Jaimemb

What would happen if you didn't put the engine TDC before replacing the hpfp?

optimusprime m1

Well why not just do as it tells you and fit it as it should be fitted ? Ther must be a reason why you have to do this . May be its like the old mechanical retrol pump that needs to sit on a cam in the engine for it to operate And by puting it on with the cam in the wrong place might damage the hpfp. Only an idea .

Jaimemb

What happened was I replaced the pump i didn't have access to wis. The only reason Im asking is because after replacing the part the car now misfires for a few seconds then smooths out on first start up after the car has been sitting for more than 4 hours. Any other time itll start right up no issue. Only code i got are the ones for misfires p0301-4 and p0300.

optimusprime m1

Can you check the fuel pressure ? Sounds as if its not holding pressure to me .

Jaimemb

I can order a pressure gauge today. I have a 2013 c250 with the m271 evo engine. It is petrol. I got a new code now it’s p0441. “Evaporative Emission System Incorrect Purge Flow”. Another thing it does is sometimes at cruising rpm it’ll misfire once or twice like a hiccup. Also whenever it’s on the colder side in the morning it’ll do it for longer/ it’ll misfire more violently than when it’s a warmer day. Note this happens only when the car has sat for more than 4 hours

Jaimemb

Idk how reliable this is but on my icarsoft scanner the fuel pressure is at 5 bar or 72.5189 psi while running. At the on position it’s at 7 bar or 101.526 psi.

chinatownabc

Hi I had the same issue I wanted to see if you ever figured out the issue. It seems that the car had no misfire beforehand and after changing the pump the car is misfiring now.