r1 emissions contd.
okay, 2 MOT emissions tests done today, both failed.
with the new cat fitted, CO and HC are well under- hooray!
I'd also fitted the Dynojet needles which dont seem to affect Idle - hooray again!
however, lambda is still above the limit... (only just on a fast idle, but definately over)
I tried fiddling and richening it up, and while the CO started to go up (and eventually over) the lambda stayed above.
its hard to tell whats going on as both tests (different garages) would never complete the standard emissions test due to errors. (it looked like the
probe was getting too hot and the machine couldnt read it properly)
first question is: how can I get the lambda down? ive blocked the hose on the AIS system that draws in air and dumps it into the exhaust as it was
presumably giving a false lambda reading...
i cant richen it any more as the CO goes over.
second question:
how can I get the heat of the gasses down before it reaches the probe. obviously if I DO ever pass an SVA (I can dream) it'll have to go for a
standard MOT in 3 years time and I will have the same problem of the machines not being able to cope with it.
I'm quite pleased that the new Cat works well but im still gutted that its not going to pass the retest..
any help appreciated!
you say is above the limits but what reading are you getting
below 1.00 is richer than optimum and over 1.00 is weaker then optimum
check for any induction and exhaust leaks even if small will affect/dilute the gas sampled at the probe giving false readings
also ensure the probe can be fully inserted into the pipe at least 6 to 9 inches sothe sample is not diluted with o2 giving a high lambda
reading(over 1.03)
post up the figures you achieved on the mot type test (BET test)
Rich
How much out was the lambda?
Were you adjusting the idle mixture on all 4 carbs by the same amount?
Have you got an air leak on one or more of the exhaust seals, or on your manifold / cat or cat / silencer joins?
Lambda is excess oxygen. Higher than 1 means too much air. You might have a leak. even so, if you're adjusting the fuel. I'd expect the
lambda reading to move a bit.
id go for an air leak somewhere if your in on co and hc, a slight blow somewhere on the exhaust system will draw air in at fast idle giving you the
high lambda reading .air leaks before the cat wil give low co and poss higher hc if its bad enough. i have to plug pin holes in cars every day to get
them throught the bet test due to lambda slightly over. check the cat for pinholes as they are well baffled and you might not be able to hear any
leaks from it
the lambda was always just outside 1.03. it was just inside on the first attempt but then crept over at the end of the test.
afterwards it was too much faffing with the machine giving up to be able to tell. sometimes it was showing 1.3 - 1.4 but that was at standard idle,
it went down when revved.
the cat is brand new as its just been changed so I guess theres a chance that when i've put it all back together i havent used enough paste.
given the lack of room, i'd rather not take the exhaust manifold off but in the interests of finding the leak I might have to.. 
quote:
Originally posted by smart51
Were you adjusting the idle mixture on all 4 carbs by the same amount?
quote:
Originally posted by smart51
Have you got an air leak on one or more of the exhaust seals, or on your manifold / cat or cat / silencer joins?
was your cat 2" ID or 2" OD in the end?
have you got a standard airbox or sausage filter
sausage filter fitted
2" OD I think Colin, the cat/silencer was the same diamater as the manifold, so theres an internal sleeve of pipe inside for them both to slide
onto.
try covering some of your airfilter up
Is your manifold sealing? If your using the MNR exhaust manifold, you may need to use 2 sets of sealing rings. I had to use 2 sets on mine to get a
seal. Not sure if this would cause an issue though.
Steve.
As has others have sugested, I'd say it was an air leak. Most cars I take for MOT are just under 1.03 due to tiny leaks. It might help to ask the
tester to switch the gas meter to diagnostic mode instead of MOT mode to set it up.
Get a butane blow lamp, take of the burner and push a pipe on. Then open the gas (just a touch) and feed it around areas of the exhaust while reading
the lamda. When it changes thats where the leak is.
Oh and don't use exhaust sealant in front of the cat' as it'll bugger it up!
Adrian
quote:
Originally posted by amalyos
Is your manifold sealing? If your using the MNR exhaust manifold, you may need to use 2 sets of sealing rings. I had to use 2 sets on mine to get a seal. Not sure if this would cause an issue though.
Steve.
You can buy a set on ebay for a fraction of the price. They aren't the OEM ones, but they did the job. I ended up with 1 set of Yamy and 1 set of
Ebay ones on.
Steve
bit of an update:
starting the engine from cold if i put my hand inbetween the 4 exhaust headers, between 1+2 and 3+4 were cold, yet inbetween 2+3 there was a definate
warmth.
i couldnt feel any air movement but it was definately warmer air.
remembering an old bicycle puncture trick, i dabbed slightly soapy water around the larger 'collars' of the headers (which are held into the
engine by the large plates with nuts on) and there was some bubbling around the tail end of the collar.
I thought these were welded on the inside to the stainless pipes so I presumed an airtight weld but I think theres a leak in there somewhere.
Im not stripping it all off again, copious amounts of fireweld around the join will have to do for now! I'll see how it goes...