Guest Vinnchan Posted October 27, 2006 Share Posted October 27, 2006 When I park the car I keep my foot on the clutch and the car in gear (usually 2nd) and my foot on the brake as well. When I turn the key to stop the car the whole car starts vibrating REALLY badly and I can hear the engine cranking still. It would make sense if it was for a half a second or so but this goes on up to 7 seconds after I turn the key. I've tried turning the key only one click (sorry I don't know the technical term) and I've also tried taking my foot off of the clutch and putting the car in neutral when I turn it off. It doesn't happen every time I turn the car off, but it's happening about 1/5 of the time. I tried taking my foot off the clutch quickly while it was still in gear one time and that stopped it fast enough, but I don't want to have to do something like that every time I park. My Z is a '71 240z with an L26 and matching transmission. I've had my Z for about 3 weeks now and this problem has shown up in the last week or so. It runs fine, handles fine and seems to be in generally good shape except for this problem. Any advice on what it might be? I'm not too experienced as a mechanic but the whole point of having a Z is learning to take care of it myself. At least that's the idea. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 27, 2006 Share Posted October 27, 2006 It's called deisling. You have carbon build up in the cylinders that gets hot and ignites the gas with no spark. The engine runs like a deisel for awhile. That was pretty common on cars back in the 70's when there were still alot of high compression, carburated 60's cars and the low octane gas of the 70's. Back then we were always too poor to do anything about it so we would just leave the car in gear when we turned it off. I seem to remember flooring the gas pedal worked sometimes also. Or was it putting on the choke? Out other solutions was to "blow the carbon out". In other words get out on the freeway and open it up. Don't know if that ever worked but was alway fun trying. Switch to premium gas for a tank or two and see if this helps. The ultimate solution is to cut off the fuel flow to the engine when the ignition is off. Fuel injected cars do that by design. My old Ford Fiesta had a Weber carb with a cut out solenoid in the idle circuit that did the same thing. Neither solution is much of an option for you. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted October 27, 2006 Share Posted October 27, 2006 Excessive advance will also cause this (like a stuck vacuum advance plate). Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted October 27, 2006 Share Posted October 27, 2006 Out other solutions was to "blow the carbon out". In other words get out on the freeway and open it up. Don't know if that ever worked but was alway fun trying. The other thing I remember doing was dumping something down the carb as you revved it. Carb cleaner, or maybe seafoam? I don't recall Automatic tranny fluid? no maybe that was to unstick a sticky lifter. Anyhow, what Pop describes is the issue at hand, maybe premium (which usually contains cleaner agents) or dump a bottle of fuel injector cleaner in the tank and run hard. Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted October 27, 2006 Share Posted October 27, 2006 It may or may not be deisling but I would definately start by running some seafoam. It won't hurt anything and will definately clean your fuel system/cylinder head. I wouldn't waste your money on Premium as it will not fix anything, although it may disguise the problem. I wish people understood a little bit more about gas composition and octane ratings. I see way too many people running premium/race gas for no reason or thinking it's going to give them more power. lol. (Sorry for the rant) Quote Link to comment Share on other sites More sharing options...
Guest Vinnchan Posted October 27, 2006 Share Posted October 27, 2006 Thanks for the help everyone. I'll try this tonight after work. I hope one day I can also give advice to the brotherhood of Zs. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 27, 2006 Share Posted October 27, 2006 It may or may not be deisling but I would definately start by running some seafoam. It won't hurt anything and will definately clean your fuel system/cylinder head. I wouldn't waste your money on Premium as it will not fix anything, although it may disguise the problem. I wish people understood a little bit more about gas composition and octane ratings. I see way too many people running premium/race gas for no reason or thinking it's going to give them more power. lol. (Sorry for the rant) Well then please enlighten me. Higher octane gas isn't more resistant to detonation? Running premium won't stop the deiseling as long as he is using it? Who said anything about more power? He just wants to stop the car from running when he turns off the key. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted October 28, 2006 Share Posted October 28, 2006 I hope one day I can also give advice to the brotherhood of Zs. You will you will, it's a great site. 71 nice nice sweetleaf: I run premium all the time, that clear stuff. why? because it's more highly refined so less varnish build up in my injectors and it contains cleaning agents, which keep my injector cleaner. And they're brand new injectors. I may not be a chemist but I know that much about it. Yeah it's more expensive but this is my Z we're talking about, money be damned. That's about all I need to know about gas. Pop... easy... down boy down... kidding Quote Link to comment Share on other sites More sharing options...
wonderllama Posted October 28, 2006 Share Posted October 28, 2006 pop is 100% correct, if carbon build-up is indeed causing a higher compression in the combustion chamber, then higher octane fuel will cease the excess detonation. that said, anyone using premium fuel for no reason is pretty much throwing money away. of course, if it makes people feel better, more power to them. Quote Link to comment Share on other sites More sharing options...
bjhines Posted October 28, 2006 Share Posted October 28, 2006 ok.. I have been driving 240Zs since the late 1980s... I have run cars with good stock engines, bad stock engines, good performance engines, and half broken performance engines... Weber DGVs, DCOEs, SUs, Solex's.... They all had ONE THING IN COMMON.... >>>>>>>>>>>>>If you put low octane gas in them you will have to shoot it to kill it... You guys with L28s and low compression don't count... The L24 engines NEED HIGH OCTANE GAS... unless you want it to keep running wiht the ignition OFF... forget about power, forget about WOT detonation... high octane gas makes them behave very nicely when you turn off the ignition... Ignition timing has absolutely nothing to do with the dieseling problem... the ignition is OFF... what difference does it make... No power no ignition no relation to dieseling... I have caught gas stations in my town trying to pass off regular as premium... I know for a fact that there is a problem with the gas because it wont shut off when I turn it off... I made one station owner refund my purchase and pay to have the bad gas drained(of course I didn't actually drain it)... I took it up with my better business bureau and they really came through for me... Quote Link to comment Share on other sites More sharing options...
ORANGEZ Posted October 10, 2008 Share Posted October 10, 2008 So has anyone used Seafoam and has it stopped the dieseling? Quote Link to comment Share on other sites More sharing options...
woldson Posted October 10, 2008 Share Posted October 10, 2008 Old Thread. Quote Link to comment Share on other sites More sharing options...
ORANGEZ Posted October 16, 2008 Share Posted October 16, 2008 So i tried Seafoaming and the damn thing still diesels. Quote Link to comment Share on other sites More sharing options...
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