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931 Head Installation Thread
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bureau13  



Joined: 07 Sep 2017
Posts: 412
Location: South Florida

PostPosted: Wed Jan 12, 2022 3:01 pm    Post subject: Reply with quote

Well, my spark plug tester thing showed a spark, and I did briefly get it to run a bit the other day, but something is definitely off. It previously started quite easily, even if the ignition timing was a bit off. I got new plugs, that's the only part of the spark side of things that wasn't tested with the spark tester. Haven't had a chance to try them yet....

924RACR wrote:
If it won't kick on starter fluid, you're not getting a spark. Something must've gotten borked on that end.

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1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

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924RACR  



Joined: 29 Jul 2001
Posts: 8546
Location: Royal Oak, MI, USA

PostPosted: Wed Jan 12, 2022 9:59 pm    Post subject: Reply with quote

For the longest time I had issues on my S2 with inconsistent spark. Countless no-starts etc.

This was a primary motivation in switching over to Microsquirt.
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Vaughan Scott
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Mike9311  



Joined: 14 Dec 2004
Posts: 1219
Location: Chicago-ish

PostPosted: Thu Jan 13, 2022 3:25 am    Post subject: Reply with quote

I second the starter fluid comments

Had a situation years back headed into night one of a 92Forty weekend. had just reassembled a bunch of stuff. S2 would not start no matter what. In the end I swapped a coil in from my original S1. It fired up like nothing was ever wrong. Of course night one celebrations were off the table that night but at least problem got solved

If memory serves at one point I did have a spark but with a plug pulled and up laying on the engine which is totally different than a spark generated in the cylinder. You may see something outside but it still isn't what you need
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1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
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bureau13  



Joined: 07 Sep 2017
Posts: 412
Location: South Florida

PostPosted: Thu Jan 13, 2022 4:01 pm    Post subject: Reply with quote

I suspect you guys are right. I know fuel is getting in there. The spark tester result made me think it had to be timing, but I've verified both ignition and cam timing multiple times. It's certainly close enough to fire.
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1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
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1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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peterld  



Joined: 10 Dec 2006
Posts: 885
Location: Noosa Heads QLD Australia

PostPosted: Thu Jan 13, 2022 6:47 pm    Post subject: Reply with quote

Does this not all keep pointing back to the 123 Ignition interface?
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bureau13  



Joined: 07 Sep 2017
Posts: 412
Location: South Florida

PostPosted: Fri Jan 14, 2022 1:03 pm    Post subject: Reply with quote

That thought has crossed my mind. I guess the thing is it started up and ran perfectly before. So the thing that changed was me removing and replacing the head (and the head itself of course) so that seems the most likely thing. And of course, getting spark in the tester also made me think that device is working as designed. But, I was about ready to yank it and put the old Ford Ranger dizzy that it came with back in.

Anyway, I replaced the plugs, cranked it, nada, then started fiddling a bit with the dizzy, got some coughs, and just kept twisting it...it's frankly way past where I thought it needed to be...and this happened:

https://drive.google.com/file/d/1h2x3Ryox_B0L39pfzwkYI_a8hOrMM_7k/view?usp=sharing

peterld wrote:
Does this not all keep pointing back to the 123 Ignition interface?

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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bureau13  



Joined: 07 Sep 2017
Posts: 412
Location: South Florida

PostPosted: Sat Jan 15, 2022 4:07 pm    Post subject: Reply with quote

So, it starts pretty consistently now. It idles OK, not super smooth, but I haven't timed it with a timing light or anything yet. The smoke is a concern. I see it, looking from the top, coming up from beneath the headers. Not sure exactly where it's coming from yet, or if it's burn-off of something dripping or something else. It doesn't really smell like exhaust or fuel to me. Tomorrow's project is to find that and hopefully fix whatever it is, and then put the rest of the car back together (air box, accessory belts) and actually drive it. Might be a little ambitious lol...
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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924RACR  



Joined: 29 Jul 2001
Posts: 8546
Location: Royal Oak, MI, USA

PostPosted: Sat Jan 15, 2022 9:47 pm    Post subject: Reply with quote

Glad to hear the progress.

