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        General >> Give/Need advice to/from others >> Autobox NOT Faulty
        
(Message started by: Mike H on Apr 14th, 2010, 5:46pm)
Title: Autobox NOT Faulty
Post by Mike H on Apr 14th, 2010, 5:46pm
This may be reiteration, but worthy of another mention I  think :)

For as long as I've had the car (a 2L 16V Exec) it's had this what seems like a persistent fault, but is it what it actually seems? As we know the PCM also controls the transmission via solenoid valves (hence "Powertrain Control Module"), nevertheless the symptom manifests itself as what appears to be like a slipping clutch or brake band for the overdrive (specifically).

The car isn't used often and mostly for short journeys, for which I usually turn O/D off. In fact turning O/D off is the simplest prevention of the problem. All is hunky dory.

Otherwise trying O/D for long runs results in what I can best describe as a "hunting" behaviour, once into O/D the rev counter needle keeps wandering up and down, which for all the world looks like exactly the drive is slipping, ergo the box is duff. No it isn't (read on)

Eventually (and the timing can vary quite a bit) the PCM throws in the towel and flashes the O/D light ("that's it I'm outa here!" ;D )

Last month I had occasion to make a long trip to Yorkshire which meant all up the M11/A1/M62. Set out leaving O/D enabled just as an "experiment"

We managed 114 miles before the PCM threw its toys out of its pram. (Incidentally to reset it and clear the TIL just stop somewhere, turn it off and restart it.)

Not a bad effort actually, at least >2 hours of motorway type cruising and good and hot by this time. What was particularly interesting, however, is that once it was left to its own devices (that is, without any further "outside interference" LOL), and because we were doing around 70 m.p.h. at the time, the box locked into overdrive of its own accord and held it perfectly. Even the slightest hints of "slipping" like behaviour glaringly absent

Which I think I can safely say finally confirmed to me that the "wandering needle" syndrome is much more likely the PCM trying out various things to try to make its numbers add up, i.e. it's a sensor problem somewhere.

Coincident with this is another symptom which occasionally manifests itself, which might be described as "kangaroo hopping" under acceleration somewhere around 45 - 55 m.p.h., (very like what we'd get with carburettor cars with manual choke, and you pushed the choke out too early before it was warm enough).

Sure the MAF was cleaned very early on soon as I found out about it, didn't seem to make a huge difference at the time, but then again (stupidly perhaps), I've no idea to be honest how old the air filter is. (Looking at the top of the filter element doesn't actually tell you very much, that's not the "dirty" side where the air actually comes in.)

Took the filter out and held it up to the sun (it was a bright sunny day), not a hint of light showing through at all. Black. Nuffink.

OK so new filter and while we're at it a new MAF ('only' £53 from BuyPartsBy, so why not ~ car is 15 years old after all, it's doubtless original and these things must get "tired" after a while)

(NB it's already got 2 new O2 sensors)

Anyway, bit of a run out around the leafy lanes today and I seem to have more torque than before, better low r.p.m. "grunt" anyway. Still very early days yet TBH bu-ut, after about an hour total of driving no sign yet of the O/D revs "hunting" behaviour.

Moral of story ~ exhaust all other possibilities before condemning the gearbox ;D

Next on the "to do" list, new cat...

Which is already lying on the floor of the spare room as I type ;D
Title: Re: Autobox NOT Faulty
Post by tlundkvi on Apr 14th, 2010, 6:40pm

on 04/14/10 at 17:46:57, Mike H wrote:
Which I think I can safely say finally confirmed to me that the "wandering needle" syndrome is much more likely the PCM trying out various things to try to make its numbers add up, i.e. it's a sensor problem somewhere.


Wandering speed needle? Add it up to O/D flashing, thumping gears, looong 1st gear before shift to 2nd, and you have a VSS issue. Takes 15 minutes to swap.
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 14th, 2010, 8:34pm
Thanks, re "looong 1st gear before shift to 2nd" no it doesn't / didn't do that
Title: Re: Autobox NOT Faulty
Post by lleewar on Apr 14th, 2010, 8:39pm
Hi Mike, Hoorah, someone who has experienced what I have been having trouble with. I know what you mean by kangaroo hopping and needle movement although the later has just started. Will change my air filter soon as. When I put this on the problem page a while ago I was told it could be the coil pack/s breaking down.   Lee
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 15th, 2010, 2:51pm
Worth a try and not difficult to do! ;D

My guess is it's not getting enough air and / or maybe not measuring it properly, so is messing about with the fuel mixture to find a combination that works. Hence the "hopping". Only for a second or two then seems to sort itself out, but which may just be falling back on the default fuel map or something like that.

