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Got myself a project in the form of an xjr from 1995 220k km. Car definitely needs a new to chain tensioner, sometimes the tension is on sometimes not. However, compression seem a bit low on some cylinders, take a look: https://docs.google.com/spreadsheets...it?usp=sharing
this is on a cold engine, as the previous owner was convinced he needed to get the head of, as the inlet side is taken of as well as the headers. Would a leak down help the diagnosis? The big question is if one should take off the head and also do all chains now as the car is in the garage and parts are already off?
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It has been some time since my last post. The engine has had the head overhauled as well as new chains and guides fitted. Of course I still have a long list of stuff to do before it's up to spec.
For passing inspection:
1. Fixing oil leak on transmission cooling lines. Both lines leak at the fitting to the 90˚ connector that goes into the auto gearbox. The line is new but the connectors are old. Are there any ideas where to find the 90˚ connectors? Prefferably in EU as new..
2. Uneven idle. Lambdas are steady at 4.55V and 4.7 (only two sensors). Cold start with throttle response is good after changing MAF. After ca 1min after start it starts to go worse with some missfires. Coils have been checked by disconnection and cyl 5&6 had new ones fitted after that. Crank position sensor has been changed. Will do an emissions test late next week.
Nice to haves (lower priority)
3. Transmission slipping when getting up to temp, works good when cold. As warm the engine hesitates/drops rpm/stutters at times when pushing the accelerator to go forward or backwards. I am thinking this has to do with the slipping as the ECU expects something that does not happen. Oil level has been checked and filled as hot and should be correct, will do more checks and fills as the oil is leaking out (se #1)
4. Sunroof not working.
5. Traction fail appears after small wheelspin. The incoming cable support to the traction motor looks shot, might have something to do with it.
6. Paint has cracked at rear left in two places, an old repair. Might tackle this one myself.
This is mostly a list for myself to keep track of the project, but if anyone has any input I appreciate it! There are probably more # to put up here but the list is getting daunting, will get better as I pass inspection.
Uneven idle. Lambdas are steady at 4.55V and 4.7 (only two sensors).
Not sure what that means. Lambda sensor voltage is not meant to be steady. It should switch between high and low volts every 0.5 - 1.0 seconds
Cold start with throttle response is good after changing MAF. After ca 1min after start it starts to go worse with some missfires.
That sounds like when it goes Closed Loop and starts using Lambda sensors
Coils have been checked by disconnection and cyl 5&6 had new ones fitted after that.
This rings some alarm bells for me. Can you confirm that Coils 5 & 6 are connected correctly. It's a common mistake to connect them the wrong way around. Coil 6 has a longer wire than coil 5. Coil 6 is orientated differently to the others and should have a small piece of yellow tape attached. Worth checking. It should look like this
The O2 sensors on the X300 are titanium o based which do not operate on a voltage generating basis but a change in resistance from a reference voltage supplied by the ECU that passes through the O2 sensors .
Must be at operating temp to read correctly
ECU does not use the O2 sensors until closed loop from the engine coolant temp sensor reaching a certain value
1. Fixing oil leak on transmission cooling lines. Both lines leak at the fitting to the 90˚ connector that goes into the auto gearbox. The line is new but the connectors are old. Are there any ideas where to find the 90˚ connectors? Prefferably in EU as new.
From memory, the 90 fittings screw into the transmission case and the cooler lines thread into the fittings. Some thread sealer would probably do the job, I doubt the fittings are bad. I'm not sure if there is an O ring in there or not. There is an O ring between the cooler lines and the radiator, but the parts book doesn't show one at the transmission case.
Not sure what that means. Lambda sensor voltage is not meant to be steady. It should switch between high and low volts every 0.5 - 1.0 seconds
That sounds like when it goes Closed Loop and starts using Lambda sensors
This rings some alarm bells for me. Can you confirm that Coils 5 & 6 are connected correctly. It's a common mistake to connect them the wrong way around. Coil 6 has a longer wire than coil 5. Coil 6 is orientated differently to the others and should have a small piece of yellow tape attached. Worth checking. It should look like this
Thank you all so much for the replies and suggestions!
I have put the #6 coil pointing the same way as the others, probably messed this one up. Thank you for the heads up. I will correct this before moving forward with O2 sensors and rough running. Now I have the guide to read up on as well, that could help!
The O2 sensors on the X300 are titanium o based which do not operate on a voltage generating basis but a change in resistance from a reference voltage supplied by the ECU that passes through the O2 sensors .
Must be at operating temp to read correctly
ECU does not use the O2 sensors until closed loop from the engine coolant temp sensor reaching a certain value
Thanks for the links! The chain is not rattling after new chain and tensioner (sorry, forgot to mention it).
