Would that not throw a code if not working properly?

Tom in Dallas

 

that does make sense. it's easy to get focused on leaks and try and figure out where the extra air is coming from when a lack of fuel is staring you in the face! especially with the secondary fuel pump and lack of filter changes being a common issue.

 

It seems to just silently fail unfortunately, from what I've read. Most people find out the secondary has gone when the primary dies (that being whichever hasn't died first, as they will switch over automatically) and they have no fuel.

 

Check the pump first.

Gus
www.jagrepair.com

 

I do not know the XKR like I do the S-type- so where are the fuel pumps and how would you test?

Another quick questions on the fuel trims in the event that it is the fuel pump- do the reading of a plus number at 2500rpm indicate that the fuel is actually be added or that merely the maf and related elements feel that is the amount it needs (which is what I think) and whether it gets it or not is a second issue.

Thanks

Tom in Dallas/ Plano

 

the pumps are both in the fuel tank. you can check by swapping/removing the relays for the pumps - see this link:

https://www.jaguarforums.com/forum/x...el-pump-85882/

the trims are what the ecu is asking for, not (necessarily) what it's getting. They max out at +25.
In the case of a vacuum leak,they will be close to what it's getting, and if there's a fuel starvation problem then they will not. that's my understanding anyway!

 

Thank all for the pump suggestion, however both are fine.


further testing does not set a code, but the fuel trims tell a different story.

at idle- Long terms are -7.5 and -8, at any acceleration at all- even at 900 rpms LT fuel trims move immediately to the +7.5 and +7.8 and stay that way all the up to 2500rpm.. As you bump up against the 3000 limiter you can see it spike in the +15 to +20 range. However when driving and I did not drive it this morning, but my friend did- he, at lower speeds, went to WOT and played around with lower gears to rev the engine, but did not get a code. I still think that at a speed of 60. one would go WOT to about 80 or 85, that would get us another code.

Reading on the MAF flow at idle are 7.5 grams a second and 2500 are 19 grams a second and that seems to be in-line with what I have read here and at Jagrepair.com.

Any other ideas? He has had a smoke test done in the past, but neither of us witnessed it and I am not sure that the mechanic is familiar with these engines or Jags in general. He may be a perhaps old school and perhaps did not know where to or what to exactly look for.

I am still of the opinion that a vac leak is around some place and most likely the egr, throttle body area.

Any other ideas?

The only one other thing I have noticed is that when the car is sitting and warming up, there is a slight irregular ping type sound from somewhere in the center of the engine around the supercharger area and the engine seems to slightly speed up and slow down on a cycle but the rpms remain the same. When at full temp you do not hear it. but as soon as you turn the car off, you hear it again for a number of minutes. Without the hood up you would think it was metal cooling down and expanding/contracting, however with the hood up it definitely sounds like perhaps a loud switch or something of that nature that is doing who knows what. He says it has been that way since he had the car. Does anyone else with an XKR or the supercharged 4.0 have that type of sound?

Thanks

Tom in Dallas

 

I also have an irregular "click" that's from the supercharger. since I bought my car 92,000 miles ago. I don't believe it's gotten any worse. There was another s/c noise that did go away when I changed the s/c oil. This of course, won't have anything to do with fuel trims, but how old is your s/c oil?

 

I have no answer to that, but will inquire.There was a head gasket job done on the car when the inter-cooler sensor's IAT for the inter-cooler did not work and apparently was the cause of an overheating. How difficult is it to change the SC oil?

Thanks

Tom in Plano/Dallas

 

Doesn't sound like an air leak but more likely a bad (dirty?) MAF.

WOT is a bad time to look at trims as it may (commonly will) run OL (open loop) when they're not actually monitored.

 

I am obsessive about MAF cleaning- far more than normal, so I appreciate that, but long since done on numerous occasions. Would you then be suggestive a bad MAF. How would one actually test the MAF to know if bad? It seems at idle and 2500 to be passing the right amount?

The reason I wanted him to run WOT was to force more of the air need issue and exacerbate the leak potentially and thus throw a code

To,

 

Replace the MAFS but if the problem still exists I would see if you could monitor the fuel pressure as you are driving. My 99 does not read the fuel pressure using the OBDII and not sure you can read it on your 2000 but it is worth a try.

