Euro SC troubleshooting over

[Vereeken]

Keywords: SC ROW Non US Euro version CIS

Symptoms:

No high idle when starting for the first time from cold.

Stumbling, hesitation at low rpms and low engine loads.


The story: I have been struggling with my SC for more then 3 years. I was always confronted with a very low engine rpm when first started from cold (after being shut down for at least 6 hours). The normal warm-up routine simply was no longer present.

Once warmed up the car would behave fairly normal except for a stumbling at 2.000 rpm and again on the uptake at low engine rpm (for instance when coming to a T and driving of again while retaining some momentum.).
Also the high RPM routine was again present as long as you started the car again after it had been warmed up before. As long as you restarted within 4-6 hours depending on outside temperature (the smart man will see a reason for this).

I could spent half a page on incompetent mechanics that have no clue and simply tune around problems rather then solve them. I will not. Life is too short. Suffice to say he has not received a Euro from me over the last 3 years.

The Pelican community was helpful as ever –and we have some CIS experts present, Kontak, Tony, Paul Porsche, Jim etc...- but a bulletin board lacks one thing and that is physical presence, smell and noise (probably for the better as well, but I digress).

Of course the experts where pointing at air leaks, fuel pressure, mixture and some lesser experts where pointing at less obvious things but that nevertheless could contribute to the problem.

Anyway, since a lot of posts on Pelican end without a nice closure on the problem at hand I decided to contribute to the board on the solution and all the mistakes I have made along the way.

In the next posts you will find information and graphs that will help you in your troubleshooting. All of my ramblings are based on personal experience and deduction, so it might well be I am out of my depths…

[Vereeken]

For those that just want to know what the problem/solution was, here we go:

The cold start issue:

The low engine RPM at cold was caused by a too low WUR control pressure in combination with an AAR that was showing an opening that was too small at dead cold, combined with the air sensor plate being too low in the throat of the air supply. So you see not easy to trace. Note:I had no air leaks but because most where so adamant, I pulled out the CIS systems and resealed everything…no improvement.

How did this combination manifest itself? The car would bog down at cold with low engine rpm because the systems where flooding the cylinders, in addition the AAR was not supplying enough extra air because the opening was too far closed to admit the extra air thus aggravating the problem even more aggravated by the fact that the air sensor plate was too low in the throat thus allowing even less air in the system.

At a certain point in time I simply stepped on the gas quite hard out of frustration and noticed that the low engine rpm immediately improved after letting go of the throttle. What had happened was that I had burned of the excess fuel on top of the intake walls so as to reduce the flooding of the cylinders.

The irritating point is that the behavior of a car that is flooding is equal to a car that is starving. The only difference (in my experience) is the smell. In the case of flooding you will make the green lobby sit-up because of the strong fuel smell.

The other clue should have been the fact that the car did its warm-up routine after only the smallest of warm-up periods. What happened of course was that the WUR was warming up thus leaning out the mixture thus providing less fuel to the cylinders thus make the flooding less of a concern. You could more or less simulate it by jumping the fuel pump and letting the WUR warm up for 2 minutes while you held the AAR disconnected from the 12v source.

The warm stumbling at low rpms:

This was easier. One, the air sensor plate was too low in the throat to start with and this translates itself not only at idle but also at low rpms, less so at high rpms since the fuel increases and some WURs have enrichment at WOT. Two, my spark plugs where not the best around (unless you like light shows- discovered that when the engine was really hot and at night, you need to look twice too notice it). Three, unproven but I am convinced, give my extreme low cold pressure the bi metal –once heated 100%- was not clearing the spring thus messing up the co mixture setting performed on hot engine.

[Vereeken]

Mistake 1. A ROW EURO car is not a US car.

The specs are quite different and what works for the US non lambda cars is not the same as a EURO car.

The differences: The WUR is totally different. WUR 089 has a vent to atmosphere and a vacuum connection to lean out the mixture. It also has two springs in its body that counteract each others work.
Attached the graph (thanks Jim) for 089. Notice that it says “cold pressure testing vacuum”. Yes indeed this graph assumes that 0,5 bar of vacuum is applied to the WUR when setting the cold control pressure. Strange as the 089 WUR comes with a Thermal Valve that holds off vacuum for at most 50 seconds when starting from dead cold. One would assume that you would set the ccp regardless of this vacuum.

Also note that the graph starts at 10° Celsius. This is a hard stop. Meaning that your control pressure can not be any lower then what you see on the graph even if the outside temp is far lower. This makes sense. If the temp would be minus 30° your ccp should be minus something if you would extrapolate. This is of course nonsense.

Because of the WUR being different the vacuum hose routing is different as well. Attached is my own picture of how the small diameter hoses should run on a Euro car that still has the Thermal valve and Decel Valve connected.