Some smoking after major engine work like that is normal, as typically some oily fingerprints etc will end up on the exhaust and such. As long as it goes away once up to temp, in the first warm-up cycle. Otherwise yeah look for leaks.
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bureau13  



Joined: 07 Sep 2017
Posts: 412
Location: South Florida

PostPosted: Sun Jan 16, 2022 11:05 am    Post subject: Reply with quote

Good call, I'm not seeing anymore smoke.

A couple things:

Fans are not coming on, so the car will overheat if I let it run. If I turn the AC on, both fans turn on, so that's working. Time to go re-familiarize myself with the fan circuit. This all worked before so I suspect I must have failed to connect something. The temp gauge is working fine, for what it's worth.

If I turn the key to on but don't turn the car on, the oil light lights up solid. The only reason I bring this up is that I was messing with it in the dark tonight, and while running, I very faintly see the oil light. VERY faintly...but when it's on solid (not running) it's plenty bright. I was thinking this is correct operation and nothing to worry about, but now I'm paranoid. Also, my oil pressure gauge is pegged, so I'll bet I screwed something up back there, ugh...
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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924RACR  



Joined: 29 Jul 2001
Posts: 8546
Location: Royal Oak, MI, USA

PostPosted: Sun Jan 16, 2022 10:24 pm    Post subject: Reply with quote

bureau13 wrote:
Good call, I'm not seeing anymore smoke.

A couple things:

Fans are not coming on, so the car will overheat if I let it run. If I turn the AC on, both fans turn on, so that's working. Time to go re-familiarize myself with the fan circuit. This all worked before so I suspect I must have failed to connect something. The temp gauge is working fine, for what it's worth.


Temp sensor is a completely different part of the electrical system.

The fans will be controlled by the switch in the radiator (as well as the AC switch). Make sure the rad switch is plugged in; try shorting it, the fans should come on. If they do, odds are your rad switch is bad - though they usually die in the "on" position.

I'd suspect one of the two rad fan relays is not working right, or disconnected, or such... it's a bit funky of a wiring design, but recently that's what we've been seeing as an issue.

bureau13 wrote:

If I turn the key to on but don't turn the car on, the oil light lights up solid. The only reason I bring this up is that I was messing with it in the dark tonight, and while running, I very faintly see the oil light. VERY faintly...but when it's on solid (not running) it's plenty bright. I was thinking this is correct operation and nothing to worry about, but now I'm paranoid. Also, my oil pressure gauge is pegged, so I'll bet I screwed something up back there, ugh...


Sounds like that's entirely possible, quite possibly the leads are switched.

The gauge will peg at max value if the sensor wire is grounded. Which will happen with the engine off, if it's connected to the switch terminal instead. The gauge will take some minutes to recover from that due to its electrical design - so it won't go right to zero when you start the engine (when miswired).
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'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
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bureau13  



Joined: 07 Sep 2017
Posts: 412
Location: South Florida

PostPosted: Mon Jan 17, 2022 12:28 pm    Post subject: Reply with quote

Apparently that radiator temp switch is bad. When I short the two wires together, ignition off, the driver's side fan comes on low speed. With ignition on, it switches to high speed (I think the other fan comes on too, I didn't verify I just noticed it got louder). I ordered another one, although I'm a little surprised, since I replaced that thing 2-3 years ago. I wouldn't have expected it to go bad.

I also noticed that my oil smells pretty "gassy," presumably from all the attempts to start it, so I did an oil change and bled the clutch while I was at it since it was acting like it needed it.

I think I'll jumper that temp switch tomorrow and let it run for a bit, just to make sure it still doesn't overheat, and then I may take it for an actual drive. I'm nervous lol...
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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