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Hey, I hate to do this to ya all but I do, I have questions. When I fit CAT-less downpipes I also fit 2 new oxygen sensors... I'm kicking myself - kinda maybe.
I think the LH sensor is bad. I'm sorry to say I still don't have a lot of faith in my use of a DMM. This is something I need to work on..., Anyways. I get fluctuating readings from 0 to it seems like 1 or 1.xx (a little over) at the RH sensor plug under the hood and the test lead in the boot - that seem normal??? The LH is stuck at just 0 to .1xxx, no higher, and doesn't fluctuate the same as the RH at all... I'll have to look at that again so I can trust myself.
I had a BAD fuel injector for a 400 to 500 mile drive (at least) a while back which I think may have killed the sensor OR, it was bad from early on. I dunno. I want to replace 1 or both.
What are the symptoms and side effects of one bad sensor? Will the car, a v12, never go into closed loop with one bad sensor?
Below are the sensors I installed, crimping in (kicking #1) to the OE plugs at the car end - I hear splicing O2 sensors can be a bad idea. Kick #2 is - I don't know really if these are the correct OXYGEN SENSORS... 234-3000 Denso Universals.
https://www.ebay.com/itm/132578305233
I have a single downstream oxegen sensors on a Marelli car, no CATs. It's a 1990. What are the right sensors and what are the readings I need to see in testing?
Any guidance is, as always, greatly appreciated...!
This is the port I was taking readings from in the boot...
The way the GR and GW wires are described in the Electrical Diagram/Guide are as "O2 Sensor Integrate"...
I'm not sure what this means. I have read in places that I'm supposed to get 2.5 volts at these leads as opposed to values that correspond to the readings I get to the wires from the sensor(s) under the hood??? I was thinking that it might be that fluctuating 1.0 to 0 around the .45 in the middle... Yup. I'm confused some.
This good Brother talks about accomplishing a 2.5v reading at the diagnostic port in the boot. I'm imagining he's talking about the port in the photo above,,, or is there another one somewhere in the boot? Also, is the capacitor necessary, or can I just look for a change in the UPPER most value and the AIM to get that upper fluctuating value (in the square wave) as close to the 2.5 as read by my DMM?
Diving right in,,, under the hood on the RH sensor lead I get a nice fluctuating voltage from about .80 down to .1 or so. Goes up and down steadily. On the LH side I got/get a solid non fluctuating .81.
I just changed the sensor and I basically got NO change in the reading. Steady .84v
In the trunk (I can't tell which is LH and RH side sensor reading - see shot above describing the test port and O2 sensor integrate) using the test port - a square wave where 2.25v is ideal (from the article above) I get a max of just over 1.28 fluctuating volts on one and SOLID .15v on the other. I can't remember whether it's the GW or the GR which is giving me what I think is a dead read of .15v...
Anyways - what will cause a stuck voltage of .84v in a sensor during operation? Is it extra air?
Will the car run in closed loop at all if one sensor is bad or will one bank operate in closed and the other open? Or, will one bad sensor CANCEL any possibility of the car running in closed loop?
Please help me out here. I'm don't know what to do.
The LH sensor is reading .84 - .88 when all warmed up. It seems to cycle for a while at first start after the heater brings it up to temp and then once the car has run a while it pegs out at the .8x... Rich?
I removed plugs from the LH bank (the easy ones) the one rear most to the firewall was covered in black and looked fouled. The other 3 I got to were dusty dry white.
I'm out of my depth here.
I don't think it's the sensor,,, maybe a bad injector?
Dry white indicates that those injectors are not firing properly and the car is very lean on those cylinders.
Black indicates far to much fuel on those ones.
I would clean the resistor pack thoroughly, it could be that.
It could also be your injector loom, have you renewed it?
It could also be the actual injectors, worth testing them too.
- I bought a set of reman bosch injectors at the beginning of all this 3yrs ago and installed them - one went bad and I replaced with a Standard Motor Products injector in the Fall 2020.
- I did renew the loom (the best I could) where I found one bad ground (fixed) and replaced all the connector plugs... All FI seem to be firing. I have NO noid light.
- I will clean the resistor pack as best I can today....
