Author Topic: Cold start engine shakes and sputters (Read 27436 times)

roundel318 · « **Reply #45 on:** November 15, 2008, 03:40:29 PM »

Also, when you mentioned Relays, did that include the O2 sensor heater relay?

bearsbmw · « **Reply #46 on:** November 15, 2008, 03:41:16 PM »

Quote from: roundel318;60843

Also, when you mentioned Relays, did that include the O2 sensor heater relay?

swaped working Horn relay for the 02 heater relay

TPS not connected would not let me start my car

roundel318 · « **Reply #47 on:** November 15, 2008, 03:46:09 PM »

and the electrical from the o2 heater relay to the o2 sensor? (darn automotive wiring)
when I disconnected my TPS, my engine starts, barely, and rumbles and vibrates like yours does.
do you know what the "evaporative purge valve" is for?

bearsbmw · « **Reply #48 on:** November 15, 2008, 03:53:09 PM »

Quote from: roundel318;60845

and the electrical from the o2 heater relay to the o2 sensor? (darn automotive wiring)
when I disconnected my TPS, my engine starts, barely, and rumbles and vibrates like yours does.
do you know what the "evaporative purge valve" is for?

Ya that has something to do with the Evap system for the fuel tank I think anyway.. Im prity sure the ECU has no control over this item but I will check bentley for ref

roundel318 · « **Reply #49 on:** November 15, 2008, 03:56:51 PM »

I was checking the factory wiring documentation here....
Bentley manuals rock

The ECU seems to have control over the evap purge unit crap, at least from the diagram in this PDF.
the O2 sensor heater works, is its wiring messed up?

bearsbmw · « **Reply #50 on:** November 15, 2008, 04:00:39 PM »

Quote from: bearsbmw;60846

Ya that has something to do with the Evap system for the fuel tank I think anyway.. Im prity sure the ECU has no control over this item but I will check bentley for ref

I take that back Evap valve is controled by ECU

roundel318 · « **Reply #51 on:** November 15, 2008, 04:03:39 PM »

Agreed per my last post, not sure if it is causing the problem.
Beyond a few other ideas we have come up with, I think the most sensible thing would be to try a spare ECU.
Were you running a custom chip right now? did you try the stock one? I think I remember you saying you had a spare / factory chip.
Perhaps I was dreaming

bearsbmw · « **Reply #52 on:** November 15, 2008, 04:06:45 PM »

Ok anyone who has this problem ... remove the onboard computer the one in the dash below the cd and unplug it and start car and see what happens

roundel318 · « **Reply #53 on:** November 15, 2008, 04:08:39 PM »

I am just curious, which OBC is this you are referring to?
below the cd?

bearsbmw · « **Reply #54 on:** November 15, 2008, 04:10:50 PM »

The onboard computer below your cd or tape deck.. remove and unplug

roundel318 · « **Reply #55 on:** November 15, 2008, 04:11:32 PM »

Do you have a E30 or E36?

bearsbmw · « **Reply #56 on:** November 15, 2008, 04:12:10 PM »

bearsbmw · « **Reply #57 on:** November 15, 2008, 04:13:26 PM »

sorry on e30s to right

roundel318 · « **Reply #58 on:** November 15, 2008, 04:14:47 PM »

E30 here, my heat / vent controls are below the cd/radio slot.
Is this the normal multi button OBC you are referring to though?
The E36 probably has a 9 or 12 button or thereabouts?
Most M42 E30 cars have a simple OBC that just has a date/time(mem) and external temp sensor (mounted in the brake duct on the drivers side i believe) that does not have so many functions / tie into other systems.

roundel318 · « **Reply #59 on:** November 15, 2008, 04:16:52 PM »

Your OBC probably takes info to calc mileage, range, etc?
It takes info from a host of other systems if so.
What sort of difference are you having with disconnecting yours?
Do you have a grounding problem?