Hi guys!
I am writing here because I know that your wide experience may solve this problem:



I have some troubles with the ignition of my car,
at the minimum the engine runs good, and if i give some gas the car starts to "jump", and then if I open all the gas the engine works fine.

I checked the plugs and I found the two in the front very dirty, then I replace them, but after 50km they turns dirty again... just the two in the fron, the other two are fine.

I try to play a bit with the air sensor under the air filter, and with the screw on my ecu (its an european version), but no changes...

what I should check?

grazie,
ciao,
zeno

Zeno, What color is the "dirt" on the plugs? If they are black, that is from running rich. How about the other two? What year is your car? Engine size? I didn't know European cars were injected. Got some pics?
We're gonna need more info.

Check the TPS (Throttle position switch) for proper adjustment.
If that is out of adjustment, it will run to rich.

Check the FI trigger points in the lower part of the distributor.
While they rarely need replacings (100k mile part) they do get dirty and the lower part of the distributor gets full of garbage.

Check the distributor advance plates, remove them, clean them, and re-grease them...the old grease is now like glue.

New points, condensor, distributor cap and WIRES...few people replace the wires, but with all the heat these motors create, the wires degrade alot faster than normal engines. Use Bosch ignition parts only.

Get a hotter coil, Bosch Blue produces a bit fatter spark.

Check your CHT (Cylinder head temp sensor) for the correct values when cold and hot.

Check for any and all vacuum leaks...a small leak makes the car run rich.

Check the MPS (Manifold pressure sensor) to ensure it not only holds a vacuum, but the electrical signals are correct.

Walking through the EFI system in a methodical way is the best and only way to clean up these issues.

Rich

Thank you Rich for your help,
I will check the system tomorrow,
where I can find the right parameters of the sensors, in order to test them?

the plugs have the black grease on,

my car is a 1973 2.0.
All the 914/4 were made with FI here in Europe...

attached a 2.0 engine without airbox and ecu...

http://members.rennlist.com/pbanders/ lots to read there.

k

Black grease on the plugs.......must be oil on the plugs....time to replace the rings

Good luck getting it taken care of and keep us posted.

finally i had some time to work on my car.

I checked out the fi system and some sensors.

The head sensor give me 1600ohm when cold and around 300\400 ohm once hot. So its working properly

the pressure sensor has the right parameters and it seems that there is no leaks on the "air pressure" pipes..

the only things that i haven't checked is the distributor, but my mechanic has checked and clean it last week.

Here attached a pic of my sparks, of the right side head,
the cleanest is the rearer and the dirties is the one in the front. As you remember I found "dirt" only in the 2 in the front.

Now the car runs pretty well at the minimum, maybe is because i clean up the sperks, but once in the road it seems that doesn't run well and seems that missfire once in a while. It has some gap while accelerationg and the car has not the max power.

Do you think that can be the valves?

finally i had some time to work on my car.

I checked out the fi system and some sensors.

The head sensor give me 1600ohm when cold and around 300\400 ohm once hot. So its working properly

the pressure sensor has the right parameters and it seems that there is no leaks on the "air pressure" pipes..

the only things that i haven't checked is the distributor, but my mechanic has checked and clean it last week.

Here attached a pic of my sparks, of the right side head,
the cleanest is the rearer and the dirties is the one in the front. As you remember I found "dirt" only in the 2 in the front.

Now the car runs pretty well at the minimum, maybe is because i clean up the sperks, but once in the road it seems that doesn't run well and seems that missfire once in a while. It has some gap while accelerationg and the car has not the max power.

Do you think that can be the valves?
Click to view attachment