"Akio Ohtori - RIP Oppo" (akioohtori)
03/20/2019 at 14:32 • Filed to: project golf ball
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"Akio Ohtori - RIP Oppo" (akioohtori)
03/20/2019 at 14:32 • Filed to: project golf ball | 2
| 11 |
Pre-Cars and Coffee bath THE COLORS!
Seriously. I took the Honda out last night to try and figure out why the fuel starvation issue suddenly came back when I adjusted the timing. After removing the carb, adjusting the float, changing the air filter, and reorienting the carb the problem should have gone away.
But it hadn’t.
So I, I think quite reasonably, decided to put the timing back where it was before I adjust the timing. Not hard, I’d made a mark so I could do just that.
Ok... now it is idling like shit, but driving fine.
Makes sense, I guess, iirc I had to pull the idle way down when I adjusted the timing the first time. So I start cranking it up an irresponsible amount and it is still idling like shit.
Ok... lets just put it back to factory timing because this is weird and hasn’t gone well.
Still idling like shit.
At this point I feel like I’ve entered the Twilight Zone. No adjustment of the idle screw is helping, even though the mix had previously worked with both timings. Out of desperation I tweak the idle mix and suddenly the engine is happy as a clam, running a much leaner mix than before, and gained about 1000 rpm of idle... which it a different problem entirely. Also the idle is now hunting slightly.
Does any of that make sense? No.
If I’d somehow introduced a vacuum leak that would make it want to run rich, not lean. Or, rather, I would expect to need to richen up the mix, not lean it out.
Oh... and the distributor is no longer in the same spot as it was the last time I’d adjusted it.
And it still has the fuel starvation issue.
I know I’ll get this eventually and hopefully I’ll have learned something, but right now it feels like everything I do makes this car worse. Woe is me, woe is me, bellyache, bellyache, etc etc...
Alright... now that we have my sad sackness out of the way...
Time to throw parts at the problem.
If I were guessing, I’d say the two problems are unrelated. This new timing/ mix issue could be a lot of things, but my focus is on the ignition system. The fuel starvation, however, it probably all in fuel delivery.
The obvious thing I need to do is check fuel pressure and flow. There is no reason I am avoiding this, I just am. That will be tonight’s project. Depending on the outcome of that I’ll look into either adding an electric fuel pump, external fuel pressure regulator, or both.
I also just found out this car has a condenser, which is a surprise considering it has an electronic ignition. Either way, that was missed when I was doing the tune up. For $20 that seems like cheap peace of mind, though, again, not certain what the point of it is.
Related, this could be a bad or failing ignition module. Similarly cheap, I have one of those on order too. Throw in a new reluctor and that should be a pretty good refresh for the dizzy. Shaft play was in tolerance and the vacuum advance was working when I checked, so I’m going to pretend all is well there, for now. New complete assemblies are available for about $200 if it comes to that.
For good measure I’m also going to check valve clearances again. It has been ticking a bit lately and if one of the lock nuts worked its way loose, that could cause all sorts of problems.
I will get this, but I’ll be damned if I’m going to be happy doing it.
Grindintosecond
> Akio Ohtori - RIP Oppo
03/20/2019 at 15:13 |
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I had a bad fuel delivery issue with a 79 Volvo whilst at University (oops, I spoke english). A mechanic just sprayed a can of ether in the vicinity of the engine and the idle speed bogged down meaning I had air getting in somewhere else , anywhere, not he intake. It ran fine above 4,000 RPM and HOW! So it was richer everywhere until it could clear itself and really use the fuel it was getting. The K-jet was borked. It was eighteen year ol d gaskets all splitting and shrinking around all the injection system fittings.
Volvo itself charged $1500 and it was awesome after that but holy shit had I just known all it needed was a complete fuel injection disassembly and rebuild, I still would have had them do it for money=time purposes. Plus I had no idea how do do that.
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Akio Ohtori - RIP Oppo
> Grindintosecond
03/20/2019 at 15:17 |
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My Saab has K-Jet and I would gladly pay someone $1500 to make its problems go away haha.
RacinBob
> Akio Ohtori - RIP Oppo
03/20/2019 at 15:37 |
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OK - As I understand it, you leaned the idle jets and gained 1000 rpm and it runs great but it is hunting at idle. First I would confirm your timing is right. Perhaps the idle is so fast you are getting into mechanical advance? Personally, I ran Hondas of the 80's about 6 degrees advanced of stock. Where is yours set?
Also, maybe the idle is too lean, and the hunting is it is outrunning it’s fuel supply, richen it back by a third and see what you get?
