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I drive a nice XJ6, X300 early 1995, roughly 150.000 km. It has allways been well tended by previous owners and myself since I bought it 4 years ago.
In short it is my summer drive, and I try too use it frequently during this period.
I have had no major problems with it so far. And the driveline has been working flawlessly.
After a fill up at the gas station 10 Days ago, where I drove home with the gas cap off (stupid). I have had some problems.
Idle is rough first minut but will smooth out, it will start but only after prolonged cranking.
Heavy gasoline smell in exhast, which seams humid with black droplets of water or unburnt fuel in it.
Fuel consumation is through the roof.
Spark plugs black and sooty, but will spark when grounded to the block.
Engine light is not on.
First I changed the Crank position sensor, with no result.
OBD read MAF sensor problems, but local jaguar dealer says, that problems with the MAF would turn on Engine light, and shift to limp home mode?
Tried testing the MAF with back probing, but couldnt get it to work,
At least I saw that 11,88 volt going to the MAF.
Coolant temp sensor, seems to change resistens with temp going up and down.
Fuel pressure regulator, is not leaking gas the diaphram ( tested with vacum hose off for 10 min), return to tank from FPR seeams adequate.
Fuel is squirting when I loosen the hose to the fuel rail.
Any help will greated with much appriciation, as I am running out og thoughts here.
Thoughts:
1) The cap off is likely unrelated to the problems
2) What do you mean by "OBD read MAF sensor problems"? Is it a code, or no reading for that parameter?
3) Engine lamp burned out?
4) What are the STFT and LTFT readings. Note, the LTFT CAN give funny results on these cars/
5) Have you tried a "hard boot"?
6) What type of OBD reader do you have? Can you trend graph parameters?
2) I got P0102, low input from MAF.
3) It is there with ignition turned to step one but lights go out with Engine on.
4) My OBD is a simple being and cannot read Fuel trim.
5) I Think soo, but could be Worth trying again.
6) A very simple dont Think graph are possible.
Water in your fuel? Was it wet when you left the fuel cap off? Water will sink straight to the bottom of the tank and be ingested quickly.
How many miles have you completed since the refuelling?
It was not wet at the time, tops 15 km ( unsure in miles) since refuelling.
Tested backprobing the MAF under idle at 800 rpm, with ground to the 3 rd pin and + to the 2nd pin.
with multi meter at 20 Vdc, it says 0,1 volt and at higher idle max 0,5 volt.
Could this be the low sensor output from the MAF, the fault code is indicating or just me who doesn´t know how to measure output from MAF..
Christian:
If you have a code from the MAF, you almost surely have a bad MAF or the wiring to it. Can your reader read current data? Even the free and $10.00 variety scanners can graph data parameters. If you post which interface you use (Chinese ELM clone?), then we can make suggestions for a software. Several come with 30 day free use.
Where I am going is that you can read the data from the MAF and get an idea if it is correct.
I do not have a running X-300 right now, so I can't check your voltages, but they sure seem low to me.
I THINK this is in Swedish! OBD2 Bluetooth
With this scnner (less than $20.00 if purchased in US) and some inexpensive or free to try software, you can trend chart your data and tell what is going on.
I suspect, though, you have a bad MAF sensor.
Ok, downloaded eobd facile seamed simpel and ok.
Fired upp the engine, and this is what I got.
STFT is -25%
LTFT is +53%
MAF voltage output at 1000 rpm's is 0 volts!
Obviously rookie on obd reads, but in thinking a new MAF, or second hand.
Well, something is wrong with the numbers, and yoiu have two banls of fuel trim and both are important, but either way, if you are scanning the correct MAF signal, then the MAF or the wiring from it to the ECU is obviously faulty. That also matches your symptoms, so I would say a new MAF is a good bet.
Reset the fault codes, and took a new drive.
Still hesitating to start, but will after a minute idle nicely at 800 rpm.
Behaves quite normal under drive, maybe a bit slow speeder response.
But fuel usage seams more reasonebly now.
Hopefully the replacement MAFS will correct your issues, but if after replacing the MAFS you still have the long cranking to start, suspect the Camshaft Position Sensor (CMP). The Engine Control Module (ECM) uses the CMP signal only at startup to identify cylinder 1 TDC on the compression stroke, usually within one full revolution of the crank. If the CMP is not providing a good signal, the ECM will then refer to the Crank Position Sensor (CKPS) signal, but it can take 30 seconds or more of trial and error before the ECM determines the correct ignition timing to start the engine.
Second hand MAF arrived today, and the cat is back.
MAF is signaling again and drive seams normal again.
Will take the car to work tomorrow for more testing.
Thank you for responding.
Allways impressed that we can communicate in this way, half across the world.
Great News!
Now, while you are thinking about it, check BOTH bank's LTFT and STFT and chart the results . Chart MAF readings. Record for later (screen capture will do)
Rough and Rich!!!
