Well I'm new to forum. However I'm a very experienced mechanic. This car has me so damn frustrated that I want to off it but at same time has my heart. Just bout this car a few months back. So far I've did a turbo swap for another basic k03 and took out stock airborne and did a pod filter. Well the car would only push 3psi Max. So I hooked up a turbosmart dual stage boost controller and bypassed the ecs tuning brown n75 unit however I left it plugged in the intake line and still plugged in to harness. Replaced spark plugs for autolite coppers gapped at .30, Boom she hits 8psi all day long. So I decided to get a forge 007 dv and run it as a bov/rv at 20 clicks. Well new issue is when I'm in 5th at 65 and floor it I'll hit 5psi but as soon as it gets to 6-7psi the motor bucks like its under extreme load. If I downshift to 4th and floor it then it won't buck and hits 8psi and pulls strong. What is causing the bucking when I'm in 5th or in town at 35 in 3rd and same thing but if I drop to 2nd 8psi and strong?

 

Sounds like some detonation going on. Adding PSI could do that. I don't have a lot of experience with turbo engines but I do know a little about supercharged engines (belt driving blower types) so the concepts are the same. Engine compression ratios have to be set up to handle certain boost PSI ranges. Depending on the stock compression ratio on your engine, increasing the boost on the turbo might be causing premature ignition of the fuel air mix (detonation). Add in the factor of the turbo heating up the air before it gets to the intake and detonation is even more likely.

We used to run B&M Superchargers on some of our SB Chevy V-8 engines. We had to build them with lower compression ratios than stock (down to around 8-9:1) running a max of 7PSI boost in order to run 87 octane gas in them as these engines were for street cars.

You might try running some 93 Octane or even add an Octane Boost to get it up even higher and see if the detonation subsides at the higher boost conditions. If it does, you'll know what the problem is. You're simply running too much boost for the engine compression ratios on regular pump gas..

 

Stock these cars push 7 to 9 psi as the internal wastegate spring is set for that amount. So hitting 8psi is not to much boost. I run 91 octane as that's the highest around and then I run Lucas octane booster with every tank as well. I need help from someone that actually knows the b5 platform

 

You'll get it figured out. I won't be much help on the turbos..

 

Sorry wasn't trying to be rude Dave. This car just has me so mad that I'm very testy with people. I just would like to know what is going on before I grenade the motor or worse push it off a cliff.

 

Dude.. I understand more than you know... LOL Been there. fortunately grenades are hard to come by.. LOL

Do like I do. Just walk away from it for a while and come back to it later.

 

Are their any OBD codes been thrown by the ECU? Pull them and see if you're getting any misfire codes. If you do, pull the plugs from the cylinders it may list. Check to see if they are either glazed or starting to getting sooty.. It could indicate a weak coil on that cylinder.

 

No codes no MIL light checked with vag com and no faults or dtc stored codes. Pulled plugs today and put in a new set gapped at .025 and its working fine for today. Give it a week to pull up any other gremlins