5L seems a bit slow.

[Jonno]

dunno what your exhaust systems like in the first place

but would be a good idea to go get a good system

 

[james1988]

pacemakers to dual 2.5 into single 3 inch, i can see the contents of the muffler by looking down the pipe with a light, its in pieces.

 

[james1988]

checked out the memcal doesnt say anything on it. so im assuming the car isnt tuned at all.

if there is a manifold restriction, upgrading the intake manifold would see an improvement on its own? or tune first?

 

[Zeussy]

Rip the exhaust off and go for a squirt, seriously, if it makes a difference there's your problem...

 

[kniever]

if the muffler is falling apart as said there is a good chance the exhaust is blocked which will make it sluggish

 

[Brett_jjj]

Id get rid of that old memcal and fit another original holden memcal that has an original holden tune that was released for your model etc. You can usually tell if a memcal is original or not by the little silvery foil sticker that covers the little round window that you can see on top of the chip, its used for erasing the eprom chip with UV light,so is usually covered by the sticker. That foil sticker I mentioned before has four letters written on it, the four letters are actually the version or the type of factory tune , once this little sticker is removed from the memcal,(so the chip can be erased and rewritten to again),then it wont stick back onto the chip again unless you use glue to glue on it, (which you wouldnt want to do). So if the sticker is there, you can be 99% sure its genuine, so has probably not been tampered with in any way. That memcal in your picture has no ID sticker over the round window on the chip, so god only knows what changes have been made to it, and by god only knows who. Theres a lot of dodgey people around who try to sell these so called tunes for heaps of cash, when they are plainly just not worth what they ask for them, "well,a lot of the time theyre not anyway", and half of the "so-called" tunes Ive opend up and looked at, or have copied from someones memcal or whatever, all have nothing that special done to them. Anyone can buy the hardware off ebay, download the programs needed, and learn about what needs to be changed etc on the memcals bin or binary file. Delcohacking is a good site to start with if you want to learn about this kind of stuff.

 

[Reaper]

just had a look at the flange sized for the cats, and i notice that the rear muffler's internals rattle when bumped, and you can hear it at idle if your near the back of the car. could a failed muffler be part of the culprit?

It certainly wouldn't help.

On those 5 litres 2.5", a functioning cat (hi flow is neither here nor there but if you have to buy one then get one) and some fre flow mufflers work great. Collapsed anything can't be good.

Reaper

 

[dobesz]

Yea a blocked muffler would not help at all, if I put my hand over my mx bikes exhaust it just about stalls. So a blocked muffler is not letting your motor get rid of gasses.
A f?cked o2 sensor will make it run rich and chew fuel.
That memcal is the correct one for hsv as u can see the knock sensor circuit board in the window. as stated has most likely been tampered with. Most "stage 2" cam packages come with cam and memcal.
But I think u should fix zorst and get it on a dyno and a proper tune, as something ain't right. Plus mail order tunes are never as good as a dyno tune. What state u from

 

[james1988]

Im from the NT, im hoping the very few tuners here will be happy enough to do it. i believe there are only 2 reputable ones.

im planning on just that, fix exhaust, do a service (filters, leads etc) and then tune it. hell i might even get a big intake manifold for it.

 

[VrWagz1]

Dont waste ur sanity. Given the work u have, its hard to diagnose over the net. Slam it on a Dyno, and have them run it till they got the solution. To me sounds like a Cam issue, like not dialled in right OR just totally miss-matched to the engine, in which case gt a new one.