Electric heads please
09-11-2015, 11:27 PM
#1
Three Wheelin'
Thread Starter
Electric heads please
Ok, still trying to get my 928s back in action. I thought replacing after-market final stage (Huco) amps with OEM (Bosch) would do it, as with Hucos, the engine had modest, related operational symptoms.
But after cranking, it wouldn't start. Weird, it would start and idle (Rough ) with Hucos. I put the Hucos back in, which had worked almost well enough to keep. Same thing, crank and no start.
When I replaced the fuel pump with a jumper, connected the battery and checked the pressure, the fuel pressure was fine. Then when I **also** turned the key to accessories, the idle control valve (ICV) began strobing at roughly a 1 hz rate. This only occurs with the fuel pump jumpered on. Weird, I don't know how powering the fuel pump and turning the key to accessories position would strobe the ICV. I just don't get what the fuel pump could possibly have to do with the ICV. RFI maybe? I have the CE panel out. Nothing suspicious yet.
Any ideas please ?
But after cranking, it wouldn't start. Weird, it would start and idle (Rough ) with Hucos. I put the Hucos back in, which had worked almost well enough to keep. Same thing, crank and no start.
When I replaced the fuel pump with a jumper, connected the battery and checked the pressure, the fuel pressure was fine. Then when I **also** turned the key to accessories, the idle control valve (ICV) began strobing at roughly a 1 hz rate. This only occurs with the fuel pump jumpered on. Weird, I don't know how powering the fuel pump and turning the key to accessories position would strobe the ICV. I just don't get what the fuel pump could possibly have to do with the ICV. RFI maybe? I have the CE panel out. Nothing suspicious yet.
Any ideas please ?
09-12-2015, 04:22 PM
#2
Rennlist Member
The fuel pump relay also supplies power to the O2 sensor as well as the idle control valve (idle speed regulator). This can be seen in page seven of the electrical diagrams immediately in the center of the page. Idle speed circuit is then grounded at the LH.
Where are you located? My first inclination is that you may have an issue with your LH. Do you have anyone close that can test your LH in their car? When I was having issues with my LH, it would cause the injectors to pulse at about that same rate, when it was malfunctioning. That was an easy way for me to tell if the engine was going to start or not. If I turned on the key and could hear the injectors firing I knew it wouldn't, but if it was quiet it would most likely start right up. I ended up opening my LH and rewetting the solder joints between the board and the plug socket. Been running great ever since.
This was just my experience and may not be related to your issue though. Good luck. let us know if you discover anything else that may allow for additional diagnosis.
Where are you located? My first inclination is that you may have an issue with your LH. Do you have anyone close that can test your LH in their car? When I was having issues with my LH, it would cause the injectors to pulse at about that same rate, when it was malfunctioning. That was an easy way for me to tell if the engine was going to start or not. If I turned on the key and could hear the injectors firing I knew it wouldn't, but if it was quiet it would most likely start right up. I ended up opening my LH and rewetting the solder joints between the board and the plug socket. Been running great ever since.
This was just my experience and may not be related to your issue though. Good luck. let us know if you discover anything else that may allow for additional diagnosis.