Unhealthy Idling/Backfiring

[antxzy]

Hi everyone,

I own a 2020 mustang gt. The only mods on it are TSP headers, exhaust, and 93/E85 tune.

I’ve been having somewhat of a consistent issue with fouling out spark plugs, along with rough idling and some crazy random backfires. My tuner can’t find anything wrong with the tune, and after scanning for codes, I only have a small ABS issue. After doing some research here, I’m seeing a few people who have similar symptoms on their 5.0 and can trace the issue to maybe a bad camshaft poison sensor or a bad evap purge valve. Not sure if that’s somewhere I should start looking to fix or not?

AFRs are usually okay, but sometimes the car dies at idle and I’ll notice for a split second the AFR is 10-11 (running rich I believe). After 4-5 months my spark plugs are fouled out and I have to get them replaced as well.

I honestly don’t know where to go from here to try and help these issues. Any advice would be helpful. I’ll try to answer any follow up questions as they come.

Thanks!

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[HKusp]

10-11 is rich but if it's just momentarily, it's not enough to foul spark plugs. The cars display of AFR isn't really the most accurate though, so there may be an issue with it being richer than you are seeing. If you send logs and your tuner can't find it, I think you may want to look at a different tuner. I should get a quarter for every time I say this but I would give Wengerd a call. I am not tuned by him, but as far a the big names go, I do not believe there is anyone better, and his customer support is top notch, to the point that I have seen him help people that aren't even customers of him and he does it in a timely manner.

 

[antxzy]

I take it I’ll need an ngauge or something then? Everytime I have an issue, I take it to my tuners shop and he just uses his computer. I’m local to Dallas. But I would definitely take help where I can with fixing this issue. Thank you!

 

[HKusp]

I don't believe Wengerd uses the nGauge. I know he uses HPTuners software and has recently started using PCMtec. Email him and see what he recommends and go from there. Update here when you can, please.

 

[Racin4ds]

I agree, I'd be looking for a new tuner... you have no radical mods so the tune should be very simple to nail down and you damn sure shouldn't be fouling plugs that often.

 

[antxzy]

I just loaded a new tune from Wengerd and it runs FANTASTIC. It doesn’t smell like fuel anymore in the exhaust and my idle is super steady. Way more responsive. Thank you so much for the recommendation. I’ll be putting E85 in it next fill up and try that tune as well.

 

[daSNAK3]

Wengerd coming in clutch yet again.

 

[HKusp]

I just loaded a new tune from Wengerd and it runs FANTASTIC. It doesn’t smell like fuel anymore in the exhaust and my idle is super steady. Way more responsive. Thank you so much for the recommendation. I’ll be putting E85 in it next fill up and try that tune as well.

Did he mention what the issue with the other tune was? I am glad he got you straight.

 

[antxzy]

Did he mention what the issue with the other tune was? I am glad he got you straight.

He said it was pulling timing, which explains my spark plugs. He said my previous tune was mainly fine, but with Wengerd, I’ve noticed no drop in idle and a lot more aggressive torque. He said it could have been bad fuel causing the car to pull timing. So I think I’m gonna try and stick to E85 as much as possible now. Need to buy an E85 testing kit too to make sure it’s as close to 85 as possible.

 

[skinnyb]

He said it was pulling timing, which explains my spark plugs. He said my previous tune was mainly fine, but with Wengerd, I’ve noticed no drop in idle and a lot more aggressive torque. He said it could have been bad fuel causing the car to pull timing. So I think I’m gonna try and stick to E85 as much as possible now. Need to buy an E85 testing kit too to make sure it’s as close to 85 as possible.

Wengerd for the Win . He is the MAN

 

[thelostotter]

If your car was fouling plugs with fuel then you should probably change your oil to get the fuel diluted oil out of there. Your old tune was WAY off.

 

[antxzy]

If your car was fouling plugs with fuel then you should probably change your oil to get the fuel diluted oil out of there. Your old tune was WAY off.

Oh shit, I didn't think about that. I wanna get new spark plugs too because I changed them maybe about 2 months ago and just got a new tune yesterday.

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