Hello All, I have a recurring issue on my '94 F355 2.7. Took the car out a while back and after about 40 minutes it lost power and appeared to be running on one bank of cylinders. My local specialist changed the relays and this appeared to cure the problem Sun was shining so took the car out yesterday and it was fine for about 30 minutes when the same thing happened again. I stopped the car and let it cool down ( and made sure the relays were well seated ). When i restarted the car, it ran fine again and got me home. Has anyone encountered a similar issue and what were your solutions? Thanks in advance for your attention,
Welcome to the forum Darran... Did you get a CHECK ENGINE light? Could you identify the faulty bank? Which country/region is the car from? Which relays did your tech replace and did he say why? Fuel pump relays? Engine ECU relays? Left? Right?
List of possibilities. Injector/ecu relay Slow down ecu Bad coil Bad power module Bad crank sensor First you have to determine if you are loosing fuel or spark.
Hello Ian, Thanks for the reply. Car is UK supplied model. He replaced four relays, including both fuel pump ones. No warning lights came up when the fault occured.
My guess is that your problem is electrical in nature given that’s it intermittent. The nice thing about an F355, especially the 2.7 is that there are nearly 2 of everything. First step is to determine which bank has the issue. Then to John’s point determine if the issue is fuel or spark related. Depending on what you find that are certain parts that are interchangeable bank to bank. Try swapping those one at a time to see if the issue moves to the other bank.
Ok, so it may not have the ECU test buttons fitted. Pity. The ECUs can still log faults. I'm assuming your tech didn't have an SD1 or similar Ferrari tool. Some faults illuminate the CHECK ENGINE light, some don't. Y = light, N = no light. Image Unavailable, Please Login e.g. a MAF (hot wire air flow meter) should generate a light. Ok, so the important relays have been changed (but we shouldn't assume that the right right part numbers were used). These 4 relays are special relays with low "pull in" voltages. As mentioned previously, it's important to identify the faulty bank. Then you can swap components to see if the problem transfers. Alternatively, when the problem occurs, you can disable a bank to see if the engine completely dies or doesn't change. Go through John's list (all are common faults): Injector/ecu relay - changed Slow down ecu - these can shut down a bank, but generally you would expect an accompanying SLOW DOWN light on the dash. Bad coil - If the engine starts running badly, you could disconnect one of the coils to see if the engine completely dies. Bad power module - ditto Bad crank sensor - Common fault. In theory, a CHECK ENGINE light should be generated, but you can have crank sensors half working. Of course, you can have clogged/overheating fuel pumps, bad fuel pressure regulators, poor earths, faulty relay panels, etc. These don't always generate fault lights. What tools do you have around the house? Anything to check for spark? Something like this: https://www.ebay.com.au/itm/125288307611? An infra red thermometer to check exhaust temperatures? Fuel pressure gauge? - Earlier cars may have a Schrader valve on the fuel rail for easy connection.
I've had this happen a few times. Issue 1: bad crank sensor (already mentioned), here both ECU's are on, won't throw a warning light, just one won't tell the coils when to go because it thinks the car isn't moving. Relatively easy fix as it's a part swap on an accessible part of the engine. Issue 2: one ECU's power cable was disconnected in the wire harness. Had to have yelcab's help on this one to trace down that the power pin to the ECU wasn't connected. Required peeling back wire loom until the break was located, then re-soldering and wrapping the connection. No ECU fault as the ECU never turned on. These ones are tricky, you may want to have help from a pro (unless you've been fiddling with it and you know it's your own fault).
Don't assume anything. A bad coil or power module will cut spark but not fuel. This can lead to a false SDL due to cat over heating. So if you should get an SDL make sure you check for spark before you start chasing an SDL problem.
