Whats happening!!!

[Kelvin Tan]

Recently, my car started to give me some problems liao!!!

On the road, when gonna pick off, sometimes, when i step on the accelerator, the car like no response like that... then maybe few seconds later, its as if i "step on the accelerator" message has gone through, the car then raved and move off...

This thing only happened like once in a while, recently a bit often only.. when sent to workshop, they said that there was nothing wrong when gone through the computer sensors...

Any bros advise? Thanks!!!

 

[centurion]

Re: Whats happening!!!

I had the same problem in the past. SOMETIMES, first once a week, then once every 3 days, then once a day, then 3 times a day, getting worse all the time. You press the throttle, car does nothing for 2 seconds, then the engine revs after 2 seconds. ONLY HAPPENS from Zero Throttle. If the throttle already open a bit, then it has no response issue.

Dangerous! You being in the middle of the road or going from rest turn into main road, you may just have 2 seconds lag and then the other car can come crashing into you.

Diagnostics did nothing. Lambda sensors all OK. E-throttle OK. Lastly, the entire problem was traced to the Bosch Motronic engine management computer. Replacement was a fortune.

So? I sold it. I hated the car after the problem cropped up.

 

[Kelvin Tan]

Re: Whats happening!!!

Exactly, whats the problem?

Any bro can give any advise how to repair and where to repair?

 

[///M3]

Re: Whats happening!!!

hmmm..u ask the workshop ppl to test drive ur car lor..let them know whats the problem..they drive liao they should know whats wrong with it..or go back to performance..

 

[centurion]

Re: Whats happening!!!

It's not an easy problem to diagnose. The CANBUS is interactive with the Motronic, and that controls the transmission control and stability systems. The E46 318 new version features the early version of Valvetronic for its 4cyl, and this system feeds to the Motronic, and others like engine speed, cam phase, throttle position, compression, oxygen sensor, knock sensor, aircon settings, all feed to the motronic.

ANY of these systems being defective, can screw the throttle up.

It this car is out of warranty, then you're in trouble, because it will take days of testing to diagnose the issue. The worst thing is that, you can't `try before you buy' when it comes to the Motronic.

So we have to narrow down the problem and check some select sensors. First, the engine compression, you have to check. Passive sensors cannot be `diagnosed' so replacement is necessary. So, replace all oxygen sensors (cheap) and check out the knock sensors (or just replace them). Run a diagnostic on the transmission control unit and the DSC+T, since these systems are `host' mode and not passive - they are self sufficient computers who interact with the Motronic only via the CANBUS. Do not need to check aircon compressor because motronic does not receive input from there.

I'm not optimistic that even after days of testing they can find the issue. And they will point to the motronic. That CANNOT be repaired, it has to be replaced. IF they replace, you have to BUY it. The Motronic has a diagnostic mode, but it is not foolproof and it may report `good health' even though it is not.

So the best thing is to sell the car if they cannot diagnose the issue.

 

[SpeedyGonzales]

Re: Whats happening!!!

Sounds serious, what was the mileage when it failed? how much it cost to replace the motronic? if its not under warranty did you bring to bvo or j4c to diagnose?

 

[centurion]

Re: Whats happening!!!

all that I mentioned is the crap you have to do if the external diagnostic software does not have a tracing function. I have once seen some software with a tracing function, which dumps a log on what is happening to a file and you can see exactly what went wrong. I have no knowledge on whether PML has such a software or not.

Even then, it takes a very good engineer to understand the log file.

 

[SpeedyGonzales]

Re: Whats happening!!!

is this a common problem with 318 valvetronic?

 

[Kelvin Tan]

Re: Whats happening!!!

Yo, just now when i was at the petrol station, i bought i bottle of "Fuel Injector Cleaner" and poured it into the fuel tank to give it a try...

Not sure if can work a not but think is a cheap try. So, why not?

Will keep you guys updated on the progress.

Cheers!!!

 

[Apogee89]

Re: Whats happening!!!

Yo, just now when i was at the petrol station, i bought i bottle of "Fuel Injector Cleaner" and poured it into the fuel tank to give it a try...

Not sure if can work a not but think is a cheap try. So, why not?

Will keep you guys updated on the progress.

Cheers!!!

Maybe you might want to try another cheap way and that's changing the spark plugs. Also maybe check the coils to eliminate ignition issues.

