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        General >> Problems >> Engine erratic at around 40-50mph
        
(Message started by: Fidget on May 23^rd, 2007, 9:31am)

Title: Engine erratic at around 40-50mph
Post by Fidget on May 23^rd, 2007, 9:31am

I have a feeling this may be a fueling issue (such as the fuel pressure regulator) but I'd be so grateful for any advice on this ...

My 2.0 16V is lurching/dropping back when cruising at between approx 40 to 50mph. By this I mean that if I hold the accelerator at a single position around these speeds, the car seems to lurch forward slightly, then drop back again (as if I was accelerating then decelerating).

I haven't had the chance to run a scan yet, but hope to today or tomorrow.

comments much appreciated, tyvvm

.

Title: Re: Engine erratic at around 40-50mph
Post by jonnycab on May 23^rd, 2007, 10:38am

Could be a coil pack problem, especially if it's only happening under a certain load :)

Not sure the fuel pressure regulator would cause these symptoms as it is under a constant pressure from the fuel pump & if it were faulty, then it would cause problems across the whole driving range....I think ;)

Title: Re: Engine erratic at around 40-50mph
Post by Simmo on May 23^rd, 2007, 11:31am

Fidget, before you do anything else have a read of THIS (http://www.fordscorpio.co.uk/cleanmaf.htm) and clean the MAF.

Title: Re: Engine erratic at around 40-50mph
Post by Fidget on May 23^rd, 2007, 11:43am

Hi Simmo, I thought of the MAF and have already replaced it with a new one - result is no difference.

Jonnycab, I did replace one coil pack a few months ago, perhaps I should try replacing the other with the same. I was racking my brains to see if anything in a scan would reveal a faulty coil pack, but can't think of anything.

thanks for the help guys.

Title: Re: Engine erratic at around 40-50mph
Post by Octavian_P on May 23^rd, 2007, 11:55am

Try to disable the over-drive. If the MAF is dirty the car starts to hunt for higher gear.

Later edit: wow the same responses in such short time

Title: Re: Engine erratic at around 40-50mph
Post by Fidget on May 23^rd, 2007, 12:02pm

We're all on an early lunch, :D

Title: Re: Engine erratic at around 40-50mph
Post by TiberiuS on May 23^rd, 2007, 4:04pm

Hi. The one that I always say but what does the loom look like where it snakes around the back of the engine to the coilpacks?

Sounds like a misfire issue, I'm getting similar part throttle hesitation on the Jag but it's more subtle, more like a power loss - maybe because each plug has it's own coil as opposed to 2 sharing on the DOHC Scorp???

That's the bummer, scan wouldn't show anything unless it triggered a misfire code and then I presume the engine would be in limp home mode anyway.

I hope Jonny's right about it causing this symptom, would make my day to lose that hesitation ;D

Title: Re: Engine erratic at around 40-50mph
Post by tintin on May 23^rd, 2007, 5:03pm

yep, worth a scan, also look for a blocked cat, might produce similar symptoms.....

Title: Re: Engine erratic at around 40-50mph
Post by Fidget on May 23^rd, 2007, 7:11pm

Thanks guys,

The cabling was replaced (cut back to good and new cable soldered in a couple of months ago), that's not to say that a new loom is not on the cards (ford parts uk still do them).

The CAT was replaced December last year, no noises from it, so I believe its ok.

I think I'll have to go with replacing the other coil pack and the fuel cut off loom. If that doesn't solve it then I'll have to spend a day with her.

Title: Re: Engine erratic at around 40-50mph
Post by hellblue on May 23^rd, 2007, 8:45pm

Dont over look the EGR this may cause this too,remove vac. hose from egr valve & plug it & go for a drive,it will be ok to run with it blocked off, also remove the egr valve & clean it & make sure it sits on its seat, ie shut.