Emmisions and MOT failure

[ButtonIt]

Does anyone know what causes an old car (1993 Vauxhall Astra 1.4l) to fail an MOT on emmisions? and any way of fixing it?

Any help, advice or suggestions greatly appreciated

No Cat converter, petrol engine.

[twouptons]

What sorts of emissions controls does it have?
If it were failing an emissions test in Georgia, USA (I don't know exactly what you folks get tested for in an emissions test in the UK)...
I would suspect things like a bad O2 sensor or a failed EGR system, assuming it has them...
It could also be something like a poor state of tune, misfiring plug, or that sort of thing.
Failures are also very likely if the car is not fully warmed up when tested.

The general rule of thumb here for an older car that fails emissions is to drive it until the gas tank is nearly empty, fill up with the best gas you can find, drive most of that tank out at high speed on the interstate, and take the still-warm car to be tested again... That will eliminate many neglect-related emissions failures (though it will still fail if there is something seriously wrong with it).


-Eric

[SiBradbury]

Here's how to fix it. Get some fuel treatment (Lucas, Forte, STP or Slick 50 do good ones, don't bother with Redex its a waste of time) add it to your tank fill up with Shell Optimax and drive your car like you stole it immediately before the re-test. I mean really cane the cr*p out of it, lots of redlining, get it nice and hot and Bobs your mothers brother, you should (hopefully) have a good chance of passing, providing of course it didn't fail in the first place cos its billowing great big clouds of black smoke! No fuel treatment will cure that. Except maybe a fivers worth of unleaded and a box of matches........

[Jaffa Racer]

Buttons as its non cat I assume it failed on high Co2 or HC emissions? Did the test staton test you car HOT obviously if cold you get a bogus reading IE FAIL.

When did you last service it? an air or fuel filter change may do the job,

Next your in to injection adjustments (sorry a garage job, I dont know where/how the adjustment is made plus you need the meter to read you adjustment)

Lastly if it failed dismally on HC's it could be a ****ed engine

Any of the above can/will benifit from from additives, but they only mask what really needs to be sorted out.

Hope this helps

Kev. camera bloke at Castle Combe

[ButtonIt]

Thanks guys

It's my housemate's car. She drives about 10 miles a day, never getting above 3k revs and in slow traffic. Took it out for a 60 mile blast just now, full revs through the gears and changing between 4t and 5th gear on the motorway. Told her to take it for a spin at lunchtime, just before she drops it off.

Muchos appreciato chappses

[pocketrocketowner]

ole twouptons has got it bang on...........here we come to that oft discussed subject of gasolines and additives and what Premium gas is all about> Crap fuel=unadditized fuel or additized to a minimum extent.
Why the additives, cuz modern gasoline cruds up the top of your intake valves like you would not believe, enter crap breathing, crap combustion, voila bad emissions, add that up to a very light usage older technology car......voila failed MOT......

[ButtonIt]

She failed

Looks like there's a bigger issue somewhere.

[Rakey]

look on the bright side, one less Astra on the roads

[ButtonIt]

Burning oil is the cause, replacement engine? or bin the bugger and get her to buy another car

[twouptons]

Quote: Originally Posted by ButtonIt

Burning oil is the cause, replacement engine? or bin the bugger and get her to buy another car

I think you know the answer you'll get here

Burning oil is never a good thing (unless you drive a diesel...)
There are a few things that it could be that wouldn't mean "new engine", but you'll want a professional opinion on that, I'd wager...

-Eric

[Rakey]

Quote: Originally Posted by ButtonIt

Burning oil is the cause, replacement engine? or bin the bugger and get her to buy another car

get her to buy something a bit more modern with a cat and injection

maybe a MINI

[Jaffa Racer]

compression test please :-)
2 tests, both cold one with 4 or 4 squirts of 20/50 from a normal oil can. Big variance = worn bores/rings if only 10/15 psi increase prolly valve guides, stems steams could be a cheep fix

HTH
Kev...

[tnoy66]

Reading this about getting the car hot before a test could explain why a car of mine failed a few years ago
Every time it had an emissions test it failed first go and then they would repeat it and it would pass 2nd time, until my last test.

Drove from home to test centre, 5 mins, and then had to wait for the guy to turn up, so basically my car was cold.
He did the emmissions test and failed it twice, went to print the report and the printer failed too, so he passed it
Sold it a few weeks later

[kapps]

If it means that much, then get a shop to fab an exhaust with a cat. You could always run a test pipe after it passes. This actually works quite well, I picked it up from some old Lotus owners. Lean out the carbs and just stick a cat where the muffler is. You don't have any control with the EFI but a cat would probably bring it a passing grade.

[ButtonIt]

£700 for a fully fitted reconditioned engine. 5 year/60k mile guarantee on it.

I reckon it's worth going for that option. She's no interested in cars, and she only drives to work and back. Her car is worthless as an MOT failure, it'll cost her much more than that to buy another car. Also the rest of the car is in great condition, none of the rust that is typical of mkIII Astra's and the interior is perfect. For £700 she's getting a guaranteed reliable car for at least 5 years.