help me diagnose

[devon.818]

here is the low down. little over a week ago i started getting hard starts with my m50. chalked it up to cold weather and heavy weight oil, figured just change to 10w30 when i have the time and no worries. few days after it started to have issues i stopped being able to start it with the starter when it was cold or sat for a long period of time or over night. it would only bump start. ok so now im thinking the battery is the issue. i got it tested, it read bad when it was sitting but it was ok when they threw load on it.

so i hooked it to the battery tender over night and it started in the morning, with some coversing and taps of the gas peddle.

that was two days ago. problem was still there the next day and today, so i thought "hey just get a jump start, if it starts then its the battery if not its something else". well we tried to jump it...and it was a no go. had to bump it again...sigh.

so i get it going and drive to the store, start to head home and i notice a surge while the motor is under load....da fuck? kinda spooked me. it died while i was slowing for a stop light and stalled a mile later. i made it home though...

now i know its not the battery. i checked the fuel pressure, not that. now i am lead to believe it is a faulty sensor. i know the MAF can cause hard cold starts AND surging...hoping it is just the MAF. otherwise i have a list of sensors to test....yippy.


so my course of actiion is to borrow someone's MAF and see what happens, if it doesn't fix the issue i will replace the fuel filter and drain the fuel tank for sediments, then if problems still persist...i will begin testing sensors and go about my troubleshooting.

can i please have some r3v opinions.

thanks guys.

[devon.818]

Takers?

[cabin]

Crank position sensor?

[devon.818]

Ok so now it cranks, but no start. Big surprise is now it wot bump start either! Wtf?

[devon.818]

Tried to do the stomp test, didn't work, guessing that's not hooked up in the harness adapter for the swap.

[7pilot]

The basics first:
Time to discover whether you don't have fuel, or you don't have fire.


m

[devon.818]

yeah battery is going on the battery tender then doing fuel/spark.
also will help me figure out if it lean/rich. helps to find a bad sensor. i'll keep this updated, sooo wish i had a second car right now.

lucky i have friends smarter than me

[devon.818]

can anyone help me figure out how to jump my fuel pump relay?
i know it is the number 1 relay , just not sure how to actually jump it. pulled a fuel line off the car and have it ready to test....

[7pilot]

Try T30 to T87 on the fuel pump relay.

m

[kingston]

What do your plugs look like?

[russhixmo]

I had a similar problem with my old 535i and it ended up being the O2 but I also had a long list of issues that went along besides hard cold starting and sputtering but it's worth a shot, also if ur on a tune it may not be set up for cold weather.

[devon.818]

I had a similar problem with my old 535i and it ended up being the O2 but I also had a long list of issues that went along besides hard cold starting and sputtering but it's worth a shot, also if ur on a tune it may not be set up for cold weather.

i know it does have an ebay chip in it...hmmm.

[russhixmo]

It's possible that the computer didn't learn the tune when it was cold out if u did it when the summer months were around and as it got colder and colder ur problems became worse and worse

[gobuffs]

Check for spark. If you don't have spark then the guess if a crank sensor is a good one.

[devon.818]

Ok so swapped in a working fuel pump. Still nothing, tested all relays and socks, they have power.

Me and my tech feel it's the fuesable link but cat find it. Car is a convertible with m50 swap....where the F is the fuseable link?