ALFAGTV6.COM

[superfly tnt]

a few days ago i changed the distibutors on my liquid gas powered TS. since then i have knocking when i fully open the throttle. specially on higer load in higher gears at lower speed. i took the complete distibutors with rotors caps and cables from my red fun 75 TS, since i crashed it in my own fence

the interesting part is : no matter how i turn the distributors, nothing changes, so i set them back at 12 degrees off the notch at the distributor. when i turn off one coil the pinging dissapears, no matter which one i turn off . but when they work together something is rattling inside the engine. i wouldnt say that this are detonations but surely its preignition and it sounds like its detonating. i tried also to enrich the AF mixture - nothign changes. the car is running smooth, and accelerating normaly.

this only happens when driving on gasoline. when i switch to liquid gas , there is no sound.

there are a few causes : bad qualitiy gasoline ( i filled half tank of 95, but i doubt its 95) , the motornic red connector is at this time switched to 97 octane, or the coils suffered damage from the previoulsy melted rotor arm.

is it possible that there is so much preignition just because the ECU thinks there is 97 octane inisde? and is it possible that coils suffer damage in that way , that when they work in pair preignition occurs, but working separatly everything is fine?

last option is to throw 25 liters of fuel, because i dont have anything in my house that is fuel powered.

anything else i didnt check?

[Maurizio]

What I remember is that the mapping is very different when you look at ron 95 and ron98 maps. But red plug is open loop RON95 or better.....
Source: http://www.users.on.net/~craigf/fuelquality.htm

GPL is ~ron100??

Somewhere alfa75 on the yahoogroups there is excel file with the standard ignition tables. What the number in there say/mean I'm not sure off.
Enrichment set on the afm when ecu in open loop only changes the idle CO and is not an offset of the complete fuel table, is told to me by the excel file originator.

Rotating the cap wrt the rotor won't change anything in timing (is ecu determined, trigger 60-1 wheel). It will only increase the travel distance of the spark (rotor <-> cap)

I have a similar problem when my ts runs on a squadra chip, original chip everything is ok, even on ron100.
A cause could be not enough fuel > low fuel pressure, fouled injectors, clogged filter etc..... I have to check my system also here.

Very strange is that it disappears when you loose one coil.
I'm no expert, could this mean that the flame front travels slower and is less prone to ping

[superfly tnt]

problem solved. i put extra 10 liters of 100octane fuel and everything dissapeared.

it seems they are mixing (we call it gazolin) condensate. it has less than 80 octanes. it can be used in older cars with huge retarding of ignition.

the thing with one coil working is i guess when one spark fires, the mixture needs more time to reach peak pressure, so it probably reached it after TDC. the last i suspected was fuel, we had problems 10 years ago but it seems there is still bad fuel on some places.

GPL is about 104 or higher