456M GTA Stumble/Misfire

I have a 1999 456M GTA that I purchased in December. I drove 1,100 miles to Florida without any issues. While using as a DD there, the idle became rough. Car was checked on Leonardo before return trip. No problems were indicated. Added injector cleaner to gas (twice) as suggested and started the trip home. After about 900 miles car started to stumble/misfire when easing off gas and then reapplying like in high speed traffic. After getting home, problem persists although it is intermittent and usually occurs at highway speeds. Idle is still rough, but not as rough as before. Any suggestions?

 

I am having the same problem with a 2000 550 Maranello, It also has the engine cut out problem when accelerating out of a tight corner. Some threads suggest it may be from deterating rubber in the fuel tank.

 

First thing to do would be to pull the fuel filters and see if they are full of rubber material. If so, time to take a look at the fuel pumps.

 

This..

But also check the connections at both ecu's. If your 456 ever had the bad windows, (and this includes the 550) you can almost bet you have corrosion in the ecu connection terminals.

 

Bill, no CEL's? Could also be an intake leak. See:

http://www.ferrarichat.com/forum/456-550-575/437604-help-i-need-550-guru-misfiring.html

Regards.....Mark

 

Mark- True that. the 456s and Maranellos have a known problem with intake manifold leaks. My manifold bolts were torqued every year, and the gaskets were shot when we did a 5 year. For the Maranellos, at least, the new intake manifold gaskets are metal surrounded by rubber-like material and should be much more robust.

 

Thanks for the suggestions. After reading several posts I had concluded the rubber issue with the fuel pumps was the likely culprit. I didn't think of the gasket issue. Is this gasket involved when the hoses are replaced under the intake plenum? That was done by the dealer before I purchased car.

What a great resource. I haven't had a Ferrari for almost thirty years. While we shared information by long lines and attending events, the amount of information pales in comparison, not to mention the speed at which it is available. We seldom, if ever, had comments from the international community and legends of the Ferrari world. I have been reading a variety of posts. Some related to my car. Some related to the cars of the sixties when I was more involved. And, some that are of interest just because they are about Ferraris.

I should've kept some of the cars I did buy, buy some of the cars I didn't!

 

Bill- Affirmative, the intake manifold gasket would have been changed when the plenum hoses were updated. I still intend to have mine torqued every year because the bolts are lightly torqued and tend to vibrate loose.

I know what you mean. I sold my last Ferrari before this one in 1983, so there was a 25 year period (2008) when I drove mostly Corvettes. Times have changed and it is much easier to get information, both good and bad. Mostly good, we hope.

 

Bill, looks like one more thing eliminated. Also, can be a loose hose. Good luck...

Taz, when you have the manifold re-torqued, to get to the nuts, do they have to remove the manifold covers, TB, MAF, etc. Looks like almost the same amount of work to re-tighten the nuts as to replace the gasket. Like Bill, my plenum hoses were replaced by the dealer before I got the car, so I haven't been down that road, yet. But would like to re-torque the manifold when I get around to annual service.

Regards..... Mark

 

Mark - Thanks for the additional suggestion. My car goes back to the dealer next week for some work as part of the sale. I'm waiting until they are done before I do anything. I don't want to create any problems for myself.