Hi everyone. I need urgent help with my golf and would appreciate any assistance. When starting the car up from cold, the engine is lumpy for about 3 -5 seconds. The revs drop slightly to about 600 and runs lumpy for a short while then the revs go up and the engine runs fine. this only happens on a cold start. I’ve literally done everything to try sort it out and have hit a brick wall. What I have done so far: -changed starter motor as my starter was weak. -changed injectors (part number: 0437502045) -changed spark plugs (multiple points) -changed fuel pump and fuel return check valve. - changed fuel filter - changed ignition coil -changed metering head from another running car. -adjusted co at mot centre to 2 %. -set idle to 960 - 1020. -swapped out thermotime sender switch from another running car. -changed 3 temperature sensors on the side of the head. -distributor timing set to advanced 7 with timing light. after about 10 seconds or so the car runs and drives perfectly. when I remove injector 5 plug then the car will start up fine, however this was done a garage. I tried replicating the same on a cold outside my house and it didn’t fire up with injector 5 disconnected. I then started it up with the 5th injector plugged in with a bit of gas acceleration. Im literally losing all my patience with this car. somebody please help me.
Sounds like it’s missing on one cylinder for a few seconds. From the parts you’ve already changes on the fuelling side of the equation I’d start looking at the electrical side. Are your HT leads in good order? Check the distributor cap and rotor arm for moisture. It could be flooding on one pot but with all the fuelling bits changed it’s unlikely. Next time you start it before it gets the chance to run on all 4 cylinders pull the spark plugs and see if one is soaked in fuel, also if one is still cold compared to the other three at least you’ll know which cylinder is in question. Also, do you have a spare 5th injector you could swap over to the car and try? Just thinking if the spray pattern is way off it may be flooding one cylinder?
Hi thank you for your reply Yes it does seem like it’s a very short miss fire. Since the last post I’ve now changed a few more components; New fuel accumulator 43113344c New Distributor cap New Distributor arm New HT leads After changing all these bits it’s still same, I’ve also tried pulling out the spark plugs before the engine fully fires up and all 4 spark plugs are ever so slightly wet and all equally as wet, but there is abit of carbon build up. Also we can’t tell if any one feels colder to the others, I’ve also tried spraying another 5th injector and both produce a good mist of fuel, about a tea spoon of fuel came out. Losing it with this car, After about 10/15seconds the car idles and runs absolutely fine.
Do you have a fuel pressure gauge? Can be bought on eBay for a reasonable price if not. With this you can check the system pressure and control pressure that your WUR is commanding. Utube tutorial here is useful. If all 4 plugs are wet, (with fuel?) sounds like it may be running too rich on start-up.
Yes I have a pressure gauge and done all the checks, I followed this video step by step, and the car runs a lot better, co adjusted to 2% and idle sits between 960-1020, once it’s abit warm it runs perfectly. The plugs don’t seem like wet it’s more like if I dabbed them on a paper towel and it was like dot, how can I adjust how rich it is on start up?
The initial control pressure (that should be around 1.5 bar) regulated by the WUR controls a richened mixture for cold start, then, as the WUR warms up it increases control pressure to approx 3.4 bar to lean off for warm running. What’s your initial control pressure immediately on cold start?
