misses when under hard bost

[thebuddrik]

just had the head completly rebuilt, new denzo plugs, all new toyota hoses, cometic HG, ARP studs, new injector clips. compressition is good. valve clearences are close to perfect. I ran the car a week real easey. I noticed if i was pulling out into traffic and i boosted a little it would kind of miss. this weekend i pulled the intake mani off and checked all gaskets and reassembled double checking everything. after all of the work i went for a drive and when accelerating hard the car misses a little. if i drive normal everything is fine. it only misses when i try to accelerate hard. the car is completely stock except for the HG.
any help is appreicated
thanks

 

[IJ.]

What are the plug gaps?

 

[suprahero]

Sounds exactly like mine when my plugs had too big a gap.

 

[Justin]

I'll give a third vote on plugs.

 

[pbasil1]

Check gap to see that its at around .028

 

[thebuddrik]

i gaped it to what it said under the hood, off the top of my head ... 31-32
i will go look in a min

 

[annoyingrob]

if you gapped them to .032, then re-gap them to .028.

It'll make a world of difference.

 

[thebuddrik]

just checked, 31.
damn you mean that 3 tho can make that big of a difference?

 

[WhtMa71]

Yeap, when i first put my motor in i gapped the plugs to 32 and had a bad miss when i hit boost. Took them out and regapped to .28 and it worked perfectly.

 

[annoyingrob]

just checked, 31.
damn you mean that 3 tho can make that big of a difference?

IIRC, electrical resistance goes up exponentially as the gap increases.

 

[thebuddrik]

thanks for all of the help guys, i will regap them tonight

 

[MK3Brent]

With a fully functional ignition system there's no big reason you cannot use a .032" gap.

For what it's worth, I made 350hp with a .042" gap AutoLite copper plug.

 

[thebuddrik]

my system is bone stock. the TSRM says .031. what the hell? is there something else that I should check out?

 

[MK3Brent]

my system is bone stock. the TSRM says .031. what the hell? is there something else that I should check out?

What grade fuel?

 

[IJ.]

With a fully functional ignition system there's no big reason you cannot use a .032" gap.

For what it's worth, I made 350hp with a .042" gap AutoLite copper plug.

ie: NOT old fucked half dead coils and leads and corroded wiring/terminals and the wrong airgaps in the CPS....

 

[thebuddrik]

super

 

[IJ.]

Most stock Ignition systems I see are so far past their useby dates they fall over at low rpm/boost.

It takes a very good Ignition to light off the fuel/air under boost, higher the boost/cylinder pressures the harder it is.

I had an issue around torque peak but having a standalone I was able to tune around it, now with less boost and hotter coils it "should" be fine.

 

[starscream5000]

Just like everyone else says, re-gap the plugs, but you may want to go over your coils and the rest of the ignition system in your freetime and check tolerances to see if any are too high on resistance, etc. from what is recommended in the repair manual.

 

[thebuddrik]

re-gapped them and the problem is still there. i guess i will have to get into it a little further. i will hit up the TSRM and see what i need to do.

 

[IJ.]

Air gaps in the CPS for starters.

Use a Multimeter on the coil packs

Ditto on the leads

Coil Grounds