IVA emissions and self centering

[Bobnic]

Hi guys. Should have an IVA date for the end of June hopefully, so not long to go!! Car's running well, drives and stops nicely. Two big things left are the emissions and self centering. Used my local friendly garage's emissions tester like they use in an MOT. The lambda reading came up as 3, should be around 1. This is basing the test against the 1994 criteria for the donor M3 E36 1994 engine. Will the IVA tester use this benchmark, or resort to the earlier test criteria?? If it's the earlier, it's fine, if it's to the 1994 criteria, we have a problem. Do you think I need to change the lambda sensors, or is an air leak in the breather/exhaust system more likely a cause??? Struggle to unravel the flow charts in the IVA manual, me being thick is the main problem I fear!!

Also, really struggling to get the steering wheel to self centre at all, have tried adding toe out as suggested by Patrick on his website, hasn't really made any difference, any other ideas please??

Yours nervously

Rob

[NigelB]

Originally Posted by Bobnic

Hi guys. Should have an IVA date for the end of June hopefully, so not long to go!! Car's running well, drives and stops nicely. Two big things left are the emissions and self centering. Used my local friendly garage's emissions tester like they use in an MOT. The lambda reading came up as 3, should be around 1. This is basing the test against the 1994 criteria for the donor M3 E36 1994 engine. Will the IVA tester use this benchmark, or resort to the earlier test criteria?? If it's the earlier, it's fine, if it's to the 1994 criteria, we have a problem. Do you think I need to change the lambda sensors, or is an air leak in the breather/exhaust system more likely a cause??? Struggle to unravel the flow charts in the IVA manual, me being thick is the main problem I fear!!

Also, really struggling to get the steering wheel to self centre at all, have tried adding toe out as suggested by Patrick on his website, hasn't really made any difference, any other ideas please??

Yours nervously

Rob

Hi Rob,

Just been playing with the same thing myself. I have an M50 from a 1994 325i coupe and the CO2 is a bit high. I have a Cat fitted and the guys at the MOT testing station suggested that the thing probably just needs a damn good run to get the Cat nicely cooked to give it a good clean out and the chemical reaction working properly. I'm not sure whether that will help lambda at all but its worth thinking about.

I have struggled with self centring as well but I took it up to our local motorsport outfit last Saturday and it now seems to be sorted. The main determining factor is castor angle, followed by toe. The standard Marlin set up is 2.5 degrees of castor but I have now got between 4 and 4.5 degrees. I'm also running 1 degree of toe out. I achieved the extra castor by moving the washer behind the front upper wishbone eyebolt to in front of the rear eyebolt, effectively moving the upper wishbone back by about 1mm. Re-check the camber angle again afterwards, but that worked for me. Failing that, unscrew the front eyebolt by half a turn but leave the rear where it is. That will also move the upper ball joint rearwards but will definitely change the camber. You'll then need to play around to get the best compromise between castor and camber, not made any easier by the coarseness of the eyebolt threads.

I think my original donor had 5 or 6 degrees of castor. (with power steering you can do that but without, the steering can get a bit heavy at larger angles). And I suspect that if your donor was an M3 it probably ran less castor to allow the front end to turn in more quickly.

I'm running 35mm offset wheels as well which doesn't help. The standard for my donor was 41mm which brings the wheels closer to the vehicle centre line and makes self centring easier.

So try moving the washer and then play around with the toe out. You don't want anymore than about 1.5 degrees though.

My IVA is at the end of the month. Could there be two new Sportsters on the road this summer............................

[Mike]

Originally Posted by Bobnic

Hi guys. Should have an IVA date for the end of June hopefully, so not long to go!! Car's running well, drives and stops nicely. Two big things left are the emissions and self centering. Used my local friendly garage's emissions tester like they use in an MOT. The lambda reading came up as 3, should be around 1. This is basing the test against the 1994 criteria for the donor M3 E36 1994 engine. Will the IVA tester use this benchmark, or resort to the earlier test criteria?? If it's the earlier, it's fine, if it's to the 1994 criteria, we have a problem. Do you think I need to change the lambda sensors, or is an air leak in the breather/exhaust system more likely a cause??? Struggle to unravel the flow charts in the IVA manual, me being thick is the main problem I fear!!

Also, really struggling to get the steering wheel to self centre at all, have tried adding toe out as suggested by Patrick on his website, hasn't really made any difference, any other ideas please??

Yours nervously

Rob

Hi Rob

Get yourself a letter from BMW stating the age of your engine and you will not need to worry about the higher emission levels - (I have confirmed this with VOSA direct). The critical date is August 1995, so you are well before that.
All you have to do is send them a letter with the number of your engine and they will write back confirming the month of manufacture.
As your car is a kit car they do not have the EXACT match so revert to the basic test which does not require a CAT.

Have a look at the contact details in my letter from BMW:

http://www.flickr.com/photos/mikes_b...in/photostream

Good luck
Mike

[peterux]

Hi Rob,
I think your suspension is of the new type with the alloy hubs so you should check with Marlin. If they can't help I would follow Nigel's advice of setting as much camber as possible and then try varying degrees of toe in or toe out until you find one that works. I didn't measure my toe out, I just put a marker on the tie rod and rotated by 1 turn both sides until I found something that worked by trail.(and lots of error) Pumping up the front tyres to about 35psi also helps a bit.
Good luck with your test!

...peter

[Mike]

Originally Posted by peterux

Hi Rob,
I think your suspension is of the new type with the alloy hubs so you should check with Marlin. If they can't help I would follow Nigel's advice of setting as much camber as possible and then try varying degrees of toe in or toe out until you find one that works. I didn't measure my toe out, I just put a marker on the tie rod and rotated by 1 turn both sides until I found something that worked by trail.(and lots of error) Pumping up the front tyres to about 35psi also helps a bit.
Good luck with your test!

...peter

........as much camber as possible? Did you mean caster?

[peterux]

Originally Posted by Mike

........as much camber as possible? Did you mean castor?

Yes, indeed, I did mean caster. Thanks Mike.

[chrislandy]

You don't need it fully setup for the road, just enough so when the guy razzes it around the compound the wheels snap back to straight. just crank the caster up as mentioned then get it aligned after you've passed

[GreatOldOne]

All of the above - when Vikki went through her test, the front tyres where at around 30psi, and the castor was set to 3 washers to the back, 1 to the front. She still didn't self centre "as required" on the day, but the tester allowed us to use the sliding pads on the lift in the station to wind the track rods out until she did...

Just be careful with the rods - after I had my diesel skating lesson, the track rods had popped out of the rod ends, as they where only in a couple of turns! I'm not convinced that the steering rack as supplied by marlin is long enough, or robust enough:



As part of the repairs, I had a steering rack reconditioner replace the rods and make me some properly engineered extensions.