My 86 ETA engine was suffering cold start problems: long periods of engine cranking with no signs of life (no sputter, no nothing), just the sound of the starter motor "wa-wa-wa" turning for 20 seconds, or up to 2 or 3 minutes before it'd hit and come to life. Once it'd start, it would immediately run perfect.
The Bentley manual has good instructions for troubleshooting this problem. Also, the wiring diagram really helped me understand how the cold start system works along with the function of the thermo-time switch.
Besides the Bentley manual, here's a quick diagnosis method to test the cold "start valve system" failure ("system" referring to the valve and the thermo-time switch together): find the vacuum line for the fuel pressure regulator. disconnect the end that plugs into the manifold, and spray engine starting fluid into the manifold port. Do this for 6-8 seconds (like the cold start valve system will do if it's functioning). reconnect the vacuum line and attempt to start the engine.
If it starts, the problem is either the valve, the thermo-time switch, or a wiring mal-function. (At this point, you can use the starter fluid trick every time to start the engine, until you've had time to make the correct repair).
The Bentley manual suggests removing the cold start valve and testing it first, but I was hesitant since I didn't know if the o-ring would be damaged by removing it, and without a known replacement o-ring, I didn't want to add fuel leak to my daily driver's list of issues. Instead, I skipped to testing the thermo-time switch.
An easy way to test this is to pull the connector on the thermo-time switch and ground the red/black wire's lead (you can roll the rubber insulator off the the connector to see the wire colors). With red/black grounded, if the cold start valve is functional, it'll discharge gas into the intake as long as the key is in "START" position. It should start the engine, no matter how cold.
If the engine doesn't start, its time to pull the cold start value like the Bentley manual suggests and make sure it sprays gas correctly.
In my case, grounding the red/black cold start valve wire started the engine thus isolating the problem to the thermo-time switch. Until the faulty switch is replaced, I ran a ground wire to a momentary toggle switch located under the head light switch. I can turn the ignition key with one hand, and flip the momentary switch with the other to start the car.
wiring mal-function is unlikely. the red/black wire runs from the switch to the valve (maybe 2 ft), and the yellow/black wire on both the valve and the switch are the engines "START" circuit and also connects to the starter. Also, note that when the ignition is in "START" mode, there is +12vdc on the yellow/black circuit, but when not in "START" mode, its at ground (or close to it) via the starter.
I hope this helps anyone trying to troubleshoot hard starting ETA's (or 318i engines with cold start valves).
The Bentley manual has good instructions for troubleshooting this problem. Also, the wiring diagram really helped me understand how the cold start system works along with the function of the thermo-time switch.
Besides the Bentley manual, here's a quick diagnosis method to test the cold "start valve system" failure ("system" referring to the valve and the thermo-time switch together): find the vacuum line for the fuel pressure regulator. disconnect the end that plugs into the manifold, and spray engine starting fluid into the manifold port. Do this for 6-8 seconds (like the cold start valve system will do if it's functioning). reconnect the vacuum line and attempt to start the engine.
If it starts, the problem is either the valve, the thermo-time switch, or a wiring mal-function. (At this point, you can use the starter fluid trick every time to start the engine, until you've had time to make the correct repair).
The Bentley manual suggests removing the cold start valve and testing it first, but I was hesitant since I didn't know if the o-ring would be damaged by removing it, and without a known replacement o-ring, I didn't want to add fuel leak to my daily driver's list of issues. Instead, I skipped to testing the thermo-time switch.
An easy way to test this is to pull the connector on the thermo-time switch and ground the red/black wire's lead (you can roll the rubber insulator off the the connector to see the wire colors). With red/black grounded, if the cold start valve is functional, it'll discharge gas into the intake as long as the key is in "START" position. It should start the engine, no matter how cold.
If the engine doesn't start, its time to pull the cold start value like the Bentley manual suggests and make sure it sprays gas correctly.
In my case, grounding the red/black cold start valve wire started the engine thus isolating the problem to the thermo-time switch. Until the faulty switch is replaced, I ran a ground wire to a momentary toggle switch located under the head light switch. I can turn the ignition key with one hand, and flip the momentary switch with the other to start the car.
wiring mal-function is unlikely. the red/black wire runs from the switch to the valve (maybe 2 ft), and the yellow/black wire on both the valve and the switch are the engines "START" circuit and also connects to the starter. Also, note that when the ignition is in "START" mode, there is +12vdc on the yellow/black circuit, but when not in "START" mode, its at ground (or close to it) via the starter.
I hope this helps anyone trying to troubleshoot hard starting ETA's (or 318i engines with cold start valves).
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