986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Boxster Misfire

Legba · 10-03-2012, 01:54 AM

Can anyone advise on the following please?

Boxster 2.5 1998 63000 miles.
Serviced 800 miles ago including new spark plugs and air filter. It had been misfiring prior to this and it improved it but it is now worse than ever.
The car is not used often and when it is used it is usually for short runs. However, I did take it for a long run last week and since then the problem has been worse.
I have not identified any air leaks.
I have tried disconnecting the MAF and it made no difference.
I have cleaned the MAF with electrical contract cleaner. Prior to cleaning it looked a bit dirty and is now clean. This made no difference.
As this problem is getting worse and the weather is getting colder could there be a connection?

Symptoms:
Cold start idle is fine. Hot idle is fine.
On revving above about 2000 rpm there is a misfire and revs drop to idle speed.
If I run it and rev it long enough for the engine to reach operating temperature the engine runs ok.
For some time prior to this the engine occasionally misfired about 4000rpm but this would eventually clear.
I borrowed a fault code reader and it showed misfire on 123, I cleared it and ran the car again and this time it showed misfire on 456. No other faults shown.

10-03-2012, 01:54 AM	#1
Legba Registered User Join Date: Sep 2012 Location: Ipswich UK Posts: 16	Boxster Misfire - suggestions? Can anyone advise on the following please? Boxster 2.5 1998 63000 miles. Serviced 800 miles ago including new spark plugs and air filter. It had been misfiring prior to this and it improved it but it is now worse than ever. The car is not used often and when it is used it is usually for short runs. However, I did take it for a long run last week and since then the problem has been worse. I have not identified any air leaks. I have tried disconnecting the MAF and it made no difference. I have cleaned the MAF with electrical contract cleaner. Prior to cleaning it looked a bit dirty and is now clean. This made no difference. As this problem is getting worse and the weather is getting colder could there be a connection? Symptoms: Cold start idle is fine. Hot idle is fine. On revving above about 2000 rpm there is a misfire and revs drop to idle speed. If I run it and rev it long enough for the engine to reach operating temperature the engine runs ok. For some time prior to this the engine occasionally misfired about 4000rpm but this would eventually clear. I borrowed a fault code reader and it showed misfire on 123, I cleared it and ran the car again and this time it showed misfire on 456. No other faults shown.