Im stumped please help

[harv666]

1983 Row sc 930/10 engine. Car will not start, its was running sluggish, I was convinced it was cis related. It was running pretty good until I stuck my hex into the mixture screw. I turned into make it richer it started choking and died. It will not start again. I do not think this is related to the problem though.

Car wont start, heres what I've checked.

Installed new spark plug wires
No vacuum leaks (smoke test)
replaced all vacuum lines.
new aar (proper for vehicle) and then old aar no difference they both work.
Removed all plugs (2 months old) cleaned and reseated.
rechecked my valve job from 2 months ago all at spec
timing was perfect before car died at 5 btdc
Installed new fuel filter - fuel pump pushes gas through fuel filter.
Changed cdi from cdi+ back to working original Bosch unit. (cdi+ does a sweep then sits, Bosch cdi bounces to 4k rpm but it wont turn over or go past there).
Tested coil amps, bosch silver it was a bit low, replaced with a friends Bosch black, it may not be perfect either, im getting yellow spark off the coil cable. im getting blue spark off the plugs.
checked all plugs with timing light and it worked on all plugs.
removed some fuel injectors because I thought it then could be fuel as coil had spark and fuel runs through lines when fuel pump is activated.
Recharged battery.

Has a fresh oil change. I'm really at a loss here is it the coil? what else could cause not enough gas and spark to turn over? I cant tell what the fuel mixture screw is doing or where it is currently but ive played with the plate and its not seated improperly as well I made sure the butterfly was seating properly on the throttle body.

Any ideas collective mind?

[john walker's workshop]

Did you turn the mixture screw clockwise or c/clockwise? How much out of 360 degrees did you turn it. Did you try putting it back where it was?

[harv666]

Well I’m guessing i turned it too far. Tried to put it back but now i have no clue where it’s supposed to be. I looked at the fuel and air lids and they look normal. I imagine it would run bad if way out but i can’t get the engine to spark or turn over yet there’s fuel and spark.

Is there a way to reset that mixture pin that i don’t know of?

Harv

Originally Posted by john walker's workshop

Did you turn the mixture screw clockwise or c/clockwise? How much out of 360 degrees did you turn it. Did you try putting it back where it was?

[john walker's workshop]

Pull out one injector and place it in a cup, keep the fuel line attached. Jump power to #6 fuel pump fuse. If the injector is spraying now, go counter- clockwise on the mixture screw until it stops spraying, but not very far beyond, as the adjustment is sensitive. If it's not spraying, go clock-wise until it does, then back off. Should get you in the ballpark. Lifting the sensor plate just a small amount should make it spray. Leaving the injectors spraying more than a few seconds can flood the cylinders.

[Schulisco]

Originally Posted by harv666

Is there a way to reset that mixture pin that i don’t know of?

You need to make a new basic setup of your CIS system. See the video I referred to in this posting for more details:
https://forums.pelicanparts.com/porsche-911-technical-forum/1144483-cis-mixture-screw-question.html#post12063522

Thomas

[harv666]

Thank you so much John, this is the type of info ive been diving to find. appreciate it.

Originally Posted by john walker's workshop

Pull out one injector and place it in a cup, keep the fuel line attached. Jump power to #6 fuel pump fuse. If the injector is spraying now, go counter- clockwise on the mixture screw until it stops spraying, but not very far beyond, as the adjustment is sensitive. If it's not spraying, go clock-wise until it does, then back off. Should get you in the ballpark. Lifting the sensor plate just a small amount should make it spray. Leaving the injectors spraying more than a few seconds can flood the cylinders.

[harv666]

I watched it, my butterfly and throttle body plate were exactly as he suggested. But he doesn't talk about the screw...

Originally Posted by Schulisco

You need to make a new basic setup of your CIS system. See the video I referred to in this posting for more details:
https://forums.pelicanparts.com/porsche-911-technical-forum/1144483-cis-mixture-screw-question.html#post12063522

Thomas

[eastbay]

Here is the official shop manual wording of what Mr. Walker was explaining

[harv666]

Wow, thank you this is perfect..

Originally Posted by eastbay

Here is the official shop manual wording of what Mr. Walker was explaining

[boyt911sc]

Originally Posted by john walker's workshop

Pull out one injector and place it in a cup, keep the fuel line attached. Jump power to #6 fuel pump fuse. If the injector is spraying now, go counter- clockwise on the mixture screw until it stops spraying, but not very far beyond, as the adjustment is sensitive. If it's not spraying, go clock-wise until it does, then back off. Should get you in the ballpark. Lifting the sensor plate just a small amount should make it spray. Leaving the injectors spraying more than a few seconds can flood the cylinders.

John,

I hate to disagree with your post. This is a technical forum and we could disagree or agree on something and nothing personal. You could be right and I could be wrong. Jumping power to fuel pump fuse, S6 or S16 (depending where you start the counting) works for Carrera 3.2 (Motronic) but NEVER in a CIS. Why? Supplying power to the fuel pump fuse does nothing to make the FP to run unless you got an electrical anomaly in the system.

