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Rasta Monsta · Joined: 12 Jul 2006 Posts: 11724 Location: PacNW

Well, I heard a large bang Thursday night....

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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

joewest · Joined: 06 Oct 2005 Posts: 234 Location: Portland, OR

Rasta - That large bang may have been that ONE backfire that has shown any signs of fire in this motor!

I updated the tables and other settings with no change. Just cranking and no firing at all.

Suspecting a basic issue, I took off the valve cover and verified the cam position with the timing mark on the flywheel, after setting the engine to TDC using the wood rod method. Double checked the trigger wheel and VR sensor setup and it seems good. I'm logging a solid RPM sync.

With a "dumb" timing light on plug wire #1 and cranking, the strobe is not consistant but does sometimes flash. The MS forums chalk this up to "That's typical with EDIS". With the plugs all out of the head and ground to the block, they do fire very well in the wasted spark pairs. Back in the head they went.

Checked fuel pressure at the Pressure Regulator and it is solid at 44PSI. Cracked open the throttle and cranked...nothing. There is sparse fuel on the spark plugs. Maybe the settings controlling the injectors are not right? I have a spare cylinder head core that I may use as an injector/rail test stand, but before I do all of that I think there is more basic troubleshooting to be done.

I logged a 20-second crank session using Tunerstuido's composite logger and opened the log in Megaviewer, but it only shows ignition behavior and no other data points. I would like to see why WUE is no longer functioning, or verify that the cranking advance matches settings, etc. I do not think that I am using the software properly and will read up on it again this AM.

Here is the log

https://app.box.com/s/rkm9f0zamvimhm4bc96u38675t1ves0d

Here is the tune

https://app.box.com/s/m5p722sm3wz4d1u0oaa1kbc109l1syuw

I tried cranking with the supercharger clutch "ON" and "OFF" with no change. Since some people are seeing at least some level of engine running after installation and basic settings in place, I still suspect some sort of fubar either in my tune settings or a component. This AM I will hook up an o-scope to test the SAW signal from the ECU to the EDIS Ignitor to see if there is a problem there.

I cannot wait to get this sorted out and running....but...patience...Thank you for taking to time to look at this with me!
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'79 924 Supercharged / Track Prepared
'80 931 Daily Driver - Sold
"The number of posts in my profile may represent the number of times I have screwed something up...and admitted it here."

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

Try starting fluid and see if it hits on that?
If it does you know it’s a fuel problem, if it doesn’t then you know you have an ignition problem..

Just one backfire sounds like it’s not getting near enough fuel.. Even with your ignition way off I would think you would be getting more backfires out the intake or out the exhaust if it was spraying and sparking at all, no matter when..

How about your fuel injector wiring?
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80 Turbo - Slightly Modified

924RACR · Posted: Mon Apr 05, 2021 4:55 am Post subject:

Agreed - it does rather sound like there's doubt you're actually getting any significant amount of fuel out of the injectors. At least that seems plausible; a test with a spare head would be a great idea. Maybe need to purge air out of the system if you dead-head into the rail? Depends if you're plumbed returnless or not.

Will pull that log trace and have a look...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

924RACR · Posted: Mon Apr 05, 2021 5:01 am Post subject:

Yeah, no, still not much to see using the composite logger; can you switch to regular logging (just Control L and Control K on the main gauge screen) and gather that data while cranking? Though it still won't matter if the problem is outside the scope of the injection system, like no fuel to the rail or such.

Could it be possible that you don't have the regulator plumbed properly?
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11724 Location: PacNW

Joe, is the blue car for racing? I think I'm running at PIR in early May...
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

joewest · Joined: 06 Oct 2005 Posts: 234 Location: Portland, OR

Rasta - Track only for the blue one. If you are running PIR I would really enjoy checking out your action there. Let me know when and I can be there. Hit me up anytime (714)six-zero-six-zero-7-one-5.

V-Money - I will run a proper log today and post as soon as possible. It's very hard to see issues with my current log data. Thank you for the hot keys. I am looking forward to trying them later tonight. The fuel regulator is plumbed per their instructions from Aeromotive and is a return system. I will get a helper to hit the cranking switch and I can watch the gauge on the regulator to see how it behaves. The stock accumulators are still on board so I should look into that relationship.

Fast Eddie - I can grab a fresh can of starter fluid tomorrow and try to fire it again. Old Skool. The injector wiring is all new and I verified continuity from the injector connector pins to the breakout box connecting the ECU. Bank 1 is cyl#1 and #4 and Bank 2 is cyl#2 and #3. My proposed cylinder head test stand will allow me to visualize flow using the Coms test controls in Tunerstudio. Might have to do it. Just need to 3D print some kind of catch under the head so I am not spraying fuel all over the bench.

The olds are coming over for some holiday distraction this afternoon so I will go dark in about an hour or so.

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'79 924 Supercharged / Track Prepared
'80 931 Daily Driver - Sold
"The number of posts in my profile may represent the number of times I have screwed something up...and admitted it here."

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11724 Location: PacNW

No spectators yet, due to plague. Maybe in the fall...
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

924RACR · Posted: Mon Apr 05, 2021 8:30 pm Post subject:

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11724 Location: PacNW

One crew person per car
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

924RACR · Posted: Tue Apr 06, 2021 12:47 am Post subject:

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11724 Location: PacNW

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

My first time planning to go to a track with my 24 was quashed by Covid

Killed it @ Vegas exotics racing gocart track the other day though, and got to fondle a 911 gt2rs quite a bit..
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80 Turbo - Slightly Modified

924RACR · Posted: Tue Apr 06, 2021 10:08 pm Post subject:

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11724 Location: PacNW

Copy that.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3