E36 M42 on E30 losing power

[selespeed]

I have had this strange but annoying problem for quite some time. I don't know what else to do...

the engine is just lazy to give me power around 3500 to 4500. stepping on the gas doesn't wake up the engine to give me power. sort of like going against the wind kind of feeling. I had many sensors changed but they don't solve the problems. however, just about 3 weeks ago, the engine started to improve day by day and then since last week, the problem comes back.

here's the observation:
1. engine idles well. afm checked and ok
2. engine is strong only up to around 3000rpm. thereafter, it exhibits sort of power containment. not willing anymore beyond 3000 to 4500. knock sensors and cam sensor replaced and still the same. revvs climb slowly
3. also made sure the vacuum hoses are ok and no leaks.
4. fuel economy is bad.
5. replaced oil filter housing gasket and oil seals due to leaks. so oil leaks should be contained. engine is washed and oil sump area looks dry.
6. under hard acceleration or long driving, the engine gives me some kind of "loose" metallic feeling, though it is smooth. but this noise goes away when engine is not driven long. more than one hour of driving the noise comes back.
7. I can hardly do 210kmh. takes a long time to do redline

it appears that it is temperamental. but it gives me no clues as to what the cause of the problem is.

OBDI fault code only shows 1 error which is the fuel ventilation hose not connected. on the e30 this is not required. it is the nose that is connected from air intake to throttle housing to the fuel tank.

so guys, what is the cause of the problem.

selespeed

[selespeed]

this engine has DISA which is the variable inlet intake lengths. I am not sure if I should open the intake to clean it?

[DesktopDave]

I'd check the fuel system first - fuel pressure and flow according to BMW specs. I'd also check to see if all the injectors are firing.

The DISA system does have an effect on the upper-RPM torque...might be a good idea to test the crossover flap with a vac pump. Have you put a vac gauge on the motor while you're driving it? Those are hard to read, but sometimes give you some important clues.

[selespeed]

I'd check the fuel system first - fuel pressure and flow according to BMW specs. I'd also check to see if all the injectors are firing.

The DISA system does have an effect on the upper-RPM torque...might be a good idea to test the crossover flap with a vac pump. Have you put a vac gauge on the motor while you're driving it? Those are hard to read, but sometimes give you some important clues.

at last, I think I have found out what caused the engine vibrations and engine losing power...

a loss of compression pressure on cylinder 3 has prompted me to do to remove the top. and two things are discovered.

1. cylinder 3 has the plug electrode hit badly and bent. the piston crown is hit with lots of small dents and one valve could not close explain the loss of pressure. this happened last week. what could cause this to happen? many e36 owners have found this to be due to some kind of DISA vanes disintegrating into the cylinder resulting in this???

2. then the startling discovery was made. piston 1 doesn't rest at top dead center. it is like 2 mm below, suggesting con rod is bent. this could be the reason why I have engine vibration and performance problem that's mysterious. then this piston is removed confirmed that con rod bent quite badly.

anyway, I'm now scrambling to get a net set of con rods and pistons. might as well. anyone of you can provide me suggestions? I sourced locally but found the quality questionable. there is no packing box and origin is not stated nor the brand. the machining also doesn't seem to be good. what after market con rods and pistons are good?

I m located in Singapore. car is now in workshop

[DesktopDave]

That sucks. If you ever figure out what went wrong be sure to let us know.

I'd be tempted to order parts from the US, if shipping isn't incredibly expensive. We got a lot of the M42's - and as they're considered small motors the parts tend to be cheap.

[mabeer]

selespeed, sorry for the late reply I suppose you've already sourced your rods & pistons but if not,  I've got a set of used e30 m42 connecting rods and pistons in good condition if you still need them.

Good luck with your repairs.

Mike

[selespeed]

That sucks. If you ever figure out what went wrong be sure to let us know.

I'd be tempted to order parts from the US, if shipping isn't incredibly expensive. We got a lot of the M42's - and as they're considered small motors the parts tend to be cheap.

selespeed, sorry for the late reply I suppose you've already sourced your rods & pistons but if not,  I've got a set of used e30 m42 connecting rods and pistons in good condition if you still need them.

Good luck with your repairs.

