Hi all,
I am new here as i got my first Jaguar (XK (X150) from 2006) a couple years back and i am facing my first problem. As i am a fan of understanding, finding and solving i am trying to understand what is happeming.
So here are the symptoms:
Cold start is perfect,
Quick hot start is ok, but after 10 min of letting it cool down then the start is very difficult.
I started reading the codes and i am running too Rich on the 2 banks, (P0172 - P0175) which i can confirm from the exhaust smell,
when reading the OBDII the 4 trims values are between -20 to -25%, which i understand is wrong.
When running iddle the Fuel pressure is around 315 KPa which is maybe a bit low but not sure,
when stopping the engine, the pressure goes immadiately down to almost 0 in few seconds, which should remain under pressure if i understand (or maybe normal)
I changed the Fuel rail Pressure sensor a year back because of fuel leakage.
I changed the MAF but no change
I changed the EVAP valve, no change.
Does anyone have an idea in my case, on why my trims could be running at -20% and the engine running to rich?

 

Okay, this may be totally off and not applicable.
Your symptoms sound like what I experience in the spring time when temperatures warm up, and I still have a tank full of winter blend gas, although I’ve never read codes or checked running parameters when this happens.
Has this been happening all season long, or perhaps just a recent issue? Is it possible that ambient temperatures are still warm and your area has started distributing winter blend gas (if that is even a thing in your region)?
Just a thought. May be totally off.

 

hi kj07xk,
thanks for your reply, it actually started before this summer, it is still the case now with temperatures going much lower. I still uses a bit the car as the only impact while driving is a loss of power if i try to accelerate suddenly, so i had the case to refill the tanks but nothing changed.

 

Hope for more ideas but it sounds like you have problems with the fuel injectors. I'd expect the pressure to stay up far better than you see and the bad trims suggest the injs are not right.

If you use OBD live data and watch those horrible trims and rev do they improve? Don't rev past about 2500-3000 as I expect the car will intervene (to save overheating trans etc).

 

Hello from Austria , the problem you told , is a problem that i have solved . I think it is the temperature sensor from the engine , this one this was check the water temperature ! Near to the Thermostat !
mfg Bernhard

 

Hi JagV8,
Thanks for the answer, I have tried and when i push the engine revs a bit, i get a spike in the trims but come down again to the -20's. Last week-end i had a doubt around te injectors but i thought i would check if the spark plugs are wet after stopping the engine, but they aren't. they are black certainly due to the fact that it's running too rich.
It is also on both banks at the same time, my spark plugs are new, so i doubt injectors are the problem.
I have this big doubt around a return valve on the fuel pump meaning as soon as i stop the engine pressure does not remains as fuel return to the tanks (maybe), would this impact the trims (maybe again if the pressure is not sufficient in the rail, which i have at 315Kpa and i think normally it is 380kPa.

 

Hi Bernhard,
Thanks for helping, your comment made me think about it, i lloked at the temperatures returned in the ODBII software and it all seems correct, the temperature of the outside air seems ok, temperature of the collant is ok BUT i don't see the measures of the fuel rail temperature and maybe it is the reason, let me double check if i can find this measure in the ODBII tool to check it value.
Thanks for it.

 

Did your problem arise shortly after you changed your spark plugs?

 

HI Sony,
It actually started before, that is why i changed them. it did not change anything...

 

99% chance the frp sensor is skewed or it’s pushing fuel out of the vac line. either way the feedback loop goes into the dumpster.

 

Pay attention to xalty - he knows these cars a lot!

 

Hi Xalty,
Thanks for helping,
I had a leak on the FRP few month back, and so this current FRP is few months old only. after replacement everything was fine, the problem appeared only a couple of months after the replacement.

Now do you think the FRP, would also drop in few second the pressure to 0 in rail when stopping the engine?

where would you see the pressure /fuel going to when i stop the engine in such amount that it drops the pressure right away. That's why i had a doubt around the fuel pump valve not retaining the pressure but could be a leak somewhere but i don't see any fuel leaking anywhere.

Thanks
José

 

Hi Guys,

Just to close the topic, i went to the garage that help me diagnose and repair and finally it was indeed the FRP sensor like xalty had mentioned. Although i had it changed before.
So to summarize: all the symptomes that i was seeing with banck too rich etc... were coming from there in case someone else looks for it in the future.

Cheers

José

 

Jose, just a reminder to make sure you change your oil because you may have been dumping a good amount of gasoline into the oil pan.

 

HI Panthera999,

It is a good reminder, to such a point that i was not aware i should do it . do you think that the oil filter should also be changed?

thanks

José

 

Yes, change the oil filter as well. Gasoline in the oil will thin it out and cause potentially significant damage, depending on how thin it got. Oil is cheap, metal is expensive.

 

Thanks Panthera999 again for the advice, will do this asap.
Thanks also for this community, it is really great to find support from experienced persons.
All the best