Long story. My 2003 4.2 V8 sprang a coolant leak. I stupidly took it to a coolant specialist. They said a hose had failed under the inlet manifold. When I picked it up it was running like a tractor as opposed to my previous sewing machine, even with 200,000 km on the clock. The mech was like ' yeah you have a new problem'

MMMMM - I don't believe in coincidences.

I got a mechanic to check it out and he found a locating pin was bent and so air was being sucked in through the gap at the inlet manifold, hence lean messages. He replaced the gasket, and straighten the pin. Soon after and ever since i've been getting the same 4 errors - P 0172, 0175, 0193 and 0405. They come and go for various lengths of time.

Cleaning the throttle control body seemed to help - even thought Jag says 'special coating - don't clean". I thought bugger this, replace the throttle control body - new, Fuel rail pressure and egr valve - new.

The damn codes keep appearing. On the plus side it seems my fuel economy has improved. I checked the wiring but can't see any issues and as I say I don't believe in coincidences - the original fools have done something.

Also the pipe carrying the gases for recirculation seems wobbly to me but given
its the first time ive delved into that part of the engine, maybe its supposed to be.

Any of you geniuses have any ideas, I want my sewing machine back?

 

P0172 and P0175 indicates it's running rich on bank 1 and bank 2 respectively.

P0193 is IP (Injection Pressure) Sensor circuit high voltage/high pressure.

One of the possible causes of P0172 and P0175 is incorrect signal from the IP Sensor so it's a common factor between these three codes.

P0405 is low voltage on the EGR valve circuit.

Graham

 

Thanks Graham, yeah Ive researched this codes and attempted to determine the intermittent cause to no avail.
The later 2 suggest a common, possibly electrical cause resulting in the first 2 errors, at least thats my take - as poor as it is.

I suspect the rich codes result from incorrect assessment by the ecm which I assume adjusts injector and throttle control body, resulting in it being rich on both rails.

But why is the question.

 

If you haven't done so already, obtain the Workshop Manual and follow the Pinpoint Tests to check the circuit(s) for bent or broken connectors and damage to the wiring loom.

What are the STFTs and LTFTs? What is the fuel pressure? It should be between 3.3 and 3.8 Bar, with 3.8 Bar for Wide Open Throttle (WOT) on the 4.2 normally aspirated engine.

 

Well on one of my captures the STFT bank 1 was -1.6%, LTFT -18.8, bank 2 STFT 0.8% LTFT -20.3% Fuel Pressure 3.87 at idle.

if that helps

I am a relative amateur at all this. I will check the loom again on the w/e, dark here now - Australia.

Thanks for input

 

It's massively having to compensate for being rich.

The things already mentioned give you the possible causes and you can't really do better than go reading.

At some point you might like to try cleaning the MAF as it's cheap and easy. But what the leak did is most likely the real issue.

 

I had a service yesterday, - inc fuel filter. So far no codes! Also the trims have changed. Could it have been the fuel filter? I will watch and see.

 

Hard to see how it would be rich. Lean, yes.

 

Thanks for replies. I have some more data, and rough graphs - the iPad software is rough. Am i reading things right, seem one of the O2 sensors is stuffed, surely they can't be reading so differently and both rails banks reprint a rich situation?

I checked the Jag info on the codes, then checked the wiring. Couldn't find any obvious damage to the loom. Did find 3 the first three injector plugs had broken locking tabs - replaced.

193 seems to occur with either a sensor failure, or wiring issue
405 seems to be the same

if these 2 are affected and feeding faulty info to the ECM presumably it can cause the engine to run rich.

Could the ECM be the culprit or the oxygen sensor?

 

Post #2 looks to nail it, especially with post #4.

 

Thanks. I checked the loom and the connectors. Nada.

Given the loom has no pinch points and the main connector hasn't been opened I can't see how the pins could have been damaged. The IP was the first thing replaced.

As I don't have the electrical skill to back trace the connectors I think its off to the auto electrician.

Given the rich codes are probably secondary, and I believe Occam's razor, the later 2 codes must be related. Maybe Ill look at the wiring diagrams.

 

1)Any chance they kinked the crap out of the return line when they did the work? Fuel pressure seems a bit high at an idle.
2) I had a Ford once that had work done by another shop and they swapped the 02 sensor plugs at the rear of the engine, it acted just like this, each sensor drove the wrong bank wild

 

+1 on docs427's comment that the indicated fuel pressure being too high at idle. According to the S-Type Workshop Manual, your 2003 4.2L N/A should run around 3 bar (43.5 psi) at idle, and at WOT should be around 3.8 bar (55 psi). The fact that you have P0172/P0175 suggests that your P0193 is correct and not just a sensor issue. It would be worth testing your fuel pressure with a gauge to confirm.



Cheers,

Don

 

Thanks Don. Well I spent ages with the I must say annoying JTIS manual.
Eventually I found the electrical checks for P0405 (303-08 - diagnosis) and what is headed P0190, P0192, P0193 which is also the same list for P0172 and P0175 (303-04B - diagnosis).

P0405
SO, what I found is the IP sensor, thats the new one I replaced - failed. I didn't do check B3 under the Jag procedure because that meant disconnecting the ECM PI001 which given its location - forget it, I assumed it passed and moved on. Internal resistance checks B5 pins 1and 2 measured 1k Ohm on the old - Jag says 10-20kOhm, the new 200 Ohm. So both old and new failed.

COULD SOME KIND SOUL WITH THE SAME SENSOR CHECK WHAT THE RESISTANCE IS BETWEEN PINS 1 AND 2 AND CONFIRM JAGS NUMBERS IE BETWEEN 10 AND 12KOHM.

Check B6 Old passed, new failed.

Check B7 Old passed , new failed.

P-0172 P0175 P0193
Then I moved onto the EGR valve, again this was replaced new, re error P0405. I got to B7 and its voltage is less than 1 volt sooooooo it says to replace EGR valve. I thought Ill check the valve, found a process in one of the jag manuals, and ok the temp here was 13C not 20-30 like it says but it passed all 6 resistance tests.

I am confused, the pressure sensor fails, ok Ill get some kind person to double check the resistance step B5 just to be sure - but what the hell do I do with the EGR - one set of Jag tests ends up at replace the EGR, but when I test the EGR the internal resistances pass!

My head hurts now.