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Backfires and Loss of Power with WOT


MemeMachine
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Hey guys, 

Feel like I'm chasing my tail with this one and going insane.

According to data logger everything is fine, no knock wideband reads plenty rich.

When accelerating at WOT as soon as I build boost I get backfires and the car loses all power (only just increasing at rpms) usually happens from about 3k rpm. But if I accelerate slowly it'll build boost and feel totally fine. Only an issue at WOT and close to WOT.

Fueling and knock is fine, I have a set of ghetto knock ears and they sound fine too.

Any ideas on where to look, I'm honestly out of ideas here

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To me it sounds like your plug gap might be too big, you're running it too rich and you don't have enough timing in it.

Pull the plugs and gap them first. Next lean it out to where it should be. After that add timing to where it should be.

If you have those things incorrect at the same time, it is nearly guaranteed to miss.

If having it tuned properly doesn't work and the plug gaps correct, look at replacing the coils.

Edited by Puffwagon
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1 hour ago, Puffwagon said:

To me it sounds like your plug gap might be too big, you're running it too rich and you don't have enough timing in it.

Pull the plugs and gap them first. Next lean it out to where it should be. After that add timing to where it should be.

If you have those things incorrect at the same time, it is nearly guaranteed to miss.

If having it tuned properly doesn't work and the plug gaps correct, look at replacing the coils.

So the issue appears to be as a result as soon as load hits 1.0 its starts to hesitate? I have gapped the plugs and they are new as well as the coils but I will reinvestigate.

I feel like as the 1.0 load is such a hard barrier maybe it's a tune issue?

20220925_115102.jpg

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1 hour ago, Puffwagon said:

To me it sounds like your plug gap might be too big, you're running it too rich and you don't have enough timing in it.

Pull the plugs and gap them first. Next lean it out to where it should be. After that add timing to where it should be.

If you have those things incorrect at the same time, it is nearly guaranteed to miss.

If having it tuned properly doesn't work and the plug gaps correct, look at replacing the coils.

So the issue appears to be as a result as soon as load hits 1.0 its starts to hesitate? I have gapped the plugs and they are new as well as the coils but I will reinvestigate.

I feel like as the 1.0 load is such a hard barrier maybe it's a tune issue?

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14 minutes ago, Puffwagon said:

If you post the tune and logs along with some info about the car and mods, that'll give us a good starting place.

Ah yeah good point, heres a full rundown:

BA NA+T BTR 4SPD

Greentop Barra

4bar reg, turbo map sensor, highmount manifold with pulsar 3584

Bosch 980cc injectors (0280158040)

New Spark Plugs and coilpacks (plugs gapped to 0.06 inches)

 

Upon further data logging it feels like as soon as it builds boost it hits a wall at 1.0 load, so maybe its less of a throttle issue and maybe more of a freaking out under boost issue? But there have been times where I've ran it and its boosted up to 12psi pretty much fine? Although it working correctly is a rare occurrence. 

250922 BA Tune.tec 25-09-2022 12-20-10 PM Log.teclog

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I had a quick look at the tune and log. A couple of issues with the log, it has no rpm reference and the cam timing appears not to be working. I would look into the cam timing first, the phasers (cam gear) shit themselves and show up in the log as not working. They don't necessarily make it miss but it does feel like hitting a wall, and in any case it should be working.

For future logs run the car up as described below.

To get a better idea of what it's doing, simulate a dyno run and it will show us what happens at WOT through the whole rev range. This means go WOT at 1500rpm and keep it there until redline, or in your case until it starts misfiring. Don't keep your foot flat when it's misfiring or you risk hurting the engine. You can do it in first or second gear so you don't go too fast. Be safe when doing this, if you can't do it safely get to a dyno where the environment can be controlled.

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1 minute ago, Puffwagon said:

I had a quick look at the tune and log. A couple of issues with the log, it has no rpm reference and the cam timing appears not to be working. I would look into the cam timing first, the phasers (cam gear) shit themselves and show up in the log as not working. They don't necessarily make it miss but it does feel like hitting a wall, and in any case it should be working.

For future logs run the car up as described below.

