Loosing 1-4 or 5-8 cycl.

OK, I have had a problem with my 308GTSi backfiring. My tach would drop for 1000 to 500 and then backfire. I take that the backfire comes from the gas building up. I checked the plugs they where a bit white. Is thiss lean? How can I change that to richer? What would cause 1-4 or 5-8 to go dead? Now, I am only guessing these are not firing. I can let it idle for about 3 min then it happens. I can get it to fire if I rev it up. Any help or suggestions is appreciated.

PS. Will I hurt the car if I run it like this? Once I break 1000rpm it drives fine.

Thanks

 

Look at my post, 308 sputtering and tach loss. I think it's our distributor and the front one at that. Let's see who writes us.

 

You can buy really cheap scope meters and metter from the local autoparts stores and Fluke co. . Use these to diagnose your spark. If it passes then you can look to fuel. But in general if you have proper corrdinated spark then it is your fuel. You can have delivery problems and vacum leak problems and even air entering from exhaust and exhaust manifold leaks that explode unburn HC's in the pipes. Distributor problems are a cause of bad spark patternes you may see on a scopemeter. Try to get the right diagnostic tools other wise you keep guessing. Sometimes you are right and sometimes you are wrong. If you ask this board you will get 7 possible answers and most likely one guy is correct. But if you diagnose it you wll save yourself time and money.

 

Do you have a pic of your scope? What brand/model do you have? Thanks.

 

If you're losing an entire bank, it could be one of your TDC sensors is crapping out.

 

OK, I a newbie. What is a TDC? The problem is much worse now. I haven't really driven the car at all today. Probably 1 mile. I do keep starting it and checking on things. Now it happens when the car is warming up. The tach drops to 500 every time. Nothing else but 500rpm. If I punch the gas it the rest kick in (I think). I wanted to drive around the block but, I am even affaid of doing that. I have only had this 308 for 1 week. Everything was fine until this morning. I am about to cry over here.

Thanks again for the help.

 

TDC....Top Dead Center is a term referring to the timing of a vehicle's engine. The term refers to the crankshaft rotational position where the piston is furthest from the crankshafts center line.

Without the correct Top Dead Center reading, the timing cannot properly adjust.

I suggest that you don't drive the car, serious damage can be done.

Whatever you though, don't panic and don't cry; the problem will be resolved.

Did you purchase it from a dealer?

 

A very common problem on 308i and QVi are the bulkhead connectors on the left side, just in front of the coolant tank. Wiggle them with the car running and see if the problem presents itself. I have fixed more than one 308 simply by cleaning that connector with contact cleaner and a brass bristle brush.

Also, check the magnetic pickup sensors that you'll find at three places around the circumference of the clutch bell housing. The wires tend to get stiff from heat cycling and tend to break off at the connector.

Dropping ignition on one bank of cylinders can (and will) result in engine damage. It can happen at cruise speeds and you may not even notice. In a short amount of time the unburned fuel will wash the oil off the cylinder walls. This results in rapidly worn rings and bores. A bottom end rebuild comes next...

 

No, from an individual. I just spoke with him. He told me to check the rotors in the distributor. Sound like a possiblity? I already used the contact cleaner on the other wires to. Never did wiggle it when it was on though.

 

It could be a hole blown in a rotor but, if that's the case, something else probably caused it to fail.

Also, there may be corrosion on the connectors of the digiplexes. They're located in the left side bottom of the trunk, under the carpet and a panel.

It's common for 308s to collect water in that area.

You can check them by disconnecting one, with the engine running, and see if there is a difference in the idle. If there is, or the engine shuts down, that means the other digiplex is malfunctioning.

If there's no change, you've found the problematic digiplex.

Clean the connectors of any corrosion, reinstall and coat the connectors with silicone grease.

Also, listen to what Ric has to say, he's a Ferrari Master Mechanic.

 

OK, I think I have found what is going on here. I have tested each coil for spark. They are both fine. Here is what I found, from the rear coil there are 2 wires - yellow/green. Neither of these produce spark. If I unplug the front coil wires and switch them to the rear coil then hook up the front bank to it they still work. From what I can see I am not getting spark from the rear coil wires (yellow, green). 1-4 are the ones with no spark from the wires. I don't have my manuals yet. They will be here Tuesday. Please bare with me as I have no mechanical knowledge. I am getting comfortable with taking things apart finally. OK, now - how do I get power to those wires?

 

#1 - To ALL of you thank you. FINALLY - it is back to life! I went back to the very beginning of my post and started reading again. Realizing I never knew what the digiplex was. YES, that was the cause of all of this. Sorry but, I am new to engines and Ferrari's. BUT, I am learning. I am glad to see what a great bunch of people really are here. I love that everyone is willing top help out everyone. Once again, thank you.

Sam

 

So, was it corrosion on one of the connectors as I suggested?

If so, did you coat the connectors with silicone grease to help prevent further corrision problems?

 

Well, I did the same thing and although NO ONE responded to my thread "sputtering 308" I fixed mine as well. Not sure just what was wrong, but I twiddled the control wires to the coils, the orange wires to the distribs, pulled up the rubber socks on the distribs and dug into the trunk to work the digiplexes. Those digis are hard to get at. They are wired to the left edge and come out on the right. With my bumb right arm (rotator curf surgery), I couldn't actually get anthing out, but probably yanking and twisting it did some good. Thanks to everyone who helped, even if your help was coincidental, accidental, incrimental, or sentimental.

Q