Can't Boost Pass 5700

[Talontsi150]

I can't get the car to boost pass 5700 rpm.

It all started 1 day I was on the dyno. My 95 Tsi made 350 fwd hp, so we let the car cool down. Started it back up tried to made a pass and she bucked really hard at 5700 rpm. It was like fuel cut, rev cut, boost cut all in one. So now I have to drive in vac all the time and that sucks. Oh yeah i was running 22psi before this all happen and had been running 20psi for the pass few years on it.. I change the fuel pump, FPR and the map sensor. Still no luck with it.

List of Mods
18g
SAFc
Slowboy fmic
1g TB
lighten Flywheel.

 

[seth98es]

Boost leak test? Compression test?

 

[romeen]

1) Boost leak test. You may have just popped off a vacuum hose, loosened a coupler or even caused an aging TB shaft seal to finally fail.

2) Check your plugs for damage or excessive gap as it could be misfire if it is doing it only under higher loads.

 

[Talontsi150]

I did the boost leak test, I found very small vacuum hose leaks, so I replace them all with new hoses. Other then that, the boost leak tester held 15 psi. If the TB seal was leaking it should have shown up on the boost leak tester right, I would have heard that hiss sound or seen bubbles from the soap and water i was spraying. I have the plugs gap at .025 on BPR7ES. Even on 10 psi, I can't boost pass 5700 rpm. I did a compression test a few months back, I was getting 158 across the board. The motor has 142000 miles on it, stock 7bolt. Hope this makes sense, I'm here at work sneaking on the net.

Marc-

 

[romeen]

I did the boost leak test, I found very small vacuum hose leaks, so I replace them all with new hoses. Other then that, the boost leak tester held 15 psi. If the TB seal was leaking it should have shown up on the boost leak tester right, I would have heard that hiss sound or seen bubbles from the soap and water i was spraying. I have the plugs gap at .025 on BPR7ES. Even on 10 psi, I can't boost pass 5700 rpm. I did a compression test a few months back, I was getting 158 across the board. The motor has 142000 miles on it, stock 7bolt. Hope this makes sense, I'm here at work sneaking on the net.

Marc-

Since you would normally be running 20+ psi I would repeat the leak test but pressurize your intake to about 25psi. Many leaks will only begin to leak after a certain pressure is reached.

Also .025" is a little small for the plug gap. I would stick with the recommended .028"

 

[Talontsi150]

I put in new spark plugs, left them at the stock gap, still the same problem. Its like the car pulls hard upto 5000, the by 5700 it just bucks really hard and you feel the power loss instantly. I was told to try and switch the coil pack. I'll give that a go today when I get home from work. I was thinking it maybe the rings, but the car doesn't smoke and passes smog with no problems. Also, i'll give that leak test a try at 25 psi, hope the tester dont pop on me.

Marc-

 

[romeen]

What size injectors do you have? Do you have a logger to see what might be going on? I wonder if you're just leaning out too much.

Let me know how the leak test at the higher pressure turns out.