spark plug gap - Ford Mustang Forums : Corral.net Mustang Forum

 
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post #1 of 21 Old 06-15-2011, 10:28 AM Thread Starter
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spark plug gap

Question.

I recently did a tune up on the car and put a new set of autolite plugs in. I have a MSD coil and wires and distributor.

I gaped the plugs at .035-.040. is this too small?

The reason I ask is a couple days after the tune up, I'm now getting a CEL with codes 137, 173 (running rich)

Could gapping the plugs to tight cause a rich condition?

What is the correct plug gap? Also I will be running a 100 shot of N2O


Laser Red 1995GT with a 408W
Best ET to date: 11.7@120
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post #2 of 21 Old 06-15-2011, 11:13 AM
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Stock is .054. Try that. It's cheap & nothing to lose other than time!!

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post #3 of 21 Old 06-15-2011, 12:45 PM Thread Starter
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spoke with AFR and they said my gap is ideal for N20. Still stumped on what is causing the 137 173 codes?

Any suggestions on how to trouble shoot this?

Laser Red 1995GT with a 408W
Best ET to date: 11.7@120
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post #4 of 21 Old 06-15-2011, 01:06 PM Thread Starter
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also since im getting both o2 reading rich, i highly doubt the o2 sensor are bad....

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post #5 of 21 Old 06-15-2011, 10:29 PM
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Copper plugs? Not platinum.
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post #6 of 21 Old 06-16-2011, 12:11 AM Thread Starter
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Copper autolites. The ones AFR recomends

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Best ET to date: 11.7@120
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post #7 of 21 Old 06-16-2011, 12:40 AM
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How does the car run otherwise?

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KB 2.1L @ 9psi, FRPP M5400-A Suspension System, FRPP Aluminum D/S, Built AODE and TC, FRPP 3.73 Gears, Balanced Roller Cammed Engine, Edelbrock Performer Heads, Comp 270AH cam, AEM EMS, 3.5 Bar MAP, Zeitronix ZT-2 WB, FRPP 70mm TB, modified UPR CAI, Be Cool Aluminum Rad
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post #8 of 21 Old 06-16-2011, 08:28 AM Thread Starter
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It runs good when the lights off. actually when the lights on it isn't missing or bucking or anything like that. The biggest issue is if its running rich and you shut it off then try to start it a few mins later the car doesent want to keep an idle unless you give it throttle. Then once your on your way it will hold an idle even if the CEL is on

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post #9 of 21 Old 06-16-2011, 10:18 AM
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I run .040 on mine, according to the wideband it had no effect on mixture, plug wires and disributor cap last longer too.

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, 1.7s, 4.30s, stock T5 living on borrowed time.
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post #10 of 21 Old 06-16-2011, 11:59 AM Thread Starter
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any other suggestions on what to check to figure out why the CEL keeps randomly turning on and off?


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post #11 of 21 Old 06-16-2011, 07:04 PM
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52
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post #12 of 21 Old 06-16-2011, 08:35 PM Thread Starter
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52? Do you mean try setting the plugs at .052"?

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post #13 of 21 Old 06-17-2011, 01:01 AM
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IIRC the CEL is triggered only by sensors monitoring emissions parameters. If the spec is outside the parameters the CEL comes on. If the condition changes and the spec falls back into the accepted parameter range the CEL will turn off. The fact that both O2 sensors read a rich condition would seemingly rule them out. However, if they have been in use for many years/heat cycles it's quite possible the signal is bogus.

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post #14 of 21 Old 06-17-2011, 09:32 AM Thread Starter
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update:

started the car to go to work this morning. didn't want to idle very well. would occasionally stall out. Got on the road and it threw a CEL. Pulled into the gas station and it went out before i could scan. filled the tank up and went to start it. it basically wouldn't run unless i gave it throttle. it felt very stumbly like it was running rich. it eventually sorted itself out and the CEL popped on again. I pulled into a parking lot and pulled codes.

137:
Heated Exhaust Gas Oxygen (HEGO) sensor - voltage signal not switching during engine run self-test. Indicates "rich" (Bank #2)

173:
Heated Exhaust Gas Oxygen (HEGO) sensor - voltage indicates "rich" (Bank #1)

327:
EGR Valve Position (EVP) sensor, pressure feedback EGR (PFE) sensor or EGR pressure transducer (EPT) - signal voltage too low.

The last code is due to not having an EGR on the car. I have a chip that has addressed this though. So the CEL is due to the 137, 173 codes.


Any thoughts?? this is really getting annoying. Especially since I'm going for a N2O dyno tune on 2 weeks.

Laser Red 1995GT with a 408W
Best ET to date: 11.7@120

Last edited by last5liter; 06-17-2011 at 09:35 AM.
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post #15 of 21 Old 06-17-2011, 05:09 PM
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Maybe it could be a coolant temp sensor. My 95 was running rich and almost seemed like it was flooded until i changed my coolant temp sensor. I don't remember what the codes were. Hopefully this helps.

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post #16 of 21 Old 06-17-2011, 05:24 PM Thread Starter
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well i took it out at lunch and it did the stalling rough running cel rich thing. just drove it home from work and no cel started and idled fine....lol talk about your intermittent issue.

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Best ET to date: 11.7@120
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post #17 of 21 Old 06-18-2011, 10:27 AM
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I would double check all you vacuum lines (for wear and leaks). You can pull up a vacuum distribution chart online to help you with location.

Have you doubled checked your timing? I'm assuming these codes were not present before the tune-up so your problems could be related to the work you did or the work area. Something got dislogded, etc.

One thing I noticed, people always have the money to do it right the SECOND time.

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post #18 of 21 Old 06-18-2011, 10:29 AM
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Quote:
Originally Posted by sn95gt View Post
Maybe it could be a coolant temp sensor. My 95 was running rich and almost seemed like it was flooded until i changed my coolant temp sensor. I don't remember what the codes were. Hopefully this helps.
I would check this as well...The sensor just may be out of range and thinks that the coolant is -40 degrees and is dumping gas. I had that happen on my 93. No CEL telling it was out of range. Easy fix.

Take the IAC off and spray it with some of that electrical cleaner. Easy fix too if you haven't done it at all. I didn't do mine for 100,000 miles and I should have done it WAY sooner. Cleaned up my idle surge.

What kind of injectors? Did you touch the stock regulator at all? I would slap a fuel pressure gauge on the schrader valve to see if it is higher than like 40 psi or something indicating that the regulator is bad. Possible injector stuck open?

How is the temp gauge? Is it getting up to operating temp? My O2s on my Explorer weren't turning on and the car was dumping gas because the T-Stat broke in the open position (fail safe).

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post #19 of 21 Old 03-21-2012, 11:55 AM Thread Starter
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update:

found out that my coil was on its way out and was likely causing all the issues, that being said I now have a SCT tune from lideo at alternative auto on the car.

doing a spring tune up and picked up some new autolite 3924

looking for recommendations on what plug gap to run

car is a stock 302 with AFR 165's crane 2031 cam, ported cobra intake and a zex 125 wet shot.

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post #20 of 21 Old 03-21-2012, 04:31 PM Thread Starter
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after some calls to ZEX and autolite. they recommended a 0.032" gap instead of the 0.054" stock gap. and depending on the condition of the plugs insulator i should stick with the autolite 3924's or go one range colder to the 3923's

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Best ET to date: 11.7@120
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post #21 of 21 Old 04-07-2012, 11:00 PM
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.035" dyno proven....I have had afr 185 and 205.....always autolites!
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