1ggte misfire when coming off gas

[86TT]

I removed my distributor cap the other day and found that the rotor arm and cap terminals are pretty nuked ....wil have a replacement this week , hope it improves things .

Thanks for all your input tho , some good useful info there

[Admiral coFF33]

i think we are all thinking to much on this one ....

consider checking the easiest thing first maybe .... the spark plugs ?

my 1ggte just had all 6 changed coz i was misfiring when taking off and when taking my foot off the gas ... so go yank a few out .. look at the gap on them , if its bigger than 3mm then CHANGE THEM!

[86TT]

I changed the spark plugs for ngk v groove BCPR6EY 11 , the motor is a lot smoother but still not right ...the way the car behave makes me think its the throttle position sensor .

Is the Throttle position sensor known to break up and cause problems .

Does anyone know how to set the TPS up or trouble shoot it with a multi meter ?

[CrUZida]

1.1mm is too big.

Regap them to 0.8mm

[86TT]

1.1mm is too big.

Regap them to 0.8mm

Yep i did that before fitting ....IIRC 0.8 is about 35 thou , thanks tho

Any ideas on setting up the TPS ..i,m going to take it apart later today and inspect the tracks .

[CrUZida]

35 thou is almost 0.89mm.
0.8mm is closer to 30 thou.

Anything over about 12psi boost and you *may* see issues on 0.9mm gap

As for the TPS, never set one but it can't be too much different to the 7M's

http://www.cygnusx1.net/supra/librar.../fi/FI_101.gif

[86TT]

Cheers mate ..i,ll reset em and check the tps

[stradlater]

I gotta admit, misfire when coming off the gas in my experience has zero to do with a plug gap issue.. Maybe bad plugs, but not plug gap.. Plug gap tends to play havoc with your idle tune and your top end power..

I'd be leaning more towards a vacuum(sp.) leak.

[86TT]

Yeah , i,ve been fighting 2 issues with it ..the other one being a hesitation and misfiring that stops the engine from reaching high rpm when the throttle pedal is floored sharply ,

If i put my foot down gently or back off when hesitation kicks in and find the sweet spot on the throttle pedal the car continues to go well......this is whats pointing me in the direction of a poor or incorrectly set Tps

[stradlater]

Well, when it boils down, it's gonna be one of two things..

Ignition

Or

Fuel.

Given I'm not an EFI man, I'd struggle to help you on the fuel side, but I've fucked around to the high heavens with the ignition systems on 1g's, so I can offer some assistance there if you want.

[86TT]

Cheers ..i might take you up on that
Time to get the multimeter out me thinks

[86TT]

Righty ...i,ve removed / stipped and cleaned the TPS ...removed stripped and cleaned the ISC valve ( which was very gummed up )
Also removed the spark plugs which were very white around the tip if the insulator But black and sooty further down ....any ideas ( yes i do have a Blitz atmos BOV }

Waiting for a new gasket before i can start the car .

[Ashe]

Sounds to me the engine is getting too rich b/c of the BOV, then cutting back on fuel when the o2 sees the extra fuel.

Are you getting any check engine lights?

[stradlater]

Righty ...i,ve removed / stipped and cleaned the TPS ...removed stripped and cleaned the ISC valve ( which was very gummed up )
Also removed the spark plugs which were very white around the tip if the insulator But black and sooty further down ....any ideas ( yes i do have a Blitz atmos BOV }

Waiting for a new gasket before i can start the car .

White tends to mean too lean, particularly VERY white..

But then again, very black and sooty means too rich..

Maybe try getting rid of that BOV and see what happens. I'd tend to think it's got stuff all to do with it, but it's worth a shot.

Check for a vacuum leak somewhere mate, that tends to be the cause of all sorts of problems.

[Hydra]

Use a site like this: http://www.gnttype.org/techarea/engine/plugs.html

It will help you figure out what the spark plugs are telling you