The co requirement for a EURO car is different as well. Non lambda US cars seem to do well with about 3% co. A EURO car does not need that. 1% co is more then enough, assuming you have routed the vacuum hoses correctly.

[timmy2]

Great job getting your troubles fixed. As I have a '78 euro, I'd be interested in the specs for CO as I only have US info. My vacuum lines are run identical to yours, except no vacuum advance on my distributor. Any tuning specs for a '78 euro would be appreciated.

[Vereeken]

Mistake 2 Co measured at the tailpipe is not the same as co measured before the exhaust.

Attached is a graph (thank you whoever you are) that explains this. I run an Innovate LM1 box. At the start I always measured co at the tail pipe when at rest. Now I have installed the Bosch sensor in the pre-cat. Quite a difference.

[Vereeken]

Originally Posted by timmy2

Great job getting your troubles fixed. As I have a '78 euro, I'd be interested in the specs for CO as I only have US info. My vacuum lines are run identical to yours, except no vacuum advance on my distributor. Any tuning specs for a '78 euro would be appreciated.

I am not sure for your car. I understand US engines have different compression specs.

In any case 1% to 1.5% co is enough for a EURO Spec non lambda car.

Attached is the table that shows the relation co vs AFR. So that is between 14.11 AFR and 13.9!

[timmy2]

I have a euro spec car and engine. Not a US version.
Thanks for the info.

[acapella8]

Good info, thanks for sharing your path.

[Vereeken]

Mistake 3 The AAR is poorly documented. You need to test its behavior from A-Z.

I based myself again on the inputs from Pelican members of whom most are US. Again there is a big difference between AARs. The difference is in the shape and size of the opening.
Look at my photo’s and you will see what I mean. Compare that with what you find on this board and you will notice how this opening is different in size and shape.
The AAR in the EURO SC has 25-32 Ohm resistance, a closing time of maximum 5 minutes assuming at least 12,9 volt . The opening needs to be 100% at 0°
When testing with an external battery make sure you also hook up a battery charger so you are sure you get 12,9V. My first test was with a battery that gave 11.9V and the AAR never closed completely, so I assumed it was kaput until it dawned on me that it gets more juice once the engine is started and behold it closed fully when supplied with a steady 12,9v.

BTW the closing time remains 5 minutes also when the opening is smaller then 100% because of a higher ambient temp. This to me is counter intuitive but makes sense when you think about it.

[Vereeken]

The AAR Internals

[Vereeken]

Mistake 4 Trusting Bentley and/or Haynes.

This is toilet paper of a dubious quality. Utter pointless use of paper. A Ponzi scheme. Wayne’s book is better but only scratches the surface. I do hope Haynes and Bentley do not produce books for lets say aircraft maintenance…

[Paulporsche]

Great work, and thanks for posting your results.

[acapella8]

Agree. Please post more of specific EURo/ROW differences as compared to US models that are commonly mistaken.

Thanks!

[Jim Williams]

Originally Posted by Vereeken

Mistake 3 The AAR is poorly documented. You need to test its behavior from A-Z.

I based myself again on the inputs from Pelican members of whom most are US. Again there is a big difference between AARs. The difference is in the shape and size of the opening.
Look at my photo’s and you will see what I mean. Compare that with what you find on this board and you will notice how this opening is different in size and shape.
The AAR in the EURO SC has 25-32 Ohm resistance, a closing time of maximum 5 minutes assuming at least 12,9 volt . The opening needs to be 100% at 0°
When testing with an external battery make sure you also hook up a battery charger so you are sure you get 12,9V. My first test was with a battery that gave 11.9V and the AAR never closed completely, so I assumed it was kaput until it dawned on me that it gets more juice once the engine is started and behold it closed fully when supplied with a steady 12,9v.

BTW the closing time remains 5 minutes also when the opening is smaller then 100% because of a higher ambient temp. This to me is counter intuitive but makes sense when you think about it.

For my data book, what is the Bosch part number of this AAR? Finding information on the Euro CIS parts is hard for us here in the US as the Bosch parts catalogs here don't list the RoW CIS components; only the US models are covered.

Thanks for your observation about the AAR not closing completely with a low battery voltage. Now I'm wondering if the WUR has a similar characteristic? Just when you think you have the CIS figured out, something new is discovered that isn't covered in the manuals... This type of info is good knowledge for anyone doing bench testing of the CIS components.

[Vereeken]

Jim,

The WUR has the same issue when tested outside of the car with a battery.

But it is difficult to tell as you need to measure the total lift of the bimetal and the difference is minimal.

I can not give you a correct AAR number because the last 3 digits are mostly rubbed off by something rubbing againts. If i need to take a guess 220 at the end.

Michel