I just had an engine from a 2003 XJR with 93k miles put in my 2000 XKR with 82k miles due to a blown head gasket and the fact that it had seen a lot of heat. Fuel trim was about right on the old engine.

Now it is always commanding about +15% on one side and +17% on the other for long term fuel trims. When I reset adaptations all trims start at 0 but short term gets up to 15 and 17 after about 30 seconds and then it switches to long term when it goes into closed loop. When I give it some gas the trims stay up, so it does not look like a vacuum leak. It also passed a smoke test when I brought it back to the shop today.

The only thing I can think of is the injectors on the new engine. The o2s and the MAF are the same ones that worked fine before, so the injectors are the only thing I have come up with. I will do some fuel treatment in case the injectors are dirty, but is there anything else that can cause this? Are there any differences with the injectors or any other reason why the ecu might treat this engine differently? The guys at the shop want to take it for a couple of days and smoke it under all different conditions. But I was there while it was smoked today from a lot of different locations and it would still have the high trim when we would run it right after passing the smoke test, so I don't think it is a vacuum leak.

 

If the trims stay high on revving I can't see how it's an air leak or why to go looking for one.

That leaves things like fuel filter, maybe MAF, maybe the injectors are different?

 

Thanks for the suggestions, I was thinking along those same lines. The fuel filter is recently changed and was fine before the swap. The MAF is the same one from before the swap and the trims were fine before (and this MAF has less than 30k miles on it). Both fuel pumps functioning properly. Only thing in the fuel system from the new engine is the fuel pressure regulator, the fuel rail, and the injectors.

I am running a fuel injector additive now to see if it takes the trims down at all. If it helps but does not fix it completely I will have them flowed (might do that either way). If it does nothing then I will be out of ideas. I guess I can check fuel pressure, but that seems unlikely to be the problem to me.

 

If you decide to address the injectors:


I had my injectors refurbished by Keith at "Injector Experts" (419-619-6650). $20 per + shipping. Great guy. Don't hesitate to call. O-rings were replaced as well as the screens. And you get a Before & After performance report card as well.


Very easy guy to work with.

 

If you don't already have them, get those fuel injectors off the old engine. If by some chance those valve covers off the old engine are any good, I'd buy those off you since I have a 98' XJR and would want to update to the later ones.

 

The fuel treatment had no impact, trims are the same. Here are some pics of the scanner under different conditions in case someone has seen trims do this before. Some images are not perfect, sorry.

The first 3 are all in the garage in park. idle was a few minutes before the other 2.
This is idle:


This is holding it at 1500RPM for about 10 seconds


This is holding it at 2500RPM for about 10 seconds


The following 3 are while driving on the freeway in steady traffic, my speed was about 70mph give or take 3 or 4mph for all 3 screen shots.

This first one is taken right after I removed all pressure from the gas pedal. I was cruising right before this with just the slightest amount of pressure on the pedal, RPM barely moved when I took my foot off. Sometimes they max out all the way at 25 when i do this.


This is a few seconds later after cruising with no throttle:


This is after I give it slight throttle:

 

Unfortunately all I have from the old engine is the s/c, intake elbow and throttle body, and I need all of that.

 

Also, it has been driven over 300 miles since I reset adaptations and evap, comprehensive component and cat monitors are all still inc. I had this same monitor issue with the old engine, so it may be possible that the trim issue was present before since I had not checked it immediately before the swap. I did record trim values in my log a few months earlier that were +4 and +6 long term trim at idle but it is possible that the trim issue had developed after that but before the new engine.

Maybe it is something with the evap system, but I have no pending codes after over 300miles and many cycles

 

I thought you said the trims stayed high on revving. But seems they drop so an air leak is a real possibility.

 

Thanks for the reply Jagv8, that is what the indy is thinking. I paid them to smoke test it already, they said their next step would be another $200 for another smoke test.(just wanted to make sure I was not missing something before I start paying to repeat the same steps). I was basing my assumptions that it was not a vacuum leak on the trims at idle, 1500, and 2500 RPM. It remains pretty constant. Long term values fluctuate but short term will then kick in to get the total about the same. (when I had reset adaptations it was a lot more clear before it reset long terms, since it was only using short term there was no need to add up the trims and they were pretty constant at the different RPMs)

I added up the short and long term trims below to get the total trim, they are constantly fluctuating slightly, but I do not see the trend of pulling fuel at higher RPM:


Bank 1 actually goes up from 1500 to 2500RPM, but I was attributing these changes to the constant minor fluctuation since the overall values are pretty consistent. When I had an intake leak my trims were actually a little higher at idle but would come WAY down by 2500RPM. I will probably just call the indy on Monday, I drove a little over 200miles on a round trip and it used a full tank of gas, haha. I really wish there was a true Jaguar expert in Sacramento, then I could just pay a couple hrs for diagnostics and have the answer.

