Rags

Hey everybody! Ran into another problem, seeing if i can get pointed in a direction or some help! My fd is doing exactly like the title says, doing a horrible hesitation at 5k. When in neutral the car revs freely up to 8k. When in gear the car drives normal and boosts hard up to 5k, right at 5k it starts reving VERY slowly and i back out of the throttle. 6 and 7k are hesitating badly as well. I'm only running about 6 psi right now and i have all 6 psi even when its hesitating. New plugs. Another thing, I know its bad, but the car will boost hard when cold. It has no hesitation. I dont boost around with it not warmed up. But i did check if it would boost cold.

Here's my mod list for info.
Power FC commander, no dataloggit
Fresh plugs
Marine coils
Half bridge
walbro 255
1000 primaries
2000 secondaries
FPR and gauge
GT45 single
50mm tial wastegate
greddy profec b spec 2 ebc
Afr gauge
3 bar gm map
0 gauge grounds and power all over.

Car starts up first hit, hot or cold, idles perfect at 1200, operates perfectly at 80c, Never gets hot or has non boost problems.

Any information that could help would be awesome!

DaveW

Had a similar issue many years ago - turned out to be a bad plug wire. Weakness in any ignition component can be magnified by heat, since resistance tends to increase with temperature. Also, spark strength can be good enough to ignite a light-throttle mixture, but not enough to ignite the more dense full throttle mixture.

So double-check all ignition components - even your coils.

Rags

Thanks for your reply. About the ignition. I had stock coils on it untill a few weeks ago. I also thought that it was ignition related, and that i had a weak coil. The marine coils were just installed about 2 weeks ago, its all bran new. The problem remained the same with stock coils and marine coils with new plugs.

DaveW

I didn't see any mention of your replacing the plug wires. Did you check them out?

Rags

Yes sir! Replaced them with MSD superconductor 8.5mm's, bran new. Problem still persistant.

Rags

I know this is kinda old but i figured out my problem and i wanted to post for others.

It ended up being a stuck side seal from running too rich. I seafoamed the car for 2 days while hand turning the motor over. I then added a rear oil breather line and a catch can, tied it into the oil filler neck and air filter on the turbo. Bam no more oil sump pressurization, and my boost was back.

DaleClark

iTrader: (55)

Awesome I love when people post up solutions to weird problems like this. How did you narrow it down to that? Did it show up on a compression test?

Dale

Rags

I did do a compression test and i had 85 all around except one face on rear was 91. Car was warm and i have the upgraded starter, so it was spinning pretty fast.
So i didn't really see it there. i didn't even know it was crankcase pressure. I happened to add a catch can, and it filled up in about 10 pulls down the street. So i added these vents to stop the can from filling, and it actually fixed my problem i was trying to figure out.

dawggpie

iTrader: (4)

Interesting. I seem to be having a similar issue. Break up above 6k rpm. I've been meaning to add a catch can, but haven't had a chance to yet. I'm not sure if I understand the reasoning on why crank case pressure causes the break up...? Is this in combination with the stuck side seal you mentioned? Is there a way I can check if my engine also has a stuck seal? Also can you explain what vents you added to stop the catch can from filling up? Didn't follow that part. As I understand, people run hoses from the 2nd turbo oil return port and the filler next to the catch can. What's the vent you're talking about? Thanks! Would be pretty pumped to finally get this car sorted.

Rags

The symptom i was having was a very bad hesitation. The car would rev fine to a point and then rev very slowly with no power. Rather than say ignition breakup.
I don't understand how crankcase pressure lowers power of the car so ridiculously, maybe somebody can chime in on how that actually works.
When my side seal was stuck i was getting tones of fuel in my oil. This went away after the seafoam and added catchcan and vents.
I figure i'm extremely lucky to have it unstick this well. They seem to keep causing problems till you rebuild them.

The vents i mentioned are exactly what you are speaking of.

I drilled/tapped the 2nd turbo oil return block off plate and added a fitting.
Ran a hose from this fitting to the oil filler neck.
Ran a 2nd hose from the oil filter necks 2nd fitting to the catch can.
Ran a 3rd hose from the catch can to the air filter, which i drilled and added a fitting like the block off plate.

I tried to run the catch can without the 3rd line. It filled up within 3-4 days of daily driving.
With the 3rd vacuum line it barly dusts the catch can with oil, i haven't had to empty it yet, and its only like a 10 oz can.

dawggpie

iTrader: (4)

I see. Not sure if I'm experiencing the same thing then, but I'll get my catch can setup and see if it makes a difference. A compression test on my engine showed somewhat low compression numbers, so maybe I'm getting a similar effect of your stuck side seal because of generally bad sealing on my rotors.

Not sure why venting your catch can to the intake would cause it to not fill up. If anything it would add more of a vacuum effect, pulling more oil. Might just be coincidence. Sounds like you're running pretty small diameter lines to the catch can. There's a couple good threads on this topic. Seems people say running -10AN lines seems to be best since the large diameter of the lines allows air (pressure) to escape through the lines without pushing excessive amounts of oil through the lines which would quickly fill up you catch can. Maybe this is what you ran into.