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Hi Folks,
I finally wrapped up the mechanical part of my "71 142E refurbishing project, which included an M41 for BW35 swap and a valve and ring job. (Well, I also accomplished a bit of painting, patching, and modest beautification on the out and inside.) When I turned the key this morning it actually started, but it idled at around 2500 rpm and, when I backed off on the throttle cable and the throttle stop screw to get the idle down to where I could adjust the timing, it went into a surge mode. I haven't touched the idle adjustment screw yet since the whole FI setup worked perfectly before I started this project. I did replace the frayed throttle cable, the airfilter, the injector seals, and any hoses that looked suspicious; and I cleaned the throttle plate and its surroundings with carb cleaner. Before I start seriously to hunt for the cause of this problem; aside from the traditional vacuum leaks (Yes, Peter, I know, it's really air leaking into where there should be a vacuum.), does anyone have any suggestions where the best place is to start. BTW, could a bad brake booster enter into the equation? My brake failure light and buzzer came on, but that probably means that I need to do some more bleeding -- I hope.
Bob S.
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posted by
someone claiming to be Ira Eisenberg
on
Thu Apr 15 10:06 CST 2004 [ RELATED]
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Couldnt this also be caused by a clogged fuel filter either inside or outside the gas tank or a fuel pump which isnt keeping the pressure up.
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Double check the ignition timing. It might require different tuning now that the mechanical is rebuilt.
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In addition try temporarily disconnecting the vaccum line to the distributor to see if that helps quell the surging.
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A bad booster could contribute to it but that is probably more air coming
in than a booster would account for. Is your Aux Air Valve good? I've now
checked 3 and not found one that works ANY. They are all paralyzed in the
open position. I'm planning to use a K-jet electric one, I think. You might
try plugging the hose to it and see if that gets the idle down.
When I got the yellow peril it had a spark plug insulator crammed into the
hose that was supposed to go to the AAV.
Yes it undoubtedly IS a vacuum leak of some kind - your vacuum makes the
idle slow and when it leaks out the idle becomes fast.
Sort of like keeping the darkroom door closed so the dark doesn't leak out.
--
George Downs, Bartlesville, Oklahoma, Central US
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Yup, George, looks like that's where the problem hangs out. I plugged the hose to the auxiliary air valve and the revs dropped to about 900 rpm. After the engine got up to temperature, I reconnected the hose to the a.a.v. and the surging started again. Guess I'll have to go hunting for another a.a.v. It's annoying, though, that the thing should have gone on the blink sitting in a plastic bag while I did the engine work. It gave me no grief before.
John, the vacuum retard hose is disconnected and its nipple on the manifold is plugged. I was already running the thing that way before.
Michael, there is an issue with the timing. It's running way advanced, but I haven't been able to retard further because the vacuum regulator sits jammed up against the block. Something definitely wrong there, but I figured I'd deal with one problem at a time. A multi front attack may, however, be needed.
Thanks all,
Bob S.
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You don't actually need the auxiliary air valve, other than when starting the car from cold. I ran a 145 for years with one plugged with epoxy resin, the car just behaves a bit awkwardly for a couple of minutes in the morning.
As you are no doubt aware the idle is set by the screw under the manifold, not with the throttle cable. If you have disturbed the throttle cable, make sure the static setting on the throttle switch is where it is supposed to be.
Regards
Pete
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I have yet to be convinced that there is a truly functional D-jet AAV in
existence. (If someone would like to send me one to prove me wrong, I'll
gladly accept it.) I think going with the electric one for the K-jet might
work out pretty well-might have to put a washer into the hose or something
if it opens too wide.
Distributor: Turn it 90° and then put the spark plug wiress back 90° and
you've got another bite.
--
George Downs, Bartlesville, Oklahoma, Central US
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George,
I assume that adapting the electric AAV from the K-jet would involve tapping into the intake manifold at some place. Are you actually contemplating going this route? If so, I'd sure like to hear how you make out with it. I was just checking on the price of a new one of the D-jet type; $389 tends to give me a lot of thought. If used ones are as likely to be as faulty as you say, have you given any thought to installing some sort of valve after the AAV, be it electrically, thermostatically(?) or manually controlled ? Perhaps, route the hose through the firewall with a manual valve under the dash that you open when you start the car and close when the engine is warmed up?
Anyway, after I shifted the distributor -- I jumped a notch with the dizzy drive before I read your easier 90 degree solution -- and adjusted the timing to about 12 btdc, I got rid of the surging and fiddled with the idle adjustment screw a bit (which I found to be totally closed). Now it idles at 900 rpm with a clamp on the AAV hose and at 1500 with the clamp off. So, no doubt, a faulty valve. So, till I find a better solution I, drive the thing with the AAV blocked off.
Bob S.
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Already got hose connections for the one that doesn't work.
I'll just run hoses to the electric one instead.
The hard thing will be deciding where to mount the cotton-picker
and running the hoses to it.
And - There is more than one way to skin a distributor!
Sort of like the tech rep told me when installing a computer
on a tensile testing machine - "You can get it to make any
calculation you want but sometimes you gotta lie to it."
--
George Downs, Bartlesville, Oklahoma, Central US
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I'm lucky - the AAV on my 1800E is stuck CLOSED!
The 90 degrees/rotate the wires is a great idea. The only other alternative is to pull the distributor, remove the drive gear, turn it a tooth or two in the desired direction, then reinsert and hassle with getting it seated fully into the oil pump drive again. All of which makes the wire rotation sound better and better.
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And having the AAV stuck closed has no serious detrimental effect on engine behavior? If so, I could just leave the hose plugged. (?)
Bob S.
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Hi Bob,
The AAV just provides fast idle until the coolant starts to warm up. It'll start just as well without it -- you'll just have to keep it running with the gas pedal for a minute or two before it'll idle on its own.
Rotating the wires on the cap is fine, but if you do decide to pull the drive gear and set it over a tooth or two, all you need to do is turn the motor by hand while applying *slight* downward pressure on the gear so you can feel it line up with the slot in the oil pump.
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