 

I thought you had stable LTFTs so ignored the STFTs. I only use STFTs when leak hunting using a burnable gas/etc.

 

Out of curiosity, besides being abnormal on your scanner, what are the symptoms of this problem?

Thanks and trying to learn.

 

I have not noticed any major drivability issues, but I have not pushed the new engine too hard, it might feel a little down on power, but I'm not sure. The MPG is significantly worse, but I have not measured an exact figure.

My goal is to get it smogged and registered. I have 3 incomplete monitors (Evap, comprehensive component, and cat) so I can not smog it right now. I started with this trim problem in an effort to get those monitors set. EVAP and CC can take a while and the drive cycles must be done right. The catalyst monitor is my main concern right now. It should have set after over 300miles (majority of that highway) of driving.

Basically I am trying to find out what is wrong with it so I can get it smogged and registered. So far the high trim is the main thing out of the ordinary I have found so that is where I started.

 

I did some data logging, maybe someone recognizes these trends. I just edited this post to put in cleaned up maps with a longer run.

 

LTFT fuel trim readings that are trending high might also be the result of a slight ignition misfire that is not bad enough yet to set a misfire code but is bad enough to cause a drop in fuel economy. One or more fouled spark plugs that are misfiring occasionally, or a weak ignition coil or bad plug wire that is allowing some occasional misfires could be the cause. I will start on remap the ecu and then take it from there.

Here you have some possible causes of RICH fuel mixtures:

Leaky fuel injector

Excessive fuel pressure due to bad fuel pressure regulator or restricted fuel return line

Extremely dirty air filter or restrictions in air intake system

Exhaust restrictions (clogged converter, crushed exhaust pipe or plugged muffler)

Bad O2 sensor (output shorted to voltage so it reads RICH all the time)

 

Thanks for the ideas. I was thinking about the slight misfire thing, I have noticed it takes a lot to get a misfire code on these jags. The plugs and coils and wires all looked good when I had them out compression testing it, but I will look into a way to test those now. That makes the most sense based on the trim as far as I can tell.

Fuel pressure was about 45psi at idle. I think it is supposed to be 42psi. I chalked it up to a cheap gauge, but maybe that is a factor. Injectors might be it but it is pretty even on both sides and fuel treatment did nothing (I expected at least a slight change if that was the problem), maybe it is a leaky injector on each side though. The air filter looked ok so I cleaned it with shop air and put it back, but I might as well replace that. It does not seem like the cat to me based on trims and the feel of the car. Also the problem remains steady after a few hrs on the road, when I had a clogged cat on another car it got worse the longer and harder it was run. O2 voltages all look good.

 

There you go, now you have something to work with. Maps are always helpful.

First, throw out all the maps except the LTFTxRPMxLoad. The ST maps are meaningless because the STFT will always jump around, it's supposed to if it's doing it's job.
One suggestion, on the LTFT Maps reverse the CLV [Load] metrics. Make it
Minimum = 100%
Maximum = 0%
The maps will be easier to read and understand.

**Sorry, I screwed up the posts I was looking at, had them backwards. You are running lean, especially at low loads, high vacuum. Hence the high positive LTFT.

So, which engine system is the car operating with? The returnless 4.2L system or the 4.0L system with a fuel pressure regulator. One has a regulator and the other has the injection pressure sensor.

 

Great, thanks for the leads Steve. I can't find the injector rail pressure sensor for the 4 litre xk or xj engines, this was the closest (for the 4.2):

Jaguar FUEL PRESSURE SENSOR ON FUEL RAIL - AJ87977

I can put the fuel pressure gauge back on it tomorrow and unplug the vacuum line for the fuel pressure regulator to make sure that is working. I will test that injector rail sensor also if it has one. Fuel pressure was around 45psi at idle when I checked it yesterday and today. I was thinking this was not the problem since the car is commanding more fuel when I would think high pressure would cause an over fuel condition leading the system to command less fuel.

Earlier today I disconnected the opposite side of the part load breather hose from what I believe is the purge line from the purge valve. I plugged the hose and ran the car in the garage. LTFT actually went up 1 or 2 percent (I was thinking that it was adding fuel when it detected more o2 left over since there was slightly less vapor to combust). I ran it for a while and revved it a few times, it looked the same as before as far as I could tell. I'm not sure if that test eliminates the purge valve as a suspect, but that was the idea.

The fuel in the oil thing is something I will have to look into, I am seeing a lot of oil (more than the old engine) coming through the full load breather so something could be going on there. I will fix those maps before my next run

 

So it's a 4.2 engine now in a car that used to have a 4.0? Or what? Like Steve I'm wondering what engine exactly.

 

No, it is still a 4.0. It is a 2000 XKR (4.0) and the engine was replaced with one from a 2003 XJR (also a 4.0).