993TT Turbo hesitation

[dlynnn22]

I have 1997 993TT. In 4th gear and above with the peddle to the floor at 4K RPM the turbo spools up to .8 bar, there is a sudden sputter and hesitation at 4,200 RPM. Some poppiong can be heard from the rear and the RPM will not climb any higher untill I let off the accelorator. There was a fault in the mass air meter, it was relaced; no help. New, stronger pop off valves were installed, no help. It was discovered the previous owner installed a V-Chip. An authorized V-Chip rep reconfigured the fuel-air mixture and the turbo settings. This helped for a short time. However, after letting the car sit in the garage for a couple months the problem resumed and to a greater degree. After throwing good money after bad, the porsche dealer could not correct the problem. There is an adjustable fuel pressure regulator in the car. The V-Chip representative does not think it is a fuel problem due to the O2 readings. Could this be a wastegate issue? I do not have access to a 4x4 dyno to fully diagnose. Does anyone have any suggestions?

[geno melici]

I have 1997 993TT. In 4th gear and above with the peddle to the floor at 4K RPM the turbo spools up to .8 bar, there is a sudden sputter and hesitation at 4,200 RPM. Some poppiong can be heard from the rear and the RPM will not climb any higher untill I let off the accelorator. There was a fault in the mass air meter, it was relaced; no help. New, stronger pop off valves were installed, no help. It was discovered the previous owner installed a V-Chip. An authorized V-Chip rep reconfigured the fuel-air mixture and the turbo settings. This helped for a short time. However, after letting the car sit in the garage for a couple months the problem resumed and to a greater degree. After throwing good money after bad, the porsche dealer could not correct the problem. There is an adjustable fuel pressure regulator in the car. The V-Chip representative does not think it is a fuel problem due to the O2 readings. Could this be a wastegate issue? I do not have access to a 4x4 dyno to fully diagnose. Does anyone have any suggestions?

have you checked the coils / plugs?

[White987S]

How many miles? Worn distributor cap???

[wvicary]

Check the operation of the distributor and that both rotors are turning.

[dlynnn22]

There are only 22k mi on the car and the plugs look okay per dealer.

[dlynnn22]

How many miles? Worn distributor cap???

There are only 22k mi on the car and the plugs look okay per dealer.

[carmstrongls1]

My car did the same exact thing. Do a compression leakdown test. Most likely you have a loss in one or more cylinders. It will be very specific when you have it tested. I had a 15% loss in cylinder #1 and sorry to say... It requires alot of work. Not too uncommon in cars that are low mileage either. Since these cars were new fuels have come a long way and carbon build up is bound to happen. If the leakdown test shows lost compression by 5% or more its time to rebuild the cylinder heads. You can try to chemically remove the build up but due to the age it is unlikely. I promise though... I had the exact same symptoms.

[GOR1X]

A common problem is failed actuators. I had noticed that boost never seemed to reach 0.8bar (0.7 max) on mine and when the car was put on the dyno it was found to be producing only 320bhp. The power curve also showed a 'spike' at about 4000rpm where it actually did very briefly hit 0.8bar, but the pressure seemed to bleed away. Anyway, new actuators (GT2 actuators) were fitted and I've got full power back. However, I do seem to now have a slight stutter at low throttle, low rpm. Waiting for that to be investigated.

[magcuda]

Before throwing money at it, put the stock chip back in and see what happens

Of course the V-Chip guy isn't going to blame the chip