Sputtering at high rpm’s.

[18Fiatsandcounting]

I believe the idling rpm is supposed to be 850rpm. If the timing is off can I rotate the distributor a bit to compensate?

Yes, 850 rpm or thereabouts. It doesn't have to be exact, just low enough that the centrifugal advance inside the distributor hasn't started advancing. As you rev the engine, the timing mark on the crankshaft pulley should move clockwise. If your centrifugal advance is working. If it doesn't move, your centrifugal advance mechanism could be stuck (which would cause the problems that you're seeing).

And yes, rotating the distributor is how you change the timing. Rotating counterclockwise (viewed from the top) will advance the timing; rotating clockwise will retard the timing. It doesn't take much. A half-inch movement on the outer circumference of the distributor cap will change the timing by about 20 degrees.

As for removing the old starter? This is one of the more challenging jobs on a spider. Those top two bolts aren't easy. You just have to play with a combination of 13mm sockets, socket extensions, and a swivel joint. Depending on how large your hands are, sometimes you can get a hand up between the bellhousing and transmission tunnel, in order to feel where the bolt is. If you can change a starter motor in a spider, you have reached elite status in your quest!

-Bryan

[Nut124]

Hi, thank you again for the advice.

I found an article on the Mirafiori database regarding the vacuum unit on the distributor. Apparently if this unit is faulty it could be the reason my engine is chocking at 3,500 rpm. I connected a tube to the top of my unit and tested it by sucking and blowing down the tube. Nada! There was no resistance either blowing or sucking. Does this mean the unit is faulty?

What do you think?

Regards

Charlie

Charlie, the vacuum unit is most likely not the cause of your problem. However, retarded timing could be the cause. Check the timing with a light and make sure timing advances as rpm goes up. As rpm goes up, more advance is needed. If not lack of advance, then your problem is likely fuel delivery under load.

Does your engine pull strong past 3500 in 1st gear?

The vac unit, when properly installed, adds power at low loads, even cruising at 55mph.

[charlielucky]

Good Morning Bryan, I had a quick check with the timing gun and it does look like my timing is advancing. A friend is coming over sometime so we can check the degree of advance properly. One thing that concerns me is the high idling rpm. I put my glasses on and it was actually idling at over 1500 rpm. I tried screwing the idle adjustment screw right in and it will not go below 1500 rpm. The Mirafiori site's detailed instructions on setting up the idle suggests that high idling can be caused by a problem in the distributor. Over here in Europe we have some good suppliers in Germany for parts and they have a new complete distributor for sale for 189 Euros. More money.... The good news is that I gave up trying to remove the starter motor and gave the terminals a good clean up on the old one and it works perfectly. My local mechanic told me the old one was a dud, so I now no he didn't check the terminals! I'm going to send back the new unit.

Charlie

[18Fiatsandcounting]

Very good Charlie, let us know what you find out. The ignition timing is a pretty critical aspect on these cars, so it's good that you have a friend to help you get it right. Incorrect ignition timing can cause a high idle, although it's often caused by an air leak.

Yes, if you got your current starter motor to work, that's definitely the easier approach.

-Bryan

[charlielucky]

Hello Bryan, So my friend came over and we checked the timing. With the gun attached to the cylinder 4 ( the back most cylinder). the timing mark was lined up exactly. We backed it off about 10 degrees so that the marker lined up with the middle mark. The engine idle was much improved but the problem still remains. So we had a good chin wag about all possible reasons and we reckon it it the AFM that for some reason is not giving the right signal. The engine chokes and is unable to recover as if the ECU is confused.

I've taken a look at the various posts on AFM issues and it could well be the culprit on my car.

I'll keep you posted.

Charlie

[charlielucky]

Hi, just a little update on the same problem. I plan to send my AFM to Arnold in Germany to have it checked over. In the meantime I did another fuel pressure test following the workshop manual. I connected up the pressure meter between the fuel rail and the cold start unit. I removed the vacuum hose from the fuel regulator and activated the fuel pump by band with the AFM flap. The pressure was 3.7 Bar. My understanding is the it should only be 3 Bar. Could this mean my new fuel regulator is faulty? Is it a problem if there is more than 3 bar pressure?

Thanks for the help.

Charlie

[18Fiatsandcounting]

I removed the vacuum hose from the fuel regulator and activated the fuel pump by band with the AFM flap. The pressure was 3.7 Bar. My understanding is the it should only be 3 Bar. Could this mean my new fuel regulator is faulty? Is it a problem if there is more than 3 bar pressure?

Charlie, that pressure does sound somewhat high. I think the fuel pump for the FI cars should have a max. pressure of 3.2 Bar, and the regulator keeps the pressure between 2.3 and 2.7 bar when the engine is off and around 2 bar with the engine idling.

Do you have the right fuel pump for your car? I'm not aware of any adjustment of the pressure.

-Bryan