To get a better idea of what it's doing, simulate a dyno run and it will show us what happens at WOT through the whole rev range. This means go WOT at 1500rpm and keep it there until redline, or in your case until it starts misfiring. Don't keep your foot flat when it's misfiring or you risk hurting the engine. You can do it in first or second gear so you don't go too fast. Be safe when doing this, if you can't do it safely get to a dyno where the environment can be controlled.

I have a feeling you could be onto something there with the cam timing, I was reading somewhere about some guy with a focus who had a similar issue and it was the result of something cam related. A better way to describe it would definitely be hitting a wall (over a misfire). I'll look into that and sort my log and give it another run (maybe once double demerits are over lol)

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32 minutes ago, Puffwagon said:

I had a quick look at the tune and log. A couple of issues with the log, it has no rpm reference and the cam timing appears not to be working. I would look into the cam timing first, the phasers (cam gear) shit themselves and show up in the log as not working. They don't necessarily make it miss but it does feel like hitting a wall, and in any case it should be working.

For future logs run the car up as described below.

To get a better idea of what it's doing, simulate a dyno run and it will show us what happens at WOT through the whole rev range. This means go WOT at 1500rpm and keep it there until redline, or in your case until it starts misfiring. Don't keep your foot flat when it's misfiring or you risk hurting the engine. You can do it in first or second gear so you don't go too fast. Be safe when doing this, if you can't do it safely get to a dyno where the environment can be controlled.

I pulled the coil cover off and sure enough one of the phasers wasn't plugged in. Unfortunately went for a run and it wasn't any better, I didn't datalog but I will next time. So must be some other issue...

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Something I saw in the tune, you've got more timing where it comes on boost than after peak torque. This is back to front. You want less timing where the boost hits and gradually increase it out the back. You'll usually get 2 to 3 more degrees of timing by the end of a pull when you're on 98 octane fuel. You can verify what the timing is doing when you get a decent run in and logged.

Perhaps the wall you are feeling is it coming on strong, then falling over due to the timing being too low. If you do increase it, be safe and make sure it isn't knocking.

Another thing to think about is valve springs. If they are soft then it won't be happy after about 10 to 12psi. You can try doing a run with gate pressure to see if it helps. It'll give you an indication about the condition of the springs.

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19 hours ago, Puffwagon said:

Something I saw in the tune, you've got more timing where it comes on boost than after peak torque. This is back to front. You want less timing where the boost hits and gradually increase it out the back. You'll usually get 2 to 3 more degrees of timing by the end of a pull when you're on 98 octane fuel. You can verify what the timing is doing when you get a decent run in and logged.

Perhaps the wall you are feeling is it coming on strong, then falling over due to the timing being too low. If you do increase it, be safe and make sure it isn't knocking.

Another thing to think about is valve springs. If they are soft then it won't be happy after about 10 to 12psi. You can try doing a run with gate pressure to see if it helps. It'll give you an indication about the condition of the springs.

Alright cheers I'll give that a run. I've ran plenty of different timings so I'm not sure if thats the issue, but could certainly contribute. (I've ran a couple timing maps from other Na+T that are verified to work correctly).

Is it possible I'm having some kind of MAP Sensor issue? I got mine from TI performance (non genuine, I know im a dickhead of that), but could there be some kind of issue there with it wigging out under boost pressure?

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You'll see it in the log if it's not working properly. Another reason to get out there and get a log from low rpm/boost up to high rpm/boost.

You did mention a total loss of power and a miss in your first post. Apart from tune related issues, this is a symptom of bad valve springs.

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Do a DTC read with Forscan and let us know what it comes up with. 

Also does it go super lean and peg at 1.05 load? Some NA cals won't read over 1.05 load until air anticipation logic is adjusted. There is a thread on this. 

You'll see the car go super lean on boost if this is your issue though. 

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1 hour ago, Roland@pcmtec said:

Do a DTC read with Forscan and let us know what it comes up with. 

Also does it go super lean and peg at 1.05 load? Some NA cals won't read over 1.05 load until air anticipation logic is adjusted. There is a thread on this. 

