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Dergside
Really Senior Member II
Joined: 16-May-2004
Location: Mid West, Ireland
Status: Offline
Points: 4000
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Posted: 27-June-2005 at 11:24 |
All e36's should have a cat, they were std from the introduction of the model in 1991.
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finite
Newbie
Joined: 12-June-2005
Status: Offline
Points: 18
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Posted: 27-June-2005 at 13:44 |
Does removal of the CAT cause a lumpy idle? I can't see how this is possible if the lambda is still in place.
As an aside, as the car is pre CAT legislation the emmisions test shouldn't be too much of an issue.
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Dergside
Really Senior Member II
Joined: 16-May-2004
Location: Mid West, Ireland
Status: Offline
Points: 4000
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Posted: 28-June-2005 at 11:53 |
finite wrote:
Does removal of the CAT cause a lumpy idle? |
Finite, sorry but I can't answer that. Needs someone with a better technical knowledge of things mechanical to chip in here. Chippeduk maybe? I'd imagine that any effects would likely have an impact back to the ecu.
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Now: BMW 523i SE '00, 318i SE - e91 '07, 325i Coupe '93.
Prev: e46 328i SE Touring, 330Ci, 318Ci. e39 523i SE. e36 325i Coupe *2, 323i SE, 316iSE. e30 325iSE 2dr, 320i Conv, 320i 2dr, 316i.
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finite
Newbie
Joined: 12-June-2005
Status: Offline
Points: 18
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Posted: 28-June-2005 at 14:14 |
Ok been doing some research.
Now from what I can make out this is what happens with the CAT/lambda (can anyone confirm if this sequence is correct- ie is the lambda before the CAT?)
air in --> fuel in --> spark --> combustion --> exhaust --> lambda detects level of oxygen and sends voltage reading to ECU --> exhaust gasses go through CAT where some chemical reactions occur to reduce emissions --> exhaust gasses out of tailpipe.
Ok so if the O2 level is too high the ECU ups the injector duty cycle and hence more fuel is used in combustion and vica versa.
From this sequence we can deduce that the lambda/ECU feedback routine would work the same regardless of whethere there is a CAT or not. Now what it doesn't tell us is how efficient the CAT is and how much it reduced emissions (and hence the smell of fuel out the exhaust).
I've had a look at the Haynes manual which also talks about the crank case emmision control (CC Valve) but goes into no detail about how to replace it/clean it. It also talks about the charcoal canister and purge valve- both of which could lead to overfueling if they are working incorrectly. Anyone have any experience with these?
Cars! They'd be so simple if it wasn't for government legislation!
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chippeduk
Really Senior Member II
ECU Tech
Joined: 04-June-2004
Location: United Kingdom
Status: Offline
Points: 696
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Posted: 28-June-2005 at 14:20 |
The cat removal will yield more power but it wont cause masses of extra emmisions but enough to failt the mot of course.
it shouldnt cause lumpy idle at all.
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jayson@chippeduk.com
www.chippeduk.com
07815-501867 - 01527-579345
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finite
Newbie
Joined: 12-June-2005
Status: Offline
Points: 18
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Posted: 28-June-2005 at 14:22 |
Have to find a friendly MOT centre I guess.
Any idea how much the emissions go up by?
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chippeduk
Really Senior Member II
ECU Tech
Joined: 04-June-2004
Location: United Kingdom
Status: Offline
Points: 696
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Posted: 28-June-2005 at 14:23 |
i am unsure but it isnt hard to find an mot that will pass a car thats decatted.
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jayson@chippeduk.com
www.chippeduk.com
07815-501867 - 01527-579345
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finite
Newbie
Joined: 12-June-2005
Status: Offline
Points: 18
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Posted: 28-June-2005 at 14:24 |
too true! or one who will pass a rotten tub bucket for the right money.
shame in many ways.
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chippeduk
Really Senior Member II
ECU Tech
Joined: 04-June-2004
Location: United Kingdom
Status: Offline
Points: 696
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Posted: 28-June-2005 at 14:42 |
To be honest, i dont know of a single place that would do that although there are some about but with decats, any mot place knows all the people will do is put the cat back on then mot it and then remove it.
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jayson@chippeduk.com
www.chippeduk.com
07815-501867 - 01527-579345
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Peter Fenwick
Bavarian-Board Contributor
Joined: 27-August-2003
Location: Lost somewhere in time...
Status: Offline
Points: 6484
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Posted: 29-June-2005 at 03:03 |
finite wrote:
How does the crank case vent valve cause overfueling? I haven't checked mine so it's a possibility.
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Sorry, no idea. It was just suggested to me as a potential cause of a lumpy idle
finite wrote:
My damned brake pad wear light's just come on too (the circle with blocks at the edge) but my pad's look ok!!!
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Could be a problem with the sensor.
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Entering an age of Austerity and now driving a Focus Diesel.
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Peter Fenwick
Bavarian-Board Contributor
Joined: 27-August-2003
Location: Lost somewhere in time...
Status: Offline
Points: 6484
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Posted: 29-June-2005 at 03:05 |
chippeduk wrote:
The cat removal will yield more power but it wont cause masses of extra emmisions but enough to failt the mot of course.
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I thought it was OK to remove the cat if the car was made pre August 1992 (J reg or older) ?
Edited by Peter Fenwick
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Entering an age of Austerity and now driving a Focus Diesel.
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finite
Newbie
Joined: 12-June-2005
Status: Offline
Points: 18
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Posted: 29-June-2005 at 10:31 |
Hi Peter,
As far as I am aware all cars pre J plate (and some J plates) did not have to have a CAT.
However in order to pass the emissions test the emissions have to be to the manufacturers specification for the car +/- x% (usually 5%) I believe. If this is the case then it is possible that a decatted e36 may output higher emissions than a non-CAT e36 as the combined emissions systems are different.
Jayson- unfortunately I live in the countryside and we have way too many "£100 MOT" centres locally.
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editfmah
Groupie
Joined: 29-June-2005
Location: United Kingdom
Status: Offline
Points: 64
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Posted: 29-June-2005 at 23:34 |
Hi,
Just a thought, why not take the oil cap off whilst it's running and see if it
gets worse or the same.
I have a 328 and that engine is smooth, one day I forgot to tighten the cap in
any way and it ran very lumpy at idle until I worked it out. It smoothed
out when revved, then after settling for a few seconds it came back. I'm
not saying it's the cap obviously but if there is a lack of pressure/vacuum
then this could be the same.
Also i've had a couple of 6 cyl BMW's all of late 24v variety and they all had
a strong petrol smell on startup and they have all been excellent runners
without any faults.
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E36 328i Touring + E36 Compact 318Ti
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finite
Newbie
Joined: 12-June-2005
Status: Offline
Points: 18
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Posted: 01-July-2005 at 17:33 |
Ok so I've fitted the standard air box back after aquiring one from a breakers. It came with a K&N pannel filter which was a bit of a result. All fitted minus the plastic cowling that fits the front of the box to the scoop in the inner wing/chassis leg (I assume there's some plastic that goes here or the box will still be sucking some hot air?). I'll try and get the cowling this w/e. It's definitely made some difference, but the idle is still lumpy. Looks like I'll have to strip down the vacuum/inlet system to look for leaks/clogged valves.
Anyone got any advise on this process?
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