I had a similar miss fire? After replacing the timing belt I fired up the engine before replacing the alternator/ serpentine belt and it ticked over fine but with light throttle it would miss fire and smoke. I thought the worst double checked valve timing, all ok. Completed all, fired it up again all ok. Disconnect the alternator and it started miss firing again. May not be the same reason on yours but if the alternator is not giving a fall charge to the battery like mine it would miss fire. I still don't understand why? and have posted here in the past with no real answers.

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2005 KJ RENAGADE 2.8 CRD 6 SPEED NP242 FULLTIME 4X4

Im pretty sure its charging fine, but i'll check it out ! mine was the same before i put the aux belt on as after. interesting fault you had tho..

ok this behaviour bothers me to,, I'm comparing this with my jeeps behaviour ,if i run engine in park (door open) at 1800rpm engine sound like its miss firing on one cylinder , going over 2000rpm and back to idle no miss , back to steady 1800rpm driver door shakes, engine shakes same like yours , but when i drive this thing on the road its normal. it has a lot of power so thats why i say its normal. yours is losing power and the next day you got power back , so to me its fuel related , i know its stressful , would you try running from fuel container ( bypass ff housing ) but put inline filter, or look for spare boost press sensor , or speak to a bosch tech seek advice , fuel return test may not be enough to tell injectors health. i know bench test is probably expensive , don't give up , and good luck.

I have some power back, it is of as lumpy I guess down to no air bubbles, but performance is blunted. Feels like 60% output (it has been torqueier recently). To note it was only better after it had been on a short run so engine was a little warmer.

I think I shall get another map/air temp sensor from eBay. It is better plugged in than not. If air temp was not right then it potentially could undersupply cold/visa versa?

So close to being good now, I can see the light at the end of the tunnel... I'll do a few more bits to it but if not I'll be taking it to a specialist see what the think..

Ok so new lift pump fitted, and new MAP / Air temp sensor fitted. did a 2 mile drive and it felt fine - good almost. stopped for 20min went to drive home then was running rough. but it was definitely modulating from good to bad, from one throttle application to another..

so my thoughts are that I have a sticking injector or air getting in.

I cant believe that air is getting in so its time to send the injectors for test.

I know some people on here have disconnected the injector wiring to test if one is not performing but if i do the car shuts off and would not restart unless they are all connected..

update, checked again and air still getting drawn in at pump head. Have run Injector cleaner closed loop in engine bay and bypassed the filter head again. in this setup there was no air going in (return has a few micro bubbles).. set up with an inline filter still drives flat up until 2500 rpm with seriously low output and lumpy driving below 2000rpm then power increases from there over 3000rpm and it goes pretty well.

with filter connected the air only gets drawn in when throttle is shut off. I would imagine that you would get back pressure with a shut off throttle but it seems to pull lots more vacuum. why? I imagine the MPROP valve is opening reacting to fuel rail pressure rise to reduce pressure which in turn pulls more vacuum? is this normal..

some air bubbles are normal , i don't think you have air in fuel issue, somehow you need to see rail pressure , but 1st i would run it direct fuel from fuel contanar bypass the fuel tank sending unit , put it on pass floor , secure it good and go around block , if it behaves the same ,then you got to check rail pressure , injector bench test , cp3 or go to bosch people to see what they think , i know some fuel shops won't talk to us ,but you need to drive around back they my be on smoke brake ,,,

Ok so I whipped out he injectors. The clamps were tight (torqued to spec) once clamp was removed it was too easy to get the injectors out and they came with the copper washers attached...

1,2,4 were loose to twist by hand and nozzles were wet. No3 was tight and was dry and sooty.

1,2 had diesel In the injector bores. I wonder if the seals were letting by under high boost & high torque , causing loss of compression- missfire and white smoke due to lack of ignition?

I think I need to re cut the injector seats as it can't have been sealing properly. This could explain the good leak back tests (nothing wrong with the injectors?)and why it idled fine (sealed under idle conditions. I imagine that the higher revs were creating more ignitions so as to seem to drive better?

