Expert advise needed

[Zim Zimmer]

Hi Guys, I am new to firstly the BMW seen and also to this forum, I am in the throws of buying a jap imported E30 1990 320 six cylinder.
I trust the guy i am buying it from (i am a keen diy'er and a have been in car sales for the last ten years in the UK and briefly here in Dubai) but have asked him to resolve an issue with the engine that is concerning but could be simple to resolve (i believe) before i seal the deal and I really want this car as everything else is good for price etc and want to help.
When running warm the engine feels smooth while driving but revs are high (700-850 rpm) and surging in idle.It also sounds as if there and distinct feel of lack of power but seems to slowly get better towards the higher revs/speeds (my mazda 323 1.6 felt spritely after driving it). There are no rattles or bangs. He said he replaced the MAF sensor but said that it ran worse so put old one back on. It has a new battery and new platinum spark plugs. He says that is brother will adjust he MAF sensor and it will be fine. Is this possible on the version or is he spinning me a yarn?

Any help would be appreciated.:help:

[Shak]

Hi Guys, I am new to firstly the BMW seen and also to this forum, I am in the throws of buying a jap imported E30 1990 320 six cylinder.
I trust the guy i am buying it from (i am a keen diy'er and a have been in car sales for the last ten years in the UK and briefly here in Dubai) but have asked him to resolve an issue with the engine that is concerning but could be simple to resolve (i believe) before i seal the deal and I really want this car as everything else is good for price etc and want to help.
When running warm the engine feels smooth while driving but revs are high (700-850 rpm) and surging in idle.It also sounds as if there and distinct feel of lack of power but seems to slowly get better towards the higher revs/speeds (my mazda 323 1.6 felt spritely after driving it). There are no rattles or bangs. He said he replaced the MAF sensor but said that it ran worse so put old one back on. It has a new battery and new platinum spark plugs. He says that is brother will adjust he MAF sensor and it will be fine. Is this possible on the version or is he spinning me a yarn?

Any help would be appreciated.:help:

Hi Bro ,

The MAF sensor is adjustable but only if you have the right diagnostic tools so that you calibrate the right amount of air to fuel ratio?
There should be no need to adjust the MAF sensor its pre-set , It seems the car has an air leak or the idle control valve is stuck.
Is the car hunting at idle ?
Have him check all the vacume pipes under inlet manifold?

Drop me a call if you need help!
**********
Shak

[Zim Zimmer]

Thank you for your help. I did forget to say that he said he replaced the stepper motor at the same time as the MAF sensor. Question i will need to ask is if they were used or new because i have a sneaky feeling. For what i saw in terms of air leaks i could not see anything but will get him to check. One thing i did see and now you mention it was the oil cap plastic on the exterior rim had cracked and from my experience tinkering with a 730i that this may be a part of the issue. What do you think?

[Shak]

Thank you for your help. I did forget to say that he said he replaced the stepper motor at the same time as the MAF sensor. Question i will need to ask is if they were used or new because i have a sneaky feeling. For what i saw in terms of air leaks i could not see anything but will get him to check. One thing i did see and now you mention it was the oil cap plastic on the exterior rim had cracked and from my experience tinkering with a 730i that this may be a part of the issue. What do you think?

If the oil cap is cracked,all you need to do is get a can of brake cleaner or WD40 and spray it over the cap,if there is a leak the engine will sound different for a few seconds.

You can also remove the dipstick.If there is an air leak the engine will sound the same with the dipstick in or out!

Also have him check the wiring just under the inlet manifold,there is a round plug (twist and pull) common issue with the wiring getting corroded.

[Zim Zimmer]

He has now replaced the oil cap and made a big difference as it now has power that i expected, even in the brakes.
The engine still sounds as if it is hunting but i think this is now down to the MAF sensor, will probably if i get it will replace that and the stepper motor just to be sure. Although i did notice that the revs are now high at 1000rpm on idle, am i right in thinking that this should be down to about 750rpm on this six cylinder engine and if so how can this be rectifide knowing that it has new spark plugs and injectors.
Saying all this i normally when buying a second hand car change the spark plugs, air filter, oil and filter and put in additives to the fuel to remove any water from the tank and clean injectors. Is there any particular oil supplement that would benefit an older bmw engine?
And thanks i will check out the wiring as that could be a big influence.

Thanks