Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
|
|
Oct 28, 2022 22:28:12 GMT
|
I’d also say MAF sounds potentially iffy. Generally speaking of you unplug it and the car reverting to the base map improves things, it’s a sign of issues.
But before you do that, I’d say 12.7v is borderline for a battery on such a electronics heavy car, and the cca being so low suggests the battery is probably calcified to an extent. Although it may start it the rest of the electrics can still be unhappy. My transit is like this at the mo, the battery is getting old (I’ve had it 4.5 years and it wasnt new then) it’ll start it but if you Rev it straight away it cuts out. Leave it idling a short while, not even long enough to warm up, and it’s fine. If I swap another battery on the problem goes away. Maybe your ‘fine once it warms up’ symptoms are actually the battery topping up like mine is. If the battery is more than 3 years old I’d swap it anyway for the price they cost, just to make sure you’re not chasing a ghost. Worst case you’ve just crossed a potential off relatively cheaply and easily. Odd symptoms are often simple things though.
|
|
Last Edit: Oct 28, 2022 22:30:00 GMT by Dez
|
|
|
ChasR
RR Helper
motivation
Posts: 10,191
Club RR Member Number: 170
|
|
Oct 29, 2022 11:12:21 GMT
|
Is this the ZF 5HP24 box? Also used in most of the first series of Audi A8 4.2 where it has a a reputation for near 100% failure rate, not helped by Audi saying it’s sealed for life but not mentioning this means a short life. Consensus seems to be that fluid changes every 40 - 60k more or less eliminates the failures. There is also the occasional story of first changes done at 100k + causing failure but my take on that is that these changes were only done in the first place because the box was already showing signs of ill health! They also talk of only having changes done by ZF agents with the correct flushing machine - which is a pricey business. Having watched a couple of oil change videos for the Jag, I don’t really see why that’s necessary. Nick Possibly! My info came from an ex-Jag specialist regarding the 5HP 'boxes. As a rule he won't touch the oil in the 'box if it's never been done before. I think you're right regarding the 'boxes showing issues before, but the fact that fresh ATF is a detergent by nature won't help things at all. The 6HP is easy to do the oil on. I think that rumour around the flushing machine is about getting all of the oil changed, as it puts through double the amount of oil required in order to get as much 'fresh' fluid in. TBH, I'd agree with you that doing a basic change is fine. Many will never have seen the oil changed. Just throwing it out there, but it wouldn't be the first time I have seen an auto that uses data from the MAF, and when the MAF goes bad it causes a whole bunch of shifting and drivability issues. Unplugging the MAF and having it "fix" the issues sounds to me like the MAF isn't operating correctly, as this is one of the common tests you do to check for a failed MAF (and the only way I could limp my old Alfa 156 home after the MAF failed). We've changed MAFs on a few autoboxed cars, despite them being in spec. After a new one, folks could have sworn we rebuilt the gearbox.
|
|
|
|
|
|
Oct 29, 2022 14:58:07 GMT
|
Thanks for the replies all.
Today, I drove the car about 60 miles. The O2 sensor has not solved the problem as the car performed almost exactly as it always does but I can notice a few little changes. The engine runs buttery smooth at idle. Any small misfires are totally cleared up. Actually, today there was a time when I could barely tell that the engine was on and thought it had stalled until I saw the rpm. Before fitting the new sensor, I would often pick up a little vibration through the seat but this is fixed now. My fuel trims are also much more in line with what I would expect and the high fuel trim on bank 2 is now solved. This has not fixed the poor shifting and stalling.
I read the replies about the MAF sensor with great interest and thought it merited more investigation. These are my findings.
- If the MAF is unplugged, and the engine cold, it will start but struggle to stay running. If I feather the throttle to prevent it from stalling, it will settle after about 5 seconds and then idle smoothly thereafter. Driving the car in this condition, it shifted more predictably, felt quicker, accelerated smoothly with no flat spots, and did not appear to stall. Idle dropped very low at one point but the car recovered and then drove well afterwards. Once up to temperature, I could turn the car on and off, and it would start stay running each time.
- If the car is up to temperature, with the MAF plugged in, and I unplug the MAF, the car will stall.
- If the car is up to temperature, with the MAF unplugged, and I plug the MAF in, the car will stall.
