The 2 knock sensors should change the spark timing but I would think it would change both firing times. It sounds like both plugs on the same cylinder should fire at the same time.
AND you might need two timing lights to see if you can watch both #1 spark plugs firing at the same time. Are the sparks timed by a Engine Speed Sensor and not a distributor?
Does this 1991 allow you to hook up any device/scanner to it's DME computer?
Keep us in the loop! good luck! Oh and better you than me!
that's the design. The main part has a hall sensor in it, and the side (slave) unit doesn't have anything but the rotor and mechanical advance parts in it. It is driven by a belt inside the distributor body. Older models suffered from belt deterioration due to the ozone rich air inside the distributor (from sparks), and later models had an air hose blowing fresh air through the distributor body to vent the ozone out and prolong the life of the belt. My belt is fine and it's vented. Also the wiring plug is attached to the side on the main unit, on the picture you linked I don't see a place for one so it may be a slightly different distributor model.
I am not sure if they fire simultaneously or if they are spaced apart just slightly, or variable separation controlled by the ECU/DME. Doesn't matter much in this case. They'd still fire on the same stroke.
Distributor has no adjustment. So it's gotta be ECU controlled. Distributors both have mechanical advance.
Yes, we have a Bosch "hammer" scanner that should be ideal for this. Initially it had two trouble codes, Hall sensor and knock sensor related errors. I replaced the whole distributor to test another Hall, no change. I don't yet know how to test or eliminate the knock sensors, they are a real bitch to get to. One for each side of the engine. I can disconnect their connector from the harness and measure whatever I can from the pins though. Just don't know what I'm looking for.
Will do
LOL
Jan
Checked it, they are still in sync
Jan
Erik Dillenkofer wrote:
Some Knock Sensors can be tested by checking the total ign. advance, some by tapping on the side of the engine with a hammer, others possibly with some other testing device.
I think that there are tests for the knock sensor functioning, but not sure of how they are performed. It is only mentioned here, but it may be for models after 1996 (R134a mentioned). Also mentions: Ignition system (normally aspirated models): Check function of #1 and #2 ignition circuits.
good luck, sounds interesting!
Solved.
It was a bad coil.
OK HOW did you finally diagnose it? You tell us the WHOLE story in DETAIL but what a small punchline!
GIVE US THE ENDING PLEASE and don't leave us hanging! lol
Did you switch wiring from one coil to the other? WHAT?
The owner had told us he replaced the coils recently, so they were pretty much last on the list of suspect parts. But they were on the list, and as I kept replacing parts with known good ones, one by one, I eventually replaced the coil that was causing the engine to not run, with a coil from a running car. All a step-by-step process of elimination, so I don't need to order new parts on a 'hunch'. I had put off coil replacement also because they are a little hard to get to. :D
I'm glad I had a temporary donor car next to this one that had an identical engine and ignition system.
Jan
So, did you make him an offer on the car when you where done?
J.
Thanks for the whole story since I was wondering if you just switch coils or not. ;-) An abundance of spare "known good" parts is always great to have for diagnosing a difficult problem. ;-)
Do you normally handle Porsches?
Have a safe and enjoyable Turkey Day!
LOL no :) Too broke to make an offer on anything. Besides.. my next goal is to get my convertible 68 here from Finland. That's the cheapest way to get a fun, fast, ready to drive car!
Jan
I recently started working for a company that does only Porsches. Mostly aircooled, but also watercooled if those happen to roll in.
We do a lot of old 356 Porsche work too.
It's a restoration, repair, maintenance and race shop. We do racing, customer race car support at races, race car building and tuning, driver's education, etc... on top of all normal work for street driven cars.
Jan
Good on you! Finished with Fireslow then?
No IT jobs your ways now? Guess it is slow all over..
J.
Whereabouts are you? I am trying to talk my buddy into selling some of his Porsche cars and parts. He does not drive them and I think he could use the $$$$. I told him to sell his 356 Convertible D first and use that "seed" money to restore the rest of them, 356A?, 356C, notchback and a few 911s and 912s. He might have heard me but I will have to see. He is also talking about trading one of the 912s for a Targa.
Does your shop do full restorations? Does it have that rotisserie? I want one that can take the 356s AND the Beetles. ;-)
A good friend of mine are looking to buy a 356 here in Norway, preferebly a Speedster, but they are expensiiiive, so anything Cabrio in good original condition. That means no rust and no hack American restoration work, seen to much of that.. That is one thing you Yanks have in common with the Brits..
If he has something solid and would like to sell, feel free to e-mail me at Bergraceattgetmaildotno .
Thanx Jørn B.
Firestone days are over, yea :)
No IT jobs to even apply for. Although, yesterday I got a phonecall from a recruiter who said he has a 6 month contract to offer, and if the business is there after that, they could change it to permanent hire. I'll have to look into that.. it's the first one in who knows how many months.
Jan
So far I have seen only one almost full resto, it is being delivered soon. A 911 turbo wide body. Engine, transmission, exterior, interior all done by us, although we used partner shops for paint and some interior stuff. Mechanical stuff stays in-house. Haven't seen a rotisserie around the shop :)
We are in Orlando
Jan
I'll ask if he has any leads. One of our customers has 6 356's. And two dozen other vehicles, many of them Porsches :)
Jan
Ok Orlando is doable. ;-) Chicago creates rust, but I will assume that you find vehicles with little to no rust down your way which is why you don't need a rotisserie. lol
I will have to check you all out when I come that way again. ;-)
thanks and have a good Turkey Day!
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