 

[SpeedyGonzales]

Re: Whats happening!!!

have tried bvo? seems like they have the autologic for bmw to diagnose engine faults.

 

[phil]

Re: Whats happening!!!

that sucks, cause my E46 does it too. I initially thought it is bound to be the oxy sensor, as is the case with most brands of cars. After reading the above I am a little concerned. Can it be electrical or something simple? I like simple, so here what i reckon i will try. For sure good fuel is number one, and this i have no clue if Singapore fuel is actually what it's supposed to be. I know in Australia if I use Shell Optimax my everyday car likes it, but my weekend cruiser hates it, actually fouls the plugs. I have mates who this happened to on their turbo cars, Skylines etc.
Air filter? sure that could be an issue, so K&N it is. Plugs, yep that could hurt it, so what plugs to buy? Irridium? Injectors, yep for sure, but will injector cleaner fix it? I doubt it. Currently i have used 2 tanks of 95 octane, after always using 98. I can see no difference in performance, but it seems the "flat spot" is not as bad. I have a 5.7 litre V8 car in Australia, trust me, driving a 4 cylinder BMW in Singapore i notice the power difference!! hahah. If you guys find on your cars it turns out to be electronic, then we all have to make a protest line with banners outside PML!!! Plus i wanna date one of the counter girls, so cant help to go there more often!! LOL

 

[centurion]

Re: Whats happening!!!

Yo, just now when i was at the petrol station, i bought i bottle of "Fuel Injector Cleaner" and poured it into the fuel tank to give it a try...

Not sure if can work a not but think is a cheap try. So, why not?

Will keep you guys updated on the progress.

Cheers!!!

The last time I used the STP fuel injector cleaner on a Bosch car, I had several sensor malfunctions which were replaced under warranty. I'm sure my case is the exception, and not the norm, BUT I'll never use them again.

Same goes for the tufoil lubrication crap which had the same effect.

sheesh!

 

[centurion]

Re: Whats happening!!!

that sucks, cause my E46 does it too. I initially thought it is bound to be the oxy sensor, as is the case with most brands of cars. After reading the above I am a little concerned. Can it be electrical or something simple? I like simple, so here what i reckon i will try. For sure good fuel is number one, and this i have no clue if Singapore fuel is actually what it's supposed to be. I know in Australia if I use Shell Optimax my everyday car likes it, but my weekend cruiser hates it, actually fouls the plugs. I have mates who this happened to on their turbo cars, Skylines etc.
Air filter? sure that could be an issue, so K&N it is. Plugs, yep that could hurt it, so what plugs to buy? Irridium? Injectors, yep for sure, but will injector cleaner fix it? I doubt it. Currently i have used 2 tanks of 95 octane, after always using 98. I can see no difference in performance, but it seems the "flat spot" is not as bad. I have a 5.7 litre V8 car in Australia, trust me, driving a 4 cylinder BMW in Singapore i notice the power difference!! hahah. If you guys find on your cars it turns out to be electronic, then we all have to make a protest line with banners outside PML!!! Plus i wanna date one of the counter girls, so cant help to go there more often!! LOL

Take a look at the motronic diagram (this one wonderful, ripped from Porsche):

You see the crap we're in now? For testing purposes, you can disregard the output. The interactive CANBUS system (host) and the inputs from the passive devices, yes, that we have to worry. Plus, you can take Variocam to be like the Valvetronic controls.

If all the interactive and inputs are checked out right, that leaves the computer to be screwed up, which in my case, that happened.

 

[MRacer77]

Re: Whats happening!!!

CAn also try looking at the MAF. I had similar problems with my car last time and it turned out to be a faulty MAF

 

[lost_soul]

Re: Whats happening!!!

It seems that BMW cars have a lot of issues with the MAF ... correct me if i am wrong ...

 

[SpeedyGonzales]

Re: Whats happening!!!

does the CEL light come on if its a MAF problem? how reliable is a e46?

 

[stevenwu]

Re: Whats happening!!!

Hi,

I also had this probelm too a year ago. Due to MAF faulty.

Do this experiment: Unclip the MAF connector and drive around for a day, see if problem exist. You will be running very rich BUT just for testing purposes. If problem disappear, then the damage is S$400+ for the MAF.

Mine MAF was down due to 'oil' from air filter