Next properly long journey let you know how it goes overall. I know I'm up Yorkshire way again next month
Title: Re: Autobox NOT Faulty
Post by Tompion on Apr 15th, 2010, 3:09pm
The MAF should work the airflow out regardless & the oxygen sensor should inform the PCM of any necessary correction needed to the injectors.
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 15th, 2010, 3:15pm
Yes indeed, hence I also renewed my MAF as well to see what happens.

What happened was its better

Deduce what you can from that ;D
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 20th, 2010, 6:57pm

on 04/14/10 at 17:46:57, Mike H wrote:
Next on the "to do" list, new cat...


Update ~ seems we have rest-of-exhaust-system-disintegrating-soon-as-look-at syndrome so the whole lot is going to be replaced. This was quite on the cards actually so I'm not at all surprised. Plus highly likely a bit bunged up as well so it's all good really.
Title: Re: Autobox NOT Faulty
Post by Tekno on Apr 21st, 2010, 9:55am
MAF cleaning does always miracles :)
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 21st, 2010, 11:45am
That's what I'm hoping

Or even a new one ...

Exhaust refit update ~ still ongoing!
Title: Re: Autobox NOT Faulty
Post by lleewar on Apr 21st, 2010, 8:28pm
Mike, changed my air filter, seemed to drive better but still having the kangaroo problems at lower speeds. I also have the 'exhaust needs changing mode' from the cat back, middle section especially. What year is your motor? Mines an 95 Ultima.   Lee
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 22nd, 2010, 1:09pm
Yep August 1995. "Only" an Exec tho ;D

Presume you've tried cleaning the MAF? Squirting the old brake cleaner in. If no difference (as mine wasn't) think you'll have to bite the bullet and try a new one I'm afraid. Considering how it works I can't believe they remain working perfectly after 15 years

Bear in mind though, previously, so-called "cut-off loom" (coil pack wiring) completely rewired, new plugs, new O2 sensors

Question ~ when you start it cold, do you get a rich petrol smell and perhaps a bit of smoke from the exhaust pipe? I did 'til I changed the filter and MAF, now it doesn't

Exhaust update ~ still ongoing!! Still waiting on the big middle bit apparently. In hindsight I could've got all this stuff together earlier
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 22nd, 2010, 1:14pm
Second question ~ "kangaroo hopping", at what m.p.h. do you get that?
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 22nd, 2010, 1:41pm
Exhaust update ~ finished!
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 22nd, 2010, 1:46pm
Appendix ~ my mechanic fellah said the old system was much heavier than the new system, so obviously full of crud
Title: Re: Autobox NOT Faulty
Post by Highlander on Apr 22nd, 2010, 4:18pm
Or made of a better quality metal ;)
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 22nd, 2010, 4:30pm
No don't start!
Title: Re: Autobox NOT Faulty
Post by lleewar on Apr 22nd, 2010, 10:24pm
Mike, Cleaned the maf though I know it was changed fairly recently before I bought the car. Kangaroo hopping was around the 30-50 but seems to disappear at higher speeds. I did used to get the rich smell of fuel but that seems to have gone. Go figure. Let me know how the car runs with the new exhaust. Was it a complete one or partial?   Lee
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 23rd, 2010, 1:54pm
Yes it was complete except the short section with the flexible joint.

It's a completely transformed car. My mechanic guy couldn't believe the difference. More urge, faster, smoother, quieter. Apart from a tiny bit of a roar if you boot it more. Which it never did before, or quite like that.

