NGK Iridium Gap?

Les Borda

Registered User
What should the gap be on these plugs on a fairly modified 89 Cougar XR7? We set them at around 38 and at high rpm it is cutting out. Probably too tight of a gap I think?
 
Les,

Mine have been gapped as tight as .030 and I never had a problem with it missing at high rpms. I'm currently gapped at .040 but would suggest you go a little wider and try .045.

If it's still misses, one of the plug wires is probably damaged.

David
 
Thanks Dave we wondered about that, one being damaged. It;s Greg Colemans CAT and he thought he heard a crack when installing number 2. We;ll check them as we pull them and regap to 045 if one is not broken,
 
this may be offsubject

But my car was having horrible tip in problems and some minor missing.....

I pulled out the Iriduims and put in APP103's and its running a HELL of Alot better. They only had about 3000 miles on them and all looked ok.


Chris
 
But my car was having horrible tip in problems and some minor missing

Sorry to jump off topic for a moment, but what is tip in referring to exactly? I do not want to confuse a tip in problem with something else when I switch to iridiums

Paul
 
Paul, if I'm not mistaken when Brian H tuned my car in Carlisle he said something about my "tip in" problem. .. I think it's as easy as it sounds. It's as soon as you hit the gas the very first reaction is considered the tip in point. Someone will correct me if I'm wrong.

Anthony
 
That implies to me that tip in would be related to exhaust pulse delay? I sure wish we had a EEC tuner forum to converse and consolodate tuner and EEC function information.

Paul
 
Paul

I believe the "tip in" has do do with how much extra fuel is provided to accelerate the car when the gas pedal is first pressed. If I'm understanding it correctly, it performs pretty much the same function as the accelerator pump does on a carburator.

My engine like lots of fuel at tip in or it will stumble.

David
 
exactly, everytime I would punch the car, it would stumble and backfire. Continually getting worse over the last two months.

Brian had it on the dyno two weeks ago and said everything is fine and suggested replacing the plugs.

Well I did just that and no more tip in problem and the car has more HP to boot!


Chris
 
Chris~ Funny you should mention that. I still have a tip in problem. But my plugs are gapped at 52. So, it's time to drop them to 40 and see if it makes a difference. Right now, I can't drop the pedal to the floor from a stop or it will stall. Also backfires slightly when I press on it too fast.Almost like it's blowing out the spark. But if I ease into the throttle and get it to the floor that way, ferrrrgetabou-tit!So, I'm putting new O2's & changing the gap. Hopefully fix the problem.

Anthony
 
Les, glad you got it worked out. Im sure we all wish it could end up being a simple cracked plug instead of the tuning issues and trial and error we all have to deal with generally.

Paul

I believe the "tip in" has do do with how much extra fuel is provided to accelerate the car when the gas pedal is first pressed. If I'm understanding it correctly, it performs pretty much the same function as the accelerator pump does on a carburator.

My engine like lots of fuel at tip in or it will stumble.

David

Ok, well that would make sense. On the dyno, I have seen the car go real lean when first hitting the gas (see attachment) then immediately recovering so I will have to try adding more fuel and see how the car reacts. My plugs are at .045" gap right now, I may pull the gap down a bit once I get past my 10MPG fuel economy issue:rolleyes: if I dont go to iridiums.

Paul
 

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Paul,

That's line goes up quite a bit at such a low RPM. Work on getting that lower quickly.

I am a little leaner than I would like on my tip in & check the curve on it.

Anthony
 

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Anthony, look a little closer at the graph, it is actually at around 13:1 just before I stab the gas peddle. The line there is indicating where it peaked at what RPM and how lean it went at that moment. I agree though, it is too lean indeed. I have been staying off the floorboard for that very reason which makes a slow car even less fun to drive.

Paul
 
Jumping back to gapping of plugs... Is it possible to regap the Autolite APP's? I took the car somewhere & he said that they shouldn't be regapped, but that doesn't sound right at all. .. Just wondering to reconfirm my beliefs. Anyone have any input.

Anthony
 
I know the issue with Greg's Cougar has already been solved, but conversely, my NGK Irdiums are gapped at .045" currently, but I have yet to dyno the car with them installed.
 
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