Engine Hesitation M20

Need technical Q/A then you're in the right place

Moderator: martauto

zd3bx
E30 Zone Regular
E30 Zone Regular
Posts: 638
Joined: Sat Apr 06, 2013 11:00 pm
Location: London

Post Tue Jun 18, 2013 10:14 pm

Got a bit of an annoying problem I've been living with since I bought the car and it's quite hard to explain.

The engine starts/runs fine and when revving it through the gears, everything seems to be ok.

However, when pulling off slowly in traffic or parking, you gently press the gas pedal to rev the engine a bit, and instead of smoothly building up the revs, it kind of sputters and the revs jump up and down quickly between 900-1k rpm.

It sort of struggles to smoothly rev up when you're progressively pressing the gas pedal, so you end up giving the pedal a few quick kicks and it comes alive...

I suspected fuel pressure regulator or maybe fuel pump, but wanted to make sure before replacing anything :)

Thanks
Top
hongkongfuey
Mad-tango-geezer
Posts: 3303
Joined: Fri Jun 08, 2007 11:00 pm
Location: portsmouth

Post Thu Jun 20, 2013 8:00 am

has it been serviced lately?
if there wern't people like me,
with cars like mine,
who would you put down to make yourself feel better?
Top
trevski
E30 Zone Camper
E30 Zone Camper
Posts: 1046
Joined: Sat Aug 26, 2006 11:00 pm
Location: milton keynes

Post Thu Jun 20, 2013 8:38 am

M20s respond to a good service really well.
Image
Top
zd3bx
E30 Zone Regular
E30 Zone Regular
Posts: 638
Joined: Sat Apr 06, 2013 11:00 pm
Location: London

Post Thu Jun 20, 2013 7:38 pm

Did the service last year in August - oil, all the filters and the spark plugs.

It has new ignition leads, distributor cap, rotor arm and a new coil as well.

I've only done about 5k miles since then, and it doesn't sound like a service related problem, as I remember it's been like this since I've had the car.

The rubber hose which goes from the FPR to the inlet manifold is all perished and looking very sad, not sure if that makes any difference...
Top
zd3bx
E30 Zone Regular
E30 Zone Regular
Posts: 638
Joined: Sat Apr 06, 2013 11:00 pm
Location: London

Post Sat Jun 22, 2013 10:23 am

So any ideas about this guys?
Top
trevski
E30 Zone Camper
E30 Zone Camper
Posts: 1046
Joined: Sat Aug 26, 2006 11:00 pm
Location: milton keynes

Post Sat Jun 22, 2013 10:29 am

Hose air leaks will contribute to such symptoms. Check underneath the air flow meter hose mine has split underneath and looked ok from above .
Image
Top
zd3bx
E30 Zone Regular
E30 Zone Regular
Posts: 638
Joined: Sat Apr 06, 2013 11:00 pm
Location: London

Post Sat Jun 22, 2013 1:17 pm

trevski wrote:Hose air leaks will contribute to such symptoms. Check underneath the air flow meter hose mine has split underneath and looked ok from above .
Thanks, will do!
Top
zd3bx
E30 Zone Regular
E30 Zone Regular
Posts: 638
Joined: Sat Apr 06, 2013 11:00 pm
Location: London

Post Sun Jun 23, 2013 3:02 pm

willnz wrote:check the throttle position sensor (TPS) is set properly and working. WIKI has instructions how to check/set.


Have you ever had the injectors overhauled? Highly recommended if not.
Haven't touched the injectors myself, so that's a possibility.

Had a quick look today for air leaks, but all the hoses look good. While doing that, found a plug under the throttle body which is un-plugged?

Here:

Image

What is it for?
Top
Grrrmachine
E30 Zone Wiki / Team Member
E30 Zone Wiki / Team Member
Posts: 8043
Joined: Sat Feb 09, 2008 11:00 pm
Location: Warsaw, Poland

Post Sun Jun 23, 2013 3:08 pm

Time for this link to make its weekly appearance :D

http://www.e30zone.net/e30zonewiki/inde ... n_Canister
Top

Return to “E30 Technical Help”