Alfa Pages

paulhide · Posted: Sat Apr 03, 2004 11:57 am Post subject: 16v running/tuning

Could anyone put forward any ideas as to why my 16v engine runs very roughly at first (perhaps on three cylinders) then clears suddenly when it warms up at about 55/60 degrees. Have changed ECU & air flow meter Sad

Could it be:- 1. Sticking valve?
2. Something to do with the automatic choke?
3. Water crossing underneath the bottom of the throttle body into the valve?
4. Anything else?
And also can the throttle bodies be tuned? There seems to be a nut and screw on the throttle bodies for each inlet. Question

_________________
Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188

Pimp_Dudu · Posted: Sun Apr 04, 2004 4:19 pm Post subject:

i'd say that u're runnin on 3 cylinders. Check spark plugs and cables and distributor...i doubt it can b anything else..except if u have injection pump..then that can b clogged

paulhide · Posted: Sun Apr 04, 2004 4:25 pm Post subject:

Cheers for the reply. Don't see how it could be leads or distributor if it runs fine after a while. Got new plugs. Injection pump sounds interesting. Any ideas where it would be? Question

_________________
Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188

Ben_nz · Posted: Mon Apr 05, 2004 8:09 am Post subject:

My car used to run on three cylinders (and stall at every opportunity) until it warmed up to 55/60. I had the plugs, leads, distributor cap, rotor and air filter changed all at once, plus the carbs balanced, so I'm not sure which was responsible. Wink

I did look at the distributor cap and rotor beforehand, though, and the metal bits where the spark jumps were pretty worn.

Pimp_Dudu · Posted: Mon Apr 05, 2004 8:37 am Post subject:

Basically when the motor is cold its harder for the distributor to spin, naturally it doesn't give a strong enough spark to the plugs. But when the car warms up a bit it gets more "strength". Now i dont know how cold the weather is where you are, but here in finland when it goes under 15degrees (celcius) then i've noticed that the rotator in the distributor kinda freezes. Another thing is that if its a moist environment u might get moisture under the spark cables causing one of the cylinders to be working without a cable...just do a very simple test. Start the car and take the distributor cap off and open a bit of the spark cables and have a friend press the gas for a while...us hould b able to see the rotator running with rythm to the gas pressing..also if i notice any sparks around the cables then that means that your spark is running away and not reaching your cylinder. Or just buy new spark cables and distributor Very Happy

RFlower · Posted: Mon Apr 05, 2004 12:22 pm Post subject:

DON'T take the distrinutor cap off when the engine is running !!!
_________________
Dick Flower, Nr. Carcassonne. '94 Trofeo 1.4 ie (F), '93 Imola 1.3/1.4 ie (now for breaking) (F), '91 1.7 ie (GB)(spare car), '86 Sprint 1.5 QV (F). '87 VW Syncro camper (F), '73 NSU Ro80 (F), '99 Fiat Seicento (F)

lesthegringo · Alfasud Joined: 23 Jul 2003 Posts: 97

Try changing the water temperature sensor that feeds info to the ECU - if my memory serves me right there is one used for the Bosch Motronic 4.1 system. If it is reading incorrectly it would change the cold running map that the fuel injection follows, so it may be running too rich if it thinks it's too cold, or too lean because it thinks the engine is hotter than it really is.

Les

paulhide · Posted: Wed Apr 07, 2004 11:43 pm Post subject:

Hey, thanks to all of you for your replies. Much appreciated and fair enough. I've found the problem. The garage who Mot'd the car replaced the plugs and said they'd checked the leads so I didn't concern myself with them and was worried because I'd changed the right hand throttle body and thought it might have been something I'd done. However the faulty cylinder was on the other side (found by pulling off distributor cap leads one at a time until one made no difference) and when I checked the lead I found that it was actually broken and had simply been pushed into the plug cap which goes over the end of the sparkplug so that it looked fine and obviously just about worked when the distributor was up to speed. Why didn't the garage work that out ? So now my P4 engine is very happy and so am I.

Once again thanks for your comments.
Still does anyone know if the throttle bodies can be tuned or does the ECU take care of everything?

Just bought a series 2 1.7 with a blown engine for £7.50! Everything (and particularly the shell) is in really good condition. Am getting a low mileage engine for £80 so I hope to have three 33s soon. Rolling Eyes

_________________
Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188