Injectors are goon for tests today so I'll cut new seats while I wait for their return

good , just don't over torque injector hold down bolts , it easy to strip threads don't go over 22ft lb

ok will do. I have been informed that all injector nozzles were burnt and damaged, 2 with very poor delivery in low range and 2 with below average delivery. I cannot disprove this so have opted for all 4 to be reconditioned at a sum of £440. If nothing else they should out last the engine..

I have been worried about the bolts torque as I have seen the posts on here when it goes wrong!!

yes ,injectors are so expensive , i don't use torque wrench on this bolts , i have better feel when to stop ,not to go pass that point with small rachet and 10 mm socket, most important part is , injector cup cleanness ! i did it with cotter tool , just skimmed some aluminum nice and flat , washer won't leak any more, lot of guys here use shot gun brush you sad you have this cutting tool , i like it works good

did you fix it ? i hope you did and went on the trip

I have just fitted the reconditioned injectors. wow immediate difference it started and Idled with alot less clatter and was idling smoother. I had recut the seats with a 17mm Flat reamer and cleaned them with a q-tip (cotton bud). I left to idle for 10min and took for a very light test drive. boost seemed to come in lower down and it pulled consistently. I am looking forward to getting it out on the open road to see how much difference the recon has done.

I have to replace the fuel filter housing. I have a new Delphi filter head with integrated primer bleed etc, sitting waiting to go on, this should eliminate the air being sucked in from here which I believe has been like this for some time causing the injector wear etc....

I have a video to upload of it idling now. be interesting to compare them one after the other.

Good news, I am tempted to have mine checked, it ticks over fine, if I floor it, it will pull like a train but a bit lifeless below 2500rpm. Did you send the injectors away? or local shop.

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2005 KJ RENAGADE 2.8 CRD 6 SPEED NP242 FULLTIME 4X4

well a test drive was taken, it is a little gutless cold but some diesel motors with auto trans are until they warm up so im putting it down to that. runs fine when warm.. was going to go for another run out but sat with the lights on too long while i was checking out under the bonnet and then it wouldnt start. so that concludes todays work.

lacbrera - if your engine idles tock tock rather than tick tick then maybe worth getting them checked, I had them checked at essexdiesels.co.uk in Tilbury essex. £15.00 each to test and £110+VAT to rebuild. Also I can recommend Dieselbob up in lancashire (i think) dieselbob.co.uk ...

https://youtu.be/_rC5kHfr0aI

Thanks. Mines tock tock lol. Compared to my older 2003 2.8 its definitely not as quiet. I know its not mechanical, rebuilt the whole engine back in the spring. Good luck with yours. o did you replace the high pressure fuel tubes? Had my injectors out a couple of times now, If they come out again I am thinking I should replace the pipes as well.

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2005 KJ RENAGADE 2.8 CRD 6 SPEED NP242 FULLTIME 4X4

Its sounds like it might be worth getting them checked. my one revs without shaking the engine now - before it wobbled all over the place.

Re the pipes, I have an audi tdi with a VP44 fuel pump issue and these have been on and off a LOT and they are still sealing perfectly, so I think that they wouldnt be a problem.

150miles of trouble free motoring since repair (still on inline filters till tuesday)

Im quite fond of the Jeep now. It will be going to a new home next week as my good friend needs a solid car..

glad to hear is ok now, yes bench testing is the accurate injector health test, i have 2 new and 2 old ones in my kj , like i told you before i can get it to shake in park at 1800rpm but ok on the road , hoping one day to replace remaining 2 injectors but for now i'll live with it because i spend to much on this spare car , happy that you like the way it runs now ,

What length flat reamer does a person need? All my heads are at the machine shop now or I'd take a measurement. I'm tired of trying to get the seat clean with the shotgun brush.
I wonder if tiny aluminum flakes will cause any problems in the chamber?

Thanks for posting!

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

Mountainman , i got this tool kit from local auto tool store but they discontinue it, it was chip , there is pilot tool and few flat 17mm 19mm reamers also 45 degrees you need 17-19 mm flat you can get it from amazon, as for aluminum shaving , don't worry get vacuum cleaner its ok when you use lube on this rimer wiped out with shop rags.