Issue Adding Stiffer Spring in the Wastegate

[hsvturbo]

I'm thinking with misfire, the volume of unburnt combustion air would pass thru the engine into the exhaust, thus the AFR would go lean, lots of oxygen.

[Doesnt Matter]

I'm thinking with misfire, the volume of unburnt combustion air would pass thru the engine into the exhaust, thus the AFR would go lean, lots of oxygen.

Great point and definitely makes sense. Hopefully it's just the coils failing and not a lean condition!

[NOTORIOUS VR]

The first video looks like you're going into boost and then your clutch slips and you hit your rev limiter...

2nd video shows that it goes extremely lean 20:1 AFR which would co-inside with the stock REV limiter (fuel-cut) being active.

I didn't see any hiccup at all while building boost...

I think you just need a new clutch.

[dburt86]

could this be a VSS isue? is your ABS light on? I keep hearing people hitting a 5500ish limiter when they have ABS/VSS issues.

I dont have those problems because i drive a dinosaur lmao.

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The first video looks like you're going into boost and then your clutch slips and you hit your rev limiter...

2nd video shows that it goes extremely lean 20:1 AFR which would co-inside with the stock REV limiter (fuel-cut) being active.

I didn't see any hiccup at all while building boost...

I think you just need a new clutch.

Thats a good thought

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I'm thinking with misfire, the volume of unburnt combustion air would pass thru the engine into the exhaust, thus the AFR would go lean, lots of oxygen.

Everytime ive had an ignition break up, it shows lean

[Doesnt Matter]

The first video looks like you're going into boost and then your clutch slips and you hit your rev limiter...

2nd video shows that it goes extremely lean 20:1 AFR which would co-inside with the stock REV limiter (fuel-cut) being active.

I didn't see any hiccup at all while building boost...

I think you just need a new clutch.

My rev limiter is 7200, so I still have a ways to rev out when this happens. Definitely a good thought.

[NOTORIOUS VR]

Can you make a video of a longer pull in a higher gear?

Does it always react the same way (around 6200)?

You started in a gear that was too high RPM wise IMO... An ignition issue should show up under high loads every time, so if you start a pull in 4th at 3500 RPM by the time you reach higher loads around 4500-5 you should already be experiencing spark issues if there is one.

[hsvturbo]

My main concern with this whole issue is what if this isn't missfire and you are in fact going lean.

What plug are you running? Buy some 4554's gap them to the .015" and maake a pull. I really have a hard time believing your are seeing misfire at a gap of .015 with what, 6 more psi? What was your original gap at 12psi?

[Doesnt Matter]

Can you make a video of a longer pull in a higher gear?

Does it always react the same way (around 6200)?

You started in a gear that was too high RPM wise IMO... An ignition issue should show up under high loads every time, so if you start a pull in 4th at 3500 RPM by the time you reach higher loads around 4500-5 you should already be experiencing spark issues if there is one.

It always reacts the same way and is completely related to the boost pressure (i.e when the wastegate opens). I only did a pull that high RPM so that it wouldn't be super laggy and take forever to spool haha, but i can do a 3k pull in 4th and video it. If i floored it at 2k, it would spool till the same RPM then start to occur

My main concern with this whole issue is what if this isn't missfire and you are in fact going lean.

What plug are you running? Buy some 4554's gap them to the .015" and maake a pull. I really have a hard time believing your are seeing misfire at a gap of .015 with what, 6 more psi? What was your original gap at 12psi?

I installed 4554's the day I upped the boost as the old plugs were misfiring with the increase. The old ones were gapped to 0.024" and were 5k old, so I swapped in new ones. These plugs are only a day or so old, originally gapped to 0.020" then i dropped them to 0.015 yesterday.

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I also checked this morning on E36Haters comment around the free revving. I can rev to redline at idle and if i stay out of full boost it will go to redline flawlessly.

[litemup]

Coils, and make sure each coil has ample grounding

[Doesnt Matter]

Switched back to the single spring and she pulls like a dream. Zero hesitation...mid 11s all the way to redline. In a few days I'll have some OBDII coils to try and I'll up it again to see. Pretty convinced it's spark plug blow out.

[dburt86]

well thats good

could you be reaching the duty cycle limit of your injectors on the higher boost

[Matutino]

Switched back to the single spring and she pulls like a dream. Zero hesitation...mid 11s all the way to redline. In a few days I'll have some OBDII coils to try and I'll up it again to see. Pretty convinced it's spark plug blow out.

Told ya

[Doesnt Matter]

Upped the boost by adding the second spring again and switched to OBDII Ignition coils and the symptoms are exactly the same... So frustrating!

So far I've tried:

1. Gapping new plugs to 0.015" - no change
2. Changing to new ignition coils - no change
3. Pressure testing to 20psi - no leaks
4. Checking fuel pressure - follows boost, idle fuel is perfect
5. Checking wastegate installation - no pinching of diaphragm
6. Going external dump - no change
7. Switching back to 10psi and a single spring - car runs flawlessly

I'm going to brainstorm some other ideas. If you have any input I would love to hear it!

[hsvturbo]

That one video reminds me of when my vacuum/boost signal came of my fuel reg at the drags and I went lean and blew the HG. Snap crackle pop. You better pray it's miss fire and not a lean condition.

If your running .015 gap and still misfiring, I would talk with your tuner and see about advanceing some timing up top.

Did you ask about timing?

[Doesnt Matter]

Did you ask about timing?

I have not as of yet. Do you mean to add a factor of safety if it's a lean condition or as a cure for the symptoms?

