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Topic: Autobox NOT Faulty (Read 1781 times) |
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Mike H
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Renault Clio
  
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Autobox NOT Faulty
« on: Apr 14th, 2010, 5:46pm » |
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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!"  )
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
Next on the "to do" list, new cat...
Which is already lying on the floor of the spare room as I type
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Mike H
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tlundkvi
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Ex. Scorpio 2.9 24V -95
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Re: Autobox NOT Faulty
« Reply #1 on: Apr 14th, 2010, 6:40pm » |
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on Apr 14th, 2010, 5:46pm, 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.
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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.
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #2 on: Apr 14th, 2010, 8:34pm » |
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Thanks, re "looong 1st gear before shift to 2nd" no it doesn't / didn't do that
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Mike H
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leewar
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Re: Autobox NOT Faulty
« Reply #3 on: Apr 14th, 2010, 8:39pm » |
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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
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Mike H
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Renault Clio
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Re: Autobox NOT Faulty
« Reply #4 on: Apr 15th, 2010, 2:51pm » |
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Worth a try and not difficult to do!
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
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Mike H
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Tompion
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1997 2.3 Ultima estate.
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Re: Autobox NOT Faulty
« Reply #5 on: Apr 15th, 2010, 3:09pm » |
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The MAF should work the airflow out regardless & the oxygen sensor should inform the PCM of any necessary correction needed to the injectors.
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ABS multiplug wheel sensor pins MK IV or MK 20
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #6 on: Apr 15th, 2010, 3:15pm » |
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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
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Mike H
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #7 on: Apr 20th, 2010, 6:57pm » |
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on Apr 14th, 2010, 5:46pm, Mike H wrote:Next on the "to do" list, new cat...
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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.
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Mike H
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Tekno
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Tenho Ruohoranta
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Re: Autobox NOT Faulty
« Reply #8 on: Apr 21st, 2010, 9:55am » |
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MAF cleaning does always miracles
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1998 Ford Scorpio Ultima Estate 2.3i 16V
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #9 on: Apr 21st, 2010, 11:45am » |
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That's what I'm hoping
Or even a new one ...
Exhaust refit update ~ still ongoing!
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Mike H
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leewar
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Re: Autobox NOT Faulty
« Reply #10 on: Apr 21st, 2010, 8:28pm » |
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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
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #11 on: Apr 22nd, 2010, 1:09pm » |
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Yep August 1995. "Only" an Exec tho
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
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Mike H
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #12 on: Apr 22nd, 2010, 1:14pm » |
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Second question ~ "kangaroo hopping", at what m.p.h. do you get that?
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Mike H
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Mike H
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Renault Clio
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Re: Autobox NOT Faulty
« Reply #13 on: Apr 22nd, 2010, 1:41pm » |
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Exhaust update ~ finished!
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Mike H
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #14 on: Apr 22nd, 2010, 1:46pm » |
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Appendix ~ my mechanic fellah said the old system was much heavier than the new system, so obviously full of crud
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Mike H
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Highlander
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13 Scorpios, XR4x4, Suzuki SJ413 for off road :)
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Re: Autobox NOT Faulty
« Reply #15 on: Apr 22nd, 2010, 4:18pm » |
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Or made of a better quality metal 
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on Oct 17th, 2011, 12:35pm, Simmo wrote:I give up !  Too much for an old boy!  |
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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #16 on: Apr 22nd, 2010, 4:30pm » |
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No don't start!
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Mike H
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leewar
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Re: Autobox NOT Faulty
« Reply #17 on: Apr 22nd, 2010, 10:24pm » |
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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
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Mike H
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Renault Clio
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Re: Autobox NOT Faulty
« Reply #18 on: Apr 23rd, 2010, 1:54pm » |
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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!
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.
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Mike H
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Mike H
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Renault Clio
Posts: 2594
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Re: Autobox NOT Faulty
« Reply #19 on: Apr 25th, 2010, 1:47pm » |
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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
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Mike H
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