flat spot on acceleration

IH8HSV · 02-06-2012, 05:43 PM

Hi fellas,

My wifes AU seems to have a flat spot. It starts ok and will idle ok.
However as soon as you push down on the acclerator it will splutter a bit befor it will come good. It will drive good at all other times - even on the highway.

Would would cause a car to have a flat spot on accleration??

Any ideas would be helpful.

Thanx

Maka · 02-06-2012, 05:58 PM

G'day IH8HSV, try fuel filter or fuel pump, clean the throttle body, also when was the last time your'e au had a service?

cheers,Maka

dieseltrain79 · 02-06-2012, 06:34 PM

Leads , plugs , also tighten inlet manifold bolts .

Mr Hardware · 03-06-2012, 10:01 AM

Yeah it's almost positively a fuel system issue. Mine has a hesitation on petrol, but gets out of the hole real nice and prompt on gas

IH8HSV · 03-06-2012, 02:05 PM

Thanks for your replies. Ill change the fuel filter and then the leads and plugs.

Hopefully it will sort it out.

Thanks

IH8HSV · 17-06-2012, 09:22 PM

Hi Fellas...

Thanks for your replies. I didnt really explain my thread topic properly.

My wifes AU runs on both gas and petrol. When it runs on Gas it drives perfectly.

However when ever it is run on petrol it runs like crap. It has trouble to start and as soon as you push the acclerator it splutters and carries on.

Today I cleaned the throttle body, replaced the fuel filter and tightend the inlet manifold bolts as you guys suggested.

Someone got any other ideas?

Thanks.

LOWAU · 18-06-2012, 02:10 AM

as for ideas, well no but my bro (SIKSIX) had the simular dramas on his car. he changed fuel pump, removed unichip, checked fuel reg filter, cleaned injectors, new ign coil, leads , plugs, oxy sensor, cleaned t/b and map/maf?, done a leakdown test.
the only thing he wanted to do was change the ecu. but never got around to it, cause the christmas storm got to it and now its in some wreckers yard rusting.

Hope that helps.

mik · 18-06-2012, 12:02 PM

to my way of thinking if it was an ignition problem you`d be feeling it heaps on the gas side, as gas is very sensitive to ignition problems imo, from what you have already checked , i`m thinking check for other vacuum leaks hoses etc, , dodgey fuel possibly? try fueling up from a different servo, perhaps do a fuel pressure test.

dieseltrain79 · 18-06-2012, 06:22 PM

Pickup in fuel tank blockage ?

IH8HSV · 18-06-2012, 09:11 PM

Ok......

After putting everything back together after cleaning throttle body e.t.c. it runs better.

However it only does it as soon as you accelerate from a stop. It will splutter / hesitate a little.

I disconnected the vacumm line from the fuel regulator and drove around. It didnt make any difference - Should it of?

Thanks.

IH8HSV · 18-06-2012, 09:21 PM

How do I test the fuel regulator?

dieseltrain79 · 18-06-2012, 09:51 PM

Fuel regulator vac line won't do it . Sounds like bad spray pattern on injectors or air leak still . Could be over fuelling . Is it vct ?

IH8HSV · 19-06-2012, 12:21 AM

Quote:

Originally Posted by dieseltrain79

Fuel regulator vac line won't do it . Sounds like bad spray pattern on injectors or air leak still . Could be over fuelling . Is it vct ?

Not sure how to tell if its vct - its a 1999 model if that helps.

Ill check all the vac lines again.

Do i check all the lines going in and out of the inlet manifold? Are these the only ones I need to concentrate on?

Thanx

**SSD-85** · 19-06-2012, 12:23 AM

Quote:

Originally Posted by IH8HSV

Not sure how to tell if its vct - its a 1999 model if that helps.

Thanx

Check the top of the motor. If its a red colour with "VCT" embossed on it, then its a VCT motor, if not then well...its not.

IH8HSV · 19-06-2012, 01:25 AM

Quote:

Originally Posted by Scotty85

Check the top of the motor. If its a red colour with "VCT" embossed on it, then its a VCT motor, if not then well...its not.

No its not VCT then,

Cheers

IH8HSV · 28-06-2012, 09:54 PM

Im at a stump now.

Its starting to now have a rough idle on gas AND petrol. Befor it was only when it ran on petrol.

Someone please throw out some ideas. Even if they are wild ones.

Cheers

dieseltrain79 · 29-06-2012, 10:00 AM

Blown head gasket !

IH8HSV · 29-06-2012, 10:21 PM

A guy suggested to swap out the computer with another AU.

Would it be worth a try?
Anything I need to know?

Thanks.

mik · 29-06-2012, 11:11 PM

running out of suggestions, did anyone mention dodgey coil pak? or corrosion on coil pack terminals?

therat58 · 30-06-2012, 03:28 PM

hi mate, had same trouble as you, tried all sorts of stuff,turned out to be manifold intake gasket, looked ok ,checked all the bolts, ended up about $8 to $10 bucks and half days work

dieseltrain79 · 30-06-2012, 06:00 PM

I'm going to change the wife's Au inlet gasket soon too . Just starting to get rough on cold starts .... I'm 99% sure it's the culprit

IH8HSV · 01-07-2012, 04:00 PM

Thanks for the suggestion.

I might just do that.

Cheers.

mash again · 02-07-2012, 07:56 AM

Saw this on a dedicated au gas car, have a look at the idle up solenoid, the gasket/plastic plate was blown through, replaced it and all good, easy to check worth a look.

Kotche · 05-07-2012, 02:15 PM

Quote:

Originally Posted by IH8HSV

Im at a stump now.

Its starting to now have a rough idle on gas AND petrol. Befor it was only when it ran on petrol.

Someone please throw out some ideas. Even if they are wild ones.

Cheers

Disregarding the advice from the guy who install the LPG on our car I ran it mostly on gas and rarely doing a complete tank of petrol.

Apparently this eventually causes the fuel injectors to get blocked up and I had to have them cleaned out and it now runs perfect.

Lesson learned.

ronwest · 05-07-2012, 06:21 PM

Quote:

Originally Posted by mik

did anyone mention dodgey coil pak? or corrosion on coil pack terminals?

Mine didn't cough and splutter but definite, huge "flat spot" on acceleration from stop. Changed coil pack and all good.

Kamikaza · 16-07-2013, 11:17 PM

Mine doesn't couph or splutter when P or N is selected.
The idling has actually got smoother after putting in new coilpack and spark plugs.
It is sitting around 700 rpm in P or N.
However, as soon as the gear is shifted to R or D without any acceleration, the engine starts to shudder, RPM drops to 500 and a lot of smoke comes out of the tailpipe (No blown Head Gasket here).
If this issue is related to the Intake Manifold Gasket, then idling should have been erratic or dropping.
If it is a matter of faulty Crank Angle Sensor, then it should be hard to start.
At the moment my bet is on O2 sensor because of some hesitation on acceleration with eventual stalling.
Again, no rough idle after having a new coilpack. Even in R or D, the RPM seems to be steady under 500.
If there was any vaccum leak, the idle will be fluctuated.
Any help will be much appreciated

Rfordsfun · 10-10-2013, 10:17 AM

Hi all. My ford au2 fairmont Ghia, seems to have a flat spot around acceleration @ 2k rpm in 2nd doing around 50kmh ? So I up shift to 3rd light acceleration picks up fine, any real grunt need to kick it in the guts, but still feels really flat. Going to check inlet gasket, last code read come up as coil pack? But think cos it was replaced! Got low k engine waiting but mine just reached 300k little noisy. Thanks all in advance, ford developers must of had the Rubix cube, on their desk in design dept