Got an '02 Turbo with 67k miles on it, upgraded turbos (larger compressor), new motorsport DVs, EPL flash, 100 cell Milltek exhaust, 5 bar FPR, and so on. Pulls strongly, no problems at WOT or spirited driving at higher rpms.


The problem is a slight hesitation when getting back on the throttle at low rpms that's been getting progressively worse. Most noticeable in 1st and 2nd gear. I apply a bit more throttle to accelerate but the car seems to cut for half a second before pulling its **** together and giving me some power. It happens at low rpms, so I guess it's not boost related. As it happens with the clutch engaged I guess it isn't driveline-related either. Engine hot or cold doesn't matter. Tried disconnecting the MAF without change. No CEL, no errors in Durametric. New plugs. The oil pressure dips at the same time as the car hesitates, which could suggest something variocam-related, but I tried the drivelinks activations for the variocam system and the rpms changed for all of them. Probably not a fail-safe way to test the system, but at least it responds. Can the dip in oil pressure be indicative of something else?

The serpentine belt squeals when wet. I replaced it and it still squeals. Not sure if that is related.


Searching the issue yields a lot of answers like MAF, vacuum leak, boost leak, bad plugs, broken variocam solenoid brackets, loose plugs, bad coilpacks, dirty trottlebody, worn clutch, worn egas cogwheels, dirty egas potentiometer, and so on... So I'm looking for some hints before I start to throw money at the problem. Although I did buy six new coilpacks so I have started...

I've tried the stock software to no avail, cleaned the trottlebody, including the potentiometer. I can feel a bit of play in the cogs for the egas system. The center cog seems to be a bit to large in the center so it moves ever so slightly and creates a bit of play. Not sure if it's enough to cause a problem, I would imagine that the spring will keep it firm either way? Is it possble to replace just the middle cog instead of the whole throttlebody?

 

What air filter setup are you using? I had an aftermarket setup and I would have a slight hesitation at low RPMs. Switched to an OEM air box after talking to GIAC, and it's night and day.

 

Stock filter and airbox. Filter is original Porsche, replaced at previous major service, about 3500 miles ago.

 

excluding the possibility of some bad fuel?

i'm going with "dirty throttle body" and/or possibly a cracked coil. lastly injectors. just swingin' wild here, but reasonably educated guessing lol. good luck

edit" oh sh*t. didn't read you'd cleaned the tb! replace the coils asap. report back!

 

Bad fuel is out, I've filled many times, from different stations. I always fill 98 RON (94 AKI).
The throttle body is cleaned and I moved the center cog about 50% around. It made it a little bit better. But it still is a bit of play as the middle cog is worn in the center.

I'll swap out the coils tomorrow and check if it improves. I ordered two new variocam actuators as well and will check them for breakage and swap them out if needed.

Thanx for the tips, I'll report back.

 

Wouldn't that be a pretty serious job???

 

Right!?

thklinge you seemingly know of the variocam "stutter" @ 3k so we would know it isn't that(?) But replacing the actuators is exactly the kind of part throwing to which you allude, and which none of us would hope to participate in.

If the new coils don't eliminate it? I'd be searching fuel issues eg injectors. Good luck man.. you'll get it sorted I'm sure.

 

Yeah, you guys are right, that would be a serious job. Luckily I misspoke and meant a lot simpler part: The brackets holding the variocam solenoids

 

If disconnecting the MAF didn't change anything could it be that the MAF is just bad or on its way out?

Did you try cleaning it? Probably not a good idea to spray stuff directly on it. I like to spray liquid into a zip-lock bag, drop the maf in, and shake it up gently.

 

Also, is it safe to assume the EPL flash was done post turbo upgrade?

What RPM does it idle at, and is it solid?

 

The first new MAF I got was broken. It ran totally ****ty with it installed, so the one currently is at least working better. The supplier is shipping me a new one. Tried cleaning the current MAF with electrical cleaner, no change.

EPL flash done post turbo upgrade. Also tried the stock software, same hesitation. Idles at 750, solid.

 

750 isn't too low? I think mine runs at 950 and I've seen most people say 850.

If I recall there was a post where someone checked the MAF voltage, got good numbers, but still saw better results with a new MAF.

Have you checked for leaks between the filter and TB? (if you use a smoke machine remove your maf sensor first).

 

issue doesn't sound like leakage. more like fuel/spark.

750-800 max are the correct idle and if there's deviation from that at all? there's an issue. a few things on these cars ( ok, maybe 13 ) that should never be in question are the maf and plugs n coils. those are the parts we want to throw at the car, as needed. which is regularly.. esp when tuned with bits.

why would you change plugs and not coils? this could be easier than thought. or not

ps. don't *clean* mafs. discard and replace lol

 

Low hesitation for mine was the DV leaking check them you will be surprised.

 

I've checked for leaks everywhere I can, nothing so far. Haven't done it with smoke though.

Changed the plugs as part of the previous major service. The local Porsche Center didn't have time to do them so I did it myself. The car was running fine back then so I didn't bother with the coils and didn't check the solenoid brackets either. Yeah, got a new MAF on the way.

The previous stock DVs felt fine, but I swapped them for 710Ns anyway. No change.