Any idea on original part# for the NTK O2 sensor?
From memory, the 90 fittings screw into the transmission case and the cooler lines thread into the fittings. Some thread sealer would probably do the job, I doubt the fittings are bad. I'm not sure if there is an O ring in there or not. There is an O ring between the cooler lines and the radiator, but the parts book doesn't show one at the transmission case.
Yes, they go straight into the transmission. More context: it does not leak between the fittings and the transmission but it is leaking between the fittings and the lines. I am thinking that the seal should not be by the thread but by mating surfaces? With that it's not leaking in the fitting but where they are mating and maybe the surfaces are scratched. The transmission was taken of at a competent shop but they could not get it to seal when putting the transmission back with the old fittings. I thought I would have a go at it myself if I could find said fittings.
Last edited by wred_e; Apr 26, 2021 at 07:11 AM.
Reason: straight into the transmission not "transmission line"
The oriiginal O2 sensor I think where Denso as a lot of parts on the engine , but they are very expensive
Bosch # 13079 are cheaper connector ready equivalents and all 4 are the same length
There are some things you can clean up in the O2 sensor circuit
Thay can also be cross connected as they are the same connector
The crush washer on installation if missing seems to have an effect
Only 2 sensors are used in engine regulation and the other 2 are only used for catalytic through conversion efficiency CEL codes
Thank you! Checked this evening if I had mixed the coil connectors for cyl 5&6, unfortunately the problem was not that easily fixed. All cylinders are firing if the "unplug test" is anything to go by.
My xjr6 only has 2 O2 sensors, might it have something to do with it being a european model? The NTKs that are on the exhaust look kind of original as there are no number on them and the connectors look about as worn car side as sensor side. I tried crossing them over but there was no difference in running even though I cycled the engine off and on.
Any idea to try running with the lambdas disconnected to prevent closed loop. I suppose that test could not conclude that it would be lambdas anyway as there could be a problem in the O2 circuit. @Parker: would you like to point out where the O2 circuit connector pictured is located?
the fwd O2 connectors are by the windshield fluid fill cap in this pic . They are 2 black connectors side by side behind the Papa Indy 1
The aft O2 conectors are behind the aft most cylinder behind the valve cover
The multi pin connector is on the ECU as the red connector
By unplugging the 2 wire coolant temp sensor connector will mimic cold , it's a thermistor . This should keep you in open loop
CEL codes for O2 sensors on this early ECU are weak in showing
Are the heaters in the sensors intact ? they will read the same resistance value
The cycling off and on may involve more then one cycle to trigger a change , A change of configuration may involve 3 cycles and time and rpm for the ECU to go into a relearn . There was a table on this and can be tricky in troubleshooting
Last edited by Parker 2; Apr 26, 2021 at 02:29 PM.
Update: got it inspected without advisories.
New FAE lambdas, seems to work. Now only some misfires when hot after driving. Also transmission does not slip that much now that it has been run a bit more.
New problems: signal trouble with passenger's window motor. Motor stays on trying to raise the window with ignition on and motor gets hot to the touch. Took apart the doors and found that the button module seems to get signal to raise the window always --> always power to the window motor. Looked at the driver's side (left) button module but could not find any shorts or anything that looked broken on the pcbs. Stop-gap solution is to have the fuse out. Has anybody had this problem?
New problems: signal trouble with passenger's window motor. Motor stays on trying to raise the window with ignition on and motor gets hot to the touch. Took apart the doors and found that the button module seems to get signal to raise the window always --> always power to the window motor. Looked at the driver's side (left) button module but could not find any shorts or anything that looked broken on the pcbs. Stop-gap solution is to have the fuse out. Has anybody had this problem?
There is power always hot to the switchpack and an ignition switched ground to activate it. Incorporated into the switchpack are relays that control the motor up and down, sounds like one the relays is stuck closed. Probably a new switchpack is the only way to fix it.
There is power always hot to the switchpack and an ignition switched ground to activate it. Incorporated into the switchpack are relays that control the motor up and down, sounds like one the relays is stuck closed. Probably a new switchpack is the only way to fix it.
You are probably right. The 2 live coming in have power and the 2 out have power. There is also 4 pins that have 12v signal but I don't know what they are. So, I suppose, the signal could come from some place else also.
Update: replaced the lambdas with FAE correct ones and it works. New problem, the car drove almost perfectly until there was rain. Checked ecu: about a teaspoon of water in the black contactor and the pin for the injectors broke or was broken.. So now I have two things to figure out:
1. Where to find ecu side black connector to be soldered on
2. How to stop water ingress
XJR6, making it roadworthy, compression
