Hi all! I need some advice on 3 issues related to cam degreeing. 1. I noticed that timing between catalyzed cars and non catalyzed is slightly different. My car with Motronic 2.7 , till now has catalysts fitted. If decided to cancel them, I understand that timing shall be adapted to the non-catalysts figure, am I right? 2. If catalysts removed and timing modified accordingly, the ECU will adapt firing timing based on camshaft position sensor data, am I right or ECU should be programmed for the modified timing? 3. Last one, I see in WSM that is mentioning Intake & Exhaust clearance 0,50 mm for timing purpose. I understand that, temporarily, clearance of valves in cyl No. 1 (as a reference) should be set to 0.50 mm. As soon as degreeing has been completed the valves' clearances should be restored to their normal values, am I right on this? Thanks!
1. Yes, without cats, you could set the cams to the non-cat specs. On the cat cars, they tend to make small cam timing differences for emission reasons. It's not going to be a night-and-day difference. 2. Unsure how the Motronic systems make the ignition timing difference for the different versions. The Mondial t SPC shows two different Motronic ECUs so may be that one is for cat and one is for non-cat. 3. Correct. With the clearance set to the 0.50mm, the "events" are when the cam lobe just touches the shim (opens) and just releases the shim (closes).
Nice, thanks for your reply! Yes, I have noticed that Motronic 2.7 appears with two different Bosh part Nos but realistic I can not enter to this challenge... Since I will put my hands on cam degreeing I will change to the non catalysts figures and let's see!
If there is any chance cats will be reinstalled do not time it to the non cat specs. That will cause the cats to overheat. It is such a minor difference in output it will never be noticed.
Actually I had an issue since first day I got the car. PO supposed he did oil change but some how instead to change oil they put another 10L. When the car arrived to Greece on truck and entered my underground parking some oil overflowed into induction manifold creating a mesh. Fooled plugs and flooded cylinders..... The workshop drained 20 Ltrs of oil! When finally engine started for more than an hour was producing white smoke burning the oil remaining until to clean... Further CEL 1-4 started to glow occasionally, the engine stumbled, idle became rough and intermittent SDL 1-4 was glowing. All plugs 1-4 side are shotted black and obviously 1-4 side has a problem. Compression is 210 psi in all cylinders. I decided to go through a major service with engine out replacing O2 sensors and any other suspect electronic item, such as coils, ignition modules. Both ECUs give fault code 4121 but not sure if is real exhaust ecu problem or a false alarm after burning all this oil. I am not sure about catalysts condition, I took out (1-4 side) and I think is a metallic one, not ceramic. It's my first time dealing with this engine, so the idea to cancel the cats is mainly to resolve future problems, I am not seeking any more power just I want the engine to be correctly tuned. That's why I consider cat delete. But if ECUs have different configuration is a point...
Update... cats were examined by an exhaust system experts. He found that they are not original but cheap replicas metallic catalysts which are almost clogged. This probably could be the reason of fault codes appeared and disappeared from nowhere 4124, 4112,4114. Anyway doing the major I will replace all suspects parts like O2 sensors, coils, ignition modules, maybe pressure regulators (remain to test them), idle control valves. Looking for the several parts with their manufacturer part No. there is a huge saving of money without compromising the quality or "originality". So, I decided to cancel the catalyst but I will keep the engine timing as cat engine due to my uncertainty on ECU programming on non-cat.
As a reference, When you do the cam timing, the clearance at the valve should be zero and you will look for .50 mm of valve movement. I have also measured the actual clearance at the valve and used the remainder for finding .50 mm movement. If the intake valve clearance is .27mm, then .23mm of valve movement gets you .50mm from zero. I have tested this and found it is very accurate. Same with exhaust, .33mm and .17mm movement gets you .50mm.
The factory method was designed so no special tools were required. It also is very accurate and repeatable. For someone who has not done it before introducing different, overlapping methods and different math calculations is not ideal. First understand and become proficient at the process then introduce modifications to the method. I have taught cam timing these engines for 30 years.
Thanks a lot for sharing your experience! I am never touching anything before study it excessively and understand the methodology...
