1988 325i, M20B25, automatic. Video attached: cold start after sitting 6 days (sound on).
The problem
- If the car sits for 5 days or more, it cranks about 1 second and catches, but then runs very rough for 10 to 20 seconds. It feels like 1 or 2 cylinders are dead. Sometimes it stalls on the first try.
- Right after start there's a strong raw fuel smell from the exhaust.
- Revving to about 3,000 rpm clears it right away. After that it runs perfectly, and it starts fine for the next 2 to 3 days.
- It got worse over July to September until it wouldn't start at all and had to be towed.
Already done
- New injectors, spark plugs and timing belt this spring
- Head work in April
- In September the shop added fuel check valves (front and rear). Rail pressure now holds after shutdown. They told me they checked the injectors and didn't think they were the problem, but I'm not sure what test they did, or if they actually tested them at all.
- Distributor cap, rotor and plug wires are still original.
My guess
One injector drips while the car sits and floods that cylinder. Cap/rotor/wires plus moisture is my second guess, but I don't think moisture would clear instantly at 3k rpm.
Questions
- Does this sound like a leaking injector, or am I missing something?
- What's the easiest way to find which cylinder it is, without much equipment?
- Has anyone had a new injector leak like this?
Thanks!