Corolla 1,6 year1988 exhaust emissions

[teho75]

Hello and greetings from Finland!

I hope you understand my text.

I am talking about my friends car. The car failed official inspection.

Toyota Corolla 1,6 1988

Carburetor, and no catalyst

Electric automatic choke.

 

Problem is exhaust emissions.

CO% 0,18
HC 1040
CO2 8,7
O2 8,59
RPM 800

There was a little hole in the exthaus pipe, but it is now fixed.

2 years ago replaced: Ignitions plugs,power distributor cover,spinner, ignition cables, Battery, cable contacts fixed.

 

 

[DerekHa]

Hi there Teemu,

Others here will likely come along and comment and offer advise. This being a largely UK based forum may cause some issues with emissions standards as you're in Finland. You're emissions stanrdards may be  more stringent/strict than here in the UK.

Has the vehicle failed the inspection on all the emssions you've listed or is there one in particular thats at fault?

[NeilMH]

Hello. In the UK there are different (lower) standards that apply to some older cars - particularly prior to 1992. If you look at the tables in this (rather long) document, you will be able to see the various categories that apply here. As Derek said it would be helpful to know what it failed on and by how much compared to the Finnish standards. My garage always give my cars a really good warming up before testing!

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/676700/in-service-exhaust-emission-standards-for-road-vehicles-19th-edition.pdf

[DerekHa]

5 minutes ago, NeilMH said:

Hello. In the UK there are different (lower) standards that apply to some older cars - particularly prior to 1992. If you look at the tables in this (rather long) document, you will be able to see the various categories that apply here. As Derek said it would be helpful to know what it failed on and by how much compared to the Finnish standards. My garage always give my cars a really good warming up before testing!

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/676700/in-service-exhaust-emission-standards-for-road-vehicles-19th-edition.pdf

Had come across that same document via a quick google Neil. Noticed that between 1986 - 1992 the only measured emissions are those of CO and HC3 nothing else is subject of testing. Then again this is from a UK Government source.

[NeilMH]

1 minute ago, DerekHa said:

Had come across that same document via a quick google Neil. Noticed that between 1986 - 1992 the only measured emissions are those of CO and HC3 nothing else is subject of testing. Then again this is from a UK Government source.

Yep - and some older cars have visible tests only - I think you have go go back to the 70s for that - eg. the Ford Crossflow I had in one of my Caterhams. 

[TonyHSD]

1 hour ago, theo75 said:

Hello and greetings from Finland!

I hope you understand my text.

I am talking about my friends car. The car failed official inspection.

Toyota Corolla 1,6 1988

Carburetor, and no catalyst

Electric automatic choke.

 

Problem is exhaust emissions.

CO% 0,18
HC 1040
CO2 8,7
O2 8,59
RPM 800

There was a little hole in the exthaus pipe, but it is now fixed.

2 years ago replaced: Ignitions plugs,power distributor cover,spinner, ignition cables, battery, cable contacts fixed.

 

 

Hi, 

if the car is running well and there are no physical problems with engine fuel or exhaust system, then you can use some quality additives prior to re test and again as mentioned above the car need to be warmed up before the initial test commence. Here perhaps a suitable additive to try: https://www.wynns.uk.com/product/pre-emission-test-treatment/

make sure you do exactly as on the label. https://wynns2021.wpengine.com/wp-content/uploads/2021/05/31164-Pre-Emission-Test-Treatment-for-Petrol-Engines_EN.pdf
Good luck 👍

[teho75]

1 hour ago, DerekHa said:

Hi there Teemu,

Others here will likely come along and comment and offer advise. This being a largely UK based forum may cause some issues with emissions standards as you're in Finland. You're emissions stanrdards may be  more stringent/strict than here in the UK.

Has the vehicle failed the inspection on all the emssions you've listed or is there one in particular thats at fault?

HC limit in Finland is 600. Test result is too high.

CO% limit is 3,5.

O2 limit is 5.

O2 result was high because hole in the exhaust pipe.

[DerekHa]

Ok Teemu,

So the Hydro Carbons are well above the defined limit.

From your original post I you say that all of the ignition components have been replaced recently. One thing crossed my mind as being missed from your list is the air filter! Has that been changed, just thinking a choked air filter would cause an over rich fuel to air ratio and the engine is pre even the original Euro 1 emissions standard.

From what I've read a vacuum leak on the inlet manifold side of the engine can also lead to high HC readings.

Came across a youtube video that explains emissions and the causes of bad readings:-

May help in leading you to solving your issue:

 

[DerekHa]

One other thing has just struck me Teemu!

There was hole in the exhaust causing the high oxygen reading. If the oxygen reading was high the sensor would have then triggered the ECU to meter more fuel for combustion as it would regard this that as a lean fuel condition! This then could be the cause of the high HC reading??

Is it possible fixing the hole in the exhaust has also cured the high HC read? Might be as simple as that Teemu.

[APS]

Hei Teemu,

Check ignition timing and put some carb cleaner in (Bensiinin jäänesto). The carb cleaner will also lower the readings in itself. 

[flash22]

its been a long time since i had a car with a carb

High HC - the fuel mix is too rich or too lean

 

Rich - it's over fuelling, the choke is getting stuck or the intake is obstructed

Lean - a vacuum leak, intake manifold leak, crankcase breather issue or carb to manifold gasket has failed

 

pull all the plugs and post a pic or compare the colour to a chart, plug colour tells you a lot about the engine's health

Click to enlarge

 

Be aware toyota engines do not like ngk, Bosch or champion plugs unless it was supplied from the factory with them - Use Denso plugs

Poor spark can cause an incomplete combustion cycle and play havoc with emissions, also the Ethanol fuel can be another issue in older cars

[flash22]

14 minutes ago, DerekHa said:

One other thing has just struck me Teemu!

There was hole in the exhaust causing the high oxygen reading. If the oxygen reading was high the sensor would have then triggered the ECU to meter more fuel for combustion as it would regard this that as a lean fuel condition! This then could be the cause of the high HC reading??

Is it possible fixing the hole in the exhaust has also cured the high HC read? Might be as simple as that Teemu.

It would, but it doesn't have an ecu for the fuel (may be very early electronic ignition) as it has a carb being pre-1991 it doesn't have a cat either

[DerekHa]

15 minutes ago, flash22 said:

It would, but it doesn't have an ecu for the fuel (may be very early electronic ignition) as it has a carb being pre-1991 it doesn't have a cat either

Can see my deliberate mistake now! There's no mention in the original post of an O2 sensor. Thanks for pointing out my error Flash.

[flash22]

People are so use to efi and fully electronic engine management carb's and dizzy's have become a dark art, even new hatched mechanics in the last 10-15 years have no experience with them

Ah the smell of raw petrol spewing out of a pair of twin, twin 45 Weber's