ECMlink WTH is going on? weird stutter / misfire under WOT pulls at high RPM

[crispyimmy]

I'm not sure exactly whats happening now but after some street tuning I'm having a weird stutter / misfire under WOT pulls at high RPM. It typically will cause a backfire and cause my RPM to stall/stagnate, usually a good puff of smoke out the exhaust.

Sharing the log to see if there's anything obvious here. The only thing I know of is maybe the low voltage (maybe alternator voltage regulator is going out ), but i don't know if that would cause this?

In this log I do a ~33% throttle position pull hitting 20psi boost and didn't have the issue but the 100% throttle pull had the issue after that.

I checked the plugs, tried br7es and br8es, gapped around 0.022. coils aren't super old but I haven't swapped them out yet. They work most of the time though, not sure if it could be blow out?

Running Ethanol. I do notice a drop from 75% to 70% during the pulls.

Anything i could be looking at?

FP Green turbo/manifold
4" FP intake
3.5" ETS intercooler & piping
Evo intake manifold
Fuelab AFPR
Tial 44mm wastegate
Walbro 450 e85 fuel pump re-wired
FIC 2150cc injectors high Z
Magnus fuel rail
Engine 7 bolt - 2.3L stroker
Mahle 9:1 coated pistons
Crower rods
Eagle crankshaft
Fluidamper
Evo beehive springs/retainers
GSC S2 cams

TIA

 

[We're on Boost]

I checked the plugs, tried br7es and br8es, gapped around 0.022. coils aren't super old but I haven't swapped them out yet. They work most of the time though, not sure if it could be blow out?

Could be. You could try less gap then that. Like 0.020" which doesn't sound much different, but maybe if you also switched to projected tip plugs (BPR instead of BR).
Anyway the stock ignition parts should be fine for boost in the high 20's as far as I know. It is on my 1990.

When English Racing built my engine they put in Iridium IX plugs (center electrode is iridium, side electrode is regular nickel) gapped very close, about 0.014". Later when I changed the plugs I bought the same plugs, NGK Iridium IX BPR7EIX (stock number 4055) and gapped them to 0.017" figuring that I'd never be running it over 30 psi of boost probably, and that's been fine. For that matter they were fine at 0.014". Lucas English told me that if I wanted to use the non-iridium type plugs to use BPR7ES gapped to 0.020".
With the iridium plugs you have to be careful not to push on the center electrode with any tool when you are gapping them. I don't find that to be hard at all, so I keep using the Iridium IX's.

Wires? What plug wires do you have?

I notice your AFR's are leaner than mine when you are on boost. Not much knock though.

On that 100% throttle pull, it looks like it's ok until the Omni 4-bar hits about 26 psi and then things get a little choppy.
Is that what you are seeing with it?

Your alternator voltage of ~13 volts (in the log) should be ok.

Car looks really nice!

 

[crispyimmy]

Could be. You could try less gap then that. Like 0.020" which doesn't sound much different, but maybe if you also switched to projected tip plugs (BPR instead of BR).
Anyway the stock ignition parts should be fine for boost in the high 20's as far as I know. It is on my 1990.

When English Racing built my engine they put in Iridium IX plugs (center electrode is iridium, side electrode is regular nickel) gapped very close, about 0.014". Later when I changed the plugs I bought the same plugs, NGK Iridium IX BPR7EIX (stock number 4055) and gapped them to 0.017" figuring that I'd never be running it over 30 psi of boost probably, and that's been fine. For that matter they were fine at 0.014". Lucas English told me that if I wanted to use the non-iridium type plugs to use BPR7ES gapped to 0.020".
With the iridium plugs you have to be careful not to push on the center electrode with any tool when you are gapping them. I don't find that to be hard at all, so I keep using the Iridium IX's.

Wires? What plug wires do you have?

I notice your AFR's are leaner than mine when you are on boost. Not much knock though.