If the OP has a Carrera 3.2 Motronic motor, your suggestion to power S6/S16 is a very sage advice. Unfortunately, the OP has an SC with CIS. Applying power to the CIS fuel pump fuse would only trigger the FP relay to switch from normally closed (87A-30) to normally open (87-30). So the FP will not run because no power is going to terminal #30 (FP terminal).

Please spend a few moments to review the wiring diagrams of the FP for both CIS and Motronic. And see the difference between these 2 systems. My two-cents.

Tony

[Schulisco]

Originally Posted by harv666

I watched it, my butterfly and throttle body plate were exactly as he suggested. But he doesn't talk about the screw...

Didn't you watched the video till the end?? Basically it's similar to the procedure John Walker described.

[harv666]

OkayJohn I’ve jumped the power to 6. Fuel pump is powered. Are you saying it should be spraying? Or I push the plate to get it to spray then turn then push again. Im sorry if I sound like an idiot but first time with this issue. If i push the plate i get lots of spray through the injectors.

Thanks

Harv

Originally Posted by john walker's workshop

Pull out one injector and place it in a cup, keep the fuel line attached. Jump power to #6 fuel pump fuse. If the injector is spraying now, go counter- clockwise on the mixture screw until it stops spraying, but not very far beyond, as the adjustment is sensitive. If it's not spraying, go clock-wise until it does, then back off. Should get you in the ballpark. Lifting the sensor plate just a small amount should make it spray. Leaving the injectors spraying more than a few seconds can flood the cylinders.

[harv666]

Originally Posted by Schulisco

Didn't you watched the video till the end?? Basically it's similar to the procedure John Walker described.

I’m an idiot. Watched again. Thank you for the push. I owe you one.

Harv

[pmax]

Originally Posted by harv666

I’ve jumped the power to 6. Fuel pump is powered. Are you saying it should be spraying? Or I push the plate to get it to spray then turn then push again. Im sorry if I sound like an idiot but first time with this issue. If i push the plate i get lots of spray through the injectors.

It shouldn't be spraying with the fuel pump on.

If it isn't spraying , as is the case now as per the update above and isn't running properly, the second part of John's instructions applies which is , and I paraphrase , to lean it out ... remember lean OUT ... until it is just on the cusp of spraying but doesn't. Remove the key aftger every adjustment.

[harv666]

First of all thank you everyone on this thread for your help, great ideas and guidance. She is a fire breathing dragon again... I discovered some things along the way that could help others stuck in a similar situation. The big breakthrough actually came when a friend shared the original Bosch manual for the cis. It had a fantastic illustration of what the mixture screw was actually doing. When I finally had a vision for what was going on I stuck my camera up there to get a closer look and what I found was what helped me solve all of this. Im not sure how but my mixture screw is either stripped at the very top threads or was set so close to the edge of fully rich that when I turned it two turns it basically unthreaded. So while I thought I was correcting it turning backwards, it wasnt turning at all. That was my first breakthrough. So with my camera up there (first my 13,99 endoscope from amazon and then just my iPhone 13 turned upside down and held at a weird angle with the light on recording video ( the light is important) I was able to see the screw turning and nothing happening, so I put some pressure on the sensor arm and was able to get it to rethread. I then turned it all the way to lean and followed the setup video that @Schulisco told me to watch. Removing one fuel line from the distributor not from the injector side and turning the mixture screw until just a bit of fuel appeared at the top. I then put it all back together and tried to start it. It didnt start but it tried to finally. I then went half turn, try to start, half turn, try to start etc, back and forth until I got the car started. It took some time but eventually I hit a spot that had idle and turned over. I then touched the sensor plate to see how much more space I had to enrich it, I had more power upon touch before it started to stall out so I took it another .5 turns and she launched into a perfect 900/950 rpm start. I hopped in the car and went on a 2 hour drive to a porsche event in the city, after the first hour hour my idle was low again, I turned it one more quarter turn and she popped back up to 950. It stayed there and I pulled 5 hours in her tonight and she stayed perfect. I do think my initial problem could be some stickiness on the sensor plate so im going to clean it properly but other than that shes running amazing, full power throughout the range. Thank you again everyone. Im going to post the illustration and a picture of what you see with your camera to help guide others. The light on helps you see the reflection of the screw turning as it's dark in there.

[harv666]

[harv666]

[PeteKz]

Harv, Glad to hear you got it sorted. It looks like someone tried to "adjust" it and ended up turning it all the way out, at which point it wasn't doing anything.

Next, 1/2 turn of the screw is a LARGE adjustment. you should now try adjusting it in 1/8 increments.

[rwest]

Originally Posted by PeteKz

Harv, Gload to hear you got it sorted. It looks like someone tried to "adjust" it and ended up turning it all the way out, at which point it wasn't doing anything.

Next, 1/2 turn of the screw is a LARGE adjustment. you should now try adjusting it in 1/8 increments.

Pete is right, if you use the factory baseline setup, you turn the screw just until the injectors spray without throttle and then back it off a half turn, so adjustments are very slight 1/16 to 1/8th of a turn.

Glad you got it running again.

[Anjizkit]

amazing thread! learnt something too! thanks for sharing