VR6 Accereration Hesitation

[Kuchster]

1995 VR6 OBD1

Hesitation when cold on acceleration. Starts and idles fine. Upon hard acceleration there is hesitation or flat spot for 2-3 seconds. It then revs. Upon quick release of the throttle the engine will stall, or stop firing on a cylinder or more and sound like a wrx.
Seems to go alright when its warm.


Throttle body - spotless
Coilpack - no visible cracks or any arcing in the dark
Maf - cleaned
Fuel pressure - 45-50psi, upon removal of vacuum pipe from regulator, pressure increases.
Vacuum pipes leak free
ECU - Nice and clean

On computer diagnostic.
No errors relating to engine.
Temp sensor working correctly.


Also, on air con, pressure guages both low (regas pressure guages). Compressor??

[stevoooish]

Loose spark plug lead on one cylinder.
Yep may sound silly but mine did that due to not having the correct tool to seat them for that "click".
You would think it would ne the same warm and cold, but mine displayed the characteristics you described.
See how u get on

[Bug_racer]

Oil pump

[Kuchster]

https://youtu.be/6IgLvhLgF74

I've replaced coil, leads, plugs.
Only does this when it's cold. Once hot, it seems to run fine.
It starts and idles fine, give it a bit of a rev and its like it's missing a cylinder or 2.