On that 100% throttle pull, it looks like it's ok until the Omni 4-bar hits about 26 psi and then things get a little choppy.
Is that what you are seeing with it?

Your alternator voltage of ~13 volts (in the log) should be ok.

Car looks really nice!

Thanks for the response.
I have NGK spark plug wires. I just ordered a new set and will be testing them likely by Monday or Tues when they arrive.
i'm still dealing with AFR issues, but targetting 11.5-12 on E85. I have a weird issue where my AFRs don't stay consistent with tune. It will be on target 1 day and a bit lean the next. I really wish i can figure out the cause of that.

The issue first presented on my new BR7ES at 0.020". I was running 0.022 before on BR8ES and then on the BR7ES at 0.020" and have no issues until recently when this issue started, but i've seen people mention 0.018. There has been no changes so definitely seems like something is now worn out or not properly working (e.g. hopefully the coils for an easy fix). I don't think 0.018 should be necessary for an issue like this though. I previously ran 35psi on E85 @0.022" BR8ES.

when i review the log even I have trouble knowing exactly when the issue is happening, but you can see RPM stop climbing temporarily (dips) and then goes back up a moment - i usually let off the throttle by this time so that's when it starts. Around the 6k RPM is when the issue usually presents. Overall, it doesn't seem consistent as it didn't happen every pull but it does seem it may be getting worse as I keep testing doing pulls.

 

[We're on Boost]

Hmm, seems like you are doing the right things and have good parts, plug wires and so-forth. AFR of 11.5 should be good. Mine goes to a minimum of about 10.8 when the boost first goes past 30 psi at about 5,000 rpm. Then goes up from there to almost 12 at the higher revs. You can see that on the dyno chart on my Specs and Photos page. That was on E60.

I have a weird issue where my AFRs don't stay consistent with tune. It will be on target 1 day and a bit lean the next. I really wish i can figure out the cause of that.

Well, that brings to mind that the Omni 4-bar MAP sensor has been losing quite a few users in here. Usually it's because they completely quit though, so it's obvious. But maybe you have one that is just being inconsistent. Several people in the last few years have switched from the Omni to an AEM stainless, either the 3.5 or 5 bar.
When did you buy your Omni? From other comments I've seen, it seems like the Omni 4-bars were ok until about 2017 - 2018 or thereabouts. People who have bought them since then are usually the ones who've had problems with them.

 

[ist dwa]

You have no timing, start at about 11* across the board at full boost, that should help, you are at 6, that is way too low.

 

[crispyimmy]

Hmm, seems like you are doing the right things and have good parts, plug wires and so-forth. AFR of 11.5 should be good. Mine goes to a minimum of about 10.8 when the boost first goes past 30 psi at about 5,000 rpm. Then goes up from there to almost 12 at the higher revs. You can see that on the dyno chart on my Specs and Photos page. That was on E60.


Well, that brings to mind that the Omni 4-bar MAP sensor has been losing quite a few users in here. Usually it's because they completely quit though, so it's obvious. But maybe you have one that is just being inconsistent. Several people in the last few years have switched from the Omni to an AEM stainless, either the 3.5 or 5 bar.
When did you buy your Omni? From other comments I've seen, it seems like the Omni 4-bars were ok until about 2017 - 2018 or thereabouts. People who have bought them since then are usually the ones who've had problems with them.

the inconsistencies is the AFR. The MAP i've had issues with before (dying), replaced it, then had to clean the connections.. its been fine since. I've learned that the 5bar loses resolution. I picked one up for the next time it fails but id rather not lose resolution and cause some laggy responses I've read.

But yeah it could be this new issue is due to the omni 4 bar as well. I'll see after the new wires come in. I also just got a new leak today on the bottom of the intake manifold so that'll be a pain to fix.

 

[We're on Boost]

I've learned that the 5bar loses resolution. I picked one up for the next time it fails but id rather not lose resolution and cause some laggy responses I've read.

