before 3 weeks i had posted that i have a serious problem with engine idle in my 1993 3.8,and some suirging in the rpm when steady throttle,it feels like its giving more fuel and sucking it again.till now i couldnt figure it out,and solve the problem,so i need some advice,especially because i live in a country that dosent know a thing about thoes cars,well,here is what i have done till know:
1-changed th o2 sensor,no diffrence.2-tried new coils also no diffrence.3-the dignosis system shows no bad throttle sensor or bad crank position sensor.4-i poured one bottle of octane booster since we have bad fuel here maybe 90 or less octane!!,still no difference.5-i have checked the earth straps,still no change.yesterday only,the dignosis system idicated a"lambada regulaion"and was written:the ecu reads out a bad mixture,would a co adjustmen cure the problem in that case?or i should send my ecu to reprogram it based on the fuel we have here?? please any help would be most appriciated.thanks
Having read your problem & the checks you have done
i would seriously check out the following before going down the ecu path.
1) fuel filter...just change it.
2) check the fuel pump over, is it noisey ?
3) check fuel lines, return lines & filler cap pressure relief operation.
4) have the air flow meter tested (or substitute with known good)
5) have the fuel system pressure at the fuel rail tested
(you will need a workshop with the correct equipment)
My 3.8 suffers from surging after sitting in traffic for more than 5mins on days hotter than 80C (especially with A/C on)
The problem is simply heat soak into the fuel system & idle/low speed running clears after a few minutes in moving air.
Obviously your problem seems to be more serious, but i would
focus on the fuel supply especially at the fuel rail area.
You have a fuel pressure regualtor & damper valve on the fuel rail
that if faulty can cause poor running.
A check needs to be made on fuel pressure to eliminate a supply problem, then you can look towards electronics.
well,the fuel filter is new,and the plugs,and we have checked the fuel pump pressure,its all right,and still the problem there.
well,i know what u mean about checking the fuel delivery system in general,but if u could help me a little,describe for me the filler cap pressure relief operation,also the damper valve on the fuel rail,where are they? where can i find them? in which area they are?
also,if it has a bad air flow meter sensor,it should come out on the diagnosis system,right? but mine is brand new,i bought it 5 months ago!!!
as u think would it need a new valve adjustment?we have don the adjustments,but the engine is newly rebuilt,it might that the valves are opened again after pressureand heat,or what do u think??
any way,i am waiting for any help alan,
Most cars have a release valve on the fuel cap.
Try (but be careful) running round the block without
the fuel cap on, if its not venting properly it could
restrict fuel flow.
There is an ocillation damper in the flexible hose leading towards
the fuel rail, and the pressure regulator sits next to the fuel rail
looking like a baby fuel filter with a vaccum lead to it.
However the only way to really test it (if it isnt leaking fuel)
is to have the fuel pressure checked at the rail.
What work has been done on the engine ?
And has it run correctly after rebuilding at all ?
I would recheck the valve clearences, as valves tend to settle down and clearences might possibly be tight or loose.
I might also be a good a idea to check that the 6 six trottle butterflies are synchronised and are opening by the same amount.
Last recomendation is to have your fuel injectors cleaned, as with age and miles nozzles clog up and dont atomise the fuel.
I would point out that the M5 3.8 is not known for its smoth idle, even on a car that is in reasonable condition and well maintained I dont think any of its owners would say that the idle is smooth.
Although it would appear that in your particular case something must be amiss.
well alan,thanks for answereng,and thanks to jrturbo too.
well i think that the clearences are a little bit out of spec,so i will check on it as soon as poss,because the car's rpm is a little bit low,it indicates about 850 rpm or less on idle.
yesterday i had a good look and i noticed that there r two fuel regulators,one of them is beside the injectors and the throttles,the other is under the air box with two little hoses on it,i will be checking on them 2omorrow.
i had rebuilted the motor 2 monthes ago,it runs fine on high rev,and v good on full trottle also,no oil cnsumption like the past,and we have checked the compression and was very good,i have changed piston rings,shells and bearings,valves guides,head gasket,the pistons was so fine also the block,i had two bad rings only.
thanks guys,i will keep u informed,but dont let go on me!!
well,i have met a mate who has a beutiful diagnosis system with some live data to help solving my idle problem,the system is fabulous,it showed that the we neeed to check fuel lines,and if its not the source of the problem, it would be then the co adjustment,because the fuel here sucks!!!
boy i miss those days when i push the throttle to full untill i reach my top speed (290km/h)!!!!!!,and the good thing is the police men here dosent care!!!!!
well its bad news,i just got the car,it still idles very bad,u can still feel the vibration when its engine runs on idle,and a lot of carbon smell when u stand behind the exaust,u can hear the exaust spitting and cutting its sound.
we have checked all fuel lines,regulators,several ecu's,i had even tried a chipped ecu maid especially for this country's fuel,all for no good result,but the mechanic guy tod me that it should be the co adjustment,so the next thing that i am going to do is adjusting the co at the dealer workshop,we have even checked out the clearences,and don some work there.
any suggestions friends??it would be most appriciated.
idle still bad
still bad
Linear Mode