- Once up to temperature, there is no real difference between how the engine idles with the MAF plugged in or unplugged.
I don't know whether this points to a defective MAF or not, but the car running better with no MAF indicates it might be. I have ordered a replacement MAF and will update once it is fitted.
If this does not fix the problem, I will most likely take it to a garage to be fully scanned.
|
|
|
|
|
|
Oct 31, 2022 13:48:14 GMT
|
Latest bit of diagnosis.
The posts about the battery got me thinking. I have noticed that when the car goes to stall, the interior lights and headlights dim for a split second, and every now and then when I bring the revs up, I hear a little whine (sounds like a supercharger).
I don't have a multimeter to hand but my obd module can read the voltage going to the obd port which, with the engine off and ignition on, was 12.2 volts. Thats a bit low, right? When the car starts it goes to 14.4v so I assume the whine is because the alternator is being overworked.
|
|
|
|
|
|
|
Hello all and thank you for your contributions to this thread.
I have largely kept it going because I hate it when you're looking for a solution to an issue, find a thread, only for it to never be concluded- so wanted to try and keep this active enough to be helpful to someone else with the same problem.
Since last update, I had noticed that the stalling issue had cleared up for the most part. Once or twice, the rpm would drop very very slightly but nothing compared to the outright stalling from before which was dangerous and embarrassing. I didn't do a hard reset of the ECU when I fitted the new o2 sensor, so I think it might have taken a few miles to relearn its parameters. Nonetheless, I still ordered the MAF sensor which has now been fitted. Very, very easy job. Also of note, I did a hard reset by disconnecting the battery and touching the terminals together for 20 seconds. I also noticed the part load breather on the passenger drive rocker cover wasn't fully clicked into place so corrected this.
I took it for a drive yesterday, and although it wasn't a long drive, it was enough for me to think that the MAF sensor has dramatically increased the performance of the car. Massive improvement in the low speed, part throttle drivability, the gearbox also feels smoother and more willing to shift down, and the car's idle felt rock solid. No stalls despite me actively trying to induce them, so without wanting to jinx it I think that the MAF has done the trick.
Once again, thanks to everyone who contributed to this thread.
|
|
|
|
vitesseefi
South West
Posts: 2,243
Member is Online
|
|
|
Well done. Glad your persistence has paid off and that it was something relatively simple and cheap. The close-off is also appreciated!
Nick
|
|
1967 Triumph Vitesse convertible (old friend) 1996 Audi A6 2.5 TDI Avant (still durability testing) 1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
|
|
|
|
|
A late entry to this thread.
Sounds like you've got it under control, but wanted to mention this in case it helps.
In Ford and JLR products with the 6hp boxes, there is a secondary brake light switch which is used by the PCM. It is considered a consumable, and I've had it make quite an improvement to a Disco4 in terms of low speed manners and 'polish'.
I could easily see this switch causing all sorts of dramas if it was properly faulty.
|
|
1964 Daimler 2.5 V8 (project)
2015 Disco 4 SDV6
|
|
ChasR
RR Helper
motivation
Posts: 10,191
Club RR Member Number: 170
|
|
|
Good to see that you cured it.
The MAF will be used for load tables on the gearbox ECU. TBH, a number of things can make a 'box behave badly, where it is electrics, linkages or vacuum present to control parts of it.
|
|
|
|
|
|
Nov 10, 2022 14:02:40 GMT
|
I was working on the throttle body today and noticed something weird. I have posted on the jaguar forums but havent got any replies so was wondering if anyone could chime in.
The car did unfortunately start to misbehave the other day which coincides with my observation that it always seems to be worse when the weather is bad. The other day the weather was torrential rain and the car was doing it's old tricks after a few days of being quite nice to drive in mild weather.
For some reason I cant see how to attach a picture, so I will do my best to describe it. I am really hoping someone will be able decipher what I mean!
If you imagine the throttle body upside down, so you're looking at the bottom of it, there are two pipes to the bottom left of the green gasket. One is a larger diameter coolant pipe and one is a small diameter pipe, which looks like a vacuum line. This has been cut and was just completely open to the elements. I guess it behaving worse in wet weather is because this was allowing moisture into the throttle body. Anyway, does anyone have any ideas on what this should attach to? Every one I find on ebay has this cut, which I guess is just to remove it from a donor car easily as most have the other pipes cut off as well. I imagine the throttle body in my car was a second hand one which the previous owner fitted and left this pipe just doing nothing. In the meantime I have blocked it with a bolt but this is not a permanent fix. Any ideas?
