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Old 10-25-2012, 12:45 AM   #1
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Default Help! Cranking but won't start (was flooded, then no CAS, replaced CAS)

I'm completely out of ideas so I'm posting here for help.

So the car was running fine on thursday. It always had intermittent starting issues. Sometimes it would fire it up but sometimes I had to hold the throttle open a little bit to get it to fire. But then I took it to an alignment shop and the key was left in the ignition ON position for about 3 hours because he was not able to work on the car immediately. After the alignment was done we found that the motor was completely filled with gas it was so full that the motor would not move at all. So we removed the plugs, unplugged the coil packs, and cranked the motor to get the gas out. OMG geysers gas sprayed everywhere. We then put everything back together and it would not start anymore. We figured it was fouled plugs so we bought a spark plugs and that did not help either. We then tested one spark plug outside of the chamber and found that we were not getting spark anymore. So I just got it towed home and that was the end of that night.

So today I suspected it might be the CAS that was dead and causing the injectors to fire and flood the engine and causing there to be no spark. So I got a used CAS to put in.

I set the motor to TDC (lined up marks on the crank pulley, pistons 1 and 4 up, 2 and 3 down). Lined up the new CAS to TDC with the notched wing pointing up, and it wouldn't go in far enough. So I turned the CAS wing 180 degrees and it went it. I guess I didn't have the motor at TDC after all, but I figured if the CAS fits in I should be fine.

Now I am getting spark, fuel pump is going, but the motor won't start. In fact I got an small explosion out of the blow off valve, so maybe the timing is all messed up. Anyone have any ideas? Thanks!!

For reference, car specs:
95 miata
99 head, 94/95 CAS on the back
GTX block
Link ECU
FM2 turbo kit


Dave
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Old 10-25-2012, 02:08 AM   #2
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Originally Posted by Joe Perez View Post
Reverse the ignition coils.

You can either flip the connectors on the low-voltage side (the little plastic connectors on the bottom), or swap the plug wires so that the 1/4 wires go to the 2/3 coil and vise-versa.
So what I did messed up the firing order? Was it because I put the CAS in when 1,4 were TDC?
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Old 10-25-2012, 02:35 AM   #3
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I deleted that message because, honestly, I have no idea what the **** is going on.

It's mechanically impossible to install the CAS the wrong way. And it would have to be 90 out in order to mess up the firing order- 180 out would actually work properly.

And yet your symptoms (eg: backfire out the intake) sound exactly like what happens when the ignition coils are reversed. Happens pretty frequently with new MS1 builds where someone followed the "old" instructions for software config, but wired the coils "properly."

I dunno. It's worth a shot just as a test, but I can't see how it's possible assuming the car was running properly before and you didn't change anything else.


Disconnect the injectors. Paint a white stripe on the crank pulley at the timing mark. Crank the engine on the starter while observing the pulley with a timing gun. That's the real way to know what's going on.
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Old 10-25-2012, 09:55 AM   #4
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I'd send the map to FM and have them look at your cranking settings and ask them why the fuel injectors are spraying with just the KEY on.

I suspect too much fuel during cranking, and why you need throttle to start (more air).

I know jack about the LINK to be able to help much further.


it also sounds like it's possible your TB is installed incorrectly, but you said the car has been running.
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Old 10-25-2012, 09:04 PM   #5
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Hopefully the ECU wouldn't have anything to do with it since I didn't touch it or reset it or anything.

I tried swapping the order to 2341 and that didn't help. Still cranks and sounds normal but doesn't fire up. This is expected though since I didn't change the firing order or anything from when the car was running last week.

Any more ideas?
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Old 10-25-2012, 09:11 PM   #6
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Any more ideas?
It's so hard to know where to go with this...

A simple test is to hook up Ye Olde' Timing Light, and see if you're getting a spark event at all, and if so, when.

But I'm troubled by what we in the software industry refer to as First Failure- that is, the first abnormal event which preceded all the rest of the symptoms. In your case, that's the fact that the cylinders somehow filled up with fuel simply because the key was left on for three hours. Under no circumstances would that be considered normal behavior, and it really makes me wonder what's going on inside that Link.

