Performance Issue

[xceptional]

Hi

The issue I have is pretty hard to describe so I appologise in advance for the long windedness, although more information is better than too little.

I have an issue with my 03 BA XR6T, 4 Sp Auto. It has done just over 155k, 96k of which consisted of highway ks.

It is a standard build with the only mods:

XR8 snorkel on the air-box

Air scoop attached to the top air intake snorkel

Sports springs – 30% firmer than BF

DBA slotted rotors all round

I have not had it custom tuned or flashed.

Just over a month ago, for no apparent reason, under full throttle I noticed the engine suddenly start missing quite badly after 2500rpm and above within boost and very much under performance. There was some sort of ticking noise too as if there was an electrical short. It seems to be ok under normal acceleration or cruising. At half or three quarter throttle the engine does not seem to miss and feels like it performs better than under full throttle.

I have since taken the vehicle to Ford twice to check it out. The first time they found nothing on the diagnostics, coil packs, etc. They did take out the plugs and adjusted the gaps (to factory standards I presume). I’m not sure if they replaced the plugs during the last service or how old the plugs are. That seemed to have smoothed out the missing somewhat and ticking noise but is still quite under powered under full throttle.

I took it back the second time within a week and tried to demonstrate the issue but you guessed it, it would not miss – motor was warm. It seems to be worse when the motor is cool. They did find a perished fuel hose that was replaced. Still performance is lacking under full throttle.

When the motor is cool (more than 2 min but less than 5 min running) the motor misses quite badly in 1st and 2nd and when it changes to 3rd at about 80 k/hr it dies in the ass, then from about 110 or 115 k/hr it surges powerfully again to about 135 k/hr where it changes to 4th. Also when cool, after slowing down or stoped at lights immediately after full throttle to about 80 k/hr the motor seems like it’s running a lumpy cam and feels like a couple of cylinders are not firing.

When the motor is warm (been running for over 5 min) I have found that power is excellent in 1st and 2nd gears with very slight missing, but when it changes into 3rd around 80 k/hr, again it dies in the ass till 110 k/hr then surges powerfully to 4th.

Other things I have noticed. Sometimes at the top of 3rd gear the change does not happen and it seems the motor hits the rev limiter. It bounces and on rare occasions backfire. If I immediately button off then accelerate again it will pass through to 4th.

And another thing, whether it’s related or not, when accelerating through corners at speed, there is latency in the time the motor takes to respond and sometimes misses (strangely occurs mostly on left handers). Feels like the traction control is inhibiting the motor however the traction control light does not appear. Traction control is working as at other times in a straight line it appears intermittently when it momentarily loses traction.

I have done what you have suggested to recalibrating the throttle (full throttle when off, then try and turn on motor – didn’t start as advised). Issue still exists. I have spent over $400 with Ford trying to diagnose the issue with no result and don’t really have any hope in them finding the fault and me spending another packet. I’d rather spend a $1k on a flash and custom tune, but the issue may still exist and rather have this cleared up first.

Any advice would be appreciated.

Cheers

[Slymeat]

Sounds alot like my car did when the coil packs started acting up, I replaced them and no more problem.

[Guest]

My bet will be that 1 or more of the coil packs will be on their way out.

Either that or plugs, but you say Ford checked both of those right? Surely if their experienced tech's had a look then they'd be fine

[xceptional]

Thanks slymeat. As 03XR6T mentioned, the techs at Ford would have checked them out I would have thought.

Don't really want to pay out more $$$ if the existing coil packs are good.

Another thing, the battery is about due for replacement. Leaving the radio on for less than 10 min while not running sees me looking for someone with jumper leads to get me going again. Sometimes when I start the car it isn't smooth. It's rough for a about a second on ignition. Could the low battery voltage affect ignition. Once running I thought the alternator would be supplying the joice to the packs.

Are there performance coil packs? What's a set of coil packs worth? What's the best plugs to use and what gaps should be applied?

Is there anything else that may be causing these issues, I.e. auto gearbox, cat, loss of back pressure, fuel pump, injectors etc.

Cheers

[Guest]

I was only kidding when I said the coil packs couldn't be at fault due to FoMoCo checking them already mate. The service department is a joke & they couldn't diagnose a dead dog!

Coil packs go for around $120 - 150 on Ebay iirc, so check that out. Type in FPV in the search field & there'll be some listed...

As for plugs, I used to use those iridium ones that are like $22 each but they were burning out too quick. Now I just use the Ford supplied ones that are pre gapped to the right spec for my tune... Not too sure what would be best on a standard T sorry.

[xceptional]

Thanks 03XR6T. You pretty sure it would be coils and/or plugs? Suppose it best to start with the cheapest solutions first.

Are the coils and plugs difficult to replace?

Cheers

[poita85]

They are pretty straight forward to replace if you are at least a little bit handy with a spanner.

Here is a guide : http://www.fordxr6turbo.com/forum/index.php?showtopic=48973

[Guest]

Never done it myself but I've seen it done a few times in my mates workshop. Fairly straight forward bud.

A good idea when replacing the coils as well is to wrap the heads with electrical tape or some other sort of insulator. Apparently it's pretty common for them to earth out on the rocker cover which causes premature death! Maybe the cause of your troubles now??

[Guest]

Coils ala Ebay...

http://cgi.ebay.com.au/FORD-BA-BF-IGNITION...1QQcmdZViewItem

[Ford_Power]

Thanks slymeat. As 03XR6T mentioned, the techs at Ford would have checked them out I would have thought.

Don't really want to pay out more $$$ if the existing coil packs are good.

Another thing, the battery is about due for replacement. Leaving the radio on for less than 10 min while not running sees me looking for someone with jumper leads to get me going again. Sometimes when I start the car it isn't smooth. It's rough for a about a second on ignition. Could the low battery voltage affect ignition. Once running I thought the alternator would be supplying the joice to the packs.

Are there performance coil packs? What's a set of coil packs worth? What's the best plugs to use and what gaps should be applied?

Is there anything else that may be causing these issues, I.e. auto gearbox, cat, loss of back pressure, fuel pump, injectors etc.

Cheers

Well the PCM actually compensates the injector coil energisation times based on battery voltage... I would first get a new battery and see what comes of it - you need a new one anyway, and it could be the source of your problem.