Hi all, On my 400i S2 the engine has started cutting out sporadically. It usually happens a few minutes after a cold start, and usually at idle. When it does cut out, the engine actually continues running, but at very low rpm and doesn't react to the throttle at all. What could be the cause of this? Is there a cut-out switch somewhere that might be playing up? Cheers Esben
1)When it is cut out at idle, check both exhaust pipes. If one is hot and one is cold, it is one fuel pump cutting out. 2) could be sticky distributor advance Ken
Is your 400i completely stock? No "with Lambda" emission modifications, and still has a Dinoplex ignition system?
Hi! It's stock with Dinoplex. It's got a new uprated fusebox (Guido's), new fuel pump relays and I checked and lubed the distributor about 4000km ago.
With your described symptom (especially if it seems to instantly come and go), I'd tend to not suspect the fuel system being the problem -- i.e., if a fuel pump goes dead it should still rev on the working bank even if weak overall. Never hurts to have a look inside the distributor cap, but same thing there -- i.e., something wrong with one of the ends on the double-ended dist rotor might kill a bank, but the engine should still quasi-operate on the working bank. Dinoplex has never been super great so you might start there. E.g., put a small cheapy Amazon oscilloscope (that you can have in the cabin with you) across the coil primary and see if anything strange happens to the coil primary voltage waveform when the problem happens -- just a thought...(and will be interested to know what you eventually find is the issue).
May or may not be relevant to your situation, but I've just experienced similar symptoms on my Jaguar V12. It had been lying idle for a few years. The engine would start immediately and run at normal warm-up speed for a minute or two, and then progressively slow down exactly as you describe, not responding to the throttle. I put a pressure gauge in-line from the delivery side of the fuel pump, and could see the delivery pressure dropping. I (foolishly) fitted a new fuel pump but the problem remained. Eventually traced the issue to a blocked feed line from the main fuel tank to the pump suction filter. (I had previously cleaned the suction filter and didn't think there was any restriction in that area). Turns out that the 12mm pipe from the tank to the filter was choked up with a combination of rust particles and crud which I think was due to the precipitation of deposits from ethanol mixing with condensation/water in the fuel. There is however a major difference between the Jaguar injection system and the Ferrari 400i. The Jaguar injectors are electrically operated and will still deliver fuel even though the pump delivery pressure is dropping, whereas the Ferrari/K-Jetronic system should not deliver fuel if the pressure drops below the breakout pressure of the injectors, which as far as I recall is just over 3bar. Still, if the 400i fuel pump suction was similarly restricted, the delivery pressure would drop, and might well give rise to the symptoms you describe.
@pattorpey might be on something :if there is some crude in the tanks, after the engine has been operating for a while the return line form the injection has somehow steered the crude in tank and could make the pumps' life much harder. I you do have k-jet pressure test gauge, it would be worth checking what's the system pressure when the engine starts to slow down. If your car did not run for years, I would check the in-tank mesh screens, and perform a drain so as to see the state of the gazoline inside the tank. There is a tap in the 'center" tank that allows to drain the gasoline. That-s in this center tank that the mesh-screens are located. Last but not least, maybe your idle is to low: when cold, the fast idle valves just raise the rpm until they get hot and let the rpm drop to "regular idle". So for an initial period of time the idle is managed by the valves that would mask a faulty idle setting. These valves can easily get stuck, so chances are that they had been stuck open for a while and suddenly started to operate properly? just guessing...
I checked and adjusted the injection system when I got the car about 6 months ago. And also changed the fuel filters obviously. 99% percent of the time the car runs great, the cutting out only occurs sporadically. More often when at idle, but still not often, and very rarely when driving. I'll ave a loot at the tank screens over the winter, but I'm still thinking it's more likely an ignition issue.... Thanks for all the suggestions guys! Esben
