RB25 surging problem

[RBZ32]

Been trying to figure out a problem now for a while and still can't pin point it.

This is an RB25DET motor:

Under WOT if I start in 2 gear pulls good, then shift to 3rd, still WOT and car will start to surge as soon as I hit boost.Or, I go WOT in 3rd and pulls good, then shift to 4th and same thing again. Hit boost and will surge. I had a friend watch the UEGO and was on the rich side, 10.8-11.5. Was the same in the previous gear though. I have checked for exhaust leaks before the turbo, all intercooler clamps and they are all good.

Running RC 750 injectors and Greddy E-manage Ultimate. Turbo is a GT6776R and this is at 11psi or 0.8 bar. need to get this worked out before turning up boost.

Anyone have ideas?

[240z4u]

I don't know exactly what you mean by surge. You mean bouncing boost gauge needle? That being the case you either need to try turning up the boost or turning it down.

I had this issue with my t3/t04e and it turned out that turbo was just a bad match for my engine and I replaced it.

[RBZ32]

by surging I mean it feels as if the throttle is being pushed on off on off in very rapid succession. Although the throttle never leaves 100% position.

[Joe]

check your timing, check your plug gaps.

[rb25det250sx]

mine was doing that last summer, and i found out i had skipped a tooth or two on the timing belt, lucky for me it didn't bend and valves. hopefully thats not the case for you either.

[RBZ32]

I have checked timing, was spot on. gap on plugs are all good.

Talked to a local guy that has a 26 and he asked if I had the ECU set up to run MAF and BOV to vent into atmosphere. if not then the fuel is loading up between shifts and what I'm talking about is the effect. So that Is my next thing to check

[Largekid]

its not a surge problem caused by your wastegate or BOV not opening all the way is it? If the exhaust gas or boost isn't released properly, wouldn't that cause it???

[Sil240]

RBZ32 is this what your car sounds like??http://www.youtube.com/watch?v=nCj6Spwl1CU

240z4u - What were the specs on the T3/to4e that you had problems with??What turbo do you have now?

[RBZ32]

No, thankfully it is nothing like that. If the new settings does not fix it, I will dust off the video camera and do a quick video for reference.

[l0nestar]

240z4u - What were the specs on the T3/to4e that you had problems with??What turbo do you have now?

Current is an HX35. I forget what the previous was though.