Hi Guys.

i hope someone can shed some light on my fault. I have a miss between 2-3rpm rev range. As car pulls you feel the power drop off for about a second each time then it continues to pull again I feel it about 3 time when accelerating from 2000 through to 3000rpm. The car has a new Egr valve fitted. Adaptation was done through basic settings on Vcds, but I noticed as it was cycling on and off it isn’t within the spec it states on the test 100 mg/str minimum difference .when cycling it drops to zero then when comes on again it goes to max 50 mg/str ? I also noticed although it might not be relaxant. Before i did egr adaptation,if you pressed throttle to floor when stationary it would only rev to 3000rpm now it rev to redline ?

My other problem I think is the mass airflow sensor it had a new pattern one  fitted by last owner but again according to Vcds it’s not in spec .

At engine idle on measuring block 10 in Vcds it’s says spec is 180 - 300 mg/str 

mine shows 20 mg/str (actual) it’s says at max load 900 - 1300mg/str mines only goes to max 55mg/str .

i assume block 10 is correct for measuring the maf ?

I graphed the manifold absolute pressure when the misfire occurs there was a noticeable drop in pressure each time it missed ?

 

so now everyone is 🤷‍♂️lol 😂😂

including me ha ha.

 

well I could be barking up the wrong tree but my thinking is if the mass air flow it giving wrong signal information to engine control unit it will request/ send wrong information for egr open close position and in turn would this effect the map pressure dropping due to the egr open closing position at wrong time ? Just a theory lol 😂 

 

Any advice help greatly appreciated it runs great apart from above.

if I ca get if fixed it will run like new .

the only thing I can think that I haven’t done yet is check the plug wires at the maf connection it has 4 wires I think .

Anyone know how to test and what the wire colours are .

 Thanks again if anyone can help.

ill update if I get a fix to share 

it’s the BMM engine 👍

43 minutes ago, Vstorm said:

the mass air flow it giving wrong signal information to engine control unit

Easy/cheap test. Disconnect the MAF, and see if the engine runs better. If it does, you need a new genuine MAF.

Thanks Ken,

if I do this does the ecu adopt maf values so the engine runs. If so would I see the mg/str readings improve in Vcds?

i also wanted to test the wiring to be sure.

 

im still wondering if maf signal effects 

thevegr position and in turn the map sensor readings.

 

will give it a try 👍

thanks for the reply