VersaTune User Forum

Hi guys

Hope everyone is doing well.

I need some help as i am currently clueless.

I installed a GT28 turbo a few weeks ago. Started with the tuning on VersaTuner.
0'd out all corrections and wgdc. Commanded a very low load of like 1.75. I did this just to see if i will be able to hit it seeing that im at 5400ft.

Slowly started to increase wgdc. At 60% commanding i was only hitting a max load of 1.55 @ 1bar 14.7psi boost. My MAF is calibrated and i only see MAF V's of 4.08-ish Volts at best. I have a 3" sri and tip. I thought that I would test the wgdc and upped it to 70% and also increased the loads to 1.8. The results where exactly the same as before. Wgdc did not go over 60%, boost did not go up nor did anything else. Im commanding an AFR of 11.4 and hitting that. Boost does not go over 1.05bar...which I think is very weird. Boost liimits are set to close throttle ar around 1.25bar.

My mods are: 3" sri + tip, full 3" turbo back, devils own d04, versatuner, GT28. Still running stock mbc.

Im at a loss guys. Thanks in advance

PS. There is part of the log where u will see actual AFR > commanded AFR. This is not my concern. The MAF was calibrated before I increased the WGDC. I actually expected a bigger difference in actual and commanded. But that is not my concern atm

You have a boost leak and you calibrated your MAF around it.
At 4.06 MAF V I'm at 214-216g/s and I'm only 1% richer. And that's with a Cobb SRI (2.69"?), while a 3" intake should flow at least 10% more at the same MAF voltage. At the same MAF V you're at 208-210g/s.

Actually it's possible that you may have both an intake leak (post MAF - pre turbo) and a boost leak (post turbo - pre IM). The turbo is sucking unmetered air through that intake leak and is spitting it out through that boost leak. Check again all the hoses, fittings, clamps, IC, meth nozzles, whatever.

Did you install a restrictor plug in your boost reference line from the compressor housing to the solenoid? A .030" MIG welder tip fits nicely inside a silicone line. Some people use nitrous jets or carburetor air bleeds.

Ive never seen > 4.10V with a 3" cai or sri on my car. The maf cal is from the K04. I left it like it was as it was in abs(2). Thought that adding the gt28, it will be a bit leaner and i can just work from there. As far as i know theres a 0.8mm restrictor pill in the line going from the actuator to the turbo. I just removed the hoses from the K04 and plugged it in as it was onto the GT28. Can it be an actuator issue? Car only boosting spring pressure as the actuator is not working properly?

The restrictor is in the nipple on the K04, not inline. Unless you added one, you probably do not have a restrictor.

Thanks Steve. I will have a look and install one. Also, i recall now that when i took my ic for a pressure test there was a leak on the ic cold pipe where the meth nozzle is installed

There is a MIG restrictor in it, 0.8mm i think, if im not mistaken, could the size of the restrictor pill have anything to do with it.

Hi Mituc, Kev, has the same turbo setup as me, but he's using the stock/oem ebcs and a top mount ic.......

It's one of the hybrids

You need to match the size of the restrictor to the flow rate of the BCS. If using the stock BCS, you need to have a restrictor the same size as stock.

Also, what spring pressure is the new wastegate actuator?

Im taking a shot in the dark here but i think the spring rate is around 1bar. Do you maybe know what the stock restrictor pill size is Steve?