You'll see the car go super lean on boost if this is your issue though. 

Yeah will do. 

Nah if it makes it past 1.0 load it'll be plenty fine, rich if anything.

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  • 2 weeks later...
On 9/28/2022 at 5:56 PM, Puffwagon said:

It does have 0's in the desired boost map. Up it to a couple of psi more than you want to run and leave it there.

I could be wrong but given that I'm running off gate pressure with an Na+t it won't be effected by this?

Unfortunately I've been away for the last two weeks but should be back next week so will do a good data logging session then.

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Just now, MemeMachine said:

I could be wrong but given that I'm running off gate pressure with an Na+t it won't be effected by this?

Unfortunately I've been away for the last two weeks but should be back next week so will do a good data logging session then.

it does not just control the boost controller hysterics, it controls the boost cut and and tq retard if you go (something like 2.8psi above)

 

so, add in some numbers. 

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5 minutes ago, Puffwagon said:

For anyone that hasn't looked at the log, it has cam timing that doesn't move, torque source is constantly driver demand and the most amount of boost it saw was only 1psi.

Yeah I really need to go do a proper datalog run as you said.

Ill give it a try changing the desired boost, but I have heard other na+ts have ran fine with it zero'd out.

But I did have a brief run after plugging in the passenger side cam phaser properly and still had the issue. That being said there could still be something not working there.

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2 minutes ago, Puffwagon said:

It's not hitting boost cut otherwise you'd see the torque source change.

Make sure rpm, cam error and boost pressure are logged so we can get a better idea of what's happening.

Ahhh ok.

And yeah cheers, I'll make sure to get that in there

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  • 2 weeks later...
On 10/10/2022 at 1:51 PM, Puffwagon said:

It's not hitting boost cut otherwise you'd see the torque source change.

Make sure rpm, cam error and boost pressure are logged so we can get a better idea of what's happening.

Hey mate, 

Too my time but got around to logging it this arvo.

Tried my best to log a 1st gear 100% throttle pull. Didnt take long to start acting up...

Hope I logged the right sources, let me know if I did anything wrong lol

Appreciate your help massively!

1st gear Pull.teclog

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Nothing really sticks out, although it looks like your alternator is stuffed and possibly the battery will be too. You can see the battery voltage drop from 13.07V down to 11.25V across the range of the log.

Look into this, rectify it, then continue with the diagnosing.

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10 minutes ago, Puffwagon said:

Nothing really sticks out, although it looks like your alternator is stuffed and possibly the battery will be too. You can see the battery voltage drop from 13.07V down to 11.25V across the range of the log.

Look into this, rectify it, then continue with the diagnosing.

This could be as a result of a completely dead battery. I left my tactrix in the obd2 port and then had the car only running for about 5-10 minutes before this was logged.

I'll trickle charge the battery and relog. Any other ideas or avenues to look into? Open to any and all things

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It should read whatever the alternator is putting out. With a flat battery you should see over 14V and a charged battery you'll see over 13.5V most of the time. Yours went from a high voltage to a low voltage which tells us that the alternator is likely stuffed. You can check if the alternator is charging with a multimeter by touching the positive terminal on the back of the alternator and the negative to earth.

By all means recharge the battery, it needs it, but I would still look into the alternator. Once the battery is charged, it should hold 13.4V minimum no load to be satisfactory. This will need to be checked with a multimeter across the battery terminals with the negative terminal disconnected. You can also head to a workshop and get them to chuck a battery tester on it. It'll cost frig all and will give you an indication of the condition of the battery.

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4 minutes ago, Puffwagon said:

It should read whatever the alternator is putting out. With a flat battery you should see over 14V and a charged battery you'll see over 13.5V most of the time. Yours went from a high voltage to a low voltage which tells us that the alternator is likely stuffed. You can check if the alternator is charging with a multimeter by touching the positive terminal on the back of the alternator and the negative to earth.

By all means recharge the battery, it needs it, but I would still look into the alternator. Once the battery is charged, it should hold 13.4V minimum no load to be satisfactory. This will need to be checked with a multimeter across the battery terminals with the negative terminal disconnected. You can also head to a workshop and get them to chuck a battery tester on it. It'll cost frig all and will give you an indication of the condition of the battery.