Mike

I just got my engine (car) back on Saturday - after more than 3 weeks in the shop mainly waiting for parts to arrive... here's what's inside my engine:

1. NEW KS pistons standard size 83.95mm. I tried usa dealers and they have to order from Germany. I tried Germany dealers and they UK and they too have to order from Germany. I tried oem maker KSpg in Germany and they told me they don't have any. then, just by luck I happened to find these from Canada dealer precision ap, usd400. shipping is cad183 ups expedited. the Canadian guy teased me I'm in love with an obsolete machine!
2. NEW con rod set from BMW Malaysia - USD220
3. NEW valves, bearings, oil pan gaskets, top gasket set, oil filters etc from Singapore - usd390

so I almost have new engine. and spent quite a lot on this. the engine is notably smoother and quieter. however, the vibrations still exist, albeit much less. I have no idea what caused this. so now I am running in the engine at <3500 rpm. how long must I do this before I can stretch its potential? I still experience periodic uneven acceleration. this must be something to do with intake fuel pressure or injectors I guess.

what went inside the cylinder  I have no idea? the plug was badly bent and the piston crown scarred badly.

I don't seem to be able to post pictures. why?

[mabeer]

There's two schools of thought on engine break-in, hard and easy.  I went hard, but admittedly I don't know which method is best. So don't take this as advice without first doing your due diligence.  I repeat, due your due diligence as this may be misguided.   I hope others chime in.   The hard school claims you have to push it a bit to create enough pressure to expand the rings and get them to seat properly.  You don't just go out and flog on it but rather run it though a controlled cycle of loading.  Warm up to operating temperature then run it 1/2 throttle 2500-4000 rpm through gears 2-4 (don't speed  ), tool around a bit then 3/4 throttle 2500-5000 rpm cool off a bit, then full throttle 2000-6500 rpm. 

I ran mine easy for maybe 1/2 an hour then did the above.  Only time will tell if it was foolish or wise.  Here's a link where I got a lot of my hard school brainwashing. http://www.mototuneusa.com/break_in_secrets.htm

[selespeed]

There's two schools of thought on engine break-in, hard and easy.  I went hard, but admittedly I don't know which method is best. So don't take this as advice without first doing your due diligence.  I repeat, due your due diligence as this may be misguided.   I hope others chime in.   The hard school claims you have to push it a bit to create enough pressure to expand the rings and get them to seat properly.  You don't just go out and flog on it but rather run it though a controlled cycle of loading.  Warm up to operating temperature then run it 1/2 throttle 2500-4000 rpm through gears 2-4 (don't speed  ), tool around a bit then 3/4 throttle 2500-5000 rpm cool off a bit, then full throttle 2000-6500 rpm. 

I ran mine easy for maybe 1/2 an hour then did the above.  Only time will tell if it was foolish or wise.  Here's a link where I got a lot of my hard school brainwashing. http://www.mototuneusa.com/break_in_secrets.htm

I actually wanted to stretch it by exercising the rpm 2000 to 4000+ and then 3500 by playing with the gears. i did this on my alfa engine and then after 125km i blast it to 5000rpm and then onto 7000rpm. the engine subsequently performed very well for 144,000km or 4 years when it got sold eventually. but the alfa engine year 2000 is a more modern and advanced engine and advanced. I'm not sure if i shold do the same to this old bmw the engine.

[selespeed]

first two pitures - bent valve due to hard hitting objet entering it
last two pitures - bent onrod in cylinder 1

[selespeed]

All new...

[selespeed]

NEw bearings too...

the "original" conrods are smaller, lighter and thinner. I think the old conrods are from mahle!

[selespeed]

no cylinder boring

[selespeed]

more pics...

[selespeed]

I'd check the fuel system first - fuel pressure and flow according to BMW specs. I'd also check to see if all the injectors are firing.

The DISA system does have an effect on the upper-RPM torque...might be a good idea to test the crossover flap with a vac pump. Have you put a vac gauge on the motor while you're driving it? Those are hard to read, but sometimes give you some important clues.

I have finally SOLVED this long running mysterious problem with just USD6... I plugged the tank breather valve socket with a resister from BMW (item and this fools the ECU there are no more such errors. The presence of this error makes the ECU run in limp mode that retards acceleration.

http://bmwfans.info/parts-catalog/E36-Coupe/Europe/318is-M42/R-M/apr1994/browse/fuel_preparation_system/fuel_tank_breath_valve_disturb_air_valve/