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        General >> Give/Need advice to/from others >> Strange acceleration issue with my Cossie
        
(Message started by: te_ess on Jul 11^th, 2010, 9:03pm)

Title: Strange acceleration issue with my Cossie
Post by te_ess on Jul 11^th, 2010, 9:03pm

Hi everybody,

recently i've noticed a strange acceleration issue on my '97 cossie with 85 thousand miles.

When accelerating and holding the gas pedal on constant position, i've recognized that the rev is increasing, then settling for a second or so, then increasing again, settling, etc..
this is happing roughly between 1500 and 3500 revs.

In Neutral the Motor revs up ok.
the autobox oil is renewed recently and looks red and good.
It does not seem like the autobox is slipping or similar. The Autobox engages all drivepositions absolutly fine and shift gears very very fine and smooth. the shifts appear at the right time/condition.
after reaching the "target-rev" the car is running without any issue.

The airfilter is quite new (less than 1000 miles), oil-filter less than a year old (with 6 month non-drive period).

Any good idea what's going wrong? Fuel-filter?

Title: Re: Strange acceleration issue with my Cossie
Post by Tons_of_fun on Jul 12^th, 2010, 8:00am

Have a look for air leaks around the inlet manifold & Idle control valve . Also check for vacum leaks & while your there cleaning the MAF sensor wouldnt hurt. It does sound like a slipping box though. Best of luck & keep us posted... Craig :-)

Title: Re: Strange acceleration issue with my Cossie
Post by te_ess on Jul 12^th, 2010, 8:21am

Hi Craig,

thanks for the reply.

The MAF was cleaned when i replaced the air filter.
Whould a slipping box be a different behavior? More of "jumping rev" ? meaning the rev is going up and down while accelerating? Mine does not go down during accel.

I'll check for air leaks at first
It much easier than checking the autobox :-)

Greetings
Torsten

Title: Re: Strange acceleration issue with my Cossie
Post by Tons_of_fun on Jul 12^th, 2010, 12:33pm

Ah hh. Ok now i understand the symptems a little more. I do remember a friend of mine had similar problems with his 12 valve Granada. After lots of head scratching he changed the Throttle position sensor on a whim, which cured the problem. Im sure someone else far more clever than me will be along shortly to sort you out ;-)

Title: Re: Strange acceleration issue with my Cossie
Post by Mike H on Jul 12^th, 2010, 1:19pm

Yep makes sense.

You could (at risk of sounding like a scratched record ;D ) try unplugging the MAF sensor just to see if it still does it, that'll prove it's not a MAF sensor associated problem

Title: Re: Strange acceleration issue with my Cossie
Post by Highlander on Jul 12^th, 2010, 1:39pm

on 07/12/10 at 13:19:05, Mike H wrote:

Yep makes sense.

You could (at risk of sounding like a scratched record ;D ) try unplugging the MAF sensor just to see if it still does it, that'll prove it's not a MAF sensor associated problem

Unless its the MAF thats causing the problem ;)

Title: Re: Strange acceleration issue with my Cossie
Post by a900one on Jul 13^th, 2010, 10:06am

Sounds like the same thing mine has, 98 cossie, 89000 on the clock. I thought it was just because I dont drive it a lot. I have cleaned the idle valve, maf etc, and checked for air leaks, none found, still the same.
Be very intrested if you can stop it, it goes away if you push a lot harder on the right pedal.

Title: Re: Strange acceleration issue with my Cossie
Post by Tons_of_fun on Jul 17^th, 2010, 1:37pm

You know, the more i think about it the more im thinking Throttle position sensor. It seems like your not getting enough fuel / air at the right time, unless your at full throttle ! By which time your getting everything...& lots of it ;-) Keep us posted te_ess. I would like to know the outcome of this one .

Title: Re: Strange acceleration issue with my Cossie
Post by te_ess on Jul 17^th, 2010, 6:24pm

Hi guys,

many thanks for your input so far.
had a busy week, was not even driving the cossie for an inch :-(

if it is not getting enough fuel, a good candidate is the fuel-filter, as it is in unknown condition. (and should therefor be exchanged anyway :-))

i'll check for wrong air, MAF, TPS and fuel filter next week - hopefully....

Title: Re: Strange acceleration issue with my Cossie
Post by te_ess on Jul 27^th, 2010, 7:48am

Hi folks,

had not much chance to take a look, but i've managed to read the obd2

3 errors were stored
p0131
p1151
p1152

i'll recheck the MAF i think.

does anybody know if a MAF from a Mondeo 1.8 or 2.5 fits?

greetings
Torsten

Title: Re: Strange acceleration issue with my Cossie
Post by Tompion on Jul 27^th, 2010, 12:20pm

They're oxygen sensor codes.
Clear them & see if they return.

The list is here:
http://www.fordscorpio.co.uk/codes.htm

Title: Re: Strange acceleration issue with my Cossie
Post by Mike H on Jul 27^th, 2010, 12:34pm

That's why I suggested unplugging the MAF, cos that forces "open loop fuelling" is that right?

The 'wandering up and down' revs in overdrive is exactly what mine had for ages, the O2 sensors were both shot as it turned out, but new ones still didn't cure it. New MAF did. Oh plus cat and complete exhaust system, most likely all fouled up by the original problem.

Title: Re: Strange acceleration issue with my Cossie
Post by Mike H on Jul 28^th, 2010, 3:39pm

I like the way the system notifies me about replies to topics that I'VE made ;D

Title: Re: Strange acceleration issue with my Cossie
Post by Thunderchild on Jul 29^th, 2010, 1:28pm

I agree with the throttle position sensor. What happens is that a small part of the resistor (that's basically what the sensor is, a rotary resistor) gets worn away by the throttle being open at one position for long periods of time. This typically happens during motorway driving where only very small throttle movements are made and the rubbing on the small patch of the sensor wears through the resistant material. I had this happen on 2 of my Sierra 4x4s when I was doing big mileages on motorways.

HTH

Tc

Title: Re: Strange acceleration issue with my Cossie
Post by te_ess on Jul 31^st, 2010, 7:18pm

Hi Tc,

but how make a broken TPS the above Codes occur?
I've done a testdrive yesterday and will recheck for codes tomorrow.

Btw: We had some cooler days (around 18 - 22 Degree Celcius) recently and i think, the Cossie behaved better, sounds like MAF, doesn't it?

Title: Re: Strange acceleration issue with my Cossie
Post by Mike H on Aug 1^st, 2010, 2:42pm

FWIW my MAF associated bad running was worst in hot weather.

Title: Re: Strange acceleration issue with my Cossie
Post by te_ess on Aug 23^rd, 2010, 7:40pm

Hi,

i've finally exchanged the MAF, and it seems to be ok.

unfortantly the weather has changed from the very day i've changed the sensor, so either it was really the MAF or the cooler weather :-)

Title: Re: Strange acceleration issue with my Cossie
Post by Mike H on Aug 23^rd, 2010, 10:50pm

Time will tell!