AU V8 Surge

[sd1800]

I have had this problem since I've owned the car, but hoping to finally sort it before I drive it to QLD and back.

I am getting a very slight & small surge in all gears around the 1400-2100rpm range. Above this and at WOT it's fine. It is pretty much constant and not intermittant. I had an Oxygen Sensor problem a month back and during this period when the oxygen sensors were duds it made the problem 3x worse. I also noticed that during this period the cats got so hot that it melted the nearby steering rack boot which would imply a lean condition, which under normal circumstances the oxygen sensors pick it up and richen it but in this case did not. When I put new oxygen sensors it returned to being a "slight" surge as was before the o2 issue. I should also mention that in neutral if I hold it at about 1600rpm, I can watch the tacho fluctuate between 1500-1600rpm so it is not only a in-gear problem.

What I have done so far:
New Coils
New Leads
20,000km old platinum plugs
new fuel filter
new oxygen sensors
New ground from Negative Post>K Frame
Replaced ground from Negative Post>Alternator

I checked the Cam Sync Sensor at TDC, and the "post" was pointing at about 7 o'clock. I moved the sensor around to meet the post at 6 o'clock but it hasn't made a difference.

I also disconnected and drove without the oxygen sensors for a day, and while it ran rich, no surging at all while in closed loop mode (also why it doesn't surge at WOT).

Any thoughts would be much appreciated.

[Whoosha]

Take 10 min. and pull the fuel pump out and see what, if any thing is sucked up into the sock, worst case, 1 less thing to tick off the list or to replace :

[sd1800]

Originally Posted by Whoosha

Take 10 min. and pull the fuel pump out and see what, if any thing is sucked up into the sock, worst case, 1 less thing to tick off the list or to replace :

Wouldn't this cause issue at WOT then? The car pulls like a freight train @ WOT. Also, I disconnected Oxygen Sensors and it ran without any surge in all conditions which makes me think has to be sensor/ecu related and not pump/injectors.

[Whoosha]

Not nesasarly , I have chased problems that seem electrical and turned out to be fuel related, promblem is with these issues is eliminating things one at a time, The pump is a easy look see option , check it , if all seems good move on to the next option .

[EV1LXR8]

i have this same sort of problem i can do the same and hold it at about 1400 rpm and it will fluxuate between 1300 and 1400 it would be a good thing if someone new what was causing it, i thought the throttle control positioner but dont even kno were it is.

[Mr_Monty]

Had the same problem here, taking off in mornings it would be normal then seem like it wants to putter out and die...

Iv done on my au s1 v8
New:
Fuel pump twice
Leads and plugs twice
TPS and Maf Brand new as of 3 weeks ago
injectors locally reconditioned. (got rid of the off the line hesitation but no the surging etc)

fixed all vacuum leaks, replaced fuel filter twice, before pump and a couple weeks ago.
Cleaned and inspected all electrical connections.
I have an x3 flash tuner which shows me and codes and im code free.

replaced o2 sensors twice, first genuine the 2nd ntk set from shop.

replaced ckp with genuine crank shaft position sensor.

All new exhaust system and cats etc.

None of this fixed it.

Until the weekend

found 2 problems, Fuel pressure is lower then it should be.
2 CMP (cam position sensor to you and me) was out by 30 degrees and by my guess since factory! the performance mods just made the symptoms worse ie, tuned length extractors and 3 inch exhaust.

so fix was 1, fitted new cmp senor on top removed cmp gear and moved one tooth over and lined her up TDC on compression stroke. walla FREAKIN POWER as it should be!

i have a new regulator ready to go in and gaskets for manifold but await some new injectors to replace my old reco's, so in the meantime run around with out vacuum on the Regulator, and yes i did the before tweakin and adding new cmp sensor and a bearly noticable difference was made.

so thats all i have learned so far and i beleive this to be my Surging problem, Think, we have sequential injection. if the cmp is telling the ecu to start injecting while valves are closed theres going to be dead spots / surges.

hope this helps some one. i did this without the positioning tool, and might have done right or wrong, im not a professional, just this is what worked for me. play with at own risk or get ford to check with a proper positioning tool.

PM me if this has been your problem or was your fix etc, id like to know. will explain more up here if op likes

[Mr Hardware]

^ now that, my friends, is one excellent post.

[urbancowboy]

By surging do you all mean a slight bunny hopping when clutch is fully out at low revs, or when you are are rolling along in say second gear with no throttle and then attempt to use very light throttle and then it slightly bunny hops?

[adrian k]

hmmm, interesting, i have a very slight surging too under normal to moderate throttle threw 1300-2400 approx rpm, then it clears and goes fine.

[Mr_Monty]

Driving an auto, surging as in power....power gone... power back... flat spot...pulling like a train.

Also read that cheap spark plug leads will cause interference with cmp as the wiring for it is right next to leads, not my case but good to know.

Also if you have like a bad miss that feels like a thud, or even worse as in my two cases where it caused a backfire type senario its because you might have cracked a plugs insulator. they backfire as they fire a secondary spark on exhaust.

those iridium crack easily and if your using the pacemakers' ph4006 like me, cyl 5 is a pain for putting the plug in on an angle and crackin it.

[sd1800]

Thank you everyone for your help. I did have a feeling CMP was causing these issues, but wanted to leave the question open-ended.

Originally Posted by Mr_Monty

2 CMP (cam position sensor to you and me) was out by 30 degrees

Firstly, thanks for your post. Tell me Mr Monty, where exactly should the "post" on the syncronizer be pointing when @ TDC, and where did you find yours was pointing? The below pic refers to the post I'm talking about. When looking directly at the engine bay, mine appears to be at about 7pm when @ TDC. Does this mean it is out, and if so, where should it be pointing? See the below pic for the "post" i am referring to.

[Mr_Monty]

At exactly TDC on cylinder 1's compression stroke its supposed to line up exactly with the hall effect sensor which you can see inside the sensor lid that goes on top of there.

If yours is at tdc1 on the compression stroke of cylinder 1 id say its pretty much where it should be, just align up the hall effect sensor with it, thats a half inch hex bolt below it which if you loosend a scotch will allow the outside the rotate and the inside stays still. if i was to guess from the pic, the case looks like it needs to be rotated 5-10 degrees clockwise.

Mine was almost in line with the left screw hole there with the outside in the same position as your is in now.

the new sensor (hall effect sensor) being just the cap on top, i got mine from bursons for $110.

to keep the point simple, in theory it needs to tell the ecu exactly when the injection begins by passing right infront of hall sensor at TDC of cylinder 1's compression stroke.

[Mr_Monty]

i found when i pulled the whole thing out its pretty much the bottom of a distributer. goes in the same. and aligns the same as an e-series dizzy, by aligning to points at one stage of the engines cycle.

i couldnt see a point for this to be so many degrees before or after the senor but rather in line with it.

[adrian k]

so if the alignment is wrong, one should be able to pick it up with a timing light?? what timing numbers do these run stock? i don't want to go pulling mine all part just incase, would be nice to know before hand.