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Problems, Servicing & Repairs Information and topics about technical problems, servicing and repairs to the Rallye

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Old 25-07-2018, 08:39 PM   #1
DanCainey
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Crazy high emissions

Okay so I finally took the pug in for its MOT - didn't expect it to pass, but thought it would be useful to have a to do list to work from. I've replaced the original 1.1 with a S1 1.3 rallye which I have fully rebuilt and seems to be running well.

Emissions results were off the charts!

Fast Idle

CO = 5.6 !! (pass is 0.3)
HC = 374 (pass is 200)
Lambda = 0.851 (pass min is 0.97 max 1.03


Natural idle

CO = 0.521 (pass is 0.500)

Any idea what this could be? It has a brand new lambda sensor. The mechanic thought it was probably the cat, but this too is fairly new (although it has had to suffer the original engine massively overheating, and running for a few miles with a big hole in the downpipe).


My plan is to simply get a new cat and retest, but thought I would check to see if there are any other causes it could be.
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Old 26-07-2018, 08:44 AM   #2
Mou1t
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Just had the exact same thing on my 16v mate...
Failed on emissions more than double, doctored a brand new cat into the pug sport and still failed !!
Plastered the whole exhaust in fire putty and it passed ?? VERY slight blow was causing the problem.
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Old 26-07-2018, 01:20 PM   #3
DanCainey
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Thanks dude, I'll bear that in mind. Just a bit worried as my CO levels at fast idle are 20x the limit!

From what I understand, high CO and HC readings combined with a low lambda indicates that the engine is running very rich. That sound correct? I wonder why it would be doing that?
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update - have just tested the coolant temp sensor and confirm that it is working. I've also tested the lambda sensor which settles at 0.8 V on idle, and fluctuates between 0.1 and 1.5 V after blipping the throttle - so that seems to be working correctly. So that's two potential causes ticked off the list, but still no idea where the culprit lies.

Last edited by DanCainey; 26-07-2018 at 01:20 PM. Reason: Automerged Doublepost
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Old 26-07-2018, 05:43 PM   #4
MHR1294
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When you hold it at fast idle, the idle should be really smooth

ANY misfiring will raise the CO level by a large margin. Large PPM also hints at a slight misifire or overfuelling

Or maybe injectors not quite working perfectly?

Could be a dodgy MAP sensor, make sure there are no splits in the hose leading to it too

Are you using the original 1.3 engine fuel pressure regulator?

It's probably not the cat, that doesn't affect the PPM - or it didn't on my Volvo anyway haha! Even with a cat that doesn't work the CO should be way lower. (like my 1978 V12 Jag is less than 2% CO and my 1995 Volvo managed 0.31 with no cat!)

Last edited by MHR1294; 26-07-2018 at 05:45 PM.
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Old 26-07-2018, 08:09 PM   #5
DanCainey
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AH YES - you mentioned the fuel pressure regulator which got me thinking. And it turns out the vacuum hose for it wasn't even connected to the manifold. After reattaching it the engine did seem to run smoother. I'd imagine that should make quite a bit of difference to the emissions readings. Slightly embarrassed that neither me nor the mechanic spotted it. Thanks for the help, much appreciated.
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Old 27-07-2018, 04:05 PM   #6
DanCainey
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UPDATE - After reconnecting the fpr pipe I took the car back in for a emissions test. This time it passed with flying colours:

Fast Idle

CO = 0.023
HC = 32
lambda = 1.010

Natural Idle

CO = 0.00

I was quite surprised by these results considering how many people I'd seen on here saying they had struggled with their emissions test (although admittedly this is with a newly rebuilt engine).
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Old 27-07-2018, 07:51 PM   #7
welshpug
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good work, the fuel pressure drops from 3 to 2.5 bar iirc when you close the throttle.
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Old 27-07-2018, 11:36 PM   #8
MHR1294
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Quote:
Originally Posted by DanCainey View Post
UPDATE - After reconnecting the fpr pipe I took the car back in for a emissions test. This time it passed with flying colours:

Fast Idle

CO = 0.023
HC = 32
lambda = 1.010

Natural Idle

CO = 0.00

I was quite surprised by these results considering how many people I'd seen on here saying they had struggled with their emissions test (although admittedly this is with a newly rebuilt engine).
Imagine how many of these cars failed emissions tests and it's been a faulty FPR or a split hose going to the FPR hahaha!

Better check mine actually, it's always ran a bit funny and rich
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