ECMlink Bucking in 3rd Gear High RPM

[kyler021]

Hey all,
I'm having an issue with my car bucking/surging in 3rd gear during a pull. For context, I just got tuned by McKenzie Lange of LangeTuned. We finished up the tune around the beginning of October. I'm on SD, have Evo 560cc injectors, Walbro 255, 16g turbo, and FMIC. I believe my build profile is current, so you may see more info there.

We had an email convo before the last tune he sent me, and it seemed to me that the car would overboost (~27 psi). He turned down the wastegate duty cycle, and that fixed it. After the duty cycle was turned down, I think I remember the boost starting around 20psi and ramping up to 23psi near redline.

When I look at the boost gauge when doing a pull, I see it goes up to ~25 psi and possibly higher when it starts jerking and bucking. I did notice that it went full lean when it occurred.

I have changed a couple of things since the final tune. One, I put an STM SD Intake on. And two, not by choice, but my AEM FAE Wideband that goes along with my X-Series Wideband failed AGAIN. So I threw my old Bosch Wideband in there. I'm gonna be honest, I didn't change the wideband scaling in ECMLink when I switched the wideband sensor. So that is not great. But I noticed it was pretty close to the expected AFRs.

My initial thoughts are:
The STM intake kinda pinches one of the MAC wastegate solenoid lines. Not really pinches to where nothing can get through but it does contact the vacuum line and not by a small amount.
Omni MAP Sensor (Again)
Boost Creep?

I added 2 logs. One from today, 10/28 (normal) and one from yesterday morning (10/27) where I could actually catch the jerking. The only reason I haven't emailed my tuner yet is because it's intermittent. Some days it's normal, and some days it's not. Today, it did it one time, then the rest of the time it didn't do it (couldn't catch it in the log).

Any ideas guys? Thanks!

 

[diambo4life]

What is your ignition setup? Which plugs? What gap?

 

[kyler021]

What is your ignition setup? Which plugs? What gap?

Stock coils, NGK plug wires, NGK BPR7ES, Plug gap is .025"

 

[Stapl3]

Tighten the plug gap.

 

[nice97civic]

Something happened at 384.560sec where your throttle is 99% but your fuel flow and injector duty are both zero. Immediately before and immediately after that point the injector comes back on. I suspect that's when you're feeling the bucking since fuel is being completely shut off.

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[kyler021]

Tighten the plug gap.

I will do that. What should I set it to, maybe like 0.022"?

Something happened at 384.560sec where your throttle is 99% but your fuel flow and injector duty are both zero. Immediately before and immediately after that point the injector comes back on. I suspect that's when you're feeling the bucking since fuel is being completely shut off.

Good catch... I didn't notice that. Does ECMLink do the fuel flow calculation? I don't recall there being a sensor for that. So something is causing all 4 injectors to cut off... Something to do with the resistor pack, maybe?

Or could it be a safety within the tune? I remember it feeling exactly like that when I overboosted during the tuning stages. I should probably email him then... I'm just not sure why it's an intermittent thing. I feel like if the tune was the issue, why does it sometimes let me pull no problem, and other times it doesn't.

 

[Stapl3]

I've gone down to .016. It's a tradeoff. You want the biggest gap possible, yet tight enough for it not to blow out during wot.

 

[nice97civic]

I will do that. What should I set it to, maybe like 0.022"?


Good catch... I didn't notice that. Does ECMLink do the fuel flow calculation? I don't recall there being a sensor for that. So something is causing all 4 injectors to cut off... Something to do with the resistor pack, maybe?

Or could it be a safety within the tune? I remember it feeling exactly like that when I overboosted during the tuning stages. I should probably email him then... I'm just not sure why it's an intermittent thing. I feel like if the tune was the issue, why does it sometimes let me pull no problem, and other times it doesn't.

ECMLink is doing it yea. Your boost at that point got to a pretty high level so it might be a fuel cut based on boost level but I don't recall you running out of injector duty. I think you were still under 80% duty there.

Edit, looks like this might have something to do with it. Your BoostEst was well over 25psi and your load factor was right at 3.00. Try changing this value or reducing the WGSDuty for your electronic boost control by a little bit to see if it goes away.

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[diambo4life]

Nice find. That is definitely it. I would also change to a non projector plug and gap it down as stated above.

 

[SixBolt_16G]

Nice find. That is definitely it. I would also change to a non projector plug and gap it down as stated above.

@diambo4life What would be the benefit of him switching to a non projector plug? Not debating, just asking for educational purposes.

 

[diambo4life]

@diambo4life What would be the benefit of him switching to a non projector plug? Not debating, just asking for educational purposes.

They are just better for boosted applications, especially us DSM guys who run lots of boost, less chances for misfires and detonation.

 

[1990TSIAWDTALON]

Less chance of blowing out spark and to keep the plug cooler since it isn't sticking out and into the combustion chamber. I run BR6ES at .018" on my Holset Turbo motors and it works great to 9k+ and 35+lbs psi.

 

[kyler021]

Edit, looks like this might have something to do with it. Your BoostEst was well over 25psi and your load factor was right at 3.00. Try changing this value or reducing the WGSDuty for your electronic boost control by a little bit to see if it goes away.

So then, I guess my question is: What are some causes of it overboosting sometimes? It kinda just came about one day at random, and I'm not so sure what I should look at. I have no problem turning down the WGS duty cycle; I'm all for reliability over power. Just want to see if something is mechanically wrong here.

They are just better for boosted applications, especially us DSM guys who run lots of boost, less chances for misfires and detonation.

I will get those changed out! My tuner also said BR7ES, and for some reason I did BPR7ES. Bit of an oversight there I guess.

 

[nice97civic]

It's likely the combination of the electronic boost control and the wastegate itself. Assuming you're using the stock internal wastegate. Another thing to try would be to switch to a manual boost controller to see if you have better luck with that. Regardless if you're targeting 25psi and have boost cut set for as soon as it goes past there, you're going to run into this issue all the time.