noticed tonight when accelorating hard the engine has a mis or cough its 5spd man and done it in 2nd 3rd and forth only once in each gear but have noticed it surges slightly when you are just cruising along is this filter like or somthing else any help would be great this is my first fuel inj 5ltr.
have just cleaned out the throttel body and changed the fuel filter took it for a drive and still does it. noticed that i can get it to miss when i give it a boot full then back off and give it again then it misses but only very briefly its as if the fuel cannot keep up for a second and wondering if it could have something to do with fuel regulator the pump has been replaced ,plugs,fuel filter also done.
any ideas. throttle body cleaned, air flow sensor cleaned. no change.
?? checked fuel pressure at idol bout 25psi and decreases with revs dissconnected vac line and pressure went to 30psi previous owner put new pump in wondering if they put 6 cyl one in. pressure should be around 36 psi idol ???

I have noticed alot of AU Windor owners complaining of very slight surging at low rpm cruise - myself included. Considering how poor AU1 electrics were, I believe it's something to do with the grounding of the Oxygen sensors which gives a fluctuating reading to the ECU. I know if I drive the car with Oxy's disconnected, the surging goes away as it's in "safe mode".

Does run rich as though so don't do it for too long

cheers i will give it a try

Yep the surging dissapeared straight away once oxy's un plugged.
Is there a way to improve earth points for these things apart from upgradeing the vehicle?

Your O2's could actually be stuffed but it's not a grounding problem as they have their own ground wire going right back to the EEC so, unless you have harness/connector damage it's unlikely to be that.
So it sounds like your disconnecting them is just masking a fuel problem. Fuel pressure should be 39psi at idle so, unless your pressure gauge is reading wrong I'd be looking there. If someone has replaced the pump check they haven't fitted it wrong causing fuel to bleed off before it leaves the tank.

changed the gauge and fuel pressure at idol is 30psi and 39psi with vac hose off regulator. book indicates well just read book and can only find xr6 specs unless the same 250kpa-300kpa or 36.25psi-43.5psi
idol and stationary pressures.if that is right im a bit low.

If fuel pressure is a bit low and you've already changed the fuel filter, doesn't that leave the fuel pump as a possibility?

yes i guess it does. I put a pin punch in the vac fitting of the regulator (carefully) and bridged the fuel pump relay the pressure can go up as high as 80 psi but i guess its only restricting the flow that it has and the flow may be down bringing my normal opp pressure down with it i guess to make sure do the flow test but i already know the pressure is not there. fuel pump!

Let me know what you end up doing and whether you resolve the problem mate!

Quite interested in fixing this once and for all on my car.

will do.

Interesting thread - I am dealing with simular issues... surging, coughing even bunny hopping in 2nd and 3rd gear at 2500 rpm.

Though before I go on - just need to say that I ve just rebuilt my top end with a Trickflow kit and stage 1 cam, so its meant to be running ruff. (engine is being chipped and dyno tunes this weekend)... but this surging issue has been going on for over a year now, though because I had dual fuel ( disconnected now) I just chose to ignore the surging.

So just last week I changed the O2 sensors - made the engine run better though did not resolve problem. Today I attempted changing the fuel filter though it looked like a was going to round off the nuts (bloody tight) so i will leave that for the mechanic friday. I did change the fuel relay fuse and it certainly made a huge difference to the point where i thought i solved the problem - but low rev's, bumper traffic and it started to chock up again.

Personally - I think its the fuel rails and regulator. Rusted fuel rails appears to be a common problem with the AU and when we where reinstalling the fuel rails on the recent topend rebuild... it took ages for the fuel to reach the #5 cylinder, which had both the mechanic and myself scratching our heads... but than it just started working. Though several weeks ago a different mechanic put a heat sensor gun on my #5 cylinder and said its not firing properly. SO at that time i thought it was the cam positioning sensor, so I sent off to summit for the alignment tool, which meant another week of driving it around like crap most of the time, just to fid out that was not the problem.

Though believe me this stuff has been doing my head in... and i am really interested in what you guys discover.

Ford wants $1200 for new fuel rails, I can not afford that. I read somewhere that a guy modified 95 Mustang fuel rails and i think thats the way i will go. If you look at the AU fuel rail design, #5 is just a dead end on the fuel rail, which is where i believe my problem is - though i just wait for to see what both the dyno and you guys discover.

i will be a happy chappy if i find out whats going on too.
with the no.5 injector at the end of the line im guessing that it should not matter as the fuel pressure should always be there as governed by the pressure reg unless the fuel is not getting through the injector i guess.
In regards to my issue i think i will wait till its been hooked up to tool and go from there bout the only thing im gonna do now is check fuel pump flow rate and maybe change it.
i have this same issue on ecu and fuel injection forum there is some different comments on there.

Just an update.

Over the last 2 days I've replaced relay fuse, inline fuel fiter, sprayed the MAF with cleaner, re oiled air filter and reset ECU...

End result - 99. 5 % of problems resolved.

Today I dropped the car of at the mechanic to have the Haltech Interceptor chip installed and tuned... see how things go then.

Re #5 injector, its possibly only an isolated situation in my case, for I had mine running on dual fuel for 8 years or more. None the less, for under $500 I can buy trickflow fuel rail, regulator, pressure gauge and Walbro fuel pump.... so that will be my September project

my heap of crap is still bugging me have replaced the fuel pump and no change in pressures i guess the reg is s**t?