Ah ok alright cheers, i think I have a spare alternator anyway. I'll give it a trickle charge and then look into the alternator properly

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14 hours ago, Puffwagon said:

It should read whatever the alternator is putting out. With a flat battery you should see over 14V and a charged battery you'll see over 13.5V most of the time. Yours went from a high voltage to a low voltage which tells us that the alternator is likely stuffed. You can check if the alternator is charging with a multimeter by touching the positive terminal on the back of the alternator and the negative to earth.

By all means recharge the battery, it needs it, but I would still look into the alternator. Once the battery is charged, it should hold 13.4V minimum no load to be satisfactory. This will need to be checked with a multimeter across the battery terminals with the negative terminal disconnected. You can also head to a workshop and get them to chuck a battery tester on it. It'll cost frig all and will give you an indication of the condition of the battery.

Got a chance to check over the car. Alternator connection was a bit lose, seemed to sort out the voltage. Car is a little better, maybe? Still playing up though, heres another datalog. Not sure if theres anything of use in there.

Once again, super grateful for your help

Rerun.teclog

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14 hours ago, Puffwagon said:

It should read whatever the alternator is putting out. With a flat battery you should see over 14V and a charged battery you'll see over 13.5V most of the time. Yours went from a high voltage to a low voltage which tells us that the alternator is likely stuffed. You can check if the alternator is charging with a multimeter by touching the positive terminal on the back of the alternator and the negative to earth.

By all means recharge the battery, it needs it, but I would still look into the alternator. Once the battery is charged, it should hold 13.4V minimum no load to be satisfactory. This will need to be checked with a multimeter across the battery terminals with the negative terminal disconnected. You can also head to a workshop and get them to chuck a battery tester on it. It'll cost frig all and will give you an indication of the condition of the battery.

On the topic of cam timing potentially being the issue, I did notice VCT source switches to part throttle mode when the issue occurs. Any chance that could be where my issue lies? Or is that just a high load related thing?

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It's saying your commanded lambda is 0.95 to 0.97 at 3600rpm in most of the rpm spikes in the log. If this is your actual afr then it will have issues running that lean with boost added. Anything leaner than about 0.94 lambda on boost will make it misfire and fall on it's face.

You might just need to add some fuel to it.

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16 minutes ago, Puffwagon said:

It's saying your commanded lambda is 0.95 to 0.97 at 3600rpm in most of the rpm spikes in the log. If this is your actual afr then it will have issues running that lean with boost added. Anything leaner than about 0.94 lambda on boost will make it misfire and fall on it's face.

You might just need to add some fuel to it.

I cant believe I didnt notice that. My base fuel is set far lower than that. I presmume theres a table leaning it out a bit?

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whats is auF0359, fuel test? and why do you have it at 179/ stock 50.

 

your fuel base cold needs to be richer, you have a few lean spots....its leaner than stock.

it should not be affecting ur last log. but i would change it. the last two load lines should really match your desired fuel table. you have 0.88 at 1 load, it should be around 0.81. the second last table 0.6 load should be around .88-.9

Edited by BeerTurbo
cant spell to save my life.
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2 minutes ago, BeerTurbo said:

whats is auF0359, fuel test? and why do you have it at 179/ stock 50.

 

your fuel base cold needs to be richer, you have a few lean spots....its leaner than stock.

it should not be affecting ur last log. but i would change it. the last two load lines should really match your desired fuel table. you have 0.88 at 1 load. prob should be 0.82 or so and 0.8 in the mid/high 8's.

 

Honestly, not sure why I've got it like that. 

I'll reconfigure the fuel base cold now. 

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On 10/22/2022 at 9:50 AM, Puffwagon said:

I've compared a lot of other files and can't see anything in the usual areas. Doesn't mean I didn't miss something though.

Here is a BA turbo auto file for you to compare and change stuff if you need to.

HAANFH4 BA Turbo Auto.tec 612.38 kB · 1 download

I'll give it a go this weekend cheers for all your help once again

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