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Author Topic: Auto Surging  (Read 2700 times)

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The Barge Captain

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Auto Surging
« on: 09 April 2007, 18:44:05 »
I collected a 98 2.5 auto on the weekend.  On the drive home, the car, particularly in 2nd and 3rd gear seemed to surge at about 2500 RPM.  Ok on motorway at about legal cruise speed.  Any ideas?
Also whilst on the run the EMU light came on twice for around a minute, but noticed no change in cruise performance.  Not had time to paperclip yet.  The autobox on this car has just been changed by two very reputable and competent people, so i trust that it is filled with oil correctly, the only thing not changed with this box was the box ECU, which the matching one from the doner car is being sent to me.

All suggestions welcome.
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TheBoy

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Re: Auto Surging
« Reply #1 on: 09 April 2007, 19:32:25 »
Quote
I collected a 98 2.5 auto on the weekend.  On the drive home, the car, particularly in 2nd and 3rd gear seemed to surge at about 2500 RPM.  Ok on motorway at about legal cruise speed.  Any ideas?
Also whilst on the run the EMU light came on twice for around a minute, but noticed no change in cruise performance.  Not had time to paperclip yet.  The autobox on this car has just been changed by two very reputable and competent people, so i trust that it is filled with oil correctly, the only thing not changed with this box was the box ECU, which the matching one from the doner car is being sent to me.

All suggestions welcome.
Presumably not during gear change?

If during gear change, I would be concerned about box, and would double check levels, in case it has suffered a small leak?

If not during gearchange, is it the engine surging?
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Grumpy old man

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Re: Auto Surging
« Reply #2 on: 09 April 2007, 19:43:07 »
You need to get those codes read....
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Re: Auto Surging
« Reply #3 on: 09 April 2007, 19:49:54 »
And I fully expect them to show an oxygen sensor fault.... (Matchless' diagnosis) :)
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The Barge Captain

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Re: Auto Surging
« Reply #4 on: 09 April 2007, 22:46:32 »
It feels as though the box is undecided about locking up, i have seen the rev counter bouncing by about 300 rpm when it is particularly bad.  I thought it had improved after about the first 80 motorway miles, but as soon as i traveled on country roads, then it was back just as badly.
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TheBoy

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Re: Auto Surging
« Reply #5 on: 09 April 2007, 23:12:16 »
Quote
It feels as though the box is undecided about locking up, i have seen the rev counter bouncing by about 300 rpm when it is particularly bad.  I thought it had improved after about the first 80 motorway miles, but as soon as i traveled on country roads, then it was back just as badly.
Hmmm, is pointing towards a box problem then....
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Re: Auto Surging
« Reply #6 on: 10 April 2007, 09:10:57 »
I would still say oxygen sensor, but until codes are read we can't say for certain.
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Matchless

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Re: Auto Surging
« Reply #7 on: 10 April 2007, 09:34:49 »
Have to work out if it is autobox or engine.
Does it feel like the engine suddenly produces more power?>>air leak, fuel canister valve, O2 sensors etc
Or does it feel like the autobox is hunting between gears? You mention lock-up, so does it only happen above 50mph and not in the lower gears?

First step has to be to get a code reader on it, paper clip will give any stored codes but may be misleading if it had problems in the past. Better to clear existing codes then read out any new ones and start from there.
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The Barge Captain

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Re: Auto Surging
« Reply #8 on: 10 April 2007, 10:43:19 »
Just done paperclip test. Ignoring 12 (start of sequence) and 19 (crank sensor - car not running) the error code 132 EGR valve incorrect signal was the only one present.
I still think that the torque converter is not locking up happily, am i right in thinking that this lockup should occur in any gear?
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Re: Auto Surging
« Reply #9 on: 10 April 2007, 10:45:59 »
Quote
Just done paperclip test. Ignoring 12 (start of sequence) and 19 (crank sensor - car not running) the error code 132 EGR valve incorrect signal was the only one present.
I still think that the torque converter is not locking up happily, am i right in thinking that this lockup should occur in any gear?
EGR could causing eratic engine speed/

19 on a v6  :o  change the sensor straight away  :o
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Re: Auto Surging
« Reply #10 on: 10 April 2007, 10:49:58 »
It's recently had a new crank sensor, although that doesn't mean it can't fail again, however i thought that they all gave that error when checked with the engine not turning?
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Matchless

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Re: Auto Surging
« Reply #11 on: 10 April 2007, 11:45:10 »
I thought torque convertor only locked-up in 4th and over 50 mph.
Those codes could be old ones but either crank sensor or EGR problems would give trouble and at least one of them must be current if the light is coming on occasionally..

EGR incorrect signal : the valve isnt moving to (or returning from) the position it was told to by the ECU, ie its probably sticking. Remove it and clean off the carbon deposits from the 'plunger' (oven cleaner / paint stripper is very effective at removing carbon) then fill with WD40 and work the plunger to free it up.

Crank sensor : If its been replaced recently where was the cable routed? Has it touched the exhaust?
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Re: Auto Surging
« Reply #12 on: 10 April 2007, 11:51:08 »
I've got a spare perfectly good EGR valve. I'll send it down to you if you PM me your address.

This will cause problems...

Oh and I am sure Matchless is right. To my (limited) knowledge, the torque convertor only locks up after 50mph in 4th.
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Re: Auto Surging
« Reply #13 on: 10 April 2007, 19:50:19 »
19 is failing crank sensor on v6, 31 is normal.  It may be an old code, though I thought the 19 disappeared fairly quickly from the flash codes once fixed.
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Re: Auto Surging
« Reply #14 on: 11 April 2007, 01:16:57 »
Motor starts right on the button, and runs fine. Might just be an old code, but if so, why no 31(?) error?
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