86 944 turbo - intermitant starting issues
#1
Track Day
Thread Starter
86 944 turbo - intermitant starting issues
Hey guys. I purchased a 86 951 a year ago. I've slowly been fixing things as i go. One issue I can't seem to figure out is the car randomly doesn't start. After waiting about ten minutes of trying the car fires up with no issues. It always seems to be a humid day when it happens. I've replaced the fuel relay, plugs, rotor and cap, fuel filter. The car still does it. It can be really frustrating when it happens. If anyone could provide some help I would greatly appreciate it! Thanks much in advance!
Josh
Josh
#2
I would try replacing the DME relay.
I had a similar problem and determined that the relay was dying a slow death.
I had a similar problem and determined that the relay was dying a slow death.
#3
Quit Smokin'
Rennlist Member
Rennlist Member
Could be a lot of different things. Sounds like you replaced the DME relay when you replaced the "Fuel Relay". When the car is acting up try to verify whether the fuel pump is actually running. Also, does the tach bounce when it's cranking? Wires in these cars are getting old, possibly the speed and reference sensor wiring is on its way out... Also failing DME and KLR units can have some strange no start symptoms too.
#4
Rennlist Member
Speed/Ref Sensors as Werks said. Next time you get a no-start, pop the hood and poke the sensors with a stick. Try again. Always works
Pull the vac lines on the fuel damper and regulator on the fuel rail when the car is running. Do you see fuel coming out of the vac nipples? If so, that's bad and they should be replaced. I've known a failed damper to cause a no-start before.
Pull the vac lines on the fuel damper and regulator on the fuel rail when the car is running. Do you see fuel coming out of the vac nipples? If so, that's bad and they should be replaced. I've known a failed damper to cause a no-start before.
#5
Instructor
A failing factory alarm module will cause the car to intermittently not start. It is very easy to bypass and even if it is not your problem now, it will be a problem in the future. It is a good preventative measure for a no start condition.
Bypass directions: http://www.clarks-garage.com/shop-manual/elect-23.htm
Bypass directions: http://www.clarks-garage.com/shop-manual/elect-23.htm
#6
Track Day
Thread Starter
Yes I replaced the dme relay. Sorry it was late last night and I was blanking on the name of it lol. Thanks for all the suggestions I will look into it and keep you guys updated! When I do try and start it the tach does bounce and shows 1 bar of pressure on the factory boost gauge.
#7
Rennlist Member
Yes I replaced the dme relay. Sorry it was late last night and I was blanking on the name of it lol. Thanks for all the suggestions I will look into it and keep you guys updated! When I do try and start it the tach does bounce and shows 1 bar of pressure on the factory boost gauge.
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#8
Another quick/easy test from Clarks is unplugging one of the injectors and then trying to start. The FPR can fail in such a way that there is crazy pressure on the rail, preventing ignition.
But if you have fuel pressure gauge, as Tom said, you can run it down. Check pressure on the rail (before and after starting, ie jump the fuel pressure/dme relay), check the fuel pressure leakdown time, check spark, check voltage and resistance of the ignition coil, etc.
But if you have fuel pressure gauge, as Tom said, you can run it down. Check pressure on the rail (before and after starting, ie jump the fuel pressure/dme relay), check the fuel pressure leakdown time, check spark, check voltage and resistance of the ignition coil, etc.
#9
Three Wheelin'
Check the fuel pump. A fellow Rennlister has had 3 or 4 brand new pumps that were bad within a week or so out of a Bosch box. Not sure if they were just well concealed Chinese knock offs or not. There was also a bad batch of DME relays from Hungary. Just because it is new does not necessarily mean it is good.
#10
Track Day
Thread Starter
Check the fuel pump. A fellow Rennlister has had 3 or 4 brand new pumps that were bad within a week or so out of a Bosch box. Not sure if they were just well concealed Chinese knock offs or not. There was also a bad batch of DME relays from Hungary. Just because it is new does not necessarily mean it is good.
#11
Track Day
Thread Starter
I'm also wondering if it's my alternator. I don't think it's charging my battery. I just put a brand new battery in like two months ago and it went from 14 on the battery gauge and sits around 12. Doesn't the car require 12.6 volts to start?
So many things to troubleshoot. What have I gotten myself into with this car?!
So many things to troubleshoot. What have I gotten myself into with this car?!