E36 flat-spots

[Whiterj]

I have an E36 325i coupe. The car is fully main dealer historied and has always been properly looked after. However, the really smooth power delivery it had in the first few months of ownership has gone. It's still smooth but with notable flat spots around 1500-2K, another small one just before the VANOS kicks in at 3500 and one final one at 4-4500. It's not that noticeable in everyday driving but is out in the open, especially on slip roads etc. It still feels just as fast but not linear. Also, the idle has gone from smooth to sending the occasional shudder through the car.
A specialist has been unable to diagnose the problem and computer diagnostics show the car to be in rude health, but it feels different. It had a new airflow meter before Christmas which was professionally fitted.
At a bit of a loss but I know it's not as it was! Anyone had similar problems?

[Demon Hill]

Borrowed this info off another forum so I don't know how accurate the prices are. Hope it helps.

'E34/36 MOTORSPORT CHIPS - These high quality chips are for the E34 and E36 cars with the 2.5 engines. These chips are programmed by Venom Design, and are of the highest quality availible, rpm idle is raised from 780rpm to 875rpm to smooth out the rough idle these cars suffer with. Power band is opened to allow a longer rate of maximum power making the car smoother, yet more powerfull for longer periods over standard. Rev limiter is set to 7025rpm but can be altered if you were wanting something special. The flat spots associated with these engines at 2200rpm and 4000rpm are both removed making the car a dream to drive with a smoothness not normally associated with these cars and there injection system. If you want quality i really cant express just how much of a difference this chip will make to your car. power increases are in the region of 15hp @ 5400rpm with torque increased by arouns 18lbft. Look at my feedback for a long list of happy customers, i sell quality items and not cheap gimmicks. If you want any further info on these chips please mail me at [e-mail] £50 inc postage. [e-mail] Tel [phone]'

[kamal996]

This could be for the follwing reasons:

1) the ignition coils are breaking down (there are six altogether)
2) the catalytic convertor is blocked
3) The injectors are in need of a clean.

There used to be a guy called Geoff Evoret who ownerd a place called AMD. He has sold it but has started up his own thing somewhere else. Try him as he has the reputation of knowing a thing or two about BMWs.

[Whiterj]

Cheers for both these replies. The problem came about pretty suddenly, hence why I think it maybe related to the airflow meter replacement around the same time.
I had intended to have the car chipped anyway so will probably try that first.
The company I take the car to is AMC in South London (Beemer and Mercs only and very good rep). They couldn't find a single fault so if the chipping doesn't work I'll start looking into the other possibilities one at a time. Got to take it in under warranty to get the one shot windows fixed so I'll suggest this to them.

[JRSE]

Whiterj said:

I have an E36 325i coupe. The car is fully main dealer historied and has always been properly looked after. However, the really smooth power delivery it had in the first few months of ownership has gone. It's still smooth but with notable flat spots around 1500-2K, another small one just before the VANOS kicks in at 3500 and one final one at 4-4500. It's not that noticeable in everyday driving but is out in the open, especially on slip roads etc. It still feels just as fast but not linear. Also, the idle has gone from smooth to sending the occasional shudder through the car. A specialist has been unable to diagnose the problem and computer diagnostics show the car to be in rude health, but it feels different. It had a new airflow meter before Christmas which was professionally fitted. At a bit of a loss but I know it's not as it was! Anyone had similar problems?

The M3 I looked at last week had similar problems. The owner told me there was a flat spot and he sent it to his local BMW dealer. They diagnosed that a stronger spark was needed and fitted different coils - approx £350 from the receipt I seen.