fomanchu

Im going back to step one and retesting using SharkSkins 16v troubleshooting guide as a reference. I get down to test 7 Checking Starting Voltage at the .4 Ohm resistor which should measure battery voltage (12v). I get 5.5v. The WSM shows this line going straight to the starter terminal 16 (middle). I check voltage at the starter and receive only 5.5v. I do have 12.5v on terminal 30. Does this mean my solenoid is bad (again)? This is the 2nd starter and was tested good by 928gt.

Ben Allison

Pin 16 from the starter (pin 15d in later years) is a power line to the coil that activates during cranking and bypasses one of the two ballast resistors - effectively compensating for the voltage sag during cranking.

Are you testing during cranking or just with the ignition on? Also, which side of the 0.4 Ohm resistor are you checking? black wire or black/yellow wire?

If it's showing low voltage during cranking, I would look to the battery, positive battery supply cable and grounding points (most importantly the negative battery cable but also the various ground points all over the car, especially in the engine bay).

If it's showing low voltage with the ignition on, it's likely a corroded wire or connector somewhere. Do you get 12volts at pin 15 of the Ignition Box harness? (near the battery jump post in the engine bay).

fomanchu

Ben,

Thanks for responding. I was testing the black/yellow wire before .04 ohm resistor w/ignition on. I also tested the starter voltage w/ignition on. I havent checked while cranking, nor have I checked pin 15 of the Ignition Box harness (engine passenger side, right?). I did clean the contacts and there was some corrosion. I do get battery voltage (~12.5 vlts) at the jump post also.

New negative battery cable, new battery on trickle charger, clean grounds in trunk and under carriage (brass showing), I get battery voltage at (~12.5 vlts) at positive battery supply, but again will test while cranking.

Does the power line from pin 16 go to the starter relay in the fuse panel at all, or is it direct to the ballast? Im kinda confused looking at the WSM wiring diagrams.

Ben..again many thanks!

Ben Allison

No problem - I was chasing down a similar problem on my car many many years ago (which ended up being the L-jet relay)

Yes, box on the passenger side engine compartment near the front.

Pin 16 of the starter only comes into play during cranking. It attaches directly between the two ballast resistors - it is not fused. It is not providing power with only the ignition on, but since there is another power source you will see voltage there if you test it there with the ignition on. It's function is to bypass one of the two ballast resistors during cranking so the coil can still power up effectively.

With ignition on - you should be seeing battery voltage at the black wire of the 0.4 ohm resistor and maybe around 11volts after (and seeing around 9 volts after the 0.6ohm resistor).

fomanchu

Ben,

I checked the following again w/ignition in run position.
coil voltage @ terminal 15: 3.9 to 4.1 v
coil voltage @ terminal 1: 1.5 v
ICU voltage at plug terminal 15: ~ 12.5 (Battery voltage)

The line leading to starter terminal 15a at 4 ohm resistor (Y shape): 8v (grrr!!)

To remedy: Eliminate break in supply line or contact 15a in starter relay.

I guess I need to do a better repair on the frayed wire on the starter. If you scroll back you'll see how bad it is. Time to solder!

Also should the statement the contact 15a in starter relay read the contact 15a in starter solenoid??

Also, is there a way I can test this like applying 12v to the resistor?

Ben Allison

You could put a long jumper between the jump post and the black-wire side of the 0.4 ohm ballast resistor and see if the voltage reads any higher.
Out of curiousity, are you getting 12.5volts on the black wire end of that resistor?

Ben Allison

For reference, I just checked my car and got 10.2, 7.8 and 4.5 volts at the different ends of the ballast resistor. 4.1v at the coil positive and 1.5v at the coil negative.
Ignition on, but engine off.

fomanchu

Ok..I just went to check ballast voltage..

8.58v at the black/yellow Y on 4 ohm resistor
10.8 at the 4 ohm black side
4.6 at the 6 ohm black

Which side does the line from the starter go to? The black/yellow Y or just straight to the 4 ohm?

fomanchu

This where I get the 8.5 v from...

Ben Allison

the wire with the big white arrow pointing to it goes to the starter.

Looks like your wiring checks out OK (at least it's more volts than mine and mine runs). You're supposed to have at least 3Volts at terminal 15 of the coil and no more than 2 volts at terminal 1.

fomanchu

I applied 12v from hot post in the engine to the 15terminal of the coil (temporarily) and tried to start..same symptoms..sputter and die. I also jumped the FI Relay 87,87 to 30 with a three way..still sputter and die.

Now Im gonna try the following:
Check for Vacuum leaks .. I got new vacuum hoses from 928Motorsports
Check the aux air valve - clean w/wd 40 (is this like a idle control valve??)
Re-Check temp ii and thermo switch .. last time I checked them it was like 30 degrees outside
Pull FI Injector to verify spray (may be clogged??)
Check my L-Jet unit
Check my ignition switch - need to find instructions.

Any other ideas?? Thanks!

Im almost out of ideas.. Im lea

Ben Allison

Good to start with those - definitely cheaper to check/fix. Vacuum leak seems unlikely at it normally just causes a very high idle.

Cold start system shouldn't have much of an impact if it's 70-80 degrees out.

Might be worth seeing if there's 12v on the fuel injector supply feed (with ignition on). maybe the car is starting off of the cold start injector alone

verify timing and position of the distributor - maybe it was installed one tooth out. You can remove the spark plugs, remove fuel pump relay and time off of the starter. You could also just align the crank damper to 0|T and make sure the distributor rotor is pointing at the #1 (or #6) cylinder. If it's more than one tooth out it would backfire, but one tooth out would just make it run really poorly (if at all)

Last option would be to check the L-Jet brain and AFM with known good ones - maybe someone's got spares you can test with. The WSM has a testing procedure for the AFM but passing the tests doesn't rule out failure.

fomanchu

Ben,

Thanks! I checked the AFM and it passed too. But I will do what you recommend.
Is it possible to pry open the AFM and try to start as a test?

Ben Allison

Here's a good primer on the AFM, it's specific to the 944 but the general principles apply.
http://www.the944.com/afm.htm

Ben Allison

Err, wait, you said the plugs were wet, right? then fuel injectors should be firing OK. Distributor timing is probably the best next step. Might be a decent idea to check that the cam gears are lined up, also.