wont start no spark

[coltabsh]

I bought my 1983 944 with the motor already torn apart and have been piecing it back together. I replaced the head gasket and was ready to start it up it just cranked and cranked so I checked and I have fuel (replaced fuel pump) but no spark at the sparkplug wires so I checked the rotor and no spark checked the coil and no spark but there is power going to the coil but nothing coming out???? What would cause this???

I got looking around at my chiltions manual and saw it had a distributor dust cap what looks like mine is missing

Where is the ignition pickup coil on the 944 ??? I don’t see one ?

i got looking at the relays and saw one, someone took and spliced on wires somewhere and has it dangling there. its a
0 332 204 151 12 v 20/30a
On the relay block there are 2 empty slots on the bottom left. anything needs to go there



Thanks for any help

Shane

[SoCal Driver]

There are two sensors on the top of the bell housing. One feeds the engine speed to the DME (brain) the other feeds the TDC info to the DME. The TDC sensor is what tells the DME to fire the coil.

Many times these have just been cross pluged -- pluged into the wrong lead.

Sometimes these need to be readjusted for the 0.8 mm clearance to the starter ring teeth on the flywheel.

Read the heck out of www.carks-garage.com and Danno's Racer-X site (need to find the link). Get the Hayes manual on the early 944's. Not all inclusive but better than what you have.

I'll have to cross check the relay you list. May be a jury rig for a stock relay. What socket does it look like it comes out of?

Yes there are a few "empty" sockets. Cars were built for the entier world even though most of the sale were in the US.

How are the timing and balance belts?

[SoCal Driver]

The relay is a Volvo fog lamp relay. Like I said jury rigged.

http://www.swedishpartswholesale.com/VO_Relay_list.html

[SoCal Driver]

Try this link. Gets you to Racer-X and Clarks.

http://www.gururacing.net/

[DannoXYZ]

Gosh, I should put this test on my RacerX website since I've typed this up about 10 times recently. SoCal is right on about the sensors. In the DME Test Manual, that's the very first thing they check because it takes only 5 minutes and will save you tonnes of time troubleshooting everything else in the car like ignition and fuel components. Hook up a 'scope to the sensors and the waveforms should look like this:



If you don't have these, nothing else will work. No spark, no fuel, nothin' kaput!

Next after verifying that the sensors are putting out the correct signals is checking you have power to the fuel-pump and DME computer. Key ON should have power at the DME's red/yellow-stripe wires. When cranking, the fuel-pump should have power.

Third check would be that fuel and spark is actually occuring at the other end. Yank the fuel-rail and put some clear plastic picnic cups under the injectors. Crank and see if fuel -flows (you can also test balance of injectors this way). Then yank the plug-wires and insert a plug into each of them. Lay on top of intake-manifold and crank. Should see them firing in 1-3-4-2 pattern.

Doing the checks in this order is the most efficient and takes the least amount of time in tracking down a problem. Good luck!

[SoCal Driver]

Just don't do the injector flow test at the same time as the spark plug test!!!

I'm still wondering about the Volvo fog lamp relay clunge. This may have been to bypass a faulty DME relay. If the DME relay does not close it's first set of contacts when the key is turned on then there is no voltage to the injectors or the DME (brain) so you would not get spark or injector firing.

Since you have voltage to the coil we can say the ignition switch is working.

[SoCal Driver]

You might want to check this out. Wilks has a whole section for the early 944's:

http://www.frwilk.com/early944/

[DannoXYZ]

Ok, just read the original post a little closer looking for clues...

"...was ready to start it up it just cranked and cranked so I checked and I have fuel (replaced fuel pump) but no spark at the sparkplug wires so I checked the rotor and no spark checked the coil and no spark but there is power going to the coil but nothing coming out???? "

This is a conflicting set of conditions:

- FUEL = yes
- SPARK = no

How do you know you have fuel? Did you pull the cap off the end of the fuel-rail and fuel squirted out when you cranked the engine? Or did you pull the fuel-rail with injectors attached, aimed it sideways and confirmed that fuel squirted at least 30-feet across the garage?

