Misfire after cold start

[BoostedNate]

My codes are gone. My AP usually reads 0 misfires now when I start it. It looks like the codes were being falsely read by the canned tune's oversensitive misfire settings. Thanks to Ryan of PD Tuning for figuring this out. I'm looking forward to continuing to refine and tune the car.
Please note to anyone that comes across this: If you get these codes after tuning the car, don't listen to Cobb if they tell you that you need to clean your valves. I have yet to talk someone that actually had any codes thrown by dirty valves on these cars. If you're questioning it, have someone run a relative compression test on the engine.
Second note: If you find someone that will do a proper valve cleaning service affordably please let me know.
I'm still a little concerned about how my idle will sometimes drop to 500 RPM with the AC on full blast. But I'm going to attribute this to the leaky evap core. I've been refilling it with refrigerant for some time now to avoid replacing it ($1,000 cost)...

I'm still debating if I want to keep my MAPerformance CAI or go back to stock. This is from witnessing the IAT temps climb quickly during idle or stop and go. My charge temps usually fluctuate around 100 -110 F, with ambient air being about 90F, the IAT will average about 15F above ambient. Sometimes charge temps will occasionally read lower than ambient if the CAI has been heat soaking. This is in Clearwater, FL where it's hell right now

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[Heggs550]

Correct me if I'm wrong, but it looks like you're saying the AP was sensing misfires that weren't actually happening? Aka there actually wasn't an issue with the Cobb tune after all?

I hope you're right in your case about the rpm drop. Unfortunately, mine did it before and after the ac evap was replaced :/

 

[BoostedNate]

Correct me if I'm wrong, but it looks like you're saying the AP was sensing misfires that weren't actually happening? Aka there actually wasn't an issue with the Cobb tune after all?

I hope you're right in your case about the rpm drop. Unfortunately, mine did it before and after the ac evap was replaced :/

Correct. The idle misfire sensitivity was too high and was reading false misfires. Especially on cold start, I’d sometimes see the AP read 30+ misfires as soon as the car cranked. Per my previous post a Ford mechanic determined the car wasn’t misfiring. This is why I didn’t get any codes with the stock tune.

I’m hoping Ryan might be able to resolve the idle RPM drop with AC on full blast. Now that I know it’s not the engine I’m less concerned about it. But I am somewhat worried my compressor could be going bad because of the evap leak and having to work so hard. I’ve also observed a minor RPM drop with AC off occasionally but I’ve been told it’s probably the evap purge valve doing it’s thing.

 

[Heggs550]

Ok got it now. I didn't think/realize the misfire sensitivity would be changed in a tune, makes sense now. Although not ideal, it's reassuring that there wasn't a problem with the actual tune.

 

[BoostedNate]

Ok got it now. I didn't think/realize the misfire sensitivity would be changed in a tune, makes sense now. Although not ideal, it's reassuring that there wasn't a problem with the actual tune.

Just made the switch to Ryan's E30 tune. Looking forward to seeing how much power it will make as he increases the timing/boost. The Cobb AP is estimating about 360 HP when I launch from 1st right now.

 

[BoostedNate]

So now I need to upgrade my BPV and/or search for a boost leak. Per Ryan:
“The bov looks like it’s leaking in this log. I commanded more on e30 and it comes up and then drops off big time. I would do a boost leak test and if you don’t find a leak I would upgrade the bov.”

 

[Heggs550]

Is the factory bov known to only hold so much boost? I would check for boost leaks elsewhere first since that's free rather than spending money to replace a part that may not be faulty.

 

[andyturbo2000]

Correct. The idle misfire sensitivity was too high and was reading false misfires. Especially on cold start, I’d sometimes see the AP read 30+ misfires as soon as the car cranked. Per my previous post a Ford mechanic determined the car wasn’t misfiring. This is why I didn’t get any codes with the stock tune.

I’m hoping Ryan might be able to resolve the idle RPM drop with AC on full blast. Now that I know it’s not the engine I’m less concerned about it. But I am somewhat worried my compressor could be going bad because of the evap leak and having to work so hard. I’ve also observed a minor RPM drop with AC off occasionally but I’ve been told it’s probably the evap purge valve doing it’s thing.

Isn’t it normal for RPMs to drop on most cars when the air con is engaged? It’s a load on the car after all.

 

[BoostedNate]

Isn’t it normal for RPMs to drop on most cars when the air con is engaged? It’s a load on the car after all.

Mine is dropping significantly more than it normally would. Drops to about 500 RPM and car shudders. Then it will eventually go back up close to 1k.

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