Swaped but not happy

[PA3.4l]

Frustratedpa3.4l 3-18-2009

A little history... 98 boxster 2.5 swaped to 3.4l in 2007 ran it for a year and was not overly impressed. Thanks to board members found that I had the boxter program in the ecu. Had ecu reprogrammed and the car really takes off and revsto 7200rpm. yeeeeeehaaaaaaa. I am very happy with the power but since the remapping of the ecu the car will spuratically act as though it is misfiring at 2500-3200rpm under light acceleration. Problem is that it is very hard to duplicate.

Things I have noticed....

• No cel lights
  
• If in neutral and I gently rev the engine to 3800rpm I can hear the same sound as when driving --like a back pressure issue??? could exhaust be causing the loss of power???
  
• Drive hard the car runs fine
  
• Cold weather car does not act up at all ....Could it be a maf thing .. I know cold air is denser so is my car starving for air under low exceleration in warm weather >40.C
  

Since its hard to duplicate how do I go about fixxing the issue are the some test that can be done

The box has Dansk headers and 100cell cats and ghl exhast with 3.4l 996 motor.

Thanks in advance for any input

[phillipj]

It sounds like the Variocam. Around 3k rpm is when it kicks in. you should cantact Todd (member name "Tholyoak") on this board. He has done many Boxster conversions and is very knowledgable. He should be able to help you sort it out.

[PA3.4l]

Will pm him. Any other ideas

[phillipj]

These swaps are really a "tuner" project. It's not as simple as installing the engine and have it work perfectly right out of the box. If you did the swap with a mechanic with little experience in swapping to a 3.4 you are bound to have issues.

There are quite a few folks here on this forum that have done these swaps. Keep asking questions and someone should chime in to help you out.

If you still don't get any answers PM me and I will get you some numbers of people to contact.

Edited March 22, 2009 by phillipj

[PA3.4l]

Becasue the issue is hard to produce while driving. I didn't want to be told that there was nothing wrong with the car. I can reproduce the misfiring sounds but it doesn't equate to loss of power just a firecracker sound at 2400rpm held steady. Im not sure what the Installers can do but I will call them. Are there any types of test that can be performed?

Thanks

Edited March 22, 2009 by PA3.4l

[tholyoak]

If the swap is done correctly They really are plug and play. Doing it correctly is the issue.

Just because you don't have a CEL doesn't mean there aren't pending codes that may shed insight into the problem.

Are you still using the stock airbox and MAF housing?

-Todd

[PA3.4l]

Hey Todd

Thanks for taking the time. Using a Actron Ob11 reader the car shows no codes. But I guess if i really want to see whats going on I'm going to need something more sophisticated. I wish I knew if I was using the stock airbox and Maf? At this point I will assume that I am not. (will call the guys who did the swap) But If I am then what needs to be done.

Edited March 24, 2009 by PA3.4l

[Stefan]

Did you properly wire up the resonance flap? That is supposed to open at 3k RPM and if it isn't that could cause a stumble.

You can tell if it's working by looking at the second intake plenum (closest to the front of the car), revving the car up and seeing if the rod turns.

[tholyoak]

Open up the engine compartment and take a look, should be quite easy to see by visual inspection. Also Stefan makes an excellent point about the correct wiring of the resonance flap.

-Todd

Hey Todd

Thanks for taking the time. Using a Actron Ob11 reader the car shows no codes. But I guess if i really want to see whats going on I'm going to need something more sophisticated. I wish I knew if I was using the stock airbox and Maf? At this point I will assume that I am not. (will call the guys who did the swap) But If I am then what needs to be done.

[PA3.4l]

thanks i will take a look this weekend