I'm going to assume that the actual conditions are as follows:

- FUEL:
fuel-pump power = yes
power to injectors = no (use voltmeter to check for+12v on each rearward pin on injector connector)
fuel coming out of injectors = no
- SPARK = no

Looking at the Volvo relay was the additional clue. If they used the SPST relay to replace the DME relay, it could have only replaced 1/2 of the functions. The DME relay is actually two relays in one. When you first turn the key to ON, this turns on 1 of the relays in the DME-relay box which powers the DME itself. Then when you crank the engine, the DME grounds the 2nd relay in the DME-relay which powers up the fuel-pump.

So my guess is whoever jury-rigged the Volvo relay in, thought that it was just a fuel-pump relay. So they powered up the fuel-pump when the key is turned to ON, but no power makes it to the DME. This is completely backwards.

Verify this by turning the key to ON and checking for +12v on the DME's power lines on pins #18 and #35 (big red/yellow-stripe wire). If you don't have power here, that's your problem. Yank that Volvo relay and get a real Porsche DME relay.

[michaelathome]

Have you looked at the timing belt? If it is not turning and the rotor is stationary between two points you could see a similar situation. One of the timing belts functions it to turn the cam on which is attached the rotor.

Might be worth looking at. Just pull the rotor and give the engine a quick turn and see if the rotor is in the same position. If it is, try taking a look at the belt.

Michael

[DannoXYZ]

What happens to the valves if the cam doesn't turn when you crank the engine?

[944 Ecology]

Originally posted by DannoXYZ
What happens to the valves if the cam doesn't turn when you crank the engine?

Typically, you would bend two valves, one exhaust and one intake, when the piston came up and hit the ones that are sticking down at any point in the camshaft's rotation.

gb

[michaelathome]

They get "bent" or pushed to a position where they will no longer hit the tops of the pistons.

Not wanting to curse the situation but that is where I was when I got my car. Was diagnosed as "will not start" I chased through electrical and DME issues and figured I would follow the no spark to where it had to be. Coil or rotor. Had a new coil that tested SO, time to look at the rotor, guess what, it's not turning but the engine is DEFINITELY turning over. Pulled the TB cover and guess what, I was missing 14 teeth on the TB. The belt was sitting stationary on the crank and not turning the cam. No spin no spark.

It's a pretty easy thing to look at to rule out before trying to get too involved.

In order to bypass the DME on the fuse panel see the following:

http://www.clarks-garage.com/shop-manual/fuel-05.htm

My .02

Michael

[DannoXYZ]

Hmmm, I think he's OK then. He said he did have power at the coil, but no spark at the coil, and no spark after the distributor. So we can safely assume that his DME's not firing the coil. If DME's OK, but there was a problem with the distributor or rotor, he'd have spark at the coil, but not at the plug-wires. So the problem is starting before the coil. Most likely a DME, DME-relay or speed/ref. sensor problem.

[michaelathome]

Danno, I think that we are all on track. As the engine was appart there is no telling what had actually been taken apart. I think that we are missing too much info regarding the situation.

1. Are the reference sensors plugged in correctly?

- Grounds to Pulse Sensors on top rear of block clean?
- Speed Transmitter (DG - Top)
- Reference Mark Transmitter (BG - Bottom)

2. Is the AFM hooked up and ALL of the associated vacuum hoses? That could also cause the problem. The DME also looks for the AFM if IIRC.

3. O2 sensor makes little dif, it would just run bad.

4. Advance in timing (sensors) if off enough could do it but would likely once again just run bad if not too far off.

5. Does the battery have a strong enough charge? Could that impact it? I had read that w/out a high enough amp it will have problems, is this true as well?

Michael

[DannoXYZ]

"1. Are the reference sensors plugged in correctly?

- Grounds to Pulse Sensors on top rear of block clean?
- Speed Transmitter (DG - Top)
- Reference Mark Transmitter (BG - Bottom)"

The grounds are actually for the DME and wiring harness. The sensors are grounded in the DME itself. The waveform test with the 'scope will tell you if you've for the speed & ref-sensors plugged in correctly.


"2. Is the AFM hooked up and ALL of the associated vacuum hoses? That could also cause the problem. The DME also looks for the AFM if IIRC."

Yup, the DME just blindly injectors some fuel when cranking to start the car. Then after the engine's running, it checks the AFM voltage and adjusts the fuel to match air-flow. You can actually start the car with the AFM completely disconnected and removed from the car. It will run for about 1-2 seconds then die.

