1990 535i E34 hunting idle

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Alvin - 05 Dec 2006 17:02 GMT

I'm the proud owner of a 1990 535i E34 but since i bought it 2 months
ago, i've had a problem with hunting idle. this is my first BMW so i'm
really not familiar with it's quirks. i've had the fuel injectors and
lines checked and cleaned but it's still "gurgling". one mechanic said
it sounded like the gas:oxygen mixture was too rich. he also mentioned
something about a lambda sensor. is he right? what else could it be?
pls HELP!

Reply to this Message

John Burns - 05 Dec 2006 18:54 GMT

> I'm the proud owner of a 1990 535i E34 but since i bought it 2 months
> ago, i've had a problem with hunting idle. this is my first BMW so i'm
> really not familiar with it's quirks. i've had the fuel injectors and
> lines checked and cleaned but it's still "gurgling". one mechanic said
> it sounded like the gas:oxygen mixture was too rich. he also mentioned
> something about a lambda sensor. is he right? what else could it be?

I don't think your car has a lambda / O2 sensor, but I may be wrong. UK
cars built in 1990 don't need a catalytic convertor and I don't think
yours has one. Our 1990 E34 Alpina B10 didn't.

It's much more likely to be a vacuum leak due to a split air hose or a
sticking idle control valve (cheap).

I'd also be very tempted to fit a new distributor cap and rotor arm.
There's a good chance yours are 16 years old! New ones can make a big
difference to mpg and top end power.

These cars need a valve adjustment every 24k miles, that's worth a go
too.

It doesn't sound like your mechanic is too familiar with BMWs. You'd
save money in the long run by going to a specialist, see my site's UK
garage review pages.

Signature

Who needs a life when you've got Unix? :-)
Email: john@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland
Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage!
Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html
www.Strathspey.co.uk - Quality Binoculars at a Sensible price

Reply to this Message

Floyd Rogers - 05 Dec 2006 22:00 GMT

>> I'm the proud owner of a 1990 535i E34 but since i bought it 2 months
>> ago, i've had a problem with hunting idle. this is my first BMW so i'm
[quoted text clipped - 6 lines]
> cars built in 1990 don't need a catalytic convertor and I don't think
> yours has one. Our 1990 E34 Alpina B10 didn't.

John, John, John. Even your web site notes our stricter pollution
requirements.
No US BMW since the late '70's has not had a cat. The changeover for the
E12/M30 was the 78 to 79 model year IIRC. I don't believe any 6 or 7
ever had a non-cat motor. As near as I can tell, the OP is in the US.

> It's much more likely to be a vacuum leak due to a split air hose or a
> sticking idle control valve (cheap).

Absolutely agree.

> I'd also be very tempted to fit a new distributor cap and rotor arm.
> There's a good chance yours are 16 years old! New ones can make a big
> difference to mpg and top end power.
>
> These cars need a valve adjustment every 24k miles, that's worth a go
> too.

FloydR

Reply to this Message

E28 Guy© - 05 Dec 2006 23:12 GMT

> John, John, John. Even your web site notes our stricter pollution
> requirements.
[quoted text clipped - 6 lines]
>
> Absolutely agree.

And on top of all that, the 3.5l M30 isn't known for having a
particularly smooth idle. If it stays *in the neighborhood* of 700-900
most of the time and it runs all right all the rest of the time, you
should normally be satisfied.
--
C.R. Krieger
(Been there; done that)

Reply to this Message

John Burns - 05 Dec 2006 23:20 GMT

> John, John, John. Even your web site notes our stricter pollution
> requirements.
> No US BMW since the late '70's has not had a cat. The changeover for the
> E12/M30 was the 78 to 79 model year IIRC. I don't believe any 6 or 7
> ever had a non-cat motor. As near as I can tell, the OP is in the US.

I THINK he said his car was a 535i SE, SE is a UK designation. I may be
wrong :-)

Signature

Reply to this Message

Floyd Rogers - 06 Dec 2006 01:14 GMT

>> John, John, John. Even your web site notes our stricter pollution
>> requirements.
[quoted text clipped - 4 lines]
> I THINK he said his car was a 535i SE, SE is a UK designation. I may be
> wrong :-)

See, if you were using a *real* newsreader like OEX rather than the
Unix/Linux
stuff you use, then you could just go back and see that he didn't. ;->

LOL, FloydR

Reply to this Message

Don - 06 Dec 2006 21:18 GMT

In addition, possibly inlet manifold gaskets as well.

> It's much more likely to be a vacuum leak due to a split air hose or a
> sticking idle control valve (cheap).
[quoted text clipped - 5 lines]
> These cars need a valve adjustment every 24k miles, that's worth a go
> too.

Reply to this Message