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maybeoneday · Posted: Sun Jul 05, 2015 1:01 pm Post subject: Almost going 77 NA

I was around about 6 months ago or so trying to get a 77 NA going in Australia. Well after a little time off on other stuff we have progress.

Earlier today it started, and ran (a little lumpy) but it ran quite well for 5 min of so when I switched her off.

Problems are it was really hard to start and would not start again about 10 min after it initially started and ran.

Has anyone got a procedure of what they would suggest to try to get it a little more reliable starting.

I have already refreshed all the Vac lines and electrical connections (mainly NEG(-) side and ran a new NEG(-) connection in places), fuel is not great but it did get her going initially, fuel distributor, injectors and injector seals are new (distributor rebuilt).

The CIS fuel system has taken a while to learn, I am thinking that the issues probably lie in this area but am open to any other suggestions. Head had been redone and I have done the valve clearances cold, but as I switched her off and couldnt get her regoing I am yet to do them warm as suggested.
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1977 924 NA Auto

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

What do you have for your CO/AFR base setting? (3mm allen screw in distributor hole)

If you don't know if you'r even in the ballpark..
Jump fuel pump, adjust screw rich (clockwise) just until the injectors start to spray with the plate at rest, then back lean just until they quit..
That should get you close enough to run..

You can pull the injectors and put them in pop bottles, jump pumps, play with air metering plate and see injector performance (cone patterns), also measure there outputs and see if they are the same (amounts in identical bottles), and see if any leak etc..

A CIS testor would let you see your control pressure, system pressure, and residual pressure if you can get your hands on one or make one, your WUR could still be causing problems..

If it will start cold but not hot it could likely be your fuel accumulator or non return valve.. (residual fuel pressure)

I would definitely drain the tank, replace fuel filter, tectron in gas tank with fresh fuel, run injectors into bottles, maybe replace fuel filter again, run more tectron.. Wouldn't want to mess up your newly refurbished dizzy with bad fuel..
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80 Turbo - Slightly Modified

maybeoneday · Posted: Sun Jul 05, 2015 9:56 pm Post subject:

CO/ARF base settings have not been touched I just installed it and when it stumbled and almost started I figured that they were probably close. After a bit of heavy cranking to blow a few things out it started when I was not really expecting it to (I had not touched the dizzy either except for initially getting it to somewhere close) I ran it for a while (5 or so min) then turned it off. So I will do that base adjustment on the fuel dizzy as described in the morning. Cone patterns are nice and all injectors are metering the same (did this test a few times before and after the fuel distributor replacement). I had run some fuel through the lines before I even attempted to start it the first time. Again I will add some techron and do this again and replace the fuel filter.

I had to make a CSI tester because I was absolutely stumped with the CIS and why it was not starting, the tester sort of allowed me to diagnose a stuck fuel dizzy hence the replacement.

I will do the things suggested and get back to you with my results. What is the best way to jump the fuel pump? I was thinking that I would probably jump it in the fuse box where the relay goes but this was only my thought after reading your suggestion.

Also please explain the non return valve, I have an idea of how the accumulator works (or in my case the 2 accumulators) but am not too sure what you are identifying as the non return valve (could be that I know it by a different name or maybe I just dont know it, as this CIS system has passed a few new things my way). With the accumulators do both have to be done? why are there 2 and not just one bigger one? and can you replace the 2 with 1 or is that not a good idea or a PITA?
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1977 924 NA Auto

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

maybeoneday · Posted: Mon Jul 06, 2015 10:39 pm Post subject:

OK, did that base setting I think, it was a little harder than I expected because it was quite hard to tell when they started to spray, because when they did they only did so a tiny bit. So what I did was hold one up to a piece of paper and when the paper started to get wet I stopped and backed it off until the paper was no longer getting wet. I thought that they would start to spray with a little more force for some reason, however when I thought about it I figured that they probably didnt need to.

