MOT

[Paul McKay]

My Delorean passed its MOT today on the first trip to the garage

Initially though it failed on the emissions test, but passed when the guy ran it again. My car has not been driven since Sept 2005, and just started on occassions. I guess i am putting it down to not having had a good run.

The CO level was 3.52%, which is still a bit high..am i right? The HC level was 110ppm.

The car is also running a bit rich, sitting at about 9 (whatever that is) the guy said, again he put it down to the car not been running for a while.

I am however going to get my system checked out.

[NickT]

Congratulations on your MOT !

If you don't have a cat then the co should be between 1 to 1.5%.
HC is <200ppm so is OK.

I don't understand the reference to 9 is as the richness is indicated by the CO reading which yours is 3.5%. The only thing I can see this relating to is the lambda reading being .9xx which for this age of car is not required.

1 = perfect stochiometric ratio 14.7 air to fuel (if I remember ok)

<1 is too rich
>1 is too lean

Limit is something like 0.9 to 1.1

I would disconnect the oxygen sensor then set the mixture to 1 to 1.5
Reconnect and it should be between 0.7 and 1 % CO.

If you do have a cat then it is running very rich !

NickT.

[Paul McKay]

Thanks Nick, i must start learning about these things...you certainly know your stuff.

I believe my Delorean has no cat.

[tracey steele]

Paul McKay Wrote:My Delorean passed its MOT today on the first trip to the garage

Initially though it failed on the emissions test, but passed when the guy ran it again. My car has not been driven since Sept 2005, and just started on occassions. I guess i am putting it down to not having had a good run.

The CO level was 3.52%, which is still a bit high..am i right? The HC level was 110ppm.

The car is also running a bit rich, sitting at about 9 (whatever that is) the guy said, again he put it down to the car not been running for a while.

I am however going to get my system checked out.

pleased it passed, i`ve got my 1st mot next week on mine since it was converted to rhd fingers cross.

[Jonny Jones]

Am I correct in saying that the DeLorean doesn't have to have a CAT installed as its an 80's car? Or something like that... which is why lots of owners take theirs off to up the BHP?

[Pilot25dmc]

Think its pre 85' cars have no need for a CAT.

Mine is set to 3% and runs/idles perfectly and it passes the gas test without fail every year, saying that though I have the stainless exhaust system and it does require a little more oomph.....

I would call 1% too lean and anywhere after 3.75% too rich, buts thats just my personal opinion!

Practicaly every car in Ireland is set to 3%, we do what the specialist tells us isnt that right Mr Omallay.....!

[Chris Hawes]

Interesting, in the UK cats had to be fitted from cars registered from August 1st 1992 (I think).

I had a Carlton Gsi (1991) model and I never got around to removing them... although with 206bhp from the 3L 24V6 straight six going to just the rear wheels I didn't need any more power

[Jonny Jones]

Chris Hawes Wrote:Interesting, in the UK cats had to be fitted from cars registered from August 1st 1992 (I think).

I had a Carlton Gsi (1991) model and I never got around to removing them... although with 206bhp from the 3L 24V6 straight six going to just the rear wheels I didn't need any more power

Yeah mate haha, that would be murder im sure... well suicide!... well, not really just a few extra horsies!

[Tourettes Tony]

Funny how garages are different, they didn't check my co because it wasn't in their book so they done a visual, also they never checked the dampers in case they marked the stainless while pushing down now thats love or is it because i know them funny ole lot :lol:
Tony TT

[Guinney1971]

I had the same thing years ago with my Ford Prefect (1958 vintage) - they said they didnt do CO tests on vehicles over a certain age, and basically just checked the exhaust to make sure it wasnt smoking too much!

[NickT]

Pilot25dmc Wrote:Think its pre 85' cars have no need for a CAT.

Mine is set to 3% and runs/idles perfectly and it passes the gas test without fail every year, saying that though I have the stainless exhaust system and it does require a little more oomph.....

I would call 1% too lean and anywhere after 3.75% too rich, buts thats just my personal opinion!

Practicaly every car in Ireland is set to 3%, we do what the specialist tells us isnt that right Mr Omallay.....!

If that what works best with your engine Alistair. Mind you, yours is a prototype so it could have differences, especially with a better free flowing designed exhaust.
I presume you have disconnected the o2 sensor making it run in an open loop mode.
I set my bog standard (but with cat bypass) set up according to my Bosch book (cross referencing to Volvo dealer manual) and works ok.

To answer Jony Jones question, in UK the MOT tests are:

Pre 1975 cars are smoke opacitiy only, no blue or black smoke for 5 seconds idle or 2500rpm for SU Carburettored engines.
1975-1986 CO < 4.5% - HC < 1200ppm
1986-1992 CO < 3.5% - HC < 1200ppm
1992-1994 Cat test CO < 0.3 - HC < 200ppm - Lambda 0.97 - 1.03
from 1994 same as basic Cat test but depends what other tests the computer may have for the car.

So , the cat is not required for a 1980-1983 car. The cat design of 1982 has a small bore catalyst so causes some back pressure so removing it can make the engine run better. Modern cats have a larger bore monolith so flow better.

NickT.

[Paul O'Malley]

"Practicaly every car in Ireland is set to 3%, we do what the specialist tells us isnt that right Mr Omallay.....!"


Hi Alistair, and all.

The general rule I use when setting these baby's up is if its on a cat and standard exhaust I would set it up as per the original spec's, as to deviate from this will inevitably kill the cat. If a car is running the original exhaust and no cat I would set the mix at approx 2.0% and if they have the freeflow stainless exhaust I set it at approx 3.0% for a slightly rich but safe set up. In my experience the freeflow systems tend to make the engine run lean on the top end so that's why I like to give them that bit of extra fuel. All our engines are 25 years old now and most will have never been rebuilt and as a result they tend to run better when running a little on the rich side.