Spark Plug Gap

[Eric Smit]

~22 PSI.


-Eric Smit

 

[rdss]

That's where I'm at. I might talk with Jerry about having Vince build a tune with lower boost pressure at lower throttle inputs, I'm peaking at 16-18 psi under mild to below medium acceleration. I will have to bring up my throttle position and see if I can correlate throttle position to boost produced and see if it's worth looking into.

 

[NextLegend]

So What should mine be for my 1.8L ?

Morepower<3?

 

[Leverus]

.028 officially.

Some people, myself included, set them somewhere between that and .035. Supposedly the higher gap results in better mileage and throttle response. Mine were quite off and I went right to a higher gap without setting them to factory first and I'm satisfied. I don't know if my .032 is any better than what's recommended officially, but my car feels much better and I'm leaving them since I've had no problems with a higher gap.

 

[Larry]

.028 officially.

Some people, myself included, set them somewhere between that and .035. Supposedly the higher gap results in better mileage and throttle response. Mine were quite off and I went right to a higher gap without setting them to factory first and I'm satisfied. I don't know if my .032 is any better than what's recommended officially, but my car feels much better and I'm leaving them since I've had no problems with a higher gap.

Wider gap = more complete burn. The problem is that if too much air is coming in it will blow out the spark resulting in hesitation, stumbling, etc. Generally, idle and part throttle will become smoother with wider gap. Setting the gap correctly is important in order to maximize fuel economy, power, and drivability.

 

[Leverus]

Thanks for the explanation. I've no trouble with any blowout on mine, even hard WOT driving. My MPG has remained the same since I regapped. I'm almost tempted to put them at the factory spec just to see if there's really a difference between that and a larger gap, but I don't want to tempt fate by going under the hood again.

 

[theenico]

Stock turbo plugs are heat range 6. Most N/A plugs are heat range 7.

That numbering/range convention works for Bosch (W6DTC (cold) vs W7DTC (hot)) and some other manufacturers. NGK, however, does their ranges backwards where a lower number is a hotter plug (6 is hotter than 7).

Here is a link to NGK's info on their heat ranges:

NGK Spark Plugs USA

 

[Papasonic]

The plugs in my 1.4 turbo were gapped > .025 but < .028 I adjusted the gap to .030 using a wire type spark plug gap gauge.
I don't know if I just wanted to experience a performance difference, but I really believe the engine shudders/stumbles less on a cold start, and seems to pull a little stronger in the lower gears.

Papasonic

 

[$ub$onic]

Would u recommend this for a 1.8?

Sent from my SAMSUNG-SGH-I747 using Tapatalk 2

 

[Leverus]

Definitely. My 1.8 feels better after regapping.

 

[Larry]

That numbering/range convention works for Bosch (W6DTC (cold) vs W7DTC (hot)) and some other manufacturers. NGK, however, does their ranges backwards where a lower number is a hotter plug (6 is hotter than 7).

Here is a link to NGK's info on their heat ranges:

NGK Spark Plugs USA

Interesting, thanks for the link. Then it's a normal heat range plug, same as the 1.8L.

 

[theenico]

No problem Larry. It's something I learned years ago during my road racing days.

Has anyone taken a picture of the factory fitted plugs? Are their any non-GM part numbers or manufacturer markings? I'm thinking of an alphanumeric string similar to IFR6W-7G. If not, no biggie. I'll have a look myself when I check my gaps here in the near future.

 

[Eric Smit]

In the 1.4 it says NGK on it. Does that mean they're NGK? DUN DUN DUN.


-Eric Smit

 

[theenico]

That would indeed make them NGK. Was there any other writing on them?

This is one of those rare occasions when I miss being at GM where I could just go to the catalog, grab the P/N, and then look up the suppliers drawing in the 2D database.

 

[Eric Smit]

Sorry, I don't remember what it said off the top of my head. I vaguely remember other things besides NGK on it.


-Eric Smit

 

[sx sonic]

I'll post.up tommorrow since I'll be messing with my car anyways. (I'm in plasti dip mode now)

Unless someone steps up to the plate before then

-tyler

 

[CoHPhasor]

That numbering/range convention works for Bosch (W6DTC (cold) vs W7DTC (hot)) and some other manufacturers. NGK, however, does their ranges backwards where a lower number is a hotter plug (6 is hotter than 7).

Here is a link to NGK's info on their heat ranges:

NGK Spark Plugs USA

That's why I was confused about people's posts here, they were talking Bosche and I was thinking NGK.
(I've only dealt with heat range with NGK)

Thanks for clearing that up.

 

[sx sonic]

Ok here's the markings.

NGK. IR,
IFR7X
7G. R6
On the nut part of the plug is, M1YP
Made in japan

That's everything

 

[theenico]

Thanks that's surprisingly close to the IFR6W-7G guess I made a few posts up (It's the plug for a 2009 Saturn Astra 1.8 ).

For the laymen, here's what the IFR7X-7G P/N means:

I = OE Iridium
F = 14mm thread and 19mm reach/depth
R = resistor type
7 = heat range
X = unknown
-
7 = gap spec (0.7mm in this case)
G = copper cored ground electrode

The following link will allow anyone to decipher 99.9% of NGK's P/Ns: http://www.ngksparkplugs.com/docs/tech/design_symbols_plugs.pdf

 

[dvn]

Checked mine in my 1.4 today and they were all ay .026. Should I re-gap? If so, to what?