Still not had a chance to try it for long enough on roads with no road-works / speed limits etc. yet ::) but so far the autobox behaves exactly like it should. Locks into overdrive, and cos the the motor is now strong enough to pull it from 2,000 rpm upward, so it stays there. Touch wood for luck, but I think we might have a result and a happy PCM! ;D

You say "was" kangarooing, do you mean it's stopped doing it now? After cleaning your MAF and so on ~ that speed range is about the same where I was getting it as well, I think the reason why it stops at higher speeds is because by that time the PCM has resorted to some default fuelling strategy. Probably fuelling gone "open loop"

I know it was worst in hot weather and rare in Winter, until properly warmed up, which suggests running on the rich side.
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 25th, 2010, 1:47pm
Extract from the 'Cattle Grid Effect' article

"I took my 1995 2.0 16v Ultima auto on its first long run down to Devon last weekend. Taking the opportunity to use the cruise control, I found that on even the slightest inclines the box shifted down a gear and then back up again, seemingly undecided about which gear to be in. (yes that's exactly what I was getting. This ultimately leads to O/D light flashing.) I just put this down to the 2.0 engine being a bit under-powered," (so did I to be honest!)

"After this, I got a couple of jerky gear changes and in a couple of instances I felt what is very accurately described as the 'cattlegrid effect.' "

Yep, cos when PCM gives up on the box and flashes O/D, from then on it won't touch it with a 10 foot pole. It goes into some minimum operation mode, which includes NOT ensuring smooth gear changes, which it normally does by briefly cutting the ignition during the change. (And possibly fuel injection as well but not sure about that.) Without this featuire, gear changing goes all horrible and jerky.

"Around town since it has been perfectly normal" yes usually is! Just to confuse the issue even further ;D
Title: Re: Autobox NOT Faulty
Post by Mike H on Apr 26th, 2010, 3:52pm
25 mile round trip to South Woodham Ferrers and back, so means could whizz up and down a bit of the A130, and all is bliss and joy. Quite amazing what freeing up the inlet and exhaust gases can do and well worth the hassle and cost of doing it.
Title: Re: Autobox NOT Faulty
Post by lleewar on May 9th, 2010, 12:49am
Mike, have all your problems disappeared since putting on the new exhaust?
Title: Re: Autobox NOT Faulty
Post by Mike H on May 9th, 2010, 10:54am
Yep! Almost like swapping the engine & gearbox for something better, that's how much difference it makes. ;D Everything works properly now.

Going to Doncaster next weekend so will be able to give it a really "proper" run then but am optimistic.

Short history ~
Was a fleet vehicle for Balfour Beatty up until 2000. The story goes anything needed doing it was just done, money no object ;D

Since 2000 however I very much doubt any serious servicing or checks were made, my neighbour who I subsequently got it from would be the first to admit he's "mechanically inept" ;D , so time took its toll so to speak. Things needed renewing that just weren't. Even simple things like air filter and plugs.

Shopping list (this time) ~
1. air filter £7.21
2. MAF sensor £53
3. cat converter £82
^ comes with a note do not fit until you're sure all other normal operations are correct (i.e. fuelling, ignition etc.) else it could be ruined!

4. exhaust centre section (3 silencer boxes), tail section (1 silencer) £150 (-ish)

Hitherto ~
Engine oil + filter last November.
New transmision fluid + filter couple of years ago.
New plugs ditto. (old ones had hardly any electrodes left!)
New O2 sensors ditto.
DOHC coil pack wiring replaced about 4 - 5 years ago (?) (by me)
Title: Re: Autobox NOT Faulty
Post by gozz on May 9th, 2010, 11:11am
Mike.
Did your new cat have the bracket onto which, part of the heat shield bolts ? the pattern part versions are much smaller and bracketless,they are also devoid of manifold studs and are supplied with four large bolts with nuts.A cheap option but not the most satisfactory.
                              GOZZ.
Title: Re: Autobox NOT Faulty
Post by Mike H on May 9th, 2010, 12:09pm
Since you ask, with 4 bolts and nuts, though did have brackety things on as well. Weren't any other choices though.
Title: Re: Autobox NOT Faulty
Post by Mike H on May 16th, 2010, 11:49pm
The oop North weekend is done and dusted, about 400 miles round trip, went like a dream.

Everything works properly and it pulls overdrive like it never could before.

Makes ya wanna go for a long drive just for the hell of it ;D


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