When I switched from the Omni 4-bar to an AEM 5-bar I was a little worried about the lower resolution I would get with it. But I haven't noticed any effect from it. Really I can't tell any difference in the way the car drives between the 2 sensors.

Our ECU with ECMLink can only distinguish voltage in increments of about 0.02 volts which is a little crude. With the 5-bar AEM that comes out to pressure increments of about 0.375 psi. But in the car at light load you are in closed loop anyway so it doesn't matter as much.

At higher loads when you are in open loop, that 0.375 psi increment becomes a smaller and smaller piece of the total pressure as boost goes up, so the problem kind of dwindles away to the point where I don't think it matters there either. At least I can't tell that it does. So I'm ok with it.

Sometimes the 2g guys mount their MAP sensor directly to the engine/intake manifold. That's probably not so good because of vibration and higher temps.
My Omni MAP was mounted to the body with some hose, about 2 feet which is not even that short. It never failed. I replaced it mostly as a precaution. The actual problem I had at that time was my Power Transistor, which would quit working after it got hot enough. My Omni was bought new in 2016.

I mounted my AEM MAP sensor on the body a few inches closer to the engine so still about 2 feet of hose. I have pics of that in my build thread.

I have the sensor angled so that any little moisture that gets into it will fall right back down the hose. That's more of an issue with the Omni's than with the AEM but still. I don't think Omni tells you that. Link sells a 4-bar MAP sensor (Link MAP4) and they do mention about mounting. Their sensor has that sort of rectangular package like the Omni.

Well that's a bunch of stuff about the MAP sensor and it's likely not even your problem. But one way or another I hope the problem will be found!

 

[92Turbski]

the inconsistencies is the AFR. The MAP i've had issues with before (dying), replaced it, then had to clean the connections.. its been fine since. I've learned that the 5bar loses resolution. I picked one up for the next time it fails but id rather not lose resolution and cause some laggy responses I've read.

But yeah it could be this new issue is due to the omni 4 bar as well. I'll see after the new wires come in. I also just got a new leak today on the bottom of the intake manifold so that'll be a pain to fix.

Hey, man. Did you ever figure out the source of your issue here?

I'm having inconsistency of phantom knock and into breakup starting as low as 3k rpm. Weird thing is, I can let off, hammer down and it'll pull clean right to redline. Very inconsistent. Professional tuning with Kevin Jewer is uncertain as well.

I've got a new coil coming and will gap the BR7ES from .020 down to .018. I read somewhere on here that Boosted Beaver gapped them way, down, something like .012 or so. Have to dig and find that...

 

[We're on Boost]

Well that's a bunch of stuff about the MAP sensor ...

Want to update this bunch of stuff a little bit, because I did change from the AEM 5 bar to an AEM 3.5 bar MAP sensor in June of 2025. The 5-bar was working fine. I only changed because I got thinking about the strange little spikes I was seeing in my AFRatioEst logs. My car will never see more than ~34 psi of boost, so the AEM 3.5 bar sensor is basically enough. I wanted to see if the 3.5 bar sensor would get rid of those spikes, and it did. I can't tell the difference driving the car though.

For the rest of the story, you can see posts 68 and 71 here.
Also just a few weeks ago I ran across a 2019 post by McKenzie Lang (perrytheplatypus157) where he says that a 5 bar can cause the spikes, and he discussed it a little with Marty in a different thread.
Again though, I can't tell the difference in how the car runs. If I had to go back to the 5 bar for some reason, I would not use smoothing to get rid of the spikes unless I could tell there was something really un-good about how the car was running.

The GM style 4-bar (like Omni) sensors were good for range and resolution (using the whole 5 volts for 4 bars of range) so it's too bad that they've apparently been less reliable lately. I see ECMtuning, on the page where they use to sell it, it's now "Product not found". And their SD bundle that used to include it, has been "Backordered" for a long time. I don't know what the story with that is, unless they just decided that they weren't reliable anymore. I haven't asked them about it.