 

The 2000 does measure fuel pressure and it is sitting in the 55-57psi range, which I assume is normal. Is there any valid way to test a maf? I do know people that have checked coils - found them fine and then they still not work correctly in the car. If you were checking a MAF, what would be your procedure?


Tom in Dallas

 

This is the only check i know of.

Link JagRepair.com - Jaguar Repair Information Resource

 

I had looked at that and the MAF seems to be doing airflow at about that rate.

Is there any sort of bench test that you might be aware of or might suggest?

Tom in Plano

 

If the car is driven under normal conditions does he get any codes? From what I am reading it seems that the only time he gets the codes he is pushing it and that tells me that a leak if any is taking place above normal conditions.

Not sure what you are using to capture codes but I would suggest monitoring the fuel trims, engine vacuum, air flow ratio, MAFS and fuel pressure when the car is driven and under load (pushing it). I do not have a XKR but I hope someone in the forum does and the two of you can compare results.

It sounds like the problem occurred when under load telling me that if it is a leak it is when the engine is out of the norm under load.

FYI Torque along with PCM software can monitor the results. When doing this you should have someone in the car monitoring the results and the speed and timing as you are doing this.

 

Thanks Gus. Actually he had put the car up for over a year and at the time before that he would easily get a p0171 and 0174 (+25 on both sides) now he has not been able to get a code at all, but the car has a 16 point difference in LT fuel trims from +7.8 at 2500 and -8.0 at idle. Clearly a problem and long term never gets anywhere close to 0. The +7.8 occurs with any acceleration even from idle to even 950 rpm.

It is only my assumption that under heavy load ie: from a WOT of going say from 50-80 might generate a code, once the SC engaged. Of course the scanner will not get to a p1111 and shows that the evap and ccm are inc. and he has been through the specific drive cycles for both of them numerous times and I think the incompletes are perhaps preventing a code or the car does not see the right conditions for the test to perform.

Yes I have ridden many times and been looking at the scanner and recorded many frames.

So this is a bizarre mystery and why it will not generate codes when before it did and all it did was to sit in a garage, I know not.

Thanks again

Tom in Plano/Dallas

 

All of this Fuel Trims, P0171 & P0174 all are related to fuel and air. If you are telling me that the MAFS test fell in the range on the chart I would say move on. If a smoke test did not reveal any leaks move on. Now we are back to fuel and air and I would be looking at the O2’s or fuel presentation to the cylinders. Since the car has been sitting for a year I would add BG44k to the fuel and see what takes place. If that has been done I would be looking at the injectors. What most of us do not think about is the adverse affects the ethanol has on the injectors when it sits for an extended period of time.

 

Well, perhaps some guidance can be had here in how to make sense of these readings and why a code is not being set.

We took out the XKR this morning and ran it in a variety of circumstance. When going to WOT at various point it would go to an open loop as expected and the LT fuels trim would be about +4.6.

At idle we are still floating in the - 6.5 and -6.0. At 1000 to 2500 rpm we are at +7.8 and +7.0.

However when cruising, at almost any speed, especially in the 55-65 mph range and after a while is became very repetitive the LT fuel trims would run at +15.6 and +16.4. I thought the threshold for the 0171 and 0174 was either a +14 or +15 on LT trims and no code was set.

Clearly cruising down the road at a steady 60mph, the LT fuel trims reading a +15.6 and +16.4 are not normal and way out of range. Short terms were jumping from a +20 or more down to a -15 (way too far of a split) and the long terms never seem to vary off this reading at cruising speed, although when going up a small incline or going down on the other side they would change but when back to cruise- back to the same 2 readings and any variation was always +6.5 or more.

The only time the LT fuel trims are negative and always the exact same number is at idle.

Help in making some sense out of this. The MAF seems to be reading in line with the chart that Gus has referred us to, fuel pressure is fine, the O2 sensors seems in electrical and graphing range.

What gives?
Thanks

Tom in Dallas/Plano

 

Maybe I missed it but what was the RPM on the original freeze frame when the code was set? Also, you said LTFT was +4.6 at WOT. Did you mean STFT? If 4.6 was the LTFT what was the STFT doing at that point?