RB30 sluggish throttle response and accelleration but excellent compression?

[88-SERIES200]

Hi i have a auto non turbo vl that has 270,000 k's that i find to be a bit laggy when i rev it ( this is in comparison to my other vl and some others i have seen). It is by no means a shit motor i just cant understand why it is not as responsive as the rb30 in my other vl which revs up instantly and sounds very strong (sounds smoother, quieter yet angrier too. you can really hear it sucking the air through the airbox). the car its in also feels as if it has wayyy more torque than this motor im having trouble with. both are completely stock rb30's with stock intake and exhaust manifolds and 2.5" systems. (i dont believe the cat is the problem either as this exhaust was off my other vl)

Basically when you rev it it just doesnt feel as strong as it should and its almost as if it hesitates very slightly before revving where as the other motor can rev up as quick as you pull the cable and sounds crisp as. I did a compression test and all cylinders were 175 psi (1200kpa) except number 4 wich was slightly higher at about 180 psi and that plug was slightly fouled. Also did a quick mixture test at 2000rpm on the ecu and both lights flash continually at the same time like they should.
All the connections are clean, intake manifold pulled apart, cleaned and put together with new gaskets, cleaned and swapped many o2 sensors, new air filter, new oil, new fuel filter (on the right way), flushed radiator and filled with coolant, new plugs and leads and i run through a oil flush and some injector cleaner every time i service it. The timing is set at 15 degrees btdc and i have also tried it on 20. I always use 95 octane fuel.

Now here are some things where i think there may be a problem or just things i've noticed. I've noticed the external fuel pump is getting noisy, i can hear it while i walk around the car. before i cleaned out the inlet manifold there was a fair bit of carbon build up and even some oil film which had me worried. i've been told this is normal. possibly since the pcv valve vents into there and the oil may have been too high before i got a hold of the car. I can smell what i think is an exhaust leak in the engine bay however if its there it must be small because i cant see anything. Can also smell it in the cabin sometimes.

I'm slowly losing coolant from the overflow bottle however i can not find leaks anywhere in the bay or around the overflow bottle or radiator. I dont think the heater is leaking either, a new TPS has been put on and may not be adjusted right, im not sure if the timing belt is out a tooth or not, AFM is yet to be tested, the motor hesitates and splutters for a second when first started and cold then kinda drives normally but with a little less power than when warm, the temp doesnt go up for a very long time i'm thinking the aftermarket thermostat could be stuck open.
On the ecu i used to get no fault codes (code 44) but now i coolant temp sensor, TPS, vehicle speed sensor, neutral switch, air con. dont quote me on them because i'll have to recheck them again after resetting the ecu. I'm also thinking there could be somthing wrong in the head like seals or valves or possibly a very small head gasket leak letting coolant into the cylinder.
I realise the old auto box could have alot to do with some of the slowish accelleration however there definately is a problem with the motor itself

So let me know what you think and if anyone has some experience with troubleshooting Rb30's or have had the same problems your assistance would be much appreciated. thanks, Jamie.

[jatsvl]

wow looks like you've done everything man, my first thought is throtle body and/or TPS and/or accelerator cable incorrectly adjusted, fuel filter (under car) fuel pressure or fuel pump, or timing.

[Degeko]

Sounds like timing or possibly a dodgy coil providing weak spark. If you can hear the fuel pumps gurgling I would replace them and see how it goes.

Also if you temp is on the lowish side have a look at the thermostat as that can cause the ECU to stay in warm up mode.

[88-SERIES200]

Sounds like timing or possibly a dodgy coil providing weak spark. If you can hear the fuel pumps gurgling I would replace them and see how it goes.

Also if you temp is on the lowish side have a look at the thermostat as that can cause the ECU to stay in warm up mode.

I've swapped the coil over a couple of times to make sure and it isnt that. But if the temp has that effect on the ECU then that could be a contributing factor since i think my thermostat is stuck open.

On a non related matter that job you've done on the vl calais is just awesome. I was reading the thread on calaisturbo but couldnt write a reply. do you have any pics of the rust that was in the windscreen by any chance? and what brand of paint and gun did you go with? I'm just in the process of prepping and painting my wagon and im after a very similar quality finish.