Mercedes 380SE idle PW setting it too low 1.9ms

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harlz
MegaSquirt Newbie
Posts: 8
Joined: Wed Sep 02, 2009 11:16 pm

Mercedes 380SE idle PW setting it too low 1.9ms

Post by harlz »

Mercedes-Benz 380SE
3.8L v8
MSII latest version
Wideband LC-1
remanufactured flow-matched ford 19lb injectors

Hi, I'm having idle setup dramas, I have the car set up for 4 squirts/cycle but i've had to set the injector opening time to 1.2 seconds to get a good idle. The idle is quite bad as well. I'm sure this is making up for a bad setting somwhere else, but not sure what. I noticed that the idle pulsewith is only 1.6-1.8ms, which I believe should be over 2 for proper tuning. When I set it to 2 squirts/ cycle the engine coughs and splutters and dies after about 10 seconds. If I have the car in gear and brakes on, with a little throttle, the engine seems to run fine.

How to increase the idle pulsewith?

-Thanks!
Bernard Fife
Master Squirter
Posts: 475
Joined: Thu Oct 29, 2009 12:54 pm

Re: Mercedes 380SE idle PW setting it too low 1.9ms

Post by Bernard Fife »

harlz,

MS-II does not have as serious issues with low idle as MS-I does. 1.6 to 1.8 milliseconds is not too low, in general.

However, to increase the idle pulse width you need to decrease the number of squirts. The standard recommendation is for 2 squirts alternating. You will have to retune the VE table to get a decent idle if you do that, there are instructions here: http://www.megamanual.com/ms2/tune.htm#ve But first set your injector open time to 1.0 then never change it again (unless you have a good reason to and some empirical evidence to back it up) - every time you change this to something else you have to retune the VE table (especially at low pulse widths). So go back to a reasonable opening time, and tune idle using the VE table instead.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it.” - George Bernard Shaw
harlz
MegaSquirt Newbie
Posts: 8
Joined: Wed Sep 02, 2009 11:16 pm

Re: Mercedes 380SE idle PW setting it too low 1.9ms

Post by harlz »

Ok, I'll give that a shot, thanks.
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