Hi Gents,
I recently did some service on the intake side (new lower radiator hose, alternator, and water pump). While I was in there I replaced the IAT sensor that lives on the bottom of the manifold and I rerouted the wires that went through the center of the manifold. For the most part this was pretty easy, but I did have to cut and move one ground wire. To move the ground I joined it with another wire from another sensor that also went to one of the many ground pins on the ECU. I mention this just to make sure I’ve not done something really wrong.

I’ve had no problems with the car (no check engine light or weird starting/running condition), but I have the impression my fuel economy has become worse. For mixed use I’m somewhere around 14mpg. Granted this is SoCal and the road to my house is hilly. So, “highway” isn’t exactly uninterrupted cruising at 65mph and around town driving does contain hills. I moved here at the start of the year so not a great baseline.

long story short, the IAT sensor I installed was a Lucas sensor with P/N EAC 2863 on it. I also see a SNB801 on another sticker. Physically it’s a little different from the one I pulled out (brass body vs plastic). The tip looked similar and it’s clearly identified as an air temp sensor.

So, can anyone confirm if this sensor is acceptable? I’m half tempted to pull the manifold (not nearly as hard as before as I can leave the supercharger installed since I moved the wires), and swap back to the old sensor. Despite this being easy….er, it’s still not fun so only want to do it if I have to. If one of you can confirm the sensor is not the issue then it would save me the trouble.

Thanks,
Daniel

 

look at your PIDs. is it reporting correctly?

there's your answer

 

What are PID’s?

Thanks,
Daniel

 

Ok, I think by PID you are referring to the data from the OBDII port. I tried hooking up my HPtuners cable that I have for other projects and was able to connect, but all I can see are trouble codes (none), engine speed, and throttle position. Should I be able to see more on these early gen OBDII computers? These are pre-CAN and there aren’t that many wires to the OBD port. So, I’m not sure what other channels I should expect to see.

Daniel

 

I think what he means is LIVE data from the ODB2 port not the fault codes.
A cheap but extremely good scanner is talked about here, highly recommended.
https://www.jaguarforums.com/forum/x...budget-249892/

 

Well I tried the AP200 tool, but it fails to read live data for the ECM. I can see climate control live data (which includes engine speed and coolant temp), and read codes, but no live data for ECM. I’m reaching out to the company.

I also checked, and HPtuners isn’t setup for many Jaguar’s so no surprise I can only get a few channels of live data.

Daniel

 

$3.99 elm327 and car scanner app does it

 

A PID is a Parameter ID, shorthand for each sensor signal that can be read via Live Data, such as engine rpm, coolant temp, intake air temp, etc.

Cheers,

Don

 

I heard back from Autel, apparently our cars are too old and not supported.

Daniel

 

$3.99 ELM327 and car scanner app


nothing else is faster or better

 

I tried that too, but I have no way to use it. All our phones/tablets are iOS which can’t connect to elm327 apparently. My work PC can connect, but the firewall blocks the software download. My personal laptop doesn’t have Bluetooth.

Any other ideas?

Daniel

 

for iOS you need to use the $5.99 wifi elm327

 

Can you point me to where you are seeing these prices?

Daniel

 

https://www.ebay.com/itm/35402768010...mis&media=COPY

i lied it’s $9.99

 

Ok, got that to work! My IAT’s look ok I think, but my short term fuel trim is not acting as I would expect. It seems to peg at 24.22 under steady state. It doesn’t seem to matter if it’s idling or driving down the road.

I can stab the gas (again idling or driving, same response) and get the trim to drop to zero before climbing back up to 24.22. This is true for both “banks”. Long term is steady and -3.91% for both banks.

The attached images give a good idea of what I’m seeing. In the first you can see the stair step shape of STFT and then see how it drops when I give it enough throttle (appears to need ~15%).

The first plot is idle the second was driving.

Intake air temp was around 100-110F from what I saw (it showed 84 before starting and coolant was 80 before starting). These seem reasonable or at least not the cause of this.

Please give me some ideas on what could cause this. I can’t prove it, but this seems to have come after the service mentioned at the start. Primary O2 sensors were replaced last year with Denso sensors so I think they are in good shape.

This 24.22% STFT seems to match my impression of how my fuel economy has been recently. If I can get that back closer to zero I think I’ll be back to what it should be.

Thanks,
Daniel

 

Hi Daniel,

I just arrived home from a 10-hour trip, so my brain is tired, but I can think of at least three possible causes of your symptoms:

1. The oxygen sensors installed were not the correct parts (unlikely but possible)

2. The hot wire in your MAFS is dirty or the MAFS has drifted out of range

3. You have one or more vacuum leaks or one or more air leaks in the intake plumbing between the MAFS and the intake manifold gasket. Inspect closely for cracks in any vacuum hoses, air intake pipes, crankcase breather pipes, etc. Common leak locations include the underside of the air intake elbow where it connects to the MAFS and intake air duct with large hose clamps. If a hose clamp is overtightened, it partially collapses the end of the elbow and causes an air leak, usually on the underside where it is difficult to see. Also check the torque of your intake manifold screws & nuts. The torque specification is fairly low, so it is common for the fastners to vibrate loose over time.

Cheers,

Don

 

Thanks for the reply! I think I may have figured it out, but ran out of time to confirm. In case I’m wrong, here is a little more info.

1) Front O2 sensors were replaced right before passing emissions (after failing). So they should be good and properly installed.

2) The MAFS could be dirty, but I did clean it not too long ago

3) Air leaks are a definite possibility. I tried to be careful but it’s a tight space so anything could have happened during the service I mentioned at the start. That said, it shouldn’t be the intake manifold as I installed a new gasket and tightened everything. I’ll double check though. One side question, is the copper gasket that connects the XJR6 plate and the pipe that goes down to the flex joint replaceable? I couldn’t find them for sale so just put the old one in. Thoughts?

4) I did find a lose connector! I think this is one of the secondary O2 sensor connectors, but I’m not 100% sure. Below are some pics on the location, you can see how two connectors appear not aligned, the left one is lose. I’ll fix that and put it back together.

thanks,
Daniel



Is the gasket that goes on this surface replaceable?

See the connectors are not even. The left one is lose

 

Jaguar shows that gasket as still available, part number EBC11426:





You can look up part diagrams and part numbers at parts.jaguarlandroverclassic.com

Cheers,

Don

 

I finally was able to put everything back together and drive the car. Despite supreme frustration in getting the ELM327 to stay connected with my phone, I was able to confirm STFT’s were back to normal!

So, the IAT sensor is acceptable, the WIFI ELM327 is not reliable (at least for me), and my whole problem was a lose connector.

Thanks everyone for the help.

Daniel