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The closed loop control on most, if not all, cars is a multi-variable algorithm largely feedforward based from a "fuel map" using throttle position, airflow and inlet air temperature and possibly air absolute pressure and engine speed. The lambda sensors are used to trim the calculated control variables when operated in closed loop. I assume this scheme is used because of the highly variable dynamic range of operating parameters, and the process lag between the process variable (the lambda sensors) and the control variable (the injector pulses).
I would buy a "ELM 327" interface module, either Bluetooth, wifi, or USB, and a software package to match whatever computer or tablet I was going to use. My preference is one of several that run on Windows with the USB interface for most diagnostics, but I keep a Bluetooth ELM 327 and a Android tablet with "Torque" software in the car.
There is a "free to try" Windows software that uses the ELM 327 interface which does well with the X-300, but my memory fails me for its name right now. I will be back to that computer later next week and report the software name then.
Last edited by sparkenzap; 11-28-2015 at 05:59 AM.
Well I bought cheap and bought trouble. Useless thing cannot connect reliably through bluetooth so I plan to buy a better one from Amazon at 3 times the price but with almost 100% 5 star rating.
When it did briefly connect the MAF reading was basically zero or piffling and the one O2 sensor I set a monitor up for was fluctuating nicely (I think it's meant to vary quite a bit around 4.5 volts or something?) Oh and the ambient air temperature was anything between -12 and -40 which seemed unlikely.
However, I can see the value of such a device so I shall invest in a better one.
I tried Torque Lite and Piston something or other which I thought was probably better both on my phone.
Well, eithr you have determined your problem or your software is not reading right. I suspect it MIGHT actually be a bad temp sensor. I do not remember for sure, but I THINK the airtemp is part of the MAF main element. I am pretty sure someone will chime in with the answer. Don? RJ?
I believe it does need air temp input, but it's a tough call as to whether it's the software or temp sensor from the data. A test with another test device would help, but the fact that the car is a early 95 makes me wonder if it's really OBD2 ready.
A couple of years ago I brought my 95 to you and it did not respond well to your IDS, if I recall correctly.
Although the MY 95 ECU is not rated as OBD compliant, it is difficult to observe any differences between it and the MY 96 ECU when connecting. All C-300s are pretty poor at self diagnosing misfires. Doug and others have had strong misfires with no code set. It my experience, the real solid misfires set codes, but the more intermittent ones did not.
BTW, IDS is not an OBD interface, although it uses the same physical connection. It has many additional functions from those defined as part of the interface. As I recall, we were trying to resolve the anomaly of high LTFT displays by doing a re-orientation. I don't remember exactly if we could not connect, or if the high LTFT display was still there after the reorientation. There have been numerous reports of the unreasonably high LTFT displays even when the car ran perfectly and I believe one of my ECUs corrected itself after a re-orientation, but I had tried so many things, I am just not sure what might have fixed it!
In any case, IDS (and WDS) are the Jaguar tools defined to do MY 95 diagnostics.
Good luck, drmike. I've been thru a collection of OBDII BT adapters, most in the $10-$15 range. The first several, connected to ECU & phone and worked fine for 4-6 months until the started reporting bogus numbers like -40 for OAT and/or transmission temp. After one shorted out and blew the OBDII port fuse, I took the plunge on the much higher priced Scantool adapter recommended in the TORQUE documentation. With both Torque AND the included scantool software, it connects, and reports data for about 15 seconds or so, then obd data freezes.(GPS Functions continue apace, tricking you into thinking everything's fine depending which screens you have up)
Basically, it will work long enough to read the monthly P0411, or to clear it, but not both. I have to exit Torque and restart after reading the code to clear it. I recently tried it on a '96 VDP with the same result.
Identical HW/SW combo works fine on the S-Types, however.
Have since tried several el-cheapo's from Amazon but have yet to find one that will connect to both phone and ECU.
Hmmh. I have had good success with both Bluetooth and USB ELM interface moidules on X-300 cars. I have even tried a chinese clone and had good results. A "real" ELM should be in the $50 range, I think. Maybe my clone was just good luck.
Well some progress of sorts. I have the Bluetooth scanner and it connects well and I have some software that reports stuff OK.
A friend joined me as scanner reader and we took the Jag for a 6 mile run.
