WJDiag Fuel Correction Test
 

Hi all - new account/first post - been lurking on this forum for a few years and it's always helped me out.

I've recently inherited the family 2003 WG with 120k on the clock. Drove it across the Nullarbor from Perth to Melbourne and it did well. The Jeep idles rough (rpm needle shaking around), and I was hoping that the long road trip might iron out some of the kinks - as you can tell my family didn't drive it much - only short trips around the city. Previous mechanic told he that he suspected an injector was on the way out. I believe the injectors are all original, and I don't see any black death.

Unfortunately, the road trip didn't iron out the rough idle ultimately, but I did notice that at the end of each 8hr driving day it seemed to idle smooth and like a dream. Hasn't been a major problem until recently when the WG seemed to be idling particularly rough at the lights and then stalled whilst waiting at the lights and MIL came on with P0190. Started right away afterwards. Since then I've had P0190 twice more whilst driving - once on the highway (didn't notice anything, kept on driving fine), and another time at 50kph when the engine seemed to shudder and jolt but then continue unabated.

I've read that P0190 "Fuel Rail Pressure Sensor Circuit Malfunction" can be related to bad injector(s), so I bought WJDiag Pro and did a few fuel correction tests. I did a bunch whilst idling and driving in different conditions, screenshotted each result then put them into Excel. Here are the results:

https://www.ausjeepoffroad.com/forum...5b11cb1eba.png

The colour-coding doesn't mean anything except lowest (red) to highest (green), just to help visualise. Since WJDiag gave me Cylinder RPM I decided to calculate the % difference of each from average to see if anything came up (right columns).

I'm not too sure what to make of these results - seems like Injector No. 3 is on the way out, but I'm not sure about the others. Should I order a new injector and swap this one out and see what happens? Am I on the right track with the P0190/stalls? There's another thread on here with similar symptoms but there's no conclusion: https://www.ausjeepoffroad.com/forum...d.php?t=153447

Thanks all.

My experience with rough idling was that one of the valve packs in the HP fuel pump was failing. The rough idling came and went, mostly "went" when the engine was at full temperature.

I had no errors. Just like rough idling.

This can mask itself as a faulty injector since the rotation of the fuel pump is synchronised with the camshaft and consequently injector firing.

In your position, I'd contact a local diesel Bosch distributor and ask for them to check a couple of your injectors. You can save money if you do the removal/installation yourself and just present the bare injectors.

Sent from my motorola edge 20 fusion using Tapatalk

Your injector no.3 is at the end of its life.
Time for exchange.
When you add all injectors you should get 0 as an result. Obey +and -.
Anything over 5 mm³ is way too much.
You can tell that 1 and 2 are trying to compensate 3.
All other values are acceptable.

I had yesterday a suspicion that one of my injector would be gone too. The Jeep was driving nice stopped the car and had it in the driveway. 4h later I wanted to leave for going somewhere suddenly the car did not start, I was cranking the engine but nothing happened. Then it started but was idling really rough and even turned off a couple of times.

I then tried it this morning again, still same thing it was idling really bad but got better once the engine got a bit hot and I was then driving for a couple of minutes. Also checked with the WJ diag and could not find any extreme outliners as above so I assume I just had some air in the fuel system. I had this already before way back just the day my radiator literally exploded in my face.

I certainly need to install the other fuel filter with the priming pump. Any idea where I can get some hose replacement for the rubber hoses from the fuel filter to the pump? I guess I have a minor leak here and a new hose could solve the issue?

I picked up a spare hose from eBay after I broke the priming valve. However, in your case you might just need the o-rings. Look in the "everything CRD" thread for the part numbers and Google will be your best bet.

Will do, thanks JeanLuke.

I found some on Ebay sold out of Latvia. They sell either 6 or 8 genuine MB o-rings. I guess I go for these rather than buying crappy Chinese knockoffs.

How many rings are you typically use and how long do they last? If i have to replace them anyway any couple of years I can go for the bigger pack and invest for future replacements.

Thanks
Joerg