Hi JF people!

Quick question from newbie - I recently imported my xj8 3.2 sport to sweden where I now live. After driving over like a dream, the timing chain/tensioner rattle came on.

Usual approach, read up on here, bought some bits and opened her up to find a broken primary slipper and old version primary tensioners. Secondaries are new models. Replaced primary tensioners and guides. Reset cam flats on RHS (they were out a couple of degrees). RHS 2ndry chain wasn't as tight as LHS but measured almost spot on to the tensioning measure gauge thing. Bolted back up in usual process. Crossed my fingers, hit the tit and all fired up ok.

That was about 2 months back.

Now I've just gone through the registration/MOT equivalent and apart from the expected "you must have headlight lens for driving on the right not the left", I got a fail on the tickover emissions...

CO 5.3 (max allowed 0.5)
HC 463 (max allowed 100)

Test bloke said all is fine at 2500 rpm but crap at tickover.

Any quick pointers please?

Tickover is smooth, no rattles while running, accelerates well.

I am thinking 2 areas to check:

1 - O2 sensors (just bought an OBDII reader)

2 - undoing the timing/front end again and checking

Your wisdom and guidance is appreciated.

Thanks Steve (mr pimp jag

 

No "CEL" or OBD codes?

 

Hi Sparkenzap

Not at home (travelling on work stuff) so I haven't plugged in the OBD untit yet. I'll post as soon as I'm home at the weekend. Thx for the speedy q's

 

When you do, read LTFT, each bank, engine hot, parked, at idle and again at about 2500rpm.

Also, check whether it's running CL.

Below for acronyms

 

Thanks JagV8 - I'll update my signature line now - it's like being back in service - all the info counts in the right place

 

OK - OBD plugged and pinged me a P1111 and a P1647 - which if i'm reading the info correctly means fault on the LH pre-cat O2 sensor... time to go to work!

 

PS - the OBD readout gave me an OL the FT - I assume this is open loop

 

You'd have to check the OBD tool's manual but OL is typically that, and it would fit with a bad sensor.

 

OK I'm at the last stage of fixing the P1647 now

1 - I have a higher mileage XJ Sport 3.2 for spares (hasn't run in 9 months - throttle body failed, plus I'm canibalising it...), I took the right hand bank (easy one) O2 sensor off - my question: can I volt/amp check this to see if it's OK ? If it works I have a cheap fix!

2 - if it fails testing, can I use a BOSCH 15627 wide band A/F or is that the downstream equivalent?

3 - otherwise any advice on EU suppliers I can get a reasonable price from please (here in Sweden, best offer is c. 180GBP/1800SEK per sensor....)


Thanks again JF people - best regards Steve

 

This is from a post on the GM forums, but good information.

Testing O2 sensors that are installed

The engine must first be fully warm. If you have a defective thermostat, this test may not be possible due to a minimum temperature required for closed loop operation. Attach the positive lead of a high impedence DC voltmeter to the Oxygen sensor output wire. This wire should remain attached to the computer. You will have to back probe the connection or use a jumper wire to get access.

The negative lead should be attached to a good clean ground on the engine block or accessory bracket. Cheap voltmeters will not give accurate results because they load down the circuit and absorb the voltage that they are attempting to measure.

A acceptable value is 1,000,000 ohms/volt or more on the DC voltage. Most, if not all digital voltmeters meet this need. Few non-powered analog (needle style) voltmeters do. Check the specs for your meter to find out.

Set your meter to look for 1 volt DC. Many late model cars use a heated O2 sensor. These have either two or three wires instead of one. Heated sensors will have 12 volts on one lead, ground on the other, and the sensor signal on the third. If you have two or three wires, use a 15 or higher volt scale on the meter until you know which is the sensor output wire.

When you turn the key on, do not start the engine. You should see a change in voltage on the meter in most late model cars. If not, check your connections. Next, check your leads to make sure you won't wrap up any wires in the belts, etc. then start the engine.

You should run the engine above 2000 rpm for two minutes to warm the O2 sensor and try to get into closed loop. Closed loop operation is indicated by the sensor showing several cross counts per second. It may help to rev the engine between idle and about 3000 rpm several times. The computer recognizes the sensor as hot and active once there are several cross counts.

You are looking for voltage to go above and below 0.45 volts. If you see less than 0.2 and more than 0.7 volts and the value changes rapidly, you are through, your sensor is good. If not, is it steady high (> 0.45) near 0.45 or steady low (< 0.45). If the voltage is near the middle, you may not be hot yet. Run the engine above 2000 rpm again. If the reading is steady low, add richness by partially closing the choke or adding some propane through the air intake.

Be very careful if you work with any extra gasoline, you can easily be burned or have an explosion. If the voltage now rises above 0.7 to 0.9, and you can change it at will by changing the extra fuel, the O2 sensor is usually good. If the voltage is steady high, create a vacuum leak. Try pulling the PCV valve out of it's hose and letting air enter. You can also use the power brake vacuum supply hose. If this drives the voltage to 0.2 to 0.3 or less and you can control it at will by opening and closing the vacuum leak, the sensor is usually good.

