GR Yaris Stage2 issues - jumpiness/hesitation coming off boost

F

fitzer

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May 19, 2022
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Hoping some of the clever minds can help me with an issue I have with my GRY.

I have fitted eventuri, opf delete and dtuk stage 2 box. I run generally on 95 octane fuel as thats all we get here, but tests are the same running NF octane booster which i generally run on trackdays. So i dont think its fuel related.

With the *correct* DTUK map2 for my hardware installed, i have a hesitation where the car is at half throttle, or coming off boost. The car just kind of kangaroos a bit and it quite jumpy only when you are easing off the throttle. With WOT no issues and it pulls really well, but when babying it about the jumpiness is noticable, as you are coming off boost say at 3k rpm.

I also notice turbo flutter coming off boost and can hear air coming back out through the airbox.

I have tried moving the vacuum blank from the t-piece on the top of the intake to the airbox solenoid, but its exactly the same.

I do notice the same with the standard maps 1 and 3 on high settings on the DTUK box but its a lot less. The hesitation does not seem to be in the car when dtuk is switched off, or just not noticable anyway.

Could it be blow off valve related? Car has only 3k miles and wouldnt expect the bov to fail to be honest.

No error lights on dash. No faults, no rough idle, no hesitation at any other time. Just coming off boost hat half throttle or just rolling off the throttle gently.
 
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Don't have first hand experience in this specific case, but I do know that at least one review of your box had similar complaints and also know that generally speaking this is a difficulty for piggyback boxes, on WOT they just add boost, however part throttle driveability is harder as boost can fluctuate quickly and the added box boost signal can become hard to blend in smoothly (as there is always some delay which can confuse the car ECU further).
Also, be aware that this doesn't exclude hardware issues, but since without the box you're fine, I am inclined to believe it's box related... Ask the manufacturer for a solution?
 
I daily it with the box off anyway. When I have it on map1 or 3 its fine. Its just on the "max attack" map that I have the issue. Never had any issues with the v1 box.
 
maybe try one thing at time so no box or fuel boost, then just box at various settings then if that works try box and fuel boost

have say I've use NF Octane boost for years on a load of cars, its by far the best fuel additive out there, on the GRY the engine runs super smooth and at 7k rpm gear change emits very healthy small blue zorst flames
 
As @Pappyjohn says it’s almost pointless using a tuning box if you’re using 95RON. The engine will pull timing so hard I’d be surprised if it’s doing much, even adding octane booster there’s an element of learning the ECU needs to do and these engines are already knock sensitive as it is.

As for your issue, quite a few reports of people with aftermarket intakes getting part throttle hesitation. Mainly GruppeM but I’ve seen a couple of people with Eventuris say the same. Simple things to check are that your MAF is sealed correctly and that your solenoid for the original intake is still connected as the car doesn’t like not seeing the change in airflow
 
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Since there is no issue without the box... But it sure can be bad interaction between intake and box/ecu. Remove intake and see if that solves it?
 
I have an OPF delete, Stage 2 DTUK box, Sprint C-tech intake, Wagner turbo elbow & HKS exhaust and did initially get the hesitation that you describe when lifting off the throttle around 3k rpm. I was also getting turbo flutter when lifting off the throttle.
Have you only just fitted the box & has the box got the most up to date maps?
As other have already said, 95 ron fuel won't be helping but you should have a play around with the maps (it looks like you already have) and see which one suits your car the best, as not all GR's are the same.
Personally I prefer map 3 + 3 with my mods as I found it better than the any of the map 2 maps, if that makes sense.
 
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