F355 M2.7 Engine running issue.

My F355 M2.7 Engine running kind of rough.

So I disconnect ECU on the right bank. The left bank is running fine and smooth alone. But on the other hand, I disconnect ECU on the left bank. The engine on the right bank is running very rough and soon stop running at all.

So I tested every sensors to see the if they are all working via an interconnector, they all seems working correctly according to the values references in the repair manual.

Should the right bank of the engine be able to run as the left bank of the engine when alone? i.e. if the ECU on the other side disconnected? If yes then there should be problem somewhere on my right bank of the engine.

Your kind suggestion would be very much appreciated.

 

I would pull the spark plugs on the right bank and check them out. A couple could be fouled up and causing the engine to run like ****.

If everything checks out ok electrically (sounds like it does if you checked correctly), I would pull them and have a look. Could be an issue on the right bank........

 

PAP348,

Thank you for the advise. Do you think that disconnecting the left ECU, The right bank engine should be running as well as the left bank engine running alone?

 

Your MAF could be faulty or not connected right.
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Just quickly, does the engine run rough when both ECU's are connected?

 

Have you tried switching ECUs (I can't tell if your post says that or not in the first paragraph). If you switch ECU's and the situation is reversed or not- then you have narrowed it down more.

 

Check your plugs first. It's the easiest fix. I have a 95 with the 2.7 and fouled plugs are very common since they tend to run rich especially at idle. Do you start your car from cold and let run for a few seconds and shut if off? This will foul plugs on a 2.7. Mine will do it and someone else in town has a 2.7 and if he backs it out of his gargage and shuts off after sitting all night he will foul plugs. Always let it warm up from cold before shutting down.

 

If your car is running properly and you use only high octane fuel such as Sunoco then your plugs should never ever foul.

 

The 2.7 runs rich. It takes a different plug than the 5.2 and the dealer, Lake Forrest Sports Cars, said they had problems with 2.7's fouling plugs. As I said a sister car to mine--2 VIN# difference had the same problem. Mine is a early 355 with a 1994 build date. The factory ran them rich but I just had my computers reprogrammed to take fuel out. I do run high octane fuel.

 

Bob, there may be something to what you say. There have been posts by Daniel at Ricambi and others, that apparently the recommended plugs for the 5.2 is now the colder NGK PMR8B, where the 2.7 sticks with the hotter PMR7A.

 

My car was running 11.2A/F ratio at idle and low end. Now it is 13.2A/F ratio. Running better off idle and chances of fouling plugs less. You are right the 95 take a hotter plug.
So if a bank is not running right I would suspect plugs.

 

Thank you very much for all advises, I will check all suggested advices before and report to you all.

First I would explain how the problem occurred. I noticed my car running not stable i.e. good but some time during the same drive it ran with less response on part throttle. Then it start showing slowdown warning flashing on and off. After the run, I noticed that the right cat are red where as left on is not. My checking procedures start as follows.
1) Check and pressure on both regulators. Result OK same on both side.
2) Check High Pressure Petrol Pump and their connection on the system. Result Clear.
3) Took the car to dealer and performed more checking using SD3 together with inter-connector. Result TDS sensor on right bank not stable, so it is replaced.

The car seems to run ok at idle for long time i.e. hours. But after test drive same problems still occurred.

Sorry I have to stop here. will report the rest shortly.

 

Continue...

The dealer then test and cleaned all injectors, change spark plugs (pmr7a). Same thing happen again. This time they took out both side engine wiring harnesses off the car to inspect for burnt and clean all connectors and put back on the car. Same problem still occurred.

Now they tried swapping ecu left to right. Same thing happen. But the differences is that disconnecting left ecu when car is running. Engine on right bank go rough and finally died. But on the other hand disconnecting the right ecu while engine is running. The left side of my engine still idle smoothly!!!

This lead back to my starting post question.

Can the engine be able to run as smooth on the right side as smooth as the left when right ecu disconnected on any other car with M2.7 with single high pressure fuel pump?

 

my 355 2.7 was running rough too. when i was changing out the waterpump engine in, we noticed when we were reinstalling the airbox that 1 cof the rubber rings had been deformed from the airbox net being put on properly. i was able to fix it and reinstall the airbox. this vastly improved the running condition of the motor. part # 145644.

hope this helps

 

how did you replace the water pump engine in?
I thought this can only be done engine out?

 

Remove the fuel tank. Hour and a half job tops to remove the tank then u have access to the pump

 

Swap the ecu around and if the bank that runs rough on just one ecu then runs ok its an ecu problem, if not then just work on every sensor and connector on the rough running side.

The 355 is basically two 4 cylinder engines side by side and the electrics work on that principal.

I have a matching pair of 2.7 challenge ecu available if you are in need.

 

I have run the engine on one bank by accident (right bank running) and it does run smooth so there may be something in your thinking process. You have a misfire, you need to find that. My 95 355 did the exact same thing when it was nasty foul plugs. Good luck.

And yes the effing 95 355 will foul plugs just because youi think about it

 

If functioning properly 2.7 like any other will idle at stoich when up to temp as it's in closed loop. (mine does as verified with wideband).

Never tested it during a cold start (so maybe excessively rich then in open loop) but as mentioned if it gets started I let it run long enough to come up to temp completely. (and never had a fouled plug)

 

Be careful Jim, you will get stoned by the masses as I did suggesting an idle warm up

 

Clean the airflow meters with MAF spray.

Or, if you want to try another test, it is only a few minutes to swap them left for right.

I am surprised you haven't mentioned this as being done yet.
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This is a 5 year sold thread guys.

 

Did not notice.

Still relevant, the early "current sensing" MAFs are overlooked how finicky they really are, because their self cleaning routine doesn't work very well in the world of rarely driven exotic cars.

 

Well it is Friday, I guess getting a little stoned is okay

I prefer to start up and drive off easy/low rpm for warm up but I will take an idle warm up to full temp over a cold start and quick shutdown any day.

 

Bumped by a guy who joined in 2012....and this was his first & only post. WTF? Weird.