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Colder plug for a renix

blondejoncherokee

NAXJA Member
NAXJA Member
Location
sacramento
Failed CA smog with high No2. Looking for a part number for a colder plug for the thing . The lambda calculator gives me a perfect 1.0005 with a 14.76 ratio.

Also going to sea foam it, check for intake/vacuum/exhaust leaks/ ordered a new EGR and FPR too since those are suspected over time. going to clean the EGR first. and try to take it in cold since all the other numbers where good.
cap, rotor, o2 sensor are all brand new.
 
Seems the NGK 3923 as from other smog threads is one heat range cooler. What about the NGK 3922? That seems to be like 3 heat ranges cooler. I just need to make sure they are the same thread pitch.

If I have to go this far, any recommendations on a good cheap aftermarket cat?
 
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CARB legal Renix-era cat's typically range from 110$ (usually universal weld/clamp on) to 180 (bolt-in) Depends on where you look. I would check amazon or performance-curve.
 
CARB legal Renix-era cat's typically range from 110$ (usually universal weld/clamp on) to 180 (bolt-in) Depends on where you look. I would check amazon or performance-curve.

Im looking from actual feedback and part numbers. There is a 95% chance the cat will get smashed in the rocks in 2 years of wheeling so Ill probably buy another in 2 years so I am not worried about it lasting longer than one single smog test.
 
going to try out the NGK FR4 plugs, one heat range colder.
also looking at the Walker 80906 cat for 120$ it seems like a good temporary cat and just get it to pass this one time basically.
 
so the FR4 are a hotter plug, they are heat range 4, which is hotter. I need a colder range plug. It seems like I could use this plug: NGK R5672A-8 (stock number 7173). The problem is, that is a jump from heat range 5 to heat range 8, which is too cold. I really want to go from 5 to 6.

using this from multiple hot rod websites:


Stock – MFG Recommendations: approx under 9:1 compression
Heat Range: 4
Gap: Consult ignition mfg.
Plug: NGK FR4 (stock number 5155); NGK BKR5EIX (stock number 6341); Autolite 3926; Champion RC12YC (stock number 71); Denso IK16 (stock number 5303)

MFG Recommendations: approx 10.5:1 compression
Heat Range: 5
Gap: Consult ignition mfg.
Plug: NGK FR5 (stock number 7373); Autolite AR3924 (Racing Plug); Autolite 3924; Champion RC9YC (stock number 2075); Denso K20PR-U (stock number 3145); Denso IK20 (stock number 5304)

MFG Recommendations: approx 11:1 compression
Heat Range: 8
Gap: Consult ignition mfg.
Plug: NGK R5672A-8 (stock number 7173); Autolite AR3911; Champion C63YC (stock number 796); Denso IQ24 (stock number 5314)

MFG Recommendations: approx 12:1 compression
Heat Range: 9
Gap: Consult ignition mfg.
Plug: NGK R5672A-9 (stock number 7405); Autolite AR3910; Champion C61YC (stock number 785); Denso IQ27 (stock number 5315)

MFG Recommendations: approx 13:1 compression
Heat Range: 9 - 10
Gap: Consult ignition mfg.
Plug: NGK R5671A-9 (stock number 5238); Autolite AR3933; Champion C59CX (stock number 296); Denso IK27 (stock number 5312)

MFG Recommendations: approx 14:1 compression
Heat Range: 10
Gap: Consult ignition mfg.
Plug: NGK R5671A-10 (stock number 5820); Autolite AR3932; Champion C57CX (stock number 295); Denso IK-31 (stock number 5321)
 
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going to try out the NGK FR4 plugs, one heat range colder.
also looking at the Walker 80906 cat for 120$ it seems like a good temporary cat and just get it to pass this one time basically.

Well, why don't you make it "bolt-in" so you can remove it when you do not need it?
 
good call. ill flange both sides then. although that makes it easier for the scum bags to steal it. there are a lot of stolen cats out here. Ordered a walker CA legal cat for the XJ. Amazon for 120$ shipped .
 
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Im dealing with a CA smog fail. High Nox. Everything else was way low and box was way high.
 
EGR flow is another possible. I haven't finished my first cup yet, so don't take this as gospel, but if the computer thinks EGR is working OK (but it isn't flowing enough or has a leak somewhere) then your nox readings are going to run high.
 
