ignition switch? how much does it control

[84 944 oneowner]

Just wanted to see if anyone knows the scoop on the ign. switch? I have replaced speed and ref sensors and dme relay and new dme, and multiple other things. Still have no tach bounce, no fuel pump, and no power from coil. Running out of ideas here. If anyone has had to deal with this much wow i really feel the pain now lol. Any ideas would be great, thanks

[Ga 951]

No tach bounce still sounds like a reference sensor issue. Did you remove the sensor bracket? If so the gap may not be correct. If you didn't remove the bracket, I would double check the connections and make sure you have the connections correct - ie ref to ref and speed to speed. If they are reversed, no signal and no start.
You can also ohm them out per Clarks garage but that is just a sensor check to my knowledge.

If you are the original owner, Congrats. Highly unusual and a sign of great taste

I know you'll get is sorted out. I know the ign sw causes problems and it MAY be your prob. but I'm pretty sure it won't cause a lack of tach bounce. Keep investigating before throwing new parts at it!

Bruce

[89-944NA]

Had a similar problem with mine, turned out to be the DME.

[84 944 oneowner]

Thanks for the input. I have a brand new dme and new sensors and relay to match. Does anyone know for sure about the ref sensor! what i am trying to say, what part on the flywheel does the sensor read? is it magnet or what? starting to think that this might be the problem. But with no power from coil and fuel pump still not running and injectors not lighting up noid light. Somehow there is a part that controls all of it together just not sure which part that is. Factory alarm, ref sensor/flywheel, ingition switch, Idk my I.Q. is dropping fast with this issue lol

[John_AZ]

Have you checked the 2 flywheel studs that the reference sensors use? Damaged?

Have you traced the wiring from the reference sensor connection to the 35 pin connector with a continuity check?

The 35 pin connector, are all of the pins intact and none broken?

With the new DME in, have you tried to wiggle the main wire while starting?
It may be a broken connection.

The back of the fuse panel, do you have any wires that are burned, fried, brittle?

Are all the fuses ceramic style and not the plastic type. The plastic type warp with heat and do not make good contact.

I can only think it will be a simple fix that is preventing the start now that you have replaced the main parts.

GL
John

[89-944NA]

Search this forum, there is a post on making a jumper to disable the factory alarm. But I am not sure what all the alarm disables.

Can't recall now, but if I remember correctly, the reference sensor picks up it's signal from the ring gear, the speed sensor uses the pins on the flywheel.

There is a magnet inside the reference sensor, about 1 1/2 inches long and maybe 5/16 diameter, be careful with your adjustment, if it catches the sensor catches the ring gear and tears the sensor apart, you get loads of copper wire and a magnet inside the bellhousing.

Ask me I know, mis-adjusted one, it caught on the gear tore open, and the magnet attached itself to the ring gear, jammed between the starter and the ring gear, and broke the aluminum nose of the starter.

[Slam]

Considering how cheap the ignition switch is, how much trouble it can cause and how easy it is to replace, I'm wondering why you haven't changed it. Always start with cheap and cheerful!

[84 944 oneowner]

Hey that sounds like some great advice from all, thank you all for taking the time out of your day to answer my question. I will for sure start from step 1, I have to agree what ever it is wrong is coming to head i hope anyway. Thankyou again very much and will be rolling the dice tonight with her.

[jpk]

If everything else is OK, A bad or no refrence sensor signal to the DME will still give you spark; it's just at the wrong time. Bad or no engine speed sensor will prevent the fuel pump from running except when there is a start (engine cranking) signal present. I'm pretty sure you need the speed sensor signal to fire the fuel injectors and spark as well. The tach is also driven from the speed sensor.
In general, the speed sensor counts every tooth on the flywheel and tells the DME exactly how fast the engine is turning; the reference sensor pulses once per revolution when a small iron set screw in the flywheel passes. This tells the DME where it is in the combustion cycle (where is TDC)
It sound to me like you are not getting any power to the DME. This could be in the relay or due to the alarm.
Power comes in to the DME through the DME relay on pins 18 and 35 in the main connector, these are heavy red wires with a yellow stripe. Check to see if you have power there while cranking and ignition on. if not, then suspect the relay and/or the alarm.

[John_AZ]

Originally Posted by 84 944 oneowner

........... and no power from coil.

Running out of ideas here.

Bad Coil---seldom happens but you may be one of the unlucky few.

running out of guesses....

GL
John

[iplagolf]

Two weeks after I drove the car home from Wash.DC, where I bought it, I went out to the garage to drive it and the motor cranked but it wouldn't start. Pulled the new DME and installed the jumper I got on my trip home, and it still wouldn't start. Had the car towed to a service shop. The mechanic reached up under the dash and the ignition switch fell out into his hand. He replaced the switch and haven't had a problem since. As I see it the ignition switch is the part that powers up every thing that is needed for the engine to turn over and fire. I'm not the sharpest tool in the shed compared to some of the people on this site and Clarks, but it seems we have (had) the same problem. Good luck and let us know what it was. Fritz

[MrTibbs]

from what i remember from getting my parts car's engine running, if there's no tach bounce the sensors aren't right. If they're new they may not be gapped correctly. I think from the searching i did at that time that unless the sensors tell the dme the engine's turning at least 200 rpm the fuel pump, injectors etc won't run or fire. Not sure what you mean by a 'brand new' dme, but if it was used it might be worth putting into a known good car to test it. There's no other practical way to test them.

I'm assuming you're following the no spark checklist on clark's. It goes through everything in sequence so should help you. I found it very useful.

Good luck.

Mike

[84 944 oneowner]

I bought a brand new/ rebuilt DME. and all new sensors and relays ,just tired of messing with her lol. But at the end of the day it turns out that this whole time one of my sensors either was damaged during shipping or bad from the get go so i orderd another one and should be in my hands somtime this week. New post to begin after its installed and hope it runs after this lol. Thank you for all the support and advice. Justin