Pajero Owners Club of South Africa

Recently swapped used 6G74 DOHC engine (for 1999 3.5L Pajero SWB), absolutely same as old one. First plonked engine as it is with all its own component and had slight missing at idle and mild thumping noise. Then replaced all components from old engine and still idle missing and thumping noise is there. Anything above 2k rpm is smooth as silk and absolutely quiet.

Installed old setup: injectors, coils, plug wires, sensors. Bought new standard plugs in place of iridium ones.
Done vacuum check: 18.5 inches at idle, quick open and close throttle showing from 3-28 inch, steady at 3k rpm fluctuating from 18-19 inches.
Done dry engine compression test before installing the engine: All cylinders showed roughly 100 PSI with three cranks on each cylinder.
Got the exhaust and exhaust manifold checked with two reputed shops confirming no exhaust leak at all.
Done 1000km with new engine with all fuel additives liquids and tablets to clean engine valve etc (if its dirty).
Fuel mileage is same as before 400km w/o AC and 350 km with AC in full tank.
Engine oil level stays fine (not consumed) and changed little dirty oil after 1000km.
Coolant level also stays fine, and heat gauge reads steady at 47% (standard).
No black smoke or white smoke from exhaust.
0-100 is almost same as before: 9-10 secs, no power loss on uphill downhill.
Once warmed, rpm isn't fluctuating.


What else i am missing here.....? To eliminate idle missing and mild thumping noise like diesel engine. Please help guys with your expert knowledge. Thanks.

I had a look at EGR valve and it wasn't going in or coming out with or w/o lil gas. (as advised from other forum)

By pressing from hand it was going in fine and was about to stall the vehicle, so that test is cool. Then dig old pictures of engine bay and found that vacuum pipes was interchanged little bit, so kind of fix that. After this removed the battery terminal so that ECU can get reset and started the car.

To my surprise, car missing and body vibration gone by 80% almost but that mild thumping noise is still there. Took the car for spin, i have got that initial throttle response back as well. May be ECU was reading or giving hesitation reading to new engine since installed.

For thumping noise please check the 10 secs video from inside the cabin and outside under the driver seat.

Inside the cabin: http://www.youtube.com/watch?v=Ac8E-f8-I8I
Outside the cabin: http://www.youtube.com/watch?v=dh2YvseKnf8

Unplug the MAF and see what happens.


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Yes i did unplug MAF couple of times to see what happen. It actually fluctuate the idle and then stabilize after few seconds. Same i tried with small sensor under throttle body, may be its idle control valve and it also behave same like changing in idle speed and kept of fluctuating within small range.

Have you seen the video, i posted? Does it sound more from inside the engine (mechanical) or outside the engine like vacuum or electrical issue sound?????

I have checked the noise from mechanical stethoscope and this thumping is more evident behind front wheels (both sides). If i stand in front of engine bay, i cannot hear this. If i go little far like 5 meters away in any direction i can hear this.

Hi,

Did you replace the hydraulic lifters (valve lifters) as well?