.

I suspect the idle control valve possibly (the car has been stored in a garage for almost 2 years).

(it flew through its last MOT and that was only 2000 miles ago)

Anyone know how I could fix this? many thanks...

[raptor95GTS]

check for error codes, could be the lambda sensor. If it's over 3.5%CO then something isn't right.

[jon]

I agree with Allan, check the error codes would be the first thing to do.

A faulty coolant temperature sensor can give the idling problem you describe, I fixed the very same issue last night! Error code 22 if I remember correctly...

Cheers,
Jon

[Frank Grimes]

I've just checked for error codes by connecting TE1 and E1 on the diagnostic port with that specialised tool known as a paperclip - nothing came up - just a steady flash of the yellow light on the dash.

I'm running an aftermarket Lamda sensor - it was from a company recommended on here some time ago. But my car passed the mot last time with it fitted so I assume it works OK.

I've read on here that the ICV can get gummed up over time causing it to jam, can it be taken off and cleaned?

Or if it isn't this, does anyone know what else it could be?

[jon]

I still reckon it could be the coolant temperature sensor, maybe it hasn't drifted far enough out of spec to trigger an error code?

If you can get hold of a multimeter, doing a resistance check of the sensor whilst it's still in the engine will confirm if it's OK or not. It should read around 4-10 ohms on a cold engine, and less than 0.5 ohms on a hot engine.

To test the ISCV, try unplugging it's electrical connector when the car is idling, if there's no change in the idle speed then it may be stuck, repeat a few times just to make sure

Cheers,
Jon

[jon]

Also, if you have the detailed emissions results, it would worth posting them here as they can give a clue to what the problem is. For example high Hydrocarbons (HC) indicates that the engine is running too rich, burning oil or a misfire.

Cheers,
Jon

[Frank Grimes]

Thanks for your help jon. I did actually replace the temperature sensor with a cheappie from my local motor factors not so long back

It was the green/brass coloured one that screws into the coolant elbow (the one with LOTS of pipes connected to it near the dizzy). Toyota wanted like 40 quid for a new one - motor factors = 4 quid (could of been a false economy though!)

Anyway, here's the CO results:

FAST IDLE TEST

CO - 0.108

HC - 66

Lambda - 1.003 (PASS)


NATURAL IDLE TEST

CO - 2.769 (FAIL)

[jon]

Is your MR2 an L or M reg? It so the CO limit is 3.5%, so it should have passed!

But anyway 2.7% is still high, on my de-catted Rev 3, CO is 0.65%.

A high CO % generally means that it's running rich at idle, could any of the engine sensors are out of spec (MAP sensor, coolant temp, lamba/O2 sensor or even the throttle position sensor).

Out of interest what was the reason for changing the coolant sensor a while back?

Cheers,
Jon

[Frank Grimes]

My cars' a N reg. Its still got the cat in, although for how much longer I wouldn't like to say

I know there is some loophole or something for the earlier Turbos with regards to emissions, given the fact they were never imported so the MOT test centres have no available information on them or something.

But its annoying that he failed it if the limit is actually 3.5% - i'll mention it to him (Is he assumng its an UK spec n/a or something?)

I changed the coolant sensor a while back to try to cure a dodgy idle. I might just pull my pants down and go to Toyota, just to be sure. Do you happen to know the part number for the coolant sensor?

[jon]

N reg is post August 1995, which is the cut off date for the loophole, so you're probably out of luck trying to get the MR2 through on the 3.5% CO limit.

The part number is 89422-35010, it's quite a common part used on lots of Toyota's from '93 to '99.

Lucas Electrical make an equivalent part, SNB842. I've ordered one for a '94 Corolla which was showing the Error 22 and struggling to idle from cold start. I actually measured the sensor today with a multimeter, it was completely open circuit.

Total cost was £10.71, from http://www.simpsonsupplies.co.uk/ Hopefully the Lucas part will do the job at a quarter of the price of Toyota part

Cheers,
Jon

[Frank Grimes]

Many thanks jon. I'll try with the 'Prince Of Darkness' part first, and hopefully that might work.

My current sensor that I got from a motor factors was made by 'Intermotor' IIRC. It was almost suspiciously cheap - might be a case of 'you get what you pay for'.

If that doesn't work i'll be on first name terms with the parts desk at my local Toyota dealership, working my way through all the various sensors you mention

[raptor95GTS]

yeah N plate is full CAT test. With the CAT in place it should not be anything like that CO value at idle. What was the HC at idle?

[jon]

If replacing the coolant temperature sensor doesn't do the trick, may I suggest investing a tenner in a multimeter?

