e34 520 m20 b20 poor performance

[samharon]

hello again,the other day i raised a red flag about my e34 block pecah.the engine was then changed at a local shop here. many parts were also changed, air filter, and some other parts looks very new.I noticed a mark difference in performance. it is no longer as torquier as it used to be. even my father (he usually drives very very very slow) noticed the depreciation especially when climbing the hill leading to our house. i know... its a 12V, but the previous engine was wonderful. most people who went on the e34 could not believe its a 520 12v. some say it drove like a 525.could it be anything related to the throttle body? like i can simply adjust the screw and improve performance?thank you.

 

[bmw4eva]

Could be several possibilities:

1.Intake air leak(usually the car backfires when you hit on the throttle if this is the problem)

2.Did you change the timing belt too? Because incorrect camshaft timing could also be the culprit

3.Check cylinder compression.If they're low, maybe head gasket blown or piston rings shot.

4.Air mass sensor improperly adjusted.(the M20 should have the flapper type AMS which is adjustable).

5.This is unlikely, but check the boots(air filter box-to-AMS and AMS-to-throttle body) to see if a wad of newspaper isn't shoved inside, blocking the airflow to the engine.I know this because its happened to my old Porsche 928 before when I had the timing belt changed(probably the mechanic's idea of a joke) and the power was effectively cut in half.

Hope that helps.

 

[samharon]

wow... they all seemed all so serious! mind you the change was done not at a BMW specialist. and the timing belt was also changed.

all in all, the car is drivable, and i dont think its dangerous.
but losing performance... hmm...

appreciate the input. many thanks