So far in testing (if one could call it that) I have individually pulled the injector plugs listening for a sound of change in the way the engine is running. All pulled FI plugs produce a change. I can hear all the injectors firing with the long screwdriver test - im pretty sure. The exhaust on the LH bank gives what sounds like is a little mis, but just a little off - while the RH sounds smooth and clear
I was able to remove all but two plugs on the LH bank (B bank I think) and all but one (the plug closest to the fire wall on the LH side) is/was BLACKened. The remaining 3 dusty dry grey/white.
In the fall, if you remember, I had a bad FI. The rear most one on the LH bank closest to the fire wall. The 6B injector. Haha,,, I remember your impatience at my willingness to just go ahead and change it... I did change it, and things got better. BUT, I replaced the injecttor with (see link) a Standard Motor Products injector from rock auto....
If ONE injector is overfueling - can it create such a rich condition that the ECU works hard to CUT fuel at the other injectors? Could it be that the SMP injector I have is bad and replacing the one injector will help ore cure?
I ask - I dont have the ability ($$$$) to replace all these injectors.
I do think its time for a new set of HT leads... I have those ordered and on the way.
I am allllll ears and open to suggestions.
Its like the sensor and the ECU TRY to correst for over fueling with fluctuating voltages for a while then gives up and it max-es out .84 - .88v at the sensor and stays there....
Going to replace the LH rearmost fuel injector with a reman bosch injector. See what happens. It's pegged out rich reading the sensor while showing all kinds of evidence for lean in the plugs - except that one cylinder with the oddball SMProducts RockAuto injector.
I disconnected the O2 sensors and am running with them off.
Interestingly, the test port in the trunk (o2 sensor integrate), both sides test at 2.35v exactly... I guess perfect would be 2.50 according to the article above...
If the left O2 sensor is reading high because of a rich mixture, it should drop if you lean the mixture on that bank by creating a vacuum leak, or disconnecting an injector. Yes, if one injector is rich, it will try to pull fuel away from the other injectors on that bank in an effort to get the O2 reading where it wants it. I didn't really read your posts until today but it looks like you are on the right path and doing about all you can do. It is difficult to determine if one particular injector is running rich on this system, it is not advanced enough to identify problems by cylinder. BRW, I have no idea what you should expect on the O2 sensor integrate readings but it appears the right O2 reading is pretty normal, and the left running rich if it is stuck at 0.85v. Good luck with it.
If the left O2 sensor is reading high because of a rich mixture, it should drop if you lean the mixture on that bank by creating a vacuum leak, or disconnecting an injector. Yes, if one injector is rich, it will try to pull fuel away from the other injectors on that bank in an effort to get the O2 reading where it wants it. I didn't really read your posts until today but it looks like you are on the right path and doing about all you can do. It is difficult to determine if one particular injector is running rich on this system, it is not advanced enough to identify problems by cylinder. BRW, I have no idea what you should expect on the O2 sensor integrate readings but it appears the right O2 reading is pretty normal, and the left running rich if it is stuck at 0.85v. Good luck with it.
D! Thank you for your thinking and ideas. Really.
I've been struggling and feeling a bit alone with this. One of my problems is, as you say, figuring out exactly WHAT is going on is difficult. Is it a plug, and injector, a HT line gone bad, the sensor - or combinations? An issue like this IS (kinda) my first rodeo...with a monsterous v12 and in general. Troubleshooting approaches and making them up as one goes isn't easy. I think I'm 3yrs into the car thing - with 4 cars. All troublemakers!
By your advice - and I should have tried it before and don't know why I haven't - on my lunch I will go and start the car, connect the O2 sensors, let it warm and discon the offending (my guess) injector. Then, create a vac leak... See what happens.
I have an injector on the way. I got the one I am replacing on Rock Auto, says it's for the XJS - but who knows...?
The other 11 injectors I installed back at the beginning of XJS rescue and the RH bank - with those injectors she seems to be in good numbers at the sensor and at the test port in the boot. I really hope it's the thing.
Once the sensor in question pegged out at .88v and stopped fluctuating I disconnected the "bad" injector and the reading plummeted to LOW (had to read because the numbers move) and then the ECU kicked in and the numbers started fluctuating again thru the range. Still hard to read and get an idea of a trim %age but it went back to making adjustments with what I'm guessing was a lot of extra air in a dead cylinder...
I reconnected the FI and things went back to pegged out. Then, I created a vac leak by disconnecting the vac hose on the LH side that controls the FPR (which thinking now may have not been the wisest choice and,,, the .88 (which I thought was the upper limit) went to .92! and froze there - no fluctuating.
