Engine starts, but will not run
07-02-2015, 12:42 AM
#1
6th Gear
Thread Starter
Join Date: May 2015
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Engine starts, but will not run
Symptons:
Motor cranks and fires, runs as long as you hold the starter. Dies seconds after the starter is released. It's a 1985.5 model.
I have read threads, researched the net and downloaded a bunch of info, work/checks done so far;
1. Exchanged DME relay (with a known good one – I have a running second 944)
2. Removed DME relay, inserted custom by-pass harness
3. Unplugged ECU and measured inputs:
3.1 RPM sensor (static ~900 ohm – cranks at 1.4V)
3.2 TDC sensor ( static ~900 ohm – cranks at 0.1V)
Now what....?
My next attempt would be to swop ECU units. The car ran fine when I parked it 3 or 4 months ago.
Has anyone experienced something similar - any tips?
Thanks!
Motor cranks and fires, runs as long as you hold the starter. Dies seconds after the starter is released. It's a 1985.5 model.
I have read threads, researched the net and downloaded a bunch of info, work/checks done so far;
1. Exchanged DME relay (with a known good one – I have a running second 944)
2. Removed DME relay, inserted custom by-pass harness
3. Unplugged ECU and measured inputs:
3.1 RPM sensor (static ~900 ohm – cranks at 1.4V)
3.2 TDC sensor ( static ~900 ohm – cranks at 0.1V)
Now what....?
My next attempt would be to swop ECU units. The car ran fine when I parked it 3 or 4 months ago.
Has anyone experienced something similar - any tips?
Thanks!
07-02-2015, 12:54 AM
#2
Addict
Sounds like a simple ignition switch failure....but that's just me. If you have a second 944 with the same harness, give them a swap and see.
Any chance you can get to the contacts to clean them?
Any chance you can get to the contacts to clean them?
07-02-2015, 01:22 AM
#3
Rennlist Member
+1 ignition switch
You say it stays running a few seconds though... maybe a fault in the fuel injection? The injector drivers will shut down if there's too high of a current draw from the injectors. If you undo the connection to one injector, will it stay running? Simple enough test, the drivers see less current and don't go into self-preservation mode.
You say it stays running a few seconds though... maybe a fault in the fuel injection? The injector drivers will shut down if there's too high of a current draw from the injectors. If you undo the connection to one injector, will it stay running? Simple enough test, the drivers see less current and don't go into self-preservation mode.
07-03-2015, 12:27 AM
#5
6th Gear
Thread Starter
Join Date: May 2015
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Thanks guys, tested the IGN switch, but there is positive at the coil. I did not suspect it tho as the motor does run on. In fact this evening it ran on more than yesterday. Hence I suspect something more "complex". In fact the "run on" ends rough as if it's trying.....going down now to disconnect an injector.
07-03-2015, 02:45 PM
#7
Intermediate
Join Date: Sep 2014
Location: Indianapolis
Posts: 27
Likes: 0
Received 0 Likes
on
0 Posts
This happened to me not long ago. I took the intake out and left one of the electrical connectors unplugged when I put it back in. I think it was the AFM. It would start and run for 2-3 seconds then stop.
Trending Topics
07-04-2015, 12:28 AM
#8
6th Gear
Thread Starter
Join Date: May 2015
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Well I disconnected an injector, no change. I fitted a good battery (poor voltage could mean higher current draw) all to no avail. Then Steve hit the nail on the head - AFM. I had fitted a new air filter element and had everything apart to clean. I must have got disturbed during re-assembly. Plugged it back in and it runs! - Many thanks. Klaus