Hello there, i am new on this so i dont know if i am the right forum Is there anyone who can help me with ignition problem? Ferrrari 308gtsi 1981 When engine is cold, cilinder 1-4 only 50% spark cilinder 5-8 10% delay on spark When engine warm evrything is ok. Temp switch in expansion tank is ok Thanks Fred
Most likely the TDC sensor for the 1-4 bank has failed or has a bad connection. Another easy diagnostiic thing to do is swap the connectors on the two Digiplex ignition ECUs: 1. If the 1-4 bank still has no spark = the Digiplex ECUs are OK. 2. If the problem of no spark moves to the 5-8 bank = bad sign for one of the Digiplex ECUs. Also, have a look inside the 1-4 distributor cap for a problem (e.g., broken rotor, filled with oil, loose) and check the coil to dist wire.
Thanks Steve, I already switched the ecu,s , new pick up sensors,new distributer cap,new rotors,new wiring etc. It looks like there is a heat protection(witch is wrong) in the ecu,s. When engine is warm it runs perfecty.
What does "1-4 50% spark" mean? Only 2 cylinders of the 4 always have spark and the other 2 always have no spark, or all 4 cylinder are (irregularly) missing spark about 50% of the time, or something else? Is this a US version 1981 308i 2-valve (I would guess it is since you state the "Temp switch in expansion tank is ok", and a euro version does not have this expansion tank thermoswitch). If it is a US version, when the thermoswitch in the coolant tank is cold (open), the Digiplex ECUs intentionally retard the ignition timing by 5 degrees. Is this what you mean by "5-8 10 degree late on timing"? Can you state what the 5-8 timing measures at 1000 RPM idle when cold and what the 5-8 timing measures at 1000 RPM when warm? (The thermoswitch in the coolant tank should close when warm, and this turns "off" the cold-running warning light in the dash, and removes the 5 degrees of ignition retardation).
all 1-4 cilinders are missing about 50% of the time. It is a us version 308i 2 valve, thanks fore your explanation of 5% delay when cold, this means bank 5-8 is ok. The cold running light does not burn at all. under te passenger site feet there is a switch and two other devices wich i believe operate the warning lights on the dash when running hot on either bank. From the switch there goes a wire to 1 of the digiplex(that explanes switching the connectors does not change anything, is it possible this device gives problems? the heat sensors are not connected on the exhaust.
If your air injection system has been removed (specifically, if the electrovalve mounted near cylinder #5, controlling the air injection system, has been unplugged or removed) that will disable the cold-running light from working IIRC. Has your air injection system been removed? I don't think that anything in the Passenger footwell can mess up the ignition system (unless that wire is shorted to ground). The special RPM relay in the passenger footwell is a thing that detects the engine RPM (by a signal from one coil) and disables the air injection system if the engine RPM exceeds something like 4400 RPM when cold (which you should never do anyway). You can always just unplug that special RPM relay if your air injection system has already been removed. Have you also tried switching the coils? That's about the only things in either bank's ignition systems that you haven't mentioned replacing or swapping.
Can we back up a little here and get some background? I was looking into how to get your cold-running light working, and found some old posts where people reported bad cold-running when they removed (disconnected) the electrovalve for the air injection system and the electrovalve for the fast cold idle system. Was your car working OK when cold, and this cold-running problem just appeared with no changes, or did the bad cold-running coincide with removing/disconnecting these electrovalves?
Hello Steve, good to go back a little. I build up the car and engine because it was departed completely. I did several car rebuilds but never a Ferrari 308. The engine is completely overhauled and never run ok The Car is at engine specialist who would like to get in contact with you on phone to explane the problem better. Is it possibe to get in contact? When possible please sent mail to me [email protected] Thanks Fred
Are you changing the description of the problem? Earlier, you stated that it runs bad cold, but good warm. Are you now saying that it runs bad both cold and warm? (Assuming that your earlier description is correct, and it's an ignition problem on bank 1-4 when cold) Does that mean that the air injection system electrovalve and the fast idle electrovalve were never reinstalled? If so, if you (or the Mechanic) have/ still got them, just plug them back in (each should have a 2-wire harness connector with a red wire and a pink-black wire), and don't connect any vacuum lines to them, to see if it helps the ignition system problem. If you don't have those electrovalves anymore, try connecting a 100 Ohm, 5 watt resistor between each red and pink-black wire (to simulate the coil inside the electrovalve) to see if that helps the ignition problem (it should also make the cold-running warning light work properly). I don't do phone calls.
The problem is stil the same like i discribe before. When engine cold running very bad,when warm ok My mechanic would like to get in touch with you by mail if possible. He connected al kind of diagnostic computer's of wich i dont have any knowlegde and he wants to sent you picture's and films to you with some questions. kind regards Fred [email protected]
Fred -- I don't like doing private communications as that just makes me an unpaid private mechanic. My "price" is that you (or your Mechanic) discuss the problem publicly so we can all maybe learn something and interact together. Is there any reason that your Mechanic can't post his/her questions and photos here? But before even doing (or worrying) about that: 1. Does your US car have both the air injection system electrovalve and the fast idle electrovalve removed/disconnected? 2. If so, this alters the signal applied to pin 6 of the Digiplex ECUs during cold-running in a bad way (the signal applied to pin 6 during warm-running is not affected). Have your Mechanic either reconnect the electrical portions of those electrovalves or install the 100 Ohm (3 or 5 watt would be OK) resistors as mentioned before to simulate the electrovalves being connected. If #1 is true, and your Mechanic does #2, but you still have a cold-running issue -- then it makes sense to dig deeper into the problem (and I would be more inclined to let your Mechanic email me privately -- although I will probably post the information here if he/she won't).