2 things to note here, the first is that every time I jumped the fuel pump I got a really strong initial burst that made all injectors spray a little for a split second before quitting. Note that the injectors are new, and it was only a very quick light burst, but it still made me wonder if that should be happening. The second thing to note is that the CSV appears to function as it should. I pulled it too to recheck all the spray patterns (which were nice) and tested it with the fuel pump relay in whilst cranking cold and it sprayed.

The base setting was a little further out than I expected maybe a 1/2 to a full turn on the adjustment screw. Does it start?? well that is the big question, not sure as the battery was flat after I did my jumping (and from all the cranking the other day) so I put it on to charge and we will see soon.

Fuel drained, new fuel, new filter, techron, fuel system flushed for 30 or so secs, also done.
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1977 924 NA Auto

maybeoneday · Posted: Tue Jul 07, 2015 11:48 am Post subject:

No it wont go. I will try the valve clearances again cold, and replace the plugs, but besides that I am at a loss. timing is on (It ran so it has to be at least in the ball park) so it has to be fuel or spark??.
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1977 924 NA Auto

maybeoneday · Posted: Wed Jul 08, 2015 3:36 am Post subject:

Wow, lesson learnt today, NEVER TRUST PO's WORK OR WHAT THEY TELL YOU.

So after getting the car started and not being able to again, and after exploring the base mixture settings, double checking the engine and ignition timing base settings, cold valve clearances, and changing out grounds and vac lines, I decided I should check into a few of the things I was told were good by the PO.

However first, I did redo the base mixture setting a different way, as I found it difficult to tell when the injectors started to spray. Solution to this was to use a slightly different technique as described in the Porsche Service Manual.

For those interested (it may give you another way if like me the one previously described provided you with a little uncertainty):

Remove the banjo bolt of one of the fuel lines on the distributor that runs to an injector.

Lean up the mixture setting by turning the 3mm allen screw CCW

Jump the pump between 30 and 87

with the plate at rest turn the allen screw CW untill you get fuel coming out of the open hole where the banjo went.

When you get fuel stop and turn back the allen screw 1/2 a turn CCW.

Done.

Still no start, so next step I figured was checking the plugs (I thought this would give me some indication of where my issues may lie also). When I pulled plug 1 wow was it fouled. As they were new plugs (according to the PO) that were put in after the head job, I decided to attempt a clean, so I started to pull them all. When I got to cylinder 4 (or is that 3, I guess it depends on how you look at it, but the second one from the back anyway) I found a plug cross threaded in the head. It was obvious it had not been forced too much as it was also not fully screwed down and was only about 3/4 of the way in, but starting and running the car (I assume) had ensured that it was well and truly f'ed. Needless to say it was a PITA to get it out but I managed to carefully, and after flashes of having to pull the head and get the plug hole re threaded, I managed to get the thread cleaned up enough to get a new plug to screw in fully by hand without it sticking at any point (the old plug was well and truly f'ed with its thread distorted and bits of the old head thread stuck in it). This did explain somethign else I had noticed which was the noise of air escaping from the spark plug area when I rotated the engine by hand to double check the timing. I had figured that if I was pulling the plugs I would probably find the cause, and that I did.

So tomorrow morning off to get 4 new plugs and we will see if it starts then. I was guessing that the air leak from the cross threaded plug combined with dodgy base mixture settings could also explain the rich running and overly fouled plugs (?? maybe, still not 100% sure I understand this CIS thing).

At this point I have to assume 1 of 2 things happened. either the PO put the plug in by hand and something made it feel like it was all the way in when it was not, from there starting the car f'ed it, or it was forced by the PO cross threaded as far as it could be without feeling too dramatic at which point he assumed that it was fully in. Anyway, lesson two for the day the angle of those plugs in the 924 makes the plug tool they gave with the car a really great thing to use to avoid cross threading, just make sure you get the plug all the way in by hand before you start the thing or you will f it anyway.

