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  #10  
Old 06-01-2018
OzRick25  OzRick25 is offline
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Originally Posted by oscar.kruse View Post
I don't have a fuel pressure gauge so for the moment I cant really go down that path. I have checked the brake booster and other vacuum lines and cant see any leaks.

I have still got the stock Y pipe and post cat loop, its just after that where I've removed the other two mufflers and installed smaller ones.
Fuel pressure and quality is certainly worth looking into.

You obviously mean physically smaller but less restrictive mufflers if so I wouldn't think them to be the issue. I was quite surprised at the hesitation after fitting a straight through hi flow cat back to my 3.8 with some of the idrive settings that worked fine prior to changing the muffler.

Throttle position sensor would be a good thing to look at if you don't have the tools to look at fuel pressure. I'd take the intake off get someone to bring it up to power in neutral and see what happens to the throtle if it occurs.

If it doesn't occur you've at least removed throttle position and can go back to fuel, spark, manifold absolute pressure/vacuum leak, or restricted exhaust (partly blocked cat)
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Last edited by OzRick25; 06-01-2018 at 07:18 PM.
  #11  
Old 06-01-2018
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Originally Posted by V82xist View Post
Yep, mine had to be changed at the 48K service due to similar issues.
I have serviced a lot of cars and a few jeeps over the years and I reckon the fuel filter for life is absolute B/S.
For example a while ago I had a WG petrol jeep with 180,000kms that the owner complained was generally down on towing power particularly on long hill climbs but no other general complaint.
Did a full service and checked the individual cylinders with a plug drop test and it was basically a sound motor. Checked fuel pressure it was lower than spec at idle which is odd because in my experience they are usually spot on spec, so I went to the so called for life fuel filter and replaced it.

The removed filter was absolutely plugged so choked I don't know how the engine even started I suppose that little electric pump is better than I give it credit for, naturally the engine power is fully restored.
Later I cut open the filter housing to see its internal condition and although the housing was around 130-150mm long and about 55mm in diameter the actual filter element only filled half of the housing the other half of the housing was taken up by the pressure regulator, so the filtering element was only around 60mm long and about 50mm in dia, much smaller in size and surface area than most other fuel filters I have cut open from various other makes that their manufacturers reckon should they should be changed around 40,000 or 60,000kms.
The so called filter for life on some jeeps is a joke, not only is the actual element usually smaller they ridiculously suggest it never needs changing

Last edited by Classic Boy; 06-01-2018 at 09:51 PM.
  #12  
Old 07-01-2018
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Quote:
Originally Posted by OzRick25 View Post
Fuel pressure and quality is certainly worth looking into.

You obviously mean physically smaller but less restrictive mufflers if so I wouldn't think them to be the issue. I was quite surprised at the hesitation after fitting a straight through hi flow cat back to my 3.8 with some of the idrive settings that worked fine prior to changing the muffler.

Throttle position sensor would be a good thing to look at if you don't have the tools to look at fuel pressure. I'd take the intake off get someone to bring it up to power in neutral and see what happens to the throtle if it occurs.

If it doesn't occur you've at least removed throttle position and can go back to fuel, spark, manifold absolute pressure/vacuum leak, or restricted exhaust (partly blocked cat)
Here is where a bluetooth OBDII adapter (quite cheap)and Torque on your mobile could be invaluable. It will allow you to graph your various sensors in real time when it happens again.
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  #13  
Old 08-01-2018
StewartVerity  StewartVerity is offline
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Iíve had the same problem now for quite some time-probably from around 65k. It normally happens around 2250-2500 rpm and particularly when accelerating lightly after cruising. Itís intermittent rather than regular and doesnít happen if accelerating heavily. Iíve replaced the MAP sensor and done a few other bits and pieces to gradually eliminate potential causes. Fuel pressure check and replace the fuel filter is next on the list. Iíll let you know how it goes, or let me know if you get there first.


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  #14  
Old 08-01-2018
oscar.kruse  oscar.kruse is offline
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I removed and cleaned the throttle body about a year ago. Did not fix the issue as i had hoped. I got the Misses to give the engine a few revs while looking down the throttle body. Seemed to move freely without any sticky points.

Was thinking about changing the MAP sensor but hesitate since no fault codes are being thrown.

I ve already got a OBDII adapter. Which sensors exactly do you think i should be graphing ?
  #15  
Old 10-01-2018
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Originally Posted by oscar.kruse View Post
I removed and cleaned the throttle body about a year ago. Did not fix the issue as i had hoped. I got the Misses to give the engine a few revs while looking down the throttle body. Seemed to move freely without any sticky points.

Was thinking about changing the MAP sensor but hesitate since no fault codes are being thrown.

I ve already got a OBDII adapter. Which sensors exactly do you think i should be graphing ?
Difficult to say as it isn't throwing any codes. My first move would be to watch the O2 sensors and the long and short term fuel trims to see if anything obvious happens to them when the problem occurs but you need to know what you are looking for.

Also watch for misfires but these should throw a code although not always.

Professional diagnoses may be a good option. I'm certainly no expert in the field, however I just found this on YouTube. It might get you heading in the right direction.


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  #16  
Old 04-03-2018
StewartVerity  StewartVerity is offline
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Try changing the plugs. Looks to have done the job for me


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