How critical is hving the right coding plug?

[Bruce_Z]

Hi all, Just found out that my 87 E30 325i is using the "wrong" instrument cluster (with the wrong code plug). According to the mech, this is why the car's RPM displays are over enthusiastic - e.g. idle RPM is 1500! Funnly, I feel the car is also a drag to drive (thiis after tuning after I first got the car abt a month ago, it cant be that the M20B25 is such a drag!). I read somewhere on the net that one guy also experienced the same, and noticed lower RPM, smoother pull/accleration when he got the right plug. Will having the right plus make the car more drivable, smoother, and accelerate better? :106:

 

[turbology]

if the instrument cluster does not control the engine manangment, I don't think it matter.

 

[Bruce_Z]

if the instrument cluster does not control the engine manangment, I don't think it matter.

Thats what I thought as well, but Im really wondering how much this things influences the car's engine performance, since my idling and pickup doesnt seem right.:106:

 

[chriseunos]

i've been using the wrong instrument cluster on my m20b25, idles perfectly at +/- 900rpm. No problem whatsoever in terms of pickup and idling. Feels like my car having a MAYJAH TURBO with its over enthusiatic display. xD

 

[astroboy]

if the instrument cluster does not control the engine manangment, I don't think it matter.

Betul.. have u tried your rpm cut? or speed cut?

 

[mizhan]

bruce, you're using a 4-pot coding plug. look for one meant for M20.

 

[chriseunos]

i've tried changing the coding plug, but the rpm still revs the same as before...any suggestion?

 

[Bruce_Z]

bruce, you're using a 4-pot coding plug. look for one meant for M20.

Yup that is the cause I think. But as you know finding a coding plug for a E30 325i is almost impossible... Even that I think it may not work with the speedo and the odometer since this code plug should probably be mated to a speedo thats mph/miles rather than what I have now, which is kmh base. Maybe I should source for a used instrument cluster with the right coding plug (mph speedo/miles for odometer, i.e.UK cars).
I guess the idling issue is not due to this...maybe the mech did not tune this engine right after all....

 

[Bruce_Z]

i've tried changing the coding plug, but the rpm still revs the same as before...any suggestion?

Bro,

You mean you have tried a code plug meant for the M20B25? Is your instrument cluster original or transplanted from a M40? Just guessing here...

 

[mizhan]

Yup that is the cause I think. But as you know finding a coding plug for a E30 325i is almost impossible... Even that I think it may not work with the speedo and the odometer since this code plug should probably be mated to a speedo thats mph/miles rather than what I have now, which is kmh base. Maybe I should source for a used instrument cluster with the right coding plug (mph speedo/miles for odometer, i.e.UK cars).
I guess the idling issue is not due to this...maybe the mech did not tune this engine right after all....

best bet is to purchase the entire instrument unit.. mahal sikit la. pm the hypermarkets - mandonna, racun, miepower etc.