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#1
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Adjusting Fuel Mixture (Problem with checking idle duty cycle)
Hey everyone,
I have, for a few days anyway, an Aglient oscilloscope, so i thought I would look at my fuel mixture on my m103. Turns out it was not right. I'll post up the measurements later, I was pretty close to getting it to spec when I lost any reading @ idle after 30 second from start... My scope shows nothing but noise.. When you rev the engine to ~1000rpm, I hear a vacuum valve pop open/closed (seems to be connected to a pot of some sort behind the headlamp and the intake manifold) and the waveform comes back to life. I checked the o2 sensor and its fine. fluctuating voltages. Anyone have any clue as to why i would get no duty cycle reading from the x11 (pin2 +,pin3 -) port @ idle? Thanks, Kris
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k Last edited by JamesDean; 03-18-2009 at 02:21 AM. |
#2
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Your '93 has to be put into 'Diagnostic Mode' to read duty cycle.
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![]() 1993 190E 2.3 2001 SLK230 1971 LS5 (454) Corvette Convertible |
#3
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really? it was reading duty cycle fine up until that point...how does one enter it into diag mode? i over adjusted lambda took it up to my shop they corrected it for me... havent had a chance to look at it w scope yet..
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#4
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From the manual:
"@1988 California and @1991 with diagnostic trouble code storage: The CFI control module must be switched over to output of on/off ratio because the signal for the diagnostic trouble code (DTC) display is output as priority. The output of the on/off ratio is performed once all the DTCs have been read out and the start button of the impulse counter scan tool or the non-locking switch on the diagnostic connector (California version only) is then once again pressed (see section m). The % readout now fluctuates when the engine is running at normal operating temperature and there are no DTCs." I built a homemade LED Tester to put my '93 190E into diagnostic mode to read duty cycle. It also reads DTC's.
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![]() 1993 190E 2.3 2001 SLK230 1971 LS5 (454) Corvette Convertible |
#5
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If i have to put it in diagnostic mode to read duty cycle..what is it outputting to my scope throu x11/2 x11/3 ?
taken before any adjustment were done. all i did was connect up to x11 http://i98.photobucket.com/albums/l250/MafiaNicky/idleafterafewminutes.jpg If it is in normal mode..why would it output anything at all?
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#6
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Was that at idle?
From the looks on that waveform, it looks like a lean mixture. My 2 cents! |
#7
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It's $80 but worth it for occasional use. A professional version will be much higher $$
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#8
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Checked current flow in the EHA:
(note: my motor is a m103 3L from a 90 300SEL) (note: my exhaust is straight pipe) Resistance: 1.116 M Ohm Key on, Engine Cold: 19.980mA Key on, Engine On Cold: 4.819mA After sitting to ~80C : 16.477 mA As engine was revved it typically went between 4 and 16mA As engine was held @ higher rpm started @ high number and decresed rapidly to around two or three mA. Used this: http://www.home.agilent.com/agilent/product.jspx?pn=34410A
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#9
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just filled up at the gas station
11.02 gallons covered 212 miles....for 19.36 Mpg..
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
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