EDIT: Apparrently its just a drain pipe and nothing should connect there.
|
|
|
|
Davey
Posted a lot
Resident Tyre Nerd.
Posts: 2,197
|
|
Nov 10, 2022 16:36:04 GMT
|
Funny behaviour in the damp could relate to a short somewhere. Moisture completing a circuit to earth.
Any flaky wiring around sensors?
|
|
K11 Micra x3 - Mk3 astra - Seat Marbella - Mk6 Escort estate - B5 Passat - Alfa 156 estate - E36 compact Mk2 MR2 T-bar - E46 328i - Skoda Superb - Fiat seicento - 6n2 Polo - 6n polo 1.6 - Mk1 GS300 EU8 civic type S - MG ZT cdti - R56 MINI Cooper S - Audi A3 8p - Jaguar XF (X250) - FN2 Civic Type R - Mk2 2.0i Ford Focus
|
|
|
jimi
Club Retro Rides Member
Posts: 1,815
|
|
Nov 10, 2022 16:54:55 GMT
|
Switch your browser to desktop mode/view then you will see the picture uploader at the bottom.
|
|
Last Edit: Nov 10, 2022 16:55:22 GMT by jimi
Black is not a colour ! .... Its the absence of colour
|
|
|
|
Dec 13, 2022 17:16:00 GMT
|
Hello everyone. The car has been parked up for the winter for the last few weeks but I have still been doing my best to figure out what the issue might be. The conclusion I have come to is that it is TPS or throttle body related but I'm hoping someone can chime in with any pointers on where to go from here.
The throttle position sensor can be adjusted by loosening the two mounting screws and rotating it. My thinking was that perhaps the throttle body was, for a split second, closing too much, starving itself of air, and then catching itself. I read online that a poorly adjusted TPS can cause issues and therefore, figured I'd have a go at adjusting it. Here are my findings.
Adjusting the Tps with the engine running does adjust the idle, so the potentiometer inside it is functioning. With the engine off and the ignition on, the Throttle body emits an electrical whine which cuts in and out as the TPS is rotated, similar to how sometimes on an old radio or guitar amp, the volume will cut in and out whilst a knob is being turned. The throttle blade visibly moves as the TPS is turning.
I saw a thread online where someone adjusted it using an OBD scanner which could detect the throttle position. I figured I would use their findings and tweak further if I needed. What I found was very odd, though. The throttle position on my OBD scanner jumped to 5.1% but did not move even when the TPS was rotated (even though I could see the blade moving). When I manually opened the throttle, the reading would change with the throttle pedal being pressed down, but by moving the TPS alone, nothing changed and it would not move from 5.1%. This indicates to me that the ECU is for some reason not detecting adjustments to the TPS even though they physically are affecting the throttle body.
Does this suggest a faulty TPS sensor, or perhaps the harness it connects to?
|
|
|
|
ChasR
RR Helper
motivation
Posts: 10,191
Club RR Member Number: 170
|
|
|
You may need SDD to see more values, or an improve diagnostics kit, like a Snap On Solus.
|
|
|
|
Davey
Posted a lot
Resident Tyre Nerd.
Posts: 2,197
|
|
Dec 14, 2022 10:36:07 GMT
|
By moving the sensor you are essentially changing the "Zero" So you are setting the point at which it reads 5.1% but not actually changing that setting.
Hopefully that makes sense?
If you get readings when pressing the throttle you should have a working sensor.
|
|
K11 Micra x3 - Mk3 astra - Seat Marbella - Mk6 Escort estate - B5 Passat - Alfa 156 estate - E36 compact Mk2 MR2 T-bar - E46 328i - Skoda Superb - Fiat seicento - 6n2 Polo - 6n polo 1.6 - Mk1 GS300 EU8 civic type S - MG ZT cdti - R56 MINI Cooper S - Audi A3 8p - Jaguar XF (X250) - FN2 Civic Type R - Mk2 2.0i Ford Focus
|
|