can engine dies from cold idle

Post Thu Aug 30, 2018 9:09 pm

Hi All , m40 1.6

Engine dies from cold idle , when i push the gas pedal . o.k when engine warm. any ideas please .

Post Fri Aug 31, 2018 9:41 am

First place I'd look is the old Blue Temp sensor - and all the leads from it to the ecu - so test from sensor to ecu for comparable readings.

I'm sure this applies to the M40 with Motronic 1.3

Paul

Post Fri Aug 31, 2018 9:47 am

Blue temp sensor location under inlet manifold, well worth changing.

Post Fri Aug 31, 2018 9:50 am

Also check AFM, remove, check mechanical parts (flap opens correctly) etc.

Post Fri Aug 31, 2018 4:15 pm

thanks for the replies. i check blue temp sensor at the ecu motronic 1.3 . removed the multi plug and check pins 24 and 45 cold was reading 2633 ohm .... hot reading 198 ohm which is a bit low ( haynes says ( 270 to 400 ohm ) , so i haven't changed it out yet.

as for the afm , i haven,t check that at all . as assumed it only works when OFF IDLE , Thats what the TPS Tell the ecu when you press the gas. however maybe i,ll removing it and make sure it s not sticking.
I looked on youtube for testing it but mines different has a round electrical connector . rather that a straight plug.
How would you test flap opens correctly ?

Post Wed Sep 12, 2018 9:19 pm

think i,ve found the issue 2 vacuum leaks . rigged up a tight seal in he rubber boot , removed from a.f.m . blew in pipe and could hear the first , sorted that then coud hear and locate the second.
idle still a bit slow . but drives well, added advantage brakes are better. obviously the servo getting more vacuum now. waiting for a cold morninng now.

Post Mon Sep 17, 2018 8:08 am

still got a cold idle . push gas and engine dies mainly if trying to go up hill from standstill . Any ideas
thanks In advance. I,ve ordered another afm from a larger cc engine. 1.6 mine 1.8 to try.
other than that car running really well. seems to have more power since i found the 2 vaccum leaks .
I,m wondering if I got another one. might try the butane gas test.

Post Mon Sep 17, 2018 9:25 pm

arrisbmw wrote:still got a cold idle . push gas and engine dies mainly if trying to go up hill from standstill . Any ideas
thanks In advance. I,ve ordered another afm from a larger cc engine. 1.6 mine 1.8 to try.
other than that car running really well. seems to have more power since i found the 2 vaccum leaks .
I,m wondering if I got another one. might try the butane gas test.

Dirty throttle body sensor/switch ?, located underneath the throttle body on a 325 but I'm not sure where it is on a 16/1.8

Post Wed Sep 19, 2018 8:19 am

yes thanks re tps throttle position sensor. working fine.

Post Fri Sep 21, 2018 8:10 am

fitted a new blue coolant sensor on m40 . not easy to get at.
removed upper half of inlet manifold first. then its do able . but you need a deep 19 mm socket and various short extensions ( and tiny hands ) a angle knuckle joint would help.

Post Fri Sep 21, 2018 9:42 pm

still got an issue no power low down , dies when cold nearly stalls , ONLY IDLE occasional misfire .
any more ideas. please . runs fine AT 70 MPH. NOT MISSING
but after long 70 mph , seems to struggle when puling away.