If you have access to a stock ECU and MAF sensor, I would strongly advise installing them before proceeding with further investigation. Yes, the fuel PW will be all wrong for your injectors, but it'll give you a solid foundation from which to troubleshoot. Once the engine is running (albeit overly-rich) and timed, then you can switch back to the Link.
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Old 10-25-2012, 10:32 PM   #7
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The very first First failure is the hard starting, sometimes would crank and start instantly with no throttle, sometimes required me to give it a little gas. Someone once told me that was possibly the CAS on its way out.

Would a broken CAS possibly be stuck where the Link might think it was time to fire injectors?

Quote:
Originally Posted by Joe Perez View Post
It's so hard to know where to go with this...

A simple test is to hook up Ye Olde' Timing Light, and see if you're getting a spark event at all, and if so, when.

But I'm troubled by what we in the software industry refer to as First Failure- that is, the first abnormal event which preceded all the rest of the symptoms. In your case, that's the fact that the cylinders somehow filled up with fuel simply because the key was left on for three hours. Under no circumstances would that be considered normal behavior, and it really makes me wonder what's going on inside that Link.

If you have access to a stock ECU and MAF sensor, I would strongly advise installing them before proceeding with further investigation. Yes, the fuel PW will be all wrong for your injectors, but it'll give you a solid foundation from which to troubleshoot. Once the engine is running (albeit overly-rich) and timed, then you can switch back to the Link.
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Old 10-25-2012, 10:52 PM   #8
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The very first First failure is the hard starting, sometimes would crank and start instantly with no throttle, sometimes required me to give it a little gas. Someone once told me that was possibly the CAS on its way out.
If you're quite certain about the application of throttle being the difference between a start or no-start condition, it's almost inconceivable that the CAS could be related to this phenomenon.



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Would a broken CAS possibly be stuck where the Link might think it was time to fire injectors?
I cannot imagine how.

It's certainly possible for the CAS to fail in a number of different ways, but you need to think about the interaction between the CAS and the ECU, and the manner in which the ECU determined when (and for how long) to fire the injectors.

In very simple terms, the CAS emits two pulses for every crankshaft rotation (one roughly 75 degrees of crank rotation prior to each ignition event), along with a second set of pulses to determine absolute engine phase.

The CAS can potentially fail in several different ways. Either of the two output signals can potentially fail high or low, such that they are always asserted or never asserted.

But neither an "always asserted" or "never asserted" condition would cause the ECU to fire the injectors continuously.

The ECU looks and the pulses coming out of the CAS, and acts on the EDGE of the pulses only. In simple terms, when it sees the primary pulse (which we call CKP) go from off to on, it says to itself "Ok, I now know that the engine is at 75 degrees BTDC, so I'm going to start a countdown timer to fire the plugs, and I'll also go ahead and inject fuel at whatever pulsewidth is appropriate for this load condition."

In other words, the transition from off to on sets into motion a chain of events that result in one coil firing and one injector firing.

Simply holding one of the CAS signals high continuously would not, however, result in continuous fuel injection or spark activity. Something much weirder is afoot.
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Old 10-26-2012, 03:39 PM   #9
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Took it to a shop. Lol. I give up!
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Old 11-05-2012, 03:27 AM   #10
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Let us know what fixed it, Im kinda in the same boat.
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Old 11-05-2012, 05:16 AM   #11
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Hey so I did get it back from the shop, basically after letting it sit it did fire up, but it's running ridiculously rich now, so I think a couple injectors might be stuck open. At least that's what the symptoms suggest (filling engine with fuel, running ultra ultra rich) so I'm in the process of upgrading to injector dynamics injectors.
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Old 11-05-2012, 06:25 AM   #12
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I do have a really strange issue though. If I pull the fuel pump fuse and turn the ignition key to ON position, my radiator fans come on. If I put the fuel pump fuse back and turn the ignition key to ON position, no fans come on. Is this normal?
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Old 11-05-2012, 01:49 PM   #13
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The INJ fuse powers the whole ECU, which in turn controls the cooling fans. If this fuse is removed and yet the rest of the car is powered up, the ECU's outputs are going to be in an indeterminate state and it's not inconceivable that voltage coming into them from the accessories could float parts of the ECU high enough to allow current to flow through the output ports.

In other words, I wouldn't fixate on this.
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