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AU XR8 missing and sluggish 3000rpm 

 

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 Post subject: AU XR8 missing and sluggish 3000rpm
Posted: Mon Feb 28, 2011 2:46 pm 
Stock as a Rock
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Location: waroona
WA, Australia

Hi Guys,

I have an AUXR8 which I have just done a T56 conversion. The engine has developed a bit of a miss fire and gets sluggish from 2,500rpm to 3,500rpm. After that seems fine. There is also a slight vibration as engine rpm increase.

The engine has had a bit of work, and I have the screamin demon coil packs that were put on about 2 years ago.

The cam sensor (CPS) assy has been replaced (was doing that horrible squeal)

I thought it would be spark, so replaced leads with livewires, and double platinum bosch plugs. Slightly better, but not perfect.

Next thing is I will disconnect battery to cancel memory and download tune.

Would the replacement CPS be a possible cause. I had a mecahnic fit it, and they said they are easy to set (set by the teeth marks, and the tool).

Could timing be out? What about any other sensors I should that would cause problems

any assistance would be great - cheers
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Feb 28, 2011 4:03 pm 
Tyre Shredder
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NSW, Australia

Could be burnt/damaged valves causing low compression on some cylinders & misfiring. Might be worth a compression test?

 

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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Feb 28, 2011 5:58 pm 
Stock as a Rock
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Age: 48

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Ride: AU2 XR8

Location: waroona
WA, Australia

sd1800 wrote:
Could be burnt/damaged valves causing low compression on some cylinders & misfiring. Might be worth a compression test?


don't think so. Still goes well. Will do a compression check anyway.
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Feb 28, 2011 6:18 pm 
Stock as a Rock
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Age: 48

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Ride: AU2 XR8

Location: waroona
WA, Australia

...I also might try some MAF cleaner
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Feb 28, 2011 8:00 pm 
Getting Side Ways
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Ride: 1999 XHII XR8, 2002 AU Fairmont

Power: 236 rwkw

Location: Perth
WA, Australia

Balancer slipped?

 

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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Tue Mar 01, 2011 11:38 am 
Stock as a Rock
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Age: 48

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Ride: AU2 XR8

Location: waroona
WA, Australia

Thanks XH5LWEPN,

yea I thought about that actually. I had it replaced about 6 months ago by Ford. Its a Powerbond. They may have not installed it right, and over time its slipped causing a slight "buzz" vibration at higher rpms' and of course would out of timing.

How would you know by looking? Might have to get it back to Ford (of course they will deny it :roll: )
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Tue Mar 01, 2011 3:44 pm 
Getting Side Ways
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balencer sliped might cause the vibration but not the miss.
i remember my el 5lt balencer weight completely seperated from the pully itself.
ran alrite and reved without a miss but holy sheet the vibrations... almost shook the street apart. haha.

 

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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Tue Mar 01, 2011 5:04 pm 
Stock as a Rock
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Location: waroona
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Benny D wrote:
balencer sliped might cause the vibration but not the miss.
i remember my el 5lt balencer weight completely seperated from the pully itself.
ran alrite and reved without a miss but holy sheet the vibrations... almost shook the street apart. haha.


I'm under the impression balancer slip will put timing out due to incorrect timing mark aligned to TDC and the crank angle sensor will pick up reading wrong.
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Tue Mar 01, 2011 6:04 pm 
Oompa Loompa
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Location: Melbourne
VIC, Australia

TKFD wrote:
Benny D wrote:
balencer sliped might cause the vibration but not the miss.
i remember my el 5lt balencer weight completely seperated from the pully itself.
ran alrite and reved without a miss but holy sheet the vibrations... almost shook the street apart. haha.


I'm under the impression balancer slip will put timing out due to incorrect timing mark aligned to TDC and the crank angle sensor will pick up reading wrong.


