Forgot to mention that I did another smoke test and no vacuum leaks apparent this time.
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Forgot to mention that I did another smoke test and no vacuum leaks apparent this time.
I had some time today to do some more testing. There is no spark at the plugs when cranking and when I probe the coil pack electrical plug there are 2 earths, a constant 12V and a voltage of only 0.08V on the ECU pin when cranking. Should there be higher voltage than this on the ECU pin?
Also I was going to pull the fuel hose off where it meets the fuel rail to test for flow but I could feel that the fuel hose was hard with fuel pressure so decided I didn't need to go any further. When I pulled the plugs after cranking there was no sign or smell of any fuel on them, so looks like I have no spark and no injectors firing. What could cause this? Is there an auto trans inhibitor switch on the MkV FSI which inhibits both spark and injectors and might be malfunctioning (but I guess it would just inhibit cranking)?
When I tested the A1 engine control relay it worked fine but the resistance across pins 86 and 85 was 170 ohm and everything I've read says it should be half this value. Could this be the problem?
After reading this article Coil-On-Plug Technology and Diagnostics Tips | 2018-02-16 | Auto Service Professional which says that some cars will shut off ALL coils and injectors if the ECU detects a major misfire in ONE cylinder, I disconnected Nr 1 coil connector and cranked the engine and it started and ran on 3 cylinders! I reconnected coil Nr 1 and cranked again and it started and ran on all cylinders. Strange. So I figure there might be an intermittant fault possibly on cylinder Nr 1 either in the spark plugs, coil, coil connector/wiring/ECU. I replaced all the spark plugs as a start and if the misfire returns I'll replace the coils one by one starting with Nr 1. Then I'll start replacing the coil connectors etc.
I tested Nr 1 and Nr 2 coils on the bench with a 5V trigger and they both fire ok but this doesn't mean they don't have an intermittant misfire under compression of course. At the moment the car is running great with the new plugs. I didn't think to replace the plugs earlier due to the fact that I've never had a car fail to start due to plugs - misfire yes but not totally fail to start. I have never heard of the ECU turning off all coils and injectors due to a misfire in one cylinder, but this will be one of the first things I check in the future. It also expalins why I had fuel pressure in the rail but the spark plugs were dry after cranking.
How easy/hard is it to replace the coil connectors? I assume you're talking about the leads to the coil packs? Last time I replaced my coil packs, I noticed the brittle plastics of the connectors had broken off in several places, and may be the cause of some mis-firing I have experienced.Quote:
Originally Posted by metako
Yes those ones. I haven't done this on a Golf yet but I imagine its just a case of pushing a fine jewelers screwdriver into the connector at the right spot and de-pinning the old connector and pushing the pins into the new connector.
Ah, I was hoping you were going to say, they can be bought in a short inexpensive loom that can be replaced relatively easily :cool:Quote:
Originally Posted by metako
Apologies for the thread necro. Do you think you can remove and replace this rubber dipstick holder without removing the intake manifold? I want to replace my dipstick funnel as it is broken but didn't realise it was captured by the manifold :facepalm:Quote:
Originally Posted by MEL744
I'd say it would be very difficult to do, even if you could get the old one out fitting the new one would be a challenge.
I have figured as much. Do you happen to have the part number for the intake clips and the intake boots?
Sorry I don't have the part numbers for those, however they should be reusable - provided they aren't damaged or lost.