All the readings fluctuated with the engine revs and throttle position. Who knows if they were right but they went up and down a lot as the engine changed so it all seemed plausible. The air intake temperature was sensible as was coolant. The MAF readings might have been OK.
One thing that bothered me was that the scanner reported Lambda sensors present as 00010001 which I take to mean bank 1 and bank 2 – or does it mean of 4 banks I had one before and one after?
That can’t be right as I can see two sensors one in each tailpipe in the engine bay.
Also it would only give readings for bank 1. That doesn’t seem sensible to me.
Anyway off we went for 3 miles all was well revved freely, pulled over to look at the readings now it was in closed loop up temperature coolant about 190 F and all seemed fine. On the way back I revved up to 4,000 and it wouldn’t really go any further it was missing and then just wouldn’t pull beyond 4,000 rpm. Under that it was Ok but nothing brilliant not its usual perky self.
Back on the drive it was by that time appalling misfiring when revved up and reversing into its bay was a challenge. All the readings looked OK as far as I could tell.
The effect is like fuel starvation as it just won’t pull but that wouldn’t be true on the drive at 2,000 rpm when very little fuel is used. If it was all lumpy and horrible on the drive you could turn it off and it would be OK until about 3,000 rpm when it went all lumpy and stayed that way. And it misfires through each exhaust not just one side. When the ignition is switched on the fuel pump whirrs.
So, our tentative conclusion is that the problem is triggered by something getting good and hot as it runs OK cold. And then reaching quite high revs triggers something that fails and causes the problem.
I have checked the seating of all plugs, we cleaned the ECU contact in the footwell and it was clean and dry anyway.
Starts on the button, no CEL, only error is that a secondary air pump isn’t working which is no surprise as it isn’t fitted.
Your symptoms sound similar but different from a recently remedied problem I had with my '97 x300...
Car ran fine until temp came up; then most noticeable when accelerating away from a stop was a horrible engine shudder - it would nearly die but would sputter up to speed and continue sputtering along. Fuel mileage suffered greatly during the life of this problem. This cycle continued: fine while cold, lousy running when up to temp. I noticed it was more pronounced with an increase in ambient air temp.
Several items checked...however the cure was a new Coolant Temperature Sensor. I was dubious about it being the fix as the temperature gauge seemed fine and OBD scans reflected seemingly accurate coolant temperature readings throughout the range. However at under $30 I figured it wouldn't hurt to replace it.
My car has been purring along with normal fuel milage ever since.
This may or may not be your solution, but it's worth consideration in my opinion!
I have actually replaced that sensor, it's the one above the thermostat I assume? As I recall there are two devices that end of the engine both I think dealing with water temperature. They are even cheaper in the UK and an easy change probably worth it.
Which one is it though?
I may have changed the wrong one in the past. I could quite accept that this is the problem.
Added to which it's low on antifreeze as it burst a pipe and was refilled with water at the roadside. I wonder if that could muddy the waters ho-ho?
Thank you. I do believe that is not the one I changed. I shall either pop in to the not very local parts place or mail order it. Thanks for the suggestion.
As a supplemental I will say that when I drove off before teh problem manifested itself it was running OK and I booted it to 4k rpm at which point it would not rev any higher and my assistant watching the MAF reading said it flat lined for as long as I had the pedal to the floor. I'm not sure what that means. I do know the air filter is OK for example.
Possibly off at a tangent, but when you say you booted it to 4k on the way back, do you mean in gear? The reason I ask is that something at the back of my mind tells me that the autos wont (and shouldnt) be revved beyond 3/4K when not in drive. In other words, if you were simply revving it in neutral, I dont think it is meant to go round the clock, as the gearbox doesnt like it.
It was in gear albeit on that occasion locked into second gear. It will rev over 4k on the drive in neutral but it was a good thought. It is as if something is preventing it revving when the problem starts but then it goes all over the place.
The replacement MAF has arrived. I am not optimistic but I'll change it when the weather allows.
I dont think it is meant to go round the clock, as the gearbox doesnt like it.
I believe the number is 2K. I saw it in a TSB but don't recall the number. It cautioned against revving to 2k when in neutral or park, lest you damage the xmsn.
11-28-2015, 05:49 AM