"3. O2 sensor makes little dif, it would just run bad."

Yup, bad O2-sensor wouldn't cause a no-start condition. However, I've blown up and completely destroyed an engine once by using a bad O2-sensor. I was using an aftermarket standalone EFI system and was using the fuel-map auto-tune feature that uses O2-sensor feedback to fine-tune the fuel-map to hit your desired targets as you drive. Problem was we had a bad O2-sensor that read lean all the time. So the computer thought air-fuel ratio was lean, so it added fuel, check the O2-sensor, then added even more fuel and more fuel. It was running so rich, it washed the oil off the cylinders and everything got chewed up in about 1000 miles.


"4. Advance in timing (sensors) if off enough could do it but would likely once again just run bad if not too far off."

Are you talking about ignition timing or cam-timing? Ignition is fixed and cannot be changed mechanically. Unless you pull the trigger screw for the reference from the flywheel and drill a new hole for it, ignition timing will always be exactly whatever values are programmed into the chips.

Sure, you can have the distributor rotor out of phase with the proper cylinder on the cap, but that will not change ignition timing. The spark will still fire at exactly the correct time, but you may end up sending that spark to the #2 cylinder instead of the #1.

"5. Does the battery have a strong enough charge? Could that impact it? I had read that w/out a high enough amp it will have problems, is this true as well?"

Yup, it's the battery voltage that counts. The coil multiplies the voltage. Yet the starter drops the battery voltage when you crank. So if you've got a weak battery, when cranking its voltage will drop from 13v to 9v. The result is that the coil will only output 22,000v instead of 30,000v and you may not have enough to jump the spark-gap. This typically manifests itself as sporadic ignition. Narrowing the spark-gap and charging up the battery will help.


However, we've got a completely dead no-start condition here. So he should check for power at the DME first, then the speed/ref. sensor waveforms. Everything else will be a waste of time.

[SoCal Driver]

Of note is that on the early 944's you can jump between Aux fuse #3 and #2 to run the fuel pump. Key does not have to be on.

Shane, You need to get back to us on this. Lots of experiance here in this thread.

[todwic]

Get a multi-meter from your local parts store, one with "RPM" setting. Not only will it be usefull in the future, you can see if there's the all important ignition "pulse" is getting to your coil. Read the directions that come with the meter (I got mine at Autozone). No pulse? DME, DME relay, wiring, or sensors.

[todwic]

um *cough* I just read Danno's post and he's on target. The meter is the easiest way that I found to read a positive yeah or nay. I have also found that you can use a small florescent drop lite to activate the sensors.

Just to breif everyone, I'm not suggesting you do this: run the bottom side of a magnet or a sensor along the plastic case of the light. You'll feel the magnet (sensors have a magnet in them) move in a direction that you didn't cause. With a little trial and error you can make the sensor pulse and run the fuel pump. I did this to check both of my sensors. (if one pulses and runs fuel pump, plug the other sensor into the socket that the rpm sensor was in. If the second sensor runs the fuel pump, it's ok too.

[michaelathome]

Todwic and Danno,

Thanks for the help, you are helping me through the questions that I had when I go to put my mess back together. My DME and everything else checked out OK but when it came down to it my belt was a little short on the tooth. My speed and ref transmitter cables connectors are shot (male end on sensor cable) and I know that I need to figure out a work around when I get my new head. I had bent valves, 4 from what I can tell.

I'll be watching this thread or adding to it soon I am sure.

Michael

[todwic]

To add to my addition: I had checked everything I thought possible: Sensors tight on the mount, Mount tight to block (a little loose), Clearance of sensor to starter ring (.8 [that's point-eight] mm), very critical, connectors......

Motor ran for a bit and then just died, shortly after second start on rebuild. What had happened is this mix of theory, sleuthing, and fact: After initial start up, and run, to op temp, of course the metal bits expanded. After shut down, they did the other thing. I think this was just enough to loosen the very hard to reach and unloc-tited sensor bracket bolts (6mm allen head). Bracket vibrated down, sheared the ref. pin on the flywheel. Nobody told me that could happen. I tested everything 3 times. Someone finally clued me in to checking the heigt of the ref. pin. What ref. pin? Could be yer problem, tod. dumbass.