If you are not able to make a change either way, stop the engine, unhook the sensor wire from the computer harness, and reattach your voltmeter to the sensor output wire. Repeat the rich and lean steps. If you can't get the sensor voltage to change, and you have a good sensor and ground connection, try heating it once more. Repeat the rich and lean steps.

If still no voltage or fixed voltage, you have a bad sensor. If you are not getting a voltage and the car has been running rich lately, the sensor may be carbon fouled. It is sometimes possible to clean a sensor in the car.

Do this by unplugging the sensor harness, warming up the engine, and creating a lean condition at about 2000 rpm for 1 or 2 minutes. Create a big enough vacuum leak so that the engine begins to slow down. The extra heat will clean it off if possible. If not, it was dead anyway, no loss. In either case, fix the cause of the rich mixture and retest. If you don't, the new sensor will fail.

Testing O2 sensors on the workbench.

Use a high impedence DC voltmeter as above. Clamp the sensor in a vice, or use a plier or vice-grip to hold it. Clamp your negative voltmeter lead to the case, and the positive to the output wire. Use a propane torch set to high and the inner blue flame tip to heat the fluted or perforated area of the sensor.

You should see a DC voltage of at least 0.6 within 20 seconds. If not, most likely cause is open circuit internally or lead fouling. If OK so far, remove from flame. You should see a drop to under 0.1 volt within 4 seconds. If not likely silicone fouled. If still OK, heat for two full minutes and watch for drops in voltage.

Sometimes, the internal connections will open up under heat. This is the same a loose wire and is a failure. If the sensor is OK at this point, and will switch from high to low quickly as you move the flame, the sensor is good. Bear in mind that good or bad is relative, with port fuel injection needing faster information than TBI systems.

ANY O2 sensor that will generate 0.9 volts or more when heated, show 0.1 volts or less within one second of flame removal, AND pass the two minute heat test is good regardless of age. When replacing a sensor, don't miss the opportunity to use the test above on the replacement. This will calibrate your evaluation skills and save you money in the future. There is almost always no benefit in replacing an O2 sensor that will pass the test in the first place.

 

Top detail thanks Fredd

Given my missus currently has one arm in a sling - I think the onboard testing may prove too difficult for me!

But! The bench test method and value ranges are really useful.

Thanks so much.

Testing time tonight when I'm back from the day job.

Steve

 

Someone / somewhere (parts list, JTIS, etc) should show the kind of upstream O2s. Downstreams are nearly always NOT wideband (they cost more and aren't needed there). Fitting an incompatible type may blow something expensive I expect.

All the sensors produce very little output (reasonable voltage, negligible current).

 

It is important to note that on AJ27 engines (NA after MY98 and SC after MY99), the precat lambda sensors are the wideband type and the sensing circuit is substantially different. The voltage test defined will not work and the resistance test may damage the sensor.

 

Thanks Ross - due to the day job I haven't got time to look at the O2 sensor swap until the weekend, but at least I'll have time get one off the "spares jag" and just try in the pimpjag without running the "heat it in a vice" test.

Great help from all, thanks /steve

 

OK back to this post.

I took the Lambda sensor (upstream of the cat) off my spares jag (1998 XJsport) - cheated and took the easy side

Spent ages fiddling with pipes and stuff on the daily driver 1999 XJsport - just as it is posted on the forum - a real PITA job.

But I persevered and swapped the exchange one in (after having to cut and mate the female connector on the '99 version, as the '98 has a male connector on the end....)

Somewhere my alarm bells are ringing, if Jag changed the connector - did they change the spec so swap-ins don't cause damage......????

Anyway, all put back together.

Started fine. Ran for 15 minutes. Switched off.

Plugged in OBDII scanner, switch ignition to pos1. Got the usual Stability Control Failure message on the dash (it has done this each time I have used the OBD tool I bought over here in Sweden...).

Ran the option to get error codes and just got a stored 1647 (which was my last one pre/swapping the sensor), then got a P1111.

So I felt pretty happy.

Until I ran the car for 30 minutes an dropped into a local garage who has a gas analyser....

Still the same readings on my CO and HC...

Questions now are:

1 - fuel system

I can't remember the OBDII readout exactly - but I ran a live reading, I was really wanting to see the O2 measurements - both about 0.9 0.8 on idle, way lower on 2500 revs...

But in the back of my mind I think I saw FuelSys1 and FuelSys2 both OL

Anyone got feedback on that FuelSys OL reading please?

2 - catalytic converters

If I'm getting crap emission readings on tickover have the cats failed?

Thanks for pointers on that


3 - Long and Short fuel trims

I don't know what they are and what they affect.


Thanks for you help again

Steve

 

OL will be Open Loop, meaning it's not using the O2 sensor to let it fine tune fuel to air mix. CL is closed loop, which is what you'd like to get.

