TheCaymans987

Hello,

My ‘08 Cayman 2.7 Tiptronic has developed a strange issue, hoping someone could shed some light on it. After searching the forums, I couldn’t find quite the same problem, so forgive me if I’ve overlooked a prior post.

I’ve noticed under light throttle (call it 5% - 10% max), the RPMs will go up as normal, but then drop to just below idle speed, then jump back up - it will do this repeatedly, all the while my foot is steady on the accelerator pedal. What would cause it to fluctuate like this, even though my foot is steady (not pushing down further or letting off) on the pedal?

Makes reversing into the garage a little interesting 🫣

The car runs beautifully otherwise and the iCarsoft POR-II tool isn’t showing any codes.

Zirconocene

Manual or automatic?

ETA: Sorry, just read more closely that it's a tiptronic.

To me this doesn't sound like a MAF issue, more of a transmission issue. I have that going on myself and suspect that it's a valve body issue. I replaced the torque converter but it didn't solve the issue.

Good luck

Zepper

he said its a tip.

Do you have a spint booster installed?

TheCaymans987

No, car is entirely stock. I’m thinking it’s the MAF. I ordered a replacement, should be here in a few days. I’ll install and post back if that made any improvements.

8Lug

This happens only when applying light throttle? Doesn’t do it when car is just idling without your foot on the gas?

TheCaymans987

Right, idle is fine and driving around is normal, it’s just under light throttle that it does this. Mostly noticeable when I’m backing up into the garage.

Zirconocene

I edited my response above, since I didn't read closely enough the first time.

Anyway, I'd be more inclined to suspect the transmission. When did you last have a fluid and filter flush on the tip?

Cheers

TheCaymans987

Transmission is good - was rebuilt not long ago. It does this issue in Neutral (see video) and Drive. Pretty sure it’s the MAF sensor - I ordered one and it should be here by Tuesday. Will post back after I swap it out.

8Lug

It could be the throttle position sensor going bad. Not delivering correct voltage/fluctuating at such a small input.

Cemlo

I had a similar issue on my BMW, at idle it would drop and rise repeatedly - it was the MAF and didn't throw a diag code. If not that then 8Lug suggestion makes sense also. Gl

old man neri

This is where a scan tool would come in handy. You could look at some data which should give you direction instead of just loading up the 'parts cannon' and hoping for the best. Just a thought.

Cemlo

"The car runs beautifully otherwise and the iCarsoft POR-II tool isn’t showing any codes" - diagnostic has been done by the op. Point is the MAF won't necesserily throw a code and be faulty, known from first hand experience.

8Lug

Using a scanner with live data functions would allow you to see if the throttle position is changing while your foot is steadily on the gas pedal. That will tell if it’s the TPS failing.

old man neri

I understand. I was suggesting looking at live data such as throttle position, fuel trims, MAF readings...etc. A tool such as the iCarsoft should show a lot more than just DTCs. Should be able to graph data as well which I found helps.