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Akio Ohtori - RIP Oppo
> RacinBob
03/20/2019 at 15:57 |
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That all sounds reasonable, yes. Mainly I think I’d cranked on my idle screw so much it was way too far in. My advance is either set at 15 or 20 degrees... it isn’t clear which. I have an el cheapo timing light, so I only have the marks on the crank to go off of and I’m centered on that. Given this is a California car, if it retains the original crank that would put it at 15 degrees, though the spec for non-CA cars is 20. I’ll play around with it after some of the parts come in.
Related: My vacuum advance has two vacuum ports and I can’t find any documentation about why . Do you happen to know? One of them is blocked off presently.
Sovande
> Akio Ohtori - RIP Oppo
03/20/2019 at 16:16 |
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I would guess you have a vacuum leak someplace. My next suggestion would be to set timing at stock and tune the idle with a vacuum gauge. You are looking for the highest vacuum you can get at idle. Once you have that dialed in, proceed to changing the timing. When you add timing you will obviously need to adjust the idle .
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Akio Ohtori - RIP Oppo
> Sovande
03/20/2019 at 16:20 |
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I hadn’t heard of that method! Interesting. Worth a shot.
Part of me also thinks it is a vacuum leak, but I did a smoke test and didn’t find anything. I guess I can try the carb cleaner technique next.
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Sovande
> Akio Ohtori - RIP Oppo
03/20/2019 at 17:48 |
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The carb cleaner should give you an idea. The vacuum gauge is how I tune the idle on my carbed cars. And I’m up to three of them now, so I’m getting good! I’ve found it helpful to have a baseline (2 turns out from fully seated or something like that) so you have a reference point every time you make changes. Does the weber have two idle mix screws? Making sure those are pretty close to even to start out will help too.
What year is the car? I want to read up now.
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RacinBob
> Akio Ohtori - RIP Oppo
03/20/2019 at 19:36 |
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I think what happens is you lean it up so much that to idle it is idling off of the main jets which aren’t so stable. T he reason we have idle jets is to get a stable set of fuel flow at idle speed.
So richen up the idle and see if you can find a happy medium.
As for timing advance, I think the theory is this.
1. You have mechanical advance so that at low RPM timing is retarded making starting easier. As speed increases, timing is advanced allowing better performance and economy.
2. You have vacuum advance to allow timing advance at idle to improve idle once the engine starts. This advance goes away under low vacuum because load. See t he below https://www.carparts.com/classroom/ignition.htm
!!! UNKNOWN CONTENT TYPE !!!
You may want to experiment with enabling or disabling vacuum advance. In some cases the advance strategy was taking away advance at load to avoid NOx emissions. We generally disabled timing advance when we ran race cars, you may find it runs better without it.
One other point, make sure you set the timing without vacuum advance hooked up.
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Akio Ohtori - RIP Oppo
> RacinBob
03/20/2019 at 21:35 |
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Interesting stuff. I have been wondering if I should be using manifold vacuum or ported vacuum for my advance. That would certainly make things... weird... if I was using the wrong source. (Currently using the ported vacuum off the carb designated for vacuum advance mechanisms)
I ran a bunch of tests today, but only found one real problem: The bowl was leaking! I didn’t get the nuts tight enough when I put everything back together and had a small leak into the carb. Oops.
Still idling like garbage, even with everything set where I think it needs to be. Beginning to suspect something in the ignition system (fouled plugs, bad ignition module, bad condenser, etc). I disconnected the condenser and it make no different to how the car ran which is... worrying. Also not sure why this car even has a condenser ...
Back to the books I suppose.
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Akio Ohtori - RIP Oppo
> Sovande
03/20/2019 at 21:44 |
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Carb cleaner was a negative and the manifold vacuum seems excellent. Manifold vacuum holds just over 20 inHg, which is basically perfect (spec is between 17 and 22). I did use the vacuum method to tune and it was pretty helpful.
1986 Civic 1.5L, but the Weber 32/36 DGEV is aftermarket. It came with a CA spec “feedback carb” which had about 16 miles of vacuum hose and two vacuum computers. PO removed it and there was a 0% chance of getting it back together.
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Sovande
> Akio Ohtori - RIP Oppo
03/21/2019 at 05:55 |
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My Nissan had a feedback carb... It had 19 feet of emissions hoses before I put the Weber on.
I'm at a loss for ideas. I do have to inspect 258 apartment units today which will give me plenty of time to think, so if I come up with any dumb ideas I'll chime back in.