My engine just stops

930cab89 · 09-07-2010, 06:18 AM

It's now the third time that the engine of my 930 stops unexpectedly. One time I was driving slowly in a traffic jam, one time in front of a red light and one time just when exiting a corner. The engine just stops. 2 times I tried to restart it by releasing the clutch (because the car still was still doing some speed). It didn't work but it generated a big explosion in the exhaust. If I simply try to restart it with the starter, it works. Does anyone know what it can be due to?

azasadny · azasadny's Garage

Do you have an old car alarm installed in the car? My '74 did this for several years until Tab Tanner found the source of the problem (old Hofco alarm) and he "surgically" removed it. The old alarm would intermittently cut off the ignition and fuel pump circuit...

930cab89 · 09-07-2010, 09:54 AM

Yes, there is an alarm system.

kidrock · 09-07-2010, 10:01 AM

930cab89,

I'm assuming you have a 1989 Turbo Cabriolet with a 3.2 motor? If so, have you checked your DME relay?

dshepp806 · dshepp806's Garage

Quote:

Originally Posted by kidrock

930cab89,

I'm assuming you have a 1989 Turbo Cabriolet with a 3.2 motor? If so, have you checked your DME relay?

+1 on that!

Doyle

Joe Bob · Joe Bob's Garage

DME or alarm......

930cab89 · 09-08-2010, 12:43 AM

No it's a 3.3 turbo.

kidrock · 09-08-2010, 06:22 AM

oh Christ, yeah...duh, what was I thinking. Does a 3.3 have the Motronic DME and the accompanying relay?

stinkydog · 09-08-2010, 07:17 AM

It'd be CIS rather than Motronic, correct?

wilke3169 · 09-08-2010, 07:26 AM

My '79 SC did this for a while. I searched and finally found that it was the coil. It started doing it on the track at DE events and would have the huge backfire. Coil replaced and no problem since...

Ron.G · 09-08-2010, 08:06 AM

My car did the same thing(80SC). After trying a few things I replaced my fuel pump relay and all was well again. It did not act like it was starving for fuel, it would just shut down like it was a electrical problem.

930cab89 · 09-09-2010, 10:44 AM

wilke3169, did you also need to switch the engine off with the key before you could restart it? Did you try to push start the car? When I try it, it does not start. I really have to switch it off and use the starter.

wilke3169 · 09-10-2010, 03:39 AM

930, I did have to turn the key off then back on. When it shut down on the highway this was a bit scary because i would turn the key off while rolling then back on which actually locked the steering as you know. I didnt have to use the starter. Instead i could just let the clutch out which would give a huge backfire. I did replace the ignition switch and disconnected the rev limiter as part of the search. I also installed a MSD ignition but the coil alone corrected the problem. Has been over a year now without one issue.

930cab89 · 09-13-2010, 11:12 PM

Wilke, I suppose you first tried to let the clutch out? Did it not start before turning the key off and then on again?

wilke3169 · 09-15-2010, 09:27 AM

930, This happened while under power and moving. The first time was at the track and I coasted to a near stop and then tried one last time and it fired back up by releasing the clutch. This was without turning the key off. After that I would say I needed to turn the key off and back on while still rolling to get it to restart. For me it always happened while being driven with some enthusiasm, i.e. the track. new coil has been in for quite some time now, a year or so, and I have had no problems.

930cab89 · 09-15-2010, 11:25 PM

Ok, I'll check the coil, thanks.

T77911S · 09-16-2010, 09:45 AM

could be ignition or fuel. fuel pumps running? FP relays?
CD unit? is it a bosch? coil, as said above. frequency valve and or rly controlling FV.
things like this are tough. you can shotgun it, replace stuff until it stops doing it, or wait until it gets worse. dont let the clutch out to restart it.
the first time it does not start up, have a spare plug you can pop on an igintion wire to check for spark. have jumper wires ready to jumper FP relays to run the pumps. but make sure it will not restart before trying any of this.

930cab89 · 09-19-2010, 11:17 PM

Thanks T77911S, that are good advices. I have just ordered a new coil though and will start from there. And first thing to do next time is to just try to restart it without turning the key off - on. By the way, it this possible on the 930? I know that on some cars, you have to turn the key off before being able to restart and on others, you just start.

T77911S · 09-20-2010, 06:43 AM

no,no, turn the key off then restart. dont let the clutch out. that backfiring may cause some damage. try to do a normal restart, if it does not start, then start troubleshooting, if it starts, drive it. just be prepaired on what to look at first.

930cab89 · 09-27-2010, 01:39 AM

I've now changed the coil, the distributor cap and rotor and disabled the alarm system but the engine cuts still happen. Any other ideas?