304 experts PLEASE HELP!!

[jonboy]

hi all
i have a series 1 vt ss 304 auto, done 220 thou. it has 2.5 single exhaust and extractors, bigger throttle body- tuned for that, fuel and air filters are new.

my prob is i recently changed the cap, leads (eagle 9mm) rotor, and plugs (champion gold gapped tp 1mm). it went really well for 1 week then started stumbling and missing/dying, done code 49.

after talking to my mechanic we endid up fitting a whole new distributor (so i have spare cap and rotor now) and now its got a miss at idle (i can feel it through the whole car) and it shakes and every about 20-30 seconds it hunts for the right rpm at idle (kind of goes back onto cold start then lowers rpm.

the car goes really well other than missing and playing up at idle or very slow speeds.
its been back to the garage and they cant figure it out? the base idle has been reset to 10 degrees.

any ideas/ sugestions would be awsomn

[dirt drifter]

mine had a dodgy valvespring which made it miss/hunt/choof at idle, but it ran ok when i gave it a bit. its a long shot but keep it in mind if all else fails.

have u compression tested it yet?

[jonboy]

hi
no i havent had a compresion test done... yet, ill be takin it back to the garage later in the week.
by valvspring you mean in the head right? how can i check these??

[GRPABT1]

Check the coolant temp sensor and try another ignition module (borrow one off a mate just to check)

[jonboy]

hi
i forgot to say i also keep getting code 49. i have reset computor twice and both times it comes back (code 49). its got a brand new hall effect sensor as well.
it used to idle sweet as before the new distributer was fitted?

[jonboy]

how do i check the coolant sensor (there are two of them a?)

[VR38]

one is for the gauge and the other signals the computer

[GRPABT1]

You can teat them with a multi meter and some hot and cold water

[jonboy]

so which one is likely to be effected? im guessing the one under the throttle body is for the computer so this would be the one to check?
were is the other one?
cheers

[Ian Johnston]

jonboy, what size throttle body you using?? Having idle issues with my daughters 355 VT Clubby.
Goes like a cut cat otherwise

[GRPABT1]

It's the one with the blue end and injector style plug.

[jonboy]

i pretty sure its 75mm, its a NZSV model, it was tuned from the shop aperantly
i think ill order that sensor and try it and see what happens,
yesterday i changed the plug gaps to 1.1mm and it made a small differance, the hunting has seemed to slow down sumhow but the miss is still there?

[BlackVXGTS]

Check out the attached file. You may have a wiring problem.

[jonboy]

hi thanks for the attached file. it sounds like it might help me hopfully. i recon the problem is in the distrubuter or wiring as it ran fine before being replaced and it now gives out code 49.
i have printed it and will take it to my mechanic.
do you no how to find the sensor curcits mentioned in the file?
many thanks

[jonboy]

i printed of the file and can see them (sensor curcits) now.
i have been to an auto electition and he seriosly dobts the temp sensor is at fault,
the ss will be going into his shop next week to have all the wiring checked and a complete reset, he recons the complet reset may fix the hunting.

[GRPABT1]

That'd the best bet, let the experts handle it. Coolant temp sensor is just a common hunting at idle cause for a Holden V8 without looking at the car though it's hard to diagnose as with most problems on a forum. Good luck mate.

[jonboy]

thanx mate,
its been to the auto electrition and they have told me that the previos mechanic has set the timing to somewere between 16-18 degrees??? and they are thinking i have a faulty distributor and wrong plugs (parts store swear these are perfect)
first thing we are gonna try is remove the champion gold plugs and replace them with the correct ngk plugs, they have been ordred today, ill fit them in the weekend and see how it runs.
next week the distributor is coming back out and getting sent to a specialist who will put it in a machine and check it, if its at fault ill be going back to the garage for a replacement, then refit it all and set it to 10 degrees like its suppossed to be.
sounds expensive but hopefully its going in the right direction.

[GRPABT1]

IMO champion plugs are shit, you should be using NGK bpr5es IIRC

[BlackVXGTS]

IMO champion plugs are shit, you should be using NGK bpr5es IIRC

You should be using the standard NGK BPR6EF-10 plugs (1.0mm gap) for your 304. Note that you may have to purchase BPR6EF-15 (V6 pre-gapped plugs) and regap them to 1.0mm since the V6 plugs are more readily available.

[delcowizzid]

champion plugs and holden 304's and 202's dont really play nice fit some bpr6efs stock copper plugs and see what happens

[jonboy]

ok so i have got a set of genuine plugs from holden they are GM T20EPR-U
ill install them later on this afternoon hopefully, after i check the gaps (have to go borrow a gauge)
they are made by DENSO apparently this is the same manufacter of ngk. they have holden genuine part on them.
fingers crossed

[jonboy]

the new plugs made it run worse!!!
it hunts ans misses constantly now? ill pull them all out in the morning when it has fully cooled down and check everything again. but im positive its the distributor now, itl be coming out and geting tested this week,
i cant understand why the correct plugs would make it worse thou?

[jonboy]

ok so i removed the plugs this morning again and checked the gaps (i ended up not checking them yesterday as i was later told they had been pregapped) and they were set at .7 so i reset them to 1mm and runs 100 times better no more hunting! it still has a miss tho.
i ended up seeing my mechanic mate up town and he came around and reset the timing for my to 10 degrees, so we are wondering if the distributor is turning by itself somehow? and altering the timing.
i think i am going to get the wires all checked before i pull the distributor for checking next
also get a leakdown/compresion test done i think maybe

[VR38]

Comp test along with a vacuum test means no more guessing.
Smart move to check the leads too.

[jonboy]

update
so the vt has been at the garage for a week now, the distributor/coil and ignition module were removed and tested the ignition module had a few dry solder conections is all they could find. all was refitted today and timing reset to 10 degrees.
and bugger it it still has the miss.
ill be taking it bake to get the wires mentioned in the attached file checked next.
its getting a bit annoying now we seem to be not getting very far.