Still, it's hard to no for SURE if it's that particular injector but I'm thinking, just may-BE... We shall see.
So, I received the new injector and installed it today in the B bank, Cylinder 6... Easy peasey... (Greg, I didn't replace the plug yet)... All the numbers on the new FI matched the other 11.
I replaced the LH O2 sensor with new last week.
The car was still pretty warm (I just drove it home from work) and had been running it base fuel map with the 02 sensors disconnected... Finished the injector install, connected the O2 sensors, and started the car (still very warm engine). Both were fluctuating to start but then,,,, both sides pegged out at .84 on the LH side and .78 on the R... Not fluctuating as they should. The RH was working correctly at last reading a few days ago.
To mention... Two days ago I installed a set of new HT leads just because, and I swear, even without O2 sensors connected, she was/is running smarter, smoother and with more power than she ever has. But could the HT leads (Denso) be the problem,,, the reason for the rich readings on the RH side which was good before the HT change?
I listen to the exhaust note and it is smooth and no misfires (that I can hear) and she sounds nice - not that I have anything to compare it to.
Anyways... I know and have read about NOT throwing PARTS at a problem (I kinda have) but I have done what I can to figure this out and to no avail.
What should I be checking, thinking about or looking for?
I think I may have figured something out. Key word, think.
I am not sure what engine temp needs to be achieved before the car, based on CTS sensor output, goes into and stays in closed loop - or uses the temp from the CTS to use the o2 sensors for trimming.
If y'all recall, and I would be amazed if you did, I elected (foolishly maybe) use a 60, 40 mix - 60% H20 - which gives me much cooler running. My car NEVER runs in N at the temp gauge. Runs just above half way to N or slightly higher.
Yesterday I drove 20 miles, backed into a parking space with a curb allowing me to leave the car in reverse, get out and take some readings. With an IR thermometer, that always reads 7 to 10 degrees cooler than actual, I read 168 degrees on the water rail on the RH side of the engine where the gauge sensor is. 172 on the LH where the CTS sensor is and low and behold BOTH o2 sensors were reading and fluctuating. Lows in the .07 range. Highs in the .7x or .8x range. Seemed to be working properly...
Now, I'm happy with my running temperatures. Rather cool than hot (although I worry some about corrosion and lubing the water pump spin with such high water ratios) but, I also want higher temps for proper and correct fuel trimming...
Q: I don't want to have to punish myself with draining coolant and bleeding the system. IF I discon the lower line on the reservoir,,, car cold and main cap on the cross pipe off, using that lower reservoir hose to drain the reservoir and SOME of the system while cold - can I refill the reservoir with 100% undeluted antifreeze without introducing a ton of air???
I want to make this adjustment painless.
Good news is the o2 sensors seem to be working correctly once the proper running temps are achieved...!
So, with replacement of one injector, you appear to have both O2 sensors reading more or less the same, and things should be happy there, correct? Now you are wanting to add heat to the engine by increasing the antifreeze concentration from about 60% h2o and 40% antifreeze up to what, 50/50%? I would not change the antifreeze concentration unless you need it for winter freeze protection. The 60/40 should be fine for lubrication and corrosion protection, assuming the water used is near neutral ph. Keeping the engine up to temperature is really the job of the thermostats, not coolant concentration, although too much antifreeze will lead to overheating. I would not go past 50/50 unless I was in the artic. That leaves the question of just when is it normal for the car to be in open loop. I don't have a good answer to that, but many older cars will go into open loop at idle, even when hot. I'm suspecting you have solved your real problem, the one rich injector, and now I think you are creating a problem where it does not exist. I think I would just drive it and be happy, unless you have other symptoms that I am not aware of.
The car runs cool and I'm thinking that might keep it in a rich-er running fuel map/trim... I think (and don't know) that the ECU on most cars with an will adjust the fuel to air mix according to engine temperature..? That until it is up to "full operating temp" it will add more fuel...?
It's a good point about thermostats being what determine temperatures controlling coolant flow. In that idea I guess I need to figure out why my car runs so cool. That is, unless the damn sender is sending the wrong signal or the gauge in the dash is reading low. Could be a combination of misreads. The IRT read 160 -170 (it seems to read 7 to 10 degrees low) after a 30 min trip at highway speeds.
What's a normal operating coolant temp number for the XJS?
03-25-2021, 06:21 AM
1990 Jaguar XJS - O2 Sensor Type & Emissions
