Spark plug gap

[jv7]

Currently have 031 gap seem to be getting what seems like spark blowout upper rpms d1 blower 16lbs boost should I run a smaller gap? Was thinking 028?

[fastlane]

It wouldn't hurt to close the gap a bit. I run .028 on NGK BKR7Es at 29 pounds of boost and I haven't experienced any spark blowout issues.

[TKat13]

if the gap change does not work, look at the wires right at the COPs, I was having a similar issue in the upper RPM range and no matter what I did , swap COPs or plugs still had it. Then I noticed the wires were very tightly twisted at the COP, I untwisted by it by a few turns and it fixed it completely. I guess at some point during the build/plug changes, etc two of the COPs were getting rotated. Had this problem on both rear locations.

May not help, but it was the final item that fixed my problem after struggling to find anything. Still seems hard to believe.

-dw

[sutyak]

Originally Posted by TKat13

if the gap change does not work, look at the wires right at the COPs, I was having a similar issue in the upper RPM range and no matter what I did , swap COPs or plugs still had it. Then I noticed the wires were very tightly twisted at the COP, I untwisted by it by a few turns and it fixed it completely. I guess at some point during the build/plug changes, etc two of the COPs were getting rotated. Had this problem on both rear locations.

May not help, but it was the final item that fixed my problem after struggling to find anything. Still seems hard to believe.

-dw

Great info. Something I'm going to try. I also have a blowout-type issue in the upper RPMs. When I actually drive my car that is.

[DSG2003Mach1]

I think mine are gapped around .028 with 15psi

[jv7]

Thanks for the info! I’ll regap and check the cops.

[01yellerCobra]

You shouldn't be having blow out at that boost level and gap. How old are the COPs? Are you sure you're not having belt slip. I thought I was having spark blow out and after chasing everything ignition related I found it was a belt issue.

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[jv7]

16lbs of boos build bottom end. Could be running rich? I have 80lb injectors that I'm going to change out to 60's and I do see puff of black smoke when I get on it on gear changes so I guess it could be a rich condition. cops are less than a year old bought oem ones. I want to get the car retuned with the 60's but want to make sure I don't have any other issues. I think Ill regap plugs and check twist in cops(easy enough to do) at least I'll know thats not the issue. Belt is new changed it within last 2 weeks(gates green belt).

[sutyak]

Changing to 60lb injectors will not help at all if the current 80lb are tuned properly.

[jv7]

I've looked into that and people go back and forth on this 80lbers dump too much fuel at idle and low rpm so hardware issue can't be tuned out. Have had 3 different competent tuners on different changes 11mpg just too low. I guess I'll find out the hard way and let you guys know.

[HAEG]

I believe the stock spark plug gap is .052 to .056 in. Just changed my plugs recently and this is what was recommended by All Data

[sutyak]

Originally Posted by jv7

I've looked into that and people go back and forth on this 80lbers dump too much fuel at idle and low rpm so hardware issue can't be tuned out. Have had 3 different competent tuners on different changes 11mpg just too low. I guess I'll find out the hard way and let you guys know.

I run 80lb injectors. As long as the 60's provide enough fuel for your setup then it won't hurt to try. I have had some injectors in other builds that are just terrible to dial in (try a 55lb injector). The best injector I've ever used are the Injector Dynamics ID1000.

[jv7]

Originally Posted by HAEG

I believe the stock spark plug gap is .052 to .056 in. Just changed my plugs recently and this is what was recommended by All Data

I have a built bottom end running 16-18lbs of boost on a D1 so my gap will be way differently than yours. But even that seems to be a wide gap for a stock setup.

[TKat13]

Originally Posted by jv7

I've looked into that and people go back and forth on this 80lbers dump too much fuel at idle and low rpm so hardware issue can't be tuned out. Have had 3 different competent tuners on different changes 11mpg just too low. I guess I'll find out the hard way and let you guys know.

I know for a fact that there are tuners that can tune a car to run properly on 80's, I drive one myself. In fact, I picked up this set of 80s from a guy that said exactly the same as you did, best 200.00 bucks spent. He said he took his car to two shops and they could not tune the car. Asked my tuner about it, he told me to buy them and he had me up and running extremely quickly, and that was on an entirely new build. He did tell me that many were having problems tuning with the 80s, something about the sample curve provided by his tuning software was way off. (if I recall correctly, its been a few years).

Although MPGs was never a concern for me at 750+hp, there are so many other factors that impact MPG, not just the injectors. I think the best I have done is 13; but that is using a TH400 trans, 3500 stall and driving around town on 315 drag radials...oh on E85. Given that, 13 is fantastic.

My normal is 10-11 but my normal driving the mach involves a heavy right foot so it is not a fair comparison.

Its about Smiles per Mile!

[TKat13]

I should also note, injector sizes should be selected based on your power goals and setup. If you are not running E85 and only what 550 HP, then 80s may be to much for you. E85 will require about 30% more fuel FWIW.

[jv7]

The tune itself is fine car runs great just dumps too much fuel at idle. Tuning can't fix hardware, the 80s don't like to run below 2ms pulsewidth, and you end up running slightly less PW than that at idle with a little 4.6, with a 5.4 you have to do all the tricks to get load up at idle and get the PW up above 2. When you are below 2ms the injectors just dump fuel and you run 11:1.

[TKat13]

Originally Posted by jv7

The tune itself is fine car runs great just dumps too much fuel at idle. Tuning can't fix hardware, the 80s don't like to run below 2ms pulsewidth, and you end up running slightly less PW than that at idle with a little 4.6, with a 5.4 you have to do all the tricks to get load up at idle and get the PW up above 2. When you are below 2ms the injectors just dump fuel and you run 11:1.

while your information may be dead perfect for your setup; today I wanted to verify and ran my mach to temp, idling the entire time. Mine at idle is 14.7 to 15.0 as it does move around a bit. Never seen a wide band not move around. Although you seem to have issues idling with 80s and running way rich at 11:1, I do not have this issue at all, which was my point in that 80s could run just fine and it is not a mechanical issue, unless I have some magical injectors, which I am sure I do not.

I am running 11:1 compression, stroker (5.0) and aggressive cams for my turbo setup and ported heads. While all this may make you say my setup allows it, I also have a buddy that has the same injectors on a 2 valve with 8.5 compression with the same 76mm turbo. He does have cams and head work as well. But, at idle, he has the same results.

The only two things that are the same between our builds are: turbo, injectors and the tuner himself.

do what you want, I just 100% completely disagree with you, 80s work fine at idle.

[TKat13]

JV7, I personally would call Manny at HPP Racing and let him try to fix your problem. Even today, he tuned a 5.0 Coyote N/A with 80s, and it turned out great. 80s are fantastic injectors that so many discount because they are not properly adjusted, if your tuner says it cannot be done, then find a better tuner, even if it is not HPP. I hate it when people waste money because of bad advice.

Feel free to throw my advice in the trash, just trying to help.

[jv7]

Ok thanks for your input Ill definitely call Manny see what he says thats what we're here for its for advise I would never toss advise in the trash if I'll keep this updated again thanks for the help.