[hsvturbo]

Most everyone has indicated your having miss fire at these higher boost levels. If in fact this is true, then ask your tuner to double check the timing at these boost levels. Your running e85. E85 burns slower then pump gas, so a person can run more timing. Advancing the timing helps eliminate miss fire because the spark plug fires earlier in the compression cycle of the engine.

The reason the plug miss fires at a higher boost level is because of the increased pressure in the combustion chamber. so your case in point, 12 psi, your running golden. You up the boost, now your miss firing because you have more air in the same volume thus a high pressure when the plug fires, or tries. Your tune could be retarding the timing more at 18psi then at 12.

I'm rambling with disjointed sentences....

Anyway, this is were I would look next. As long as your certain you are not having detonation and or a lack of fuel.

When I went lean with e85, my engine didn't buck, it kept pulling but sounded like snap crackle and pop in my e30.

[Doesnt Matter]

Most everyone has indicated your having miss fire at these higher boost levels. If in fact this is true, then ask your tuner to double check the timing at these boost levels. Your running e85. E85 burns slower then pump gas, so a person can run more timing. Advancing the timing helps eliminate miss fire because the spark plug fires earlier in the compression cycle of the engine.

The reason the plug miss fires at a higher boost level is because of the increased pressure in the combustion chamber. so your case in point, 12 psi, your running golden. You up the boost, now your miss firing because you have more air in the same volume thus a high pressure when the plug fires, or tries. Your tune could be retarding the timing more at 18psi then at 12.

I'm rambling with disjointed sentences....

Anyway, this is were I would look next. As long as your certain you are not having detonation and or a lack of fuel.

When I went lean with e85, my engine didn't buck, it kept pulling but sounded like snap crackle and pop in my e30.

Thanks for the input my man! I'll talk with Jordan and see what we can do.

[crazyyardie]

Did thks get resolved. Sounds familiar since I upped my wastegate spring cant pass 10 psi with car coming to a halt at 4k exactly

[Nutzy]

It sounds so much like compressor surge, but you're hardly the first to blaze the trail on a 2.5 with an S366. Or so I would have thought.

I've seen some odd effects from surge under boost. https://www.youtube.com/watch?v=nCj6Spwl1CU

A friend demonstrated twin T28BB's on a Nissan V8 surging against each other at idle! A very light chuffing sound that alternated from side to side.

Ages ago when I first went turbo I thought I had a boost misfire. It just turned out to be I had the ECU set to cut ignition at 160kp.

The fact that despite the coil and plug changes you are still looking at an identical issue would tend to steer me away from ignition. But what are your dwell settings? How much faith do you have in your wiring loom when the engine torques over and moves things? How about good solid grounds? Is there any noise in the data logs from TPS CLT or MAP? Are you hoses running to the MAP and fuel reg solid with no splits?

[dburt86]

It sounds so much like compressor surge, but you're hardly the first to blaze the trail on a 2.5 with an S366. Or so I would have thought.

I've seen some odd effects from surge under boost. https://www.youtube.com/watch?v=nCj6Spwl1CU

A friend demonstrated twin T28BB's on a Nissan V8 surging against each other at idle! A very light chuffing sound that alternated from side to side.

Ages ago when I first went turbo I thought I had a boost misfire. It just turned out to be I had the ECU set to cut ignition at 160kp.

The fact that despite the coil and plug changes you are still looking at an identical issue would tend to steer me away from ignition. But what are your dwell settings? How much faith do you have in your wiring loom when the engine torques over and moves things? How about good solid grounds? Is there any noise in the data logs from TPS CLT or MAP? Are you hoses running to the MAP and fuel reg solid with no splits?

He is on a stock DME still

[Doesnt Matter]

Did thks get resolved. Sounds familiar since I upped my wastegate spring cant pass 10 psi with car coming to a halt at 4k exactly

No resolution sadly. I put the car away for winter a few months ago and it was still doing it right up to that day. When I went external dump, it would boost up to 13psi no issues. This winter it's going to an electronic boost setup and we'll see what happens.

[torbj796]

Hi I'm new around here. I seem to have the exact same problem.
I run a cheap turbo build. E36 320i m50b20tu, T3/T4 china turbo.
I can run low boost all day without this issue. Going for 1 bar or above 0.9 gives me fuel-cut type symptome.

I tried everything from rich/leaner AFRs around 10.9-13.0. I tried retarding and advancing ignition timing. Nothing helps.

I ran a few pulls without the MAF connected (I run a 3.5" 540i ebay copy MAF) and it ran flawless on boost. No hesitations or "fuel-cuts". I'm tuning myself and just flash the eeprom everytime I change something. It's annoying to take appart the ECU, remove chip and burn everytime but works for me.
Plugs gapped to 0.5mm didn't change nothing.

Should I look over my grounds or is it a waste of time?
Maybe I'll experiment with trying to put together a Alpha-N Tune.
I managed to clear inspection/smog or whatever you call it here in Sweden by running no MAF, E85 and tuned just with my wideband. No lambdas connected.
It brought a smile to my face.

Oh and I run 650cc injectors and a aftermarket fuelpump that should work up to 400hp on E85. I'm not near that powerlevel yet. So fuel shouldn't be the problem.

[Doesnt Matter]

Update: I managed to snag an eboost2 to control the boost vs. nested wastegate springs and the boost problem has been resolved. I can boost to any setting and it pulls great. If anyone can theorize why this would help, I would love to hear!

The solution could be related to a new battery also, as that has been changed as preventative maintenance since I had this problem. Hopefully this helps with anyone who has a similar problem!