Should be going soon I will keep you updated, thanks for the help to date it has been great. I am sure I will need some more before this car is done.
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1977 924 NA Auto

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

maybeoneday · Posted: Mon Jul 13, 2015 5:10 pm Post subject:

OK she seems to start fairly regularly now. I did a few more minor adjustments including readjusting the valve clearances (a few were a turn or so out) but nothing major. The biggest thing I did was unplug the CSV and now she seems to start most times. However she is still running like a dog rough as hell and really lumpy, I take it that I will need to get the AFR a little better (but how?) and I probably need to sort a few other things out too. Couldnt get her running much better with just the ignition timing but got it as good as I could for now. What is the best approach as far as order of things to do from here to get her running a little better.

Probably the biggest thing is how do I get the AFR a little tighter. I assume that I need to ensure the system pressure, control pressure and pump volume are all correct (which I can do with the CIS tester I made up, and measuring flask?) then I need to turn that screw in conjunction with the idle speed screw to get it running as best as I can (would this be correct? maybe? sorry still getting my head around the whole CIS thing)
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1977 924 NA Auto

maybeoneday · Posted: Sun Jul 26, 2015 8:21 pm Post subject:

OK so I got my CIS gauge hooked up and checked the system pressure it was 4.8 Bar or about 70 PSI this seems ok. When I opened the valve to get cold control pressure it was 4.8 Bar or 70 PSI, ok not good and probably means I have a blockage in the WRU or one of its lines... right?

My problem with this is that I thought I was having issues with an overly rich condition from the fouling of my plugs and was expecting a low cold control pressure but in fact it appears that I have a high control pressure which would suggest lean running, Then why are my plugs really sooty when I pull them after I have been running it. Failing to understand, usually at these times it is just best to do what your gauges tell you and fix the WUR and then see where you are at but was interested in any opinions on this.

Also seem to be holding pressure ok pressure after 10min is about 1.2 Bar with it dropping to about 1 Bar after 25 min and 0.9 after 20-30 min.
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1977 924 NA Auto

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

from the Porsche 924 Technical Specifications Booklet

1976-1984 Porsche 924 NA Fuel System Specifications
(all markets except as noted below)
Electric fuel pump Delivery rate: Min. 750 cm3/30 s
System pressure test value: 4.5...5.2 bar
Adjust, value: 4.7...4.9 bar
Control pressure cold (approx. 20° C): 1.3...1.7 bar
Control pressure warm: 3.4...3.8 bar
Leak test
Min. pressure after 10 min.: 1.7 bar
Min. pressure after 20 min.: 1.5 bar
Opening pressure of inject valves: 2.5...3.6 bar

1980-1982 US, Canada, Japan 924 NA
All the same as above EXCEPT for:
Control pressure cold (approx. 20° C): 1.7...2.1 bar

Credit to ideola..
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80 Turbo - Slightly Modified

maybeoneday · Posted: Mon Jul 27, 2015 12:27 pm Post subject:

OK WUR rebuilt, yes this was a problem, absolutely horrible inside. Now I have the cold control pressure slightly high but close enough for now, about 1.7 bar at 18 ish degrees. But with the valve open on the CIS tester I now loose all pressure almost instantly after the pump stops. CIS Drives me crazy, but to tell you the truth its one of those puzzles that drives your crazy but you keep coming back for more because you really like being driven crazy.

I will Post some pics of the WUR rebuild when I get a chance.
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1977 924 NA Auto

maybeoneday · Posted: Mon Jul 27, 2015 2:53 pm Post subject:

cleaned valve in fuel dist and replaced o ring no change on open valve leak down test.
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1977 924 NA Auto

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

It's still your WUR..

The full pdf is here but it won't load right now... I downloaded it a while back just incase such a thing were to occur..
http://www.ferrari400parts.com/Warmupregulatorrepair.php

Was there rust on your valve body surfaces? Your WUR may be just shot if it was that bad..

You should try to put the best side of the steel diaphragm toward the top, away from the spring.. Maybe I should have said flip it depending on its condition on either side..

Your warm control pressure is the one you need to worry about, that's what your engine runs on for the most part.. Cold control pressure is just for starting up..

If your car proves hard to start hot with no residual pressure you can jump the pump before you start it to help it out, maybe also move the air metering plate a tad to give your cylinders a shot of fuel, barely squeak the injectors..
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80 Turbo - Slightly Modified