4+ years of near trouble free ownership of my 2007 997.1! Friday the car developed an issue under hard acceleration. Everything is perfect and normal up to 4k RPM, then I get a distinct shutter/stumble (three shutters to be exact) then it continues on, but will much less torque. It's very consistent/repeatable.

Instinct says secondary injectors are out, but I want to get opinions from the board. The car has tune/exhaust/semisolid mounts/sachs 2.5/TPC suspension module and some other supporting mods. Tune/exhaust have been on for 8k miles and 2.5 years without issue. The plugs and all injectors were replaced at the time of tune.

Let's hear some ideas . Nearest dealer is 3hours away and nearest mechanic 2:20. I'd like to have some idea ahead of time. Thanks!!

 

What's a secondary injector on a 997.1?

Plugs or bad O2?

 

Have you logged the car? That would be the first step. Send the log to your tuner they should be able to provide insight.

Sounds like missfires but without logs and codes from the ecu it's a guessing game.

If you have a canned ots tune and no means of logging get a durametric cable. Or a Cobb accesport.

 

+1 on plugs or faulty O2

 

Would the plugs or O2 sensor be such a reliable shutter at 4K rpm? Below 4K everything is completely normal, like nothing is wrong. I do not have a Cobb access but will look into getting one now

 

That is exactly how the plugs manifest. I know you said you changed them, but are they the correct ones for your tune? And are they gapped down properly? Proper heat range?

That is what my guess would be.

DC

 

I'll find out what plugs EVOMS recommends and order. Will replace O2 as well. If that doesn't worked, then make the long drive...

 

I'll find out what plugs EVOMS recommends and order. Will replace O2 as well. If that doesn't worked, then make the long drive...

 

Plugs and/or coils. Replace both and be on your way.

 

interesting sounds more like a sticking or faulty actuator rod to me. Let us know what it turns out to be.

 

While that certainly could be the case....You are more likely to get a boost issue/low boost than you would see sputtering in that case. Seems more like the classic plug/coil issue at that RPM and with the sputtering described....

Assume we will find out if/when he reports back his findings.

DC

 

If plugs and coils doesn't fix it. My next step would check for proper fuel delivery. I would be checking on injectors and fuel pressure. I think O2 sensor failure would throw a code.

 

If its an actuator rod issue it will be low on boost. Is it?


If not then it will usually be the plugs/coils and it will feel like you are hitting your limiter earlier in the rev range.


Hope you get it sorted.