I ordered a new EGR and diaphragm , walker cat, NGK o2 sensor, and a new FPR as well already those are two things I've wanted to do for a long time.
 
i went through a similar situation with my renix recently.
i tried all kinds of things from seafoam, to cold water decarb, colder plugs, new o2, new egr(backpressure transducer was toast), removed my hi altitude cps(put it back), new iat and cts sensors, etc. nothing made more than 100-200ppm nox difference.
all my other numbers were well within passing. finally, i put in a new magnaflow cat....my nox went down to single digits @ 3ppm. the o2 and cat made the biggest difference by far.
interestingly, the change from a non-functioning egr to a new one made very little difference in the smog numbers.
 
i went through a similar situation with my renix recently.
i tried all kinds of things from seafoam, to cold water decarb, colder plugs, new o2, new egr(backpressure transducer was toast), removed my hi altitude cps(put it back), new iat and cts sensors, etc. nothing made more than 100-200ppm nox difference.
all my other numbers were well within passing. finally, i put in a new magnaflow cat....my nox went down to single digits @ 3ppm. the o2 and cat made the biggest difference by far.
interestingly, the change from a non-functioning egr to a new one made very little difference in the smog numbers.

This is the helpful information I needed!
this is very good to know. I have a new NGK o2 and a walker cat coming(CA legal) . I figure at this point my time is worth something and if I have to keep paying to re-smog it every 2 times it fails (one free re-test) Ill just try to nip it in the butt now and just do it all at once. I got a lot of the parts on rock auto and amazon and joined the trial version of Amazon Prime so I am getting free 2 shipping on everything.

So far I don't have much into this thing for SMOG:
NGK plugs-13$
walker cat (CA legal) -120$
NGK o2 sensor-40$
FPR ad EGR and diaprhagm. 80$
sea foam and HEET and some odds and ends 20$ -(no smoke came out with the sea foam this time, probably since I sea foam the rig once a year, finally coming out clean)

so far only ~278$ in parts for all of that so that is cheaper than taking it to an exhaust shop just to do a cat, of course ill weld the cat up myself and probably flange both sides.

ill install everything when it comes in during the next 5-7 days and take it back.




as for the plugs, from NGK directly through customer service and I ordered the BKR6E on amazon as an add on with free 2 day shipping :

Part number FR4 is one heat range hotter than part number FR5, to go to a colder heat range a plug with a slightly smaller projection is required. One heat range would be part number BKR6E and two heat ranges would BKR7E.
 
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i ran one step colder plug with autolite ap3923's, i'm just going to leave them in there. i drive the hell out of the xj, so i'm not worried about the plugs being too cold.
ngk is the only mfr i'm aware of where a higher number is a colder plug.

i did all my stuff in 3-4 steps. everything i did made it a *little* better, but i failed 3 times. when i put the cat on, all my numbers dropped significantly, but the nox was dramatic. went from around 1000ppm to just 3ppm. in fact, it did so well that the machine went into a quick test mode, and was over within a couple minutes. not bad for a 200k+ renix.
 
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i ran one step colder plug with autolite ap3923's, i'm just going to leave them in there. i drive the hell out of the xj, so i'm not worried about the plugs being too cold.
ngk is the only mfr i'm aware of where a higher number is a colder plug.

i did all my stuff in 3-4 steps. everything i did made it a *little* better, but i failed 3 times. when i put the cat on, all my numbers dropped significantly, but the nox was dramatic. went from around 1000ppm to just 3ppm. in fact, it did so well that the machine went into a quick test mode, and was over within a couple minutes. not bad for a 200k+ renix.

what magna flow cat did you use? the larger one ? I just ordered the cheap walker weld on one since it was way cheaper. This way I should pass on my Free Retest and not have to keep dealing with all of this.
 
nice. Looks you ordered the nice legit one with the flange and everything. ill hopefully get everything on this week and post up any SMOG results afterward.
 
Has anyone used those fancy plugs with multiple ground gaps to the electrode? Bosch even made some, I think, but what comes to mind is one called "Split-Fire", and other such attempts. There have been some with exotic materials too. Some have Ford, Dodge, Chevy like debates as per plugs too, i.e., Champion versus fill in the blank. I can't remember ever having a problem with Champions, NGK, Autolite performances, but maybe I've been lucky. Is the KISS Principle mandated?

Really appreciate the input as per heat ranges, especially the NGK reverse number thing, but am not too certain as to why one would want something different to a standard heat range than for that described for the RENIX 4.0 suggested variety of say the 'heat range 4' type brands of plugs.

What's up blondejoncherokee? Are you thinking, saying that a colder plug will less likely burn the nitrogen gas in the atmosphere creating an oxide to be measured?
 
I'm really only doing
It for smog reasons . High nox is lean or rig is running hot. Rig runs cool . I really am just giving it a shot . Normally you wold only want to run colder plugs if you had like a performance motor that you were dialing in. Colder plug will help bring those temps down and reduce nox. Also hot rodder types run hotter or colder plugs to dial in big hp motors .
 
My old-school learnin' has me not understanding how a spark plug's ability to burn off deposits, can change the combustion temperatures.
 
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