Fuel cut or pre-det??
 

Hi. I was out in my IX earlier on the boost in 5th and the car hesitated for a split second. It happened once in my old IX but I never found out what the cause was. After having a read I'm thinking it might have been fuel cut or pre-det. My car is 'safe mapped' to shell v-power I think and at the time I had tesco's momentum in it, so is it likely the car was just not loving the fuel and maybe there was some pre-det? I'd heard that there's not a lot of difference between shell v-power and tesco's momentum and seeing as my car is supposedly safe mapped I figured the boost wouldn't be too high. Also I've heard about pre-det damaging cylinders and bores, is that the kind of thing that can kill an engine quickly or is it something that will cause damage if it's an ongoing untreated problem, and does that fit the symptom here?

Any opinions appreciated

More likely an ignition issue/misfire. Pre det/knock that makes the car hesitate would likely instantly/quickly blow the engine up and wouldn't happen just once.

Oh ok, well that's reassuring I guess. It just seemed a bit weird that the exact same thing happened in my old car that was aggressively mapped so I figured maybe it was knocking or something. I've just had another quick read up and see that I slightly mixed terms in my original post and there's no reason to think it's PRE-IGNITION. I just thought maybe the ecu was killing the boost to stop engine damage, possibly due to the apparently slightly lower quality fuel that was in it

That wouldn't be a split second hesitation.
I would start with a fresh set of plugs gapped at .020"/.508mm...

OK cool, thanks. I've just had a look through my car docs and even though the history is immaculate the plugs haven't been changed in 20k unless it's been done with no receipts kept, so that seems like a good place to start.

Thanks

Did you boost every gear up to 5th and not notice the hesitation and then only notice on 5th? If you got on it at a low RPM in 5th you really probably shouldn't do that.

Do you have EBCS? If so then it could have been boost cut from boosting over the set target PSI in 5th. Higher gears build boost much sooner and will build more boost at the same WGDC.

I was cruising in 5th and then put my foot down. To describe it better the car basically lost all power for a 10th of a second, or that's what it felt like anyway. It's mapped on the standard boost controller.

What RPM was it when you hit it on 5th gear?

Not sure, I was watching the road lol about 5.5k is a reasonable guess I reckon

Happened again last night, WOT in 6th. I've got new plugs in so it's not that I guess. Dodgy coil?

Have a datalog of it happening?

Nah I haven't got evoscan, I plugged in my obd adapter and loaded the torque app but it didn't do it again, although i'm not sure torque app can even log data anyway

First of all why are you smashing your foot in 5th o_O. BYE BYE RODS. (Unless you are 4K+ rpms... but still I wouldn't mash the gas pedal in 5th.)

So you're telling me I shouldn't go WOT in 5th or 6th?? I had actually gone through the gears rather than just stuck my foot down in 5th, but in certain situations I do exactly that. if I'm overtaking for example. No offence but I find it a little hard to believe that my cars going to be so aggressively mapped that simply accelerating in the wrong gear is going to cause my rods to let go

This is not an issue in a properly tuned car.