Revs Get Knocked Back (intermittent) - Would Welcome Opinions

[Nick]

Only notice this on motorway driving, get up to around 3000 revs (78 'ish mph) now and again I can feel it hesitate and then the revs/speed drops off. If I lift off then reapply the gas we are ok, for a while. Most noticeable on inclines when on cruise, you feel it knock back.

Last service was done by Ford. They changed the fuel filter so I'm hoping I can rule that out.

What do you guys think? Sticky injector?

Your opinions very welcome.

[NikpV]

whenever I see hestitation - incline - tdi I think MAF - pretty good mileage - can't think why it should be intermittent but worth a look at I think - try unplugging the MAF and running the car

[bigdaddy]

Does it only happen at 3000rpm, what happens if you don't lift off and reapply the gas, Is the 1997 desiel fly by wire, might be a faulty pedal assembly,

 

Dont know much about the desiel, so i will probably be wrong :lol:

[NikpV]

A thought - given the mileage (and BD's post) wonder if one of the throttle position tracks is starting to wear but again why is it intermittent

[Nick]

Thanks for the replys. MAF was changed a while back (a good while back). The sensor blade was missing! Good call but unlikley I think, 'cause 90% of the time she would pull the horns off a bull.

Yes, if I leave it on cruise and just pump the throttle it does seem to pick up sometimes - but this is a 90bhp and there's not a lot to pick up at 80mph!

I've been thinking fuel/delivery. But don't know how to fault find these?

Edited February 5, 2007 by Nick

[Guest raquelgal]

Hi i'v just had the same problem as you i only do motorway driving and had just bought my galaxy when i noticed it pulling back on me when i got to around 70mph and the needle just dropped no matter how hard my foot went to the floor! then if i lifted my foot off n on the gas it would go again sometimes it wouldnt do it so i had to drop a gear to get the power back ! And going up hills were a real struggle too!! ... luckily i havent had it long so i returned it to the garage where they said straight away it was the air flow meter they changed that and its been fantastic since try ebay they are selling them on there and it says if your galaxy is slow or sluggish and feels like the turbo isnt working hope this helps you.

[Guest raquelgal]

sorry it was called the mass air flow sensor (technical terms ~) lol!

[mumof4]

Only notice this on motorway driving, get up to around 3000 revs (78 'ish mph) now and again I can feel it hesitate and .

 

 

the fact that you can do this speed makes me doubt the MAF....and intermittant???..MAF failure as far as i know does not come and go.....gotta be summit else.

[Guest MATT jr]

agree with mumof4, if MAF was knackered, then he would notice its sluggishness at such speeds (plus hes suffered MAF failure before - so he must know what its like!)

 

only thing that could relate to the MAF is a dodgy connection - but unlikely.

 

could it be the turbo? :16: :)

 

intermittent loss of boost pressure at higher revs? small crack in pipe? or some sort of over boost bypass thingy lol (technical hey)

 

MJR

[Guest BagPuss]

Sounds similar to my hesitation I had not so long back.

Turned out to be the HT Leads.

 

Here's my original post to see if you have similar symptons to mine.

 

BagPuss's Hesitation Post (Click Me)

Edited February 6, 2007 by BagPuss

[Guest MATT jr]

Turned out to be the HT Leads.

 

dude - its a diesel :16:

 

MJR

[mumof4]

agree with mumof4,

 

could it be the turbo? :) :D

 

intermittent loss of boost pressure at higher revs? small crack in pipe? or some sort of over boost bypass thingy lol (technical hey)

 

MJR

 

 

agree with me???blimey..i said summit right? :D :16:

 

Surely if it was a turbo problem..it would happen at all speeds?..not just fast speed?

 

Could it be fuel injector thingywhateveritis?

[Smilge]

agree with mumof4,

 

could it be the turbo? :16: :)

 

intermittent loss of boost pressure at higher revs? small crack in pipe? or some sort of over boost bypass thingy lol (technical hey)

 

MJR

 

 

agree with me???blimey..i said summit right? :D :D

 

Surely if it was a turbo problem..it would happen at all speeds?..not just fast speed?

 

Could it be fuel injector thingywhateveritis?

 

Not speed related Maz .... rev related if the turbo's at fault ..... numerous things to check first before considering the Turbo. I had a look at some of the previous posts regarding turbo problems. Could try the boost control valve or the T-MAP sensor first as it appears the turbo is overboosting ..... any thoughts?

[mumof4]

oops my mistake...course turbo is rev related..kicks in around 1.9/2k mark...works on exhaust gas......but surely it wouldnt just happen at 3k revs?..hmmmm3k revs is over revving it a bit as i dont even hit 3k revs at higher than 78mph.

[andymet]

Hi Had the same problem and it was a vacume pipe come adrift. It was the one which goes from the big black pipe next to the battery (goes from the air intake to intercooler) down to the turbo waste gate. It should be attached next to the air intake temperature sensor and run to the turbo. If this is detached or leaking the turbo waste gate will not operate properly and cause these symptoms. Worth checking

 

Hope this helps

 

Andy Met

[Nick]

Thanks Andy, I'll check all the pipes. More than possible that those monkeys at Ford disturbed something. Will report back Edited February 6, 2007 by Nick

[Richard gal]

I would check the fuel filter, there is no reason it cant be blocked, a new one will block in ten minutes with enough dirt in the system.