The BGB describes how to check most sensors in detail, the lambda/O2 sensor and throttle position sensor are pretty easy to check.

I hate to think how much replacing 4 or 5 sensors would cost at Toyota prices!

Cheers,
Jon

[Frank Grimes]

If replacing the coolant temperature sensor doesn't do the trick, may I suggest investing a tenner in a multimeter?

The BGB describes how to check most sensors in detail, the lambda/O2 sensor and throttle position sensor are pretty easy to check.

I hate to think how much replacing 4 or 5 sensors would cost at Toyota prices!

Cheers,
Jon

I took your advice and splashed out on a multimeter...Slightly confused by the sheer number of stuff on the dial but i'm pretty technically minded, so i'll give it a bash. On the 'Ohm' section of the multimeter I can choose between 2m, 200k, 200 & 2 (I think). Now, as the resistance of the water temp sensor is about 4-10 cold, I imagine I set the dial to '20' (as 4-10 is more than '2') then connect the red and black leads to each one of the contacts on the sensor and see what it says?

The 'BGB' - is that that American manual that covered early turbo's? I think i've got that on CD somewhere is PDF format...

[Moo]

Camskill do replacement ECU temp sensors for £14.68. I've had one in mine for years without any problems.

http://www.camskill.co.uk/products.php? ... 0s605p4331

[jon]

I took your advice and splashed out on a multimeter...Slightly confused by the sheer number of stuff on the dial :scratch: but i'm pretty technically minded, so i'll give it a bash. On the 'Ohm' section of the multimeter I can choose between 2m, 200k, 200 & 2 (I think). Now, as the resistance of the water temp sensor is about 4-10 cold, I imagine I set the dial to '20' (as 4-10 is more than '2') then connect the red and black leads to each one of the contacts on the sensor and see what it says?

The 'BGB' - is that that American manual that covered early turbo's? I think i've got that on CD somewhere is PDF format...

Sounds like you've got it sussed out!, the BGB is the service manual for the MR2, the American version will do job, it's available online:

http://www.mr2-tech.com/bgb/mechanical/ ... anical.htm
http://www.mr2-tech.com/bgb/mechanical/ ... tem/29.htm

Alternatively there's a UK version kicking around on the internet, do a search for RM396E.pdf & RM398E.pdf

[StevenstonWullie]

yeah N plate is full CAT test. With the CAT in place it should not be anything like that CO value at idle. What was the HC at idle?

what is the levels for the full cat test? mine is a n-reg dec 95
is in for mot nxt month ive got a berk downpipe fitted havnt got a cat to put on, although previous owner put it through the mot without a cat

[timecorp1]

I had a similar problem last year - my CO2 was something like 5.0+

I have a de-catted M-reg rev 3 but according to Rogue the date of registration is about 1 month too new to be able to go through the MOT on the 'non-cat test'

I asked my local MOT station to put my CAT back on the car for the MOT, but when they realised how difficult a job it was they decided against it, passed the MOT anyway and said I owe them a beer!

Recently the car overheated (which turned out to be due to a slight leak in the coolant). I have replaced the coolant and bled the air out properly after sealing the system with radweld.
When the car overheated initially I called out the RAC - I chatted about the car with the mechanic for a while and he said that the car shouldn't be putting out such high CO2 even without a cat. He also said that he thought the car was 'running on choke' all of the time or something like that.

My MOT is due end of april and really wanted to get it sorted properly this year. I was also considering a re-map of the ECU this year as well - will this help the situation or help uncover any underlying problems?!

[RobCrezz]

I had a similar problem last year - my CO2 was something like 5.0+

I have a de-catted M-reg rev 3 but according to Rogue the date of registration is about 1 month too new to be able to go through the MOT on the 'non-cat test'

I asked my local MOT station to put my CAT back on the car for the MOT, but when they realised how difficult a job it was they decided against it, passed the MOT anyway and said I owe them a beer!

Recently the car overheated (which turned out to be due to a slight leak in the coolant). I have replaced the coolant and bled the air out properly after sealing the system with radweld.
When the car overheated initially I called out the RAC - I chatted about the car with the mechanic for a while and he said that the car shouldn't be putting out such high CO2 even without a cat. He also said that he thought the car was 'running on choke' all of the time or something like that.

My MOT is due end of april and really wanted to get it sorted properly this year. I was also considering a re-map of the ECU this year as well - will this help the situation or help uncover any underlying problems?!

Sounds like your lambda sensor could be broken. Standard toyota ecu cant be remapped, you would need to replace with another ECU (Power FC, link etc).

[holdthefone]

Mine failed MOT but the garage put some fuel additive in and it passed!