Don't think it would cause a miss as i'm pretty sure that the pickup for the crank position is fixed to the inner of the balancer and it's only the outer part with the timing marks that slips.
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Wed Mar 02, 2011 12:58 am 
Stock as a Rock
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Age: 48

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Ride: AU2 XR8

Location: waroona
WA, Australia

On the weekend I will check

All connections
Clean MAF and TB
Bought a voltmeter and will check TPS voltage - can you check voltage from the plug leads?
Check comp on all cylinders (hopefully this is OK :shock: )
Check vacuum/intake leaks.
Throw in some injector cleaner

...then get Lane Ford to check the balancer and timing.
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Mar 07, 2011 1:15 pm 
Stock as a Rock
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Age: 48

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Ride: AU2 XR8

Location: waroona
WA, Australia

Well had a play with the XR8 over the weekend.

Did a compression test. All cylinders around 170psi (high?), but the #5 (back left) cyl was 155psi. I don't think I did the test right though. I did it cold (didn't want to burn my fingies), and didn't WOT as stated in manual. Also found that unburnt fuel was getting squirted in, which was raising the comp (due to decreased volume caused by the added fuel). Reason why the first few were around 160psi, then others were 170psi, and then went back to re-check and they raised to 170psi, and saw fuel deposits on gauge nozzle. Anyway will re-do :roll:

I also had a go at setting TPS voltage and idle from that sticky thread. That thread is for EL-EF and the AU TPS are different (no elongation). Nevertheless I went thru the procedure and it was out showing 1.07V. I then adjusted idle (950rpm) with TPS disconnected, and then went about setting TPS hopefully getting the right wire, as they are also different. I had to butcher TPS to elongate holes, and managed 0.98V (very sensitive hey!), but the idle has that run-on effect (blip throttle but takes a while for idle to settle - 2-3secs, sometimes longer when moving?). Any ideas on what I may be doing wrong?

I also cleaned MAF/TB, checked vacuum leaks (none), and checked connections (all seem OK).

It does seem to run better, but still seems to have a slight "buzz" vibration at 3000rpm up.

I have recently done a T56 conversion, so I am hoping its not an unbalanced flywheel.
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Mar 07, 2011 3:29 pm 
Getting Side Ways
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Did you need a new driveshaft for the t56 conversion?
Was it balanced?
Did you get around to checking the harmonic balancer.
There was a guy in another thread on here somewhere i was reading had similar problems (as in the vibrations, not the misfire) and he found out it was a mixture of the harmonic balancer and the rest of the pulleys being dirty and clogged with crap. Cleaned them and said it disappeared. Might be worth having a geez yourself at all moving parts, just checking they are all clean and moving freely.

Cheers

Sam

 

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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Tue Mar 08, 2011 12:26 am 
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WA, Australia

TKFD wrote:
Benny D wrote:
balencer sliped might cause the vibration but not the miss.
i remember my el 5lt balencer weight completely seperated from the pully itself.
ran alrite and reved without a miss but holy sheet the vibrations... almost shook the street apart. haha.


I'm under the impression balancer slip will put timing out due to incorrect timing mark aligned to TDC and the crank angle sensor will pick up reading wrong.


Nope, The encoder wheel is pressed onto the centre of the balancer hub so if the outer slips it has no effect on timing.
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Mar 14, 2011 3:16 pm 
Stock as a Rock
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Age: 48

Posts: 150

Joined: 6th Nov 2009

Ride: AU2 XR8

Location: waroona
WA, Australia

well I had a crack at setting TPS voltage and Idle.

I have set my idle to where I want (950rpm - got a cam) and then set the TPS to 0.98v. However, if I blip the throttle the idle runs on.

What would be the cause of this?

cheers
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 Post subject: Re: AU XR8 missing and sluggish 3000rpm
Posted: Mon Mar 14, 2011 3:55 pm 
EFI Guru
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Location: Perth
WA, Australia

Did you disconnect the IAC valve when you set your idle?
Is the throttle blade being pulled back properly by the return spring?
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