Author Topic: Runs but wont start if stopped [NOT evil cat. plug] (Read 8418 times)

DesktopDave · « **Reply #15 on:** January 13, 2010, 02:18:58 PM »

Sounds like you're making progress... You're right about that 1216 code...might be the harness. That shouldn't have anything to do with the warm start issue. I'm not sure what pins the AFM thermo is on...I have to dig out the old Bentley.

I hate chasing wiring problems, but that's what I have to live with to drive an e30. Just had her out today...sun broke through after nearly two weeks overcast. Sweet.

KidneyBoy · « **Reply #16 on:** January 13, 2010, 02:54:11 PM »

Well, heres a little more insight..

I talked to my friend, he says if you drive the car for a while [30 minutes] it will start up fine after being turned off. The issue is when the car has been running for only a few minutes and is then turned off [before coming up to op temp] then it will not start.

I noticed a lot of water coming out of the tail pipe, and some in the intake boot. Has no smell, looks brownish. No major vacuum leaks and i had the head pressure check when it was rebuilt.

The plugs are dirty, so the car is running rich even when it running fine.

DesktopDave · « **Reply #17 on:** January 13, 2010, 07:59:58 PM »

Yeah...something isn't cutting off the cold start enrichment. It's likely running something like 5 to 1 ratio; there's no way a warm engine will start like that. Getting another AFM to test might not do it either...they're all so old now, who knows what those sensors will do?

I get a bit of water out of the pipe too, how much is a lot? Water condensing in the intake can be normal too in cold weather, but I would worry if it's enough to be sloshing around. Happily mine has enough oil to drive off the water!

KidneyBoy · « **Reply #18 on:** January 13, 2010, 09:36:15 PM »

Ive got a 318is myself that has run like a champ for 6 years now, never once let me down **knock on wood**

i can try my AFM on it but i hate throwing things at it without knowing exactly why is not working right.

Is the O2 sensor cut out on a cold start up? im pretty sure thats how it works. The only major peice of sensor i have not checked at all is the O2 sensor.

DesktopDave · « **Reply #19 on:** January 13, 2010, 09:43:56 PM »

No, the O2 sensor will take a while to heat itself up, then signal the DME that it's up to temperature. That (and coolant temp) will switch the DME into the more economical 'closed loop' (except at wide-open throttle).

I think the O2 heater relay is closest to the driver's fender of the three firewall relays.

KidneyBoy · « **Reply #20 on:** January 14, 2010, 02:52:40 PM »

Well today i told my friend that the car was ready for him. Before i was to drop it off, i decided to do the stomp test and see if it threw a code. And what do you know, the CEL didnt do anything.

So i thought i found it. Check the connection to the TPS and it was fine, checked it all the way back to the ECU and it was fine. Threw the car back together and the damn thing started idling at 4200rpm. Check the temp sensor, checked the temp wires to the ECU. All was fine, just like before.

My friend lent me a spare ECU if it came down to it. So i tossed it in and guess what....

Heres the old one after i opened it up:

FleaBay chip FTL

KidneyBoy · « **Reply #21 on:** January 15, 2010, 02:43:29 PM »

Pin 43 Common 5v Coolant and TPS BR/BK

Coolant?

DesktopDave · « **Reply #22 on:** January 15, 2010, 03:46:23 PM »

Damn...that DME trace is cooked! To be totally fair, the chip might not be the culprit. Might just be a short in the harness...those traces can't tolerate 12v for long.

Swapping parts FTW.

KidneyBoy · « **Reply #23 on:** January 15, 2010, 04:42:19 PM »

yeah, i know the chip was not at fault, wish it was that easy.

I hooked up the battery without the ECU and plugged into pin 43 and a ground... only .4v going through it. Wiggled some stuff around and it did not jump.

This car has had a hard life, i bought it from a friend with a bad head. It was a 318is, then got an M20 swap, then back to the M42. Im banking on some error when the PO put one of the few engines that have been in this car.

DesktopDave · « **Reply #24 on:** January 15, 2010, 05:36:57 PM »

I don't know what that pin 43 is for. I found a reference to "CO Pot." It's for non-cat models, perhaps it's the infamous wire on the firewall? On non-cat models it senses the CO screw on the throttle body & adjusts CO electronically somehow.

I love e30s...they all seem to have a story. BMWs are a bit like legos too; mostly all the parts fit.

KidneyBoy · « **Reply #25 on:** January 15, 2010, 08:52:48 PM »

Pin 43 is the common ground for the TPS and Coolant sensor

DesktopDave · « **Reply #26 on:** January 15, 2010, 09:17:31 PM »

Hmmm. I'll add that to my documentation. Do you have a complete pinout of the Motronic?

KidneyBoy · « **Reply #27 on:** January 16, 2010, 03:29:59 AM »

From another source...

Motronic Control unit
Function Color
1 Fuel Pump Relay BR/GN
2
3 Injectors 1-3 BR/WT
4
5
6 Ground BR/OR
7
8 Check Engine light BR
9
10
11
12 TPS Signal 5v BR
13
14 Common 5v GY/BU
15
16 Camshaft sensor input YL
17 Fuel rate output WT
18
19
20
21
22
23
24 Ignition cyl 3 BK
25 Ignition cyl 1 BK
26 Power Input RD/WT
27 Main Relay control BR
28 Ground BR/OR
29 Idle Speed Control WT/YL
30
31
32 Injectors 2-4 BR/WT
33
34 Ground
35
36 Charcoal Canister control BR
37 O2 relay control BR/GN
38
39
40
41 AFM Input (5v) GY/YL
42
43 Common 5v Coolant and TPS BR/BK
44 Camshaft sensor input BK
45
46
47
48
49
50
51 Ignition cyl 4 BK
52 Ignition cyl 2 BK
53
54 Power Input RD/WT
55 Ground
56 Start Input GN/YL
57
58
59 Refrence output (Ground??) GY/WT
60
61
62
63
64
65
66
67 Crankshaft input sensor BK
68 Crankshaft input sensor YL
69
70 O2 Input BK
71 O2 Ground YL
72
73 Speed Signal input BK/WT
74 Engine Speed Output
75
76
77 Air temp input GY/VI
78 Coolant temp input BR/RD
79
80 Diagnostic voltage GN/BU
81
82
83
84
85 A/C Input BK/GY
86 A/C Input BK/VI
87 RXD Diagnostic WT/YL
88 TXD Diagnistic WT/VI