Van runs whilst driving but when it comes to a stand still it goes into limp home, live data then shows boost control locked at 4% until ignition cycled. fault code is for map sensor but that works ok and has previously been swapped. The van has a boost sensor, no maf and from what I can see no atmospheric sensor. It looks like it youses the boost sensor for atmospheric on ignition on and then for boost during running. the problem seems to be that the atmospheric reading is 600 millibar on the live data and the boost is the usual 1003 millibar at standstill with acc. pedal percent 0%. I think it is seeing this difference as excess boost and shutting down the boost control and going into limp home. Can anyone tell me why if it uses the same sensor for boost and atmospheric readings why I am getting this confliction or where I have gone wrong, also obviously = what I might do to fix it. thanks, jon.
You dont have a MAP sensor on this model ? how can you have only 600 millibar 980 to 1026 is an approximate range of normal atmospheric pressure regardless of engine conditions what part did you swap and did you reset the adaption data for the component ?
Testimonial: "HI. Yes it does have a boost sensor but does not have an atmospheric sensor. Yes the atmospheric reading was 600 - that was the question?, Why? Posted july 2013. Thanks. Jon"
Hi again yes it does use the boost pressure sensor for both readings I just remembered I had a similar problem and although the boost pressure sensor had been swapped it was not a genuine merc part I put in the genuine part and the problem was cured
Also check for air loss on the boost pressure system all the obvious things like do you have the updated red boost pressure pipe on the turbo outlet side the old one was black in colour, Also a common fault on this vehicle is a broken stud on the underside of the plastic inlet manifold it is always the second stud from the front on the underside you will need a diagnostic camera to see it I normally use a snap on device with bendy flexible to see this
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SOURCE: asr limp home MB 600
Model years 93 and 94 have the L.H. type fuel injection system. There is also e.z.l.(ignition),a.s.r.(acceleration slip regulation-traction)i.s.c.-c.c.-e.a.(idle speed control,cruise control and electronic acuater),d.m.(diagnostic mod.)and the base module. With a v-12 there is 2 of everything exept base and d.m.. the d.m. mod. overlooks the entire system and the base supplies voltage to the computers. This system is complicated and difficult to diag. Most likley one of your electronic acuaters is faulty. That is your throttle motor. These era vehicles have wire harness issues. Have the car ran for codes starting with the d.m.. at least this vehicle will store faults-the light does not have to be on to read the fault. More than likley you will find an e.a. code. You can have these motors rebuilt for about 1/4 the cost of a new one. Also never attempt to raise idle at one of the actuaters because if they are not both moved at the same time you will lose throttle synchronization and have to have the memmory cleared and resynch. motors. It will cause the exact symptoms like you described-also when the pigtail harness wires short and the modules lose the throttle synch. Good luck
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any way you feel vibrations travel in whicth speed?
if it is up then 90-100 kmh get your tires balanced ,(they put a piece of metal in them to not vibrate in high speed) if you have done this, see how is your alignment tires. if this have done see your arm steering , you have them problematic(losting fluid inside, or if you have hited something hard with your tires.
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SOURCE: hi. can anyone tell me
It is either under the Windshield Wiper Cover, just forward of the firewall or in the TRUNK of the car.
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Hi. It does have a boost sensor but no atmospheric sensor. posted july 2013, Thanks Jon
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