OL it needs to run rich to save the engine but it means bad emissions. It looks up fuel from things like air, temperature and so on but keeps it rich (extra fuel). In brief, in CL it can see if there's no O2 from the sensors so knows it's too rich and reduces the fuel until it can see O2.

It's doing the checks multiple times per second so can get accurate fuel very quickly, but only CL.

It needs O2 sensors (& wiring etc) that work.

 

Hi JagV8

Thanks for the info.

One last question - will a hard reset (battery disconnected for however long) alter anything in terms of it looking for the sensors just in case both are now ok but the system is running in OL?

Tell me if I'm being a plum - and i'll get 2 new upstream sensors from the UK

Thx again - steve

 

Hi JF members!

OK - back to this thread - my XJ8 3.2 sport - failing emissions on tickover.

I've ordered 2 new upstream O2 sensors from Jagspares Northeast - they're winging their way over to Sweden as I write. Hopefully I can fit them before the weekend.

To repeat from previous reply - I pulled an O2 sensor from 1998 XJ 3.2 sport I have for spares. Following the swap in of the spare and running the engine for 15 minutes, I ran KeyOnEngineOff OBD and didn't get a P1647.

Then I ran KeyOnEngineOn live data on the OBD and didn't get any change in code but looking at the FuelSys1 and FuelSys2 they are both showing OL... which is Open Loop.

And as all the knowledgeable JF advisors state - this is going to run rich and fail emissions.

So here's my question (and the reason I'm trying to be proactive is that I have only until Monday to fix the emissions then my retest here in Sweden is expired, so pre-advice is appreciated) :

If I still get OL after swapping in the brand O2 sensors - where do I start to look to fix the tickover richness?

Air intake side - leaks, MAF etc.

Fuel pump - what checks etc.

Are there any ECU overrides that make the engine run FuelSys OL in Park or things I can "fix"

Help appreciated.

Thanks again /steve

 

Steve:
i know nothing of the 3.2 engine variant, but on the 4.0, a MY 98 is an AJ26 engine, and a MY99 is a AJ 27 and the pre cat oxygen sensor are completely different. The AJ 27 engine uses wide band sensors. The post cat sensors on the AJ 27 engine match the precat sensors for the AJ26. I THOUGHT the plugs were different on the two types of sensors.

 

OK - next installment...

Battery earth lead off.

Hood up.

Hands into the LH side water hose spaghetti and undoing the coolant reservoir, overflow pipes.

I siphoned the coolant out in 2 steps, first to empty the reservoir, then stuck my syphon tube (piece of rubber fuel pipe) into the main hose to the cooling system as far as it would go. Suck, spit (this is a family forum, I'm not going anywhere else with this line) and drain into a bucket.

Took off the hose from the heater pump motor on the inside of the wing and bent it out of the way, this gave me enough room to get at the 3 exhaust heat shield studs.

Pushing the remaining hoses out of the way, got the heat shield out.

It's so fiddly to get the O2 connectors apart from the tray/clip thing up underneath the fuel evap catch pot but now with experience, I released the mated pair off the metal clip they are supported on, then I could manage to press the release prong thing and split the male/female plugs.

Fiddled with the sawn off 22mm spanner and breaker extension - and out came the bodged sensor from the previous job (the upstream O2 from my 1998 spares jag... which I now know to be incompatible - thanks to forum members).

Old one out, in went the new one, cabled up - and started in reverse order putting back heat shield, pipes and reservoir.

Filled up the coolant from the bucket.

Now the RH side - started by taking off the intake pipe from the throttle body and the filter box to get good access.

Easy to get to the sensor connectors, but a devil of a job to prise the mated pair off the metal support post... a fiddle with a little flat blade screwdriver after bending the post towards me to gain access. Then with the pair off the post, easy to press the release prong and split the connectors.

Not too tough to take out the O2 sensor. The breaker bar on the spanner made good leverage - I just felt the tension and eased it free with a slight pull to break the grip in the threads. Out it came. New one in and tightened up, cable connected back into place.

2 new O2 sensors fitted - much quicker than my previous effort. About 1:45 in total

I reconnected the battery and started up.

All ran OK, so test drive.

Seemed to be a bit more responsive unless I was just elated...

Drove steady for a about 30 minutes.

Back home, did the "steve's nose test" - I get close up to the tail pipe and have a sniff.

Mmmmmmmm gas kandy

No seriously, I get a little close with my vehicles and previously could tell she was running too rich just by the sweet gas smell even after she was warmed up and should have been running leaner.

Anyway - smelt different - not as a sweet... maybe I've fixed my emission problem...

Engine off, OBD scanner in. Ignition on, not started.

Scanner rigmarole kicks off - doesn't know it's a jag as usual... click through everything, see my old P1647 stored, erased all that and did a live data test...

FuelSys1 and FuelSys2 show a CL !!!!!!!!!!!!!!!!!! Closed Loop!!!!!!

Yay!!!!

So off to my mates tomorrow to get the gas anlayser confirmation then I can get the old girl registered here in Sweden.

Confirmation of job done tomorrow (or whatever the news is!)