The 75 and ZT Owners Club Forums - View Single Post - Power issue after swapping to alloy inlet manifold 1.8t

Ste.Sales · 21st September 2018, 06:54

Hi all,
Got sick of changing IMG on plastic manifold so I obtained an alloy one to finally cure the leak.
All ran fine until I floored the accelerator a couple weeks later. It accelerated very swiftly until 4000rpm when it started to misfire and splutter.
After investigation, I found the spark plugs gapped at 1.1mm so I changed to 0.6mm. misfire and spluttering now gone. But:
When the revs reach 4000rpm full throttle (2nd and 3rd gear), the car takes off like s**t off a shovel! In fact the acceleration is so severe that the clutch has now started to slip when hitting 4000rpm.
I used torque pro to monitor boost levels. It climbs to 12psi at around 2000rpm then drops off back to 10psi by 3000rpm and holds steady thereafter. I am not getting any boost cut, and there are no fault codes stored.
Any ideas why this has started to happen? Anyone experienced anything similar? Or should I drive with a lighter foot?

21st September 2018, 06:54	#1
Ste.Sales Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Preston Posts: 233 Thanks: 9 Thanked 37 Times in 35 Posts	Power issue after swapping to alloy inlet manifold 1.8t Hi all, Got sick of changing IMG on plastic manifold so I obtained an alloy one to finally cure the leak. All ran fine until I floored the accelerator a couple weeks later. It accelerated very swiftly until 4000rpm when it started to misfire and splutter. After investigation, I found the spark plugs gapped at 1.1mm so I changed to 0.6mm. misfire and spluttering now gone. But: When the revs reach 4000rpm full throttle (2nd and 3rd gear), the car takes off like s**t off a shovel! In fact the acceleration is so severe that the clutch has now started to slip when hitting 4000rpm. I used torque pro to monitor boost levels. It climbs to 12psi at around 2000rpm then drops off back to 10psi by 3000rpm and holds steady thereafter. I am not getting any boost cut, and there are no fault codes stored. Any ideas why this has started to happen? Anyone experienced anything similar? Or should I drive with a lighter foot?