Topic: High RPM (5100+ RPMS) WOT Hesitation!!!!!

[MattM]

So....As the title says......I'm still dealing with a high RPM hesitation above 5100rpms in third and fourth gear (prolly in 1st and 2nd but too quick to feel it).  I have the Trifecta base tune....

The wierd thing is.....I've changed the plugs to the stock AC Delco 108s I gapped them to between .026 and .028 (can't fully tell because my feeler guage only has from .026 to .030 which is stupid) and changed the air filter to a stock AC Delco Air filter.  Still getting it. 

I logged the events and tried to look at misfires....NONE!!!!!!!   It's starting to piss me OFF!!!!!!!

So here is what it feels like.....regardless of whether I'm flooring it from 1st through 2nd and into 3rd Always at around 5100 rpms or sitting in 3rd at 3000rpms and flooring it to redline the nice torquey pull feel I was getting sort of "lets off" (as if I let off the gas a bit) then quickly gets going again.  Sometimes it does it more than once.  Like I said, I checked the datalogs for cylinder misfires and nothing!  In some cases the Air Fuel goes to low 11s but not lower.  This happens regardless of KR as well!!!!!  I can't understand what could be happening. 

Also I should say that once it gets above 5100 rpms boost goes from 23psi to 20.5 psi or so, but that doesn't seem to be enough to sort of interrupt the torque pull (as I'm feeling).  Anybody else have this issue and fix it?

[Steelmesh]

Do you have your old (copper?) plugs just to see what happens? 

[Wartie]

The wierd thing is.....I've changed the plugs to the stock AC Delco 108s I gapped them to between .026 and .028 (can't fully tell because my feeler guage only has from .026 to .030 which is stupid)

 By chance does your feeler gage have other blades that can be put together to add up to what you want? That may be the stupid part.
 One more  question, can the traction control have an affect on this situation?

[MattM]

By chance does your feeler gage have other blades that can be put together to add up to what you want? That may be the stupid part.
 One more  question, can the traction control have an affect on this situation?

NO! ITS STUPID HOWM MUCH IT JUMPS!!!!

[MattM]

Do you have your old (copper?) plugs just to see what happens?

WAS DOING IT ON THOSE TOO.

[MattM]

Sorry I'm on my phone so my messages might be hard to decifer.  The feeler gauge jumps around with the sizes.  There aren't any .002 to add to the .026.  It's kind of stupid..

[Steelmesh]

The good ol' medallion style is infinitely variable 

[Sol Asylum]

Sorry I'm on my phone so my messages might be hard to decifer.  The feeler gauge jumps around with the sizes.  There aren't any .002 to add to the .026.  It's kind of stupid..

Is there an .010 and .018 or some other combo that adds up at .028 or whatever number your looking for?

Are our plugs really gapped that small anyway?

[MattM]

Is there an .010 and .018 or some other combo that end us at .028 or whatever number your looking for?

Are our plugs really gapped that small anyway?

A .018 added to .026 would make the gap .044 (way too big).

I would need a .002 to make it larger.

Also Vince from Trifecta recommends .028 for gap.  I've tried at larger gaps and still this happened. 

The thing is....as I said...my datalogs aren't showing misses on any cylinders when it does this.

To answer a previous question...I wouldn't think it's traction control because it happens when I'm in 3rd at 3500 rpms and floor it to redline...still does it at 5100 rpms.

I dunno..I just can't figure it out....

I guess what should the afr be at wot around 5100 rpms?  I'm showing 11.2-11.5.  From 4000 to 5000 my afr is from 12.0 to 12.5.

Does 11.2-11.5 sound too rich?

[Sol Asylum]

Is .026 the smallest gauge you have?  If so maybe spend $5 and buy a set of gauges that has what you need.

[MattM]

Is .026 the smallest gauge you have?  If so maybe spend $5 and buy a set of gauges that has what you need.

DUDE!  That isn't causing my current issue!  It does it with any gap!  FOCUS!  Does anyone have an idea as to why I would get a high rpm hesitation without misfiring of a cylinder.

[Steelmesh]

DUDE!  That isn't causing my current issue!  It does it with any gap!  FOCUS!  Does anyone have an idea as to why I would get a high rpm hesitation without misfiring of a cylinder.

Bro, you should be getting codes I agree, but I have had blowout without throwing the CEL.  Have you done a bunch of WOT pulls without clearing the codes? Not saying you should hurt your car that's on you, just wondering haha maybe it will eventually set a code that would be super helpful so you can swap coils and then injectors to see if the code follows as usual if those things are flaking out or died.

Are all your coils plugged in and wiring is tip top?  Injector system wiring?  You are freaking out clearly, so at this point if I were in your shoes I'd be open to looking at stuff that sounds crazy especially if it's quick/dirty, the occurrence at the same engine speed is important but don't let it 'box you in'.

If you're feeling a torque loss then we can assume it's cylinder pressure dropping out, you ruled out traction control and you're the judge on mechanical feeling.  Then going down to 'tree level' inside the figurative forest of [cylinder pressure dropping out], I suggest looking at all things related to creating cylinder pressure consistently: spark, fuel, compression, or air and as you know each of them have their own system to consider.  What I am getting at here is it might not be throwing a misfire code but your descriptions sure makes it seem like your car is stumbling like it's misfiring (not creating cylinder pressure from combustion).


As far as your AFR and my LE5 tuning experience: I've not had misfire/blowout with my LE5 setup running 25+psi reaching down to 0.70 lambdas while I was tuning in the car.  0.70 lambda is 30% richer than stoich (stoich = 1.00).  If your stoich is 14.70 running pure gasoline, then 14.70 * 0.70 = 10.29:1

I'm targeting 0.78 right now and run richer, running big methanol is proving to make fueling difficult below top engine speed so I am on the rich side.  I have many things on the list before I start leaning it out. Anecdotally, I ran a small methanol jet in my Cruze 1.4T and caused blowout pretty easily, so I don't think methanol suppresses blowout if anything will cause it.

However it's possible your LNF doesn't like it that rich and being direct injected I would assume it can be leaner than low 11's to 1 AFR.  +1 for getting HPT or EFIlive so you can do advanced diag by recalibrating your car.

[Sol Asylum]

DUDE DON'T BE A DOUCHE TO PEOPLE TRYING TO HELP

Seriously this is just a forum of people with a common interest trying to help each other out none of us are getting paid so if you act like a ungrateful no one is going to help you.

Your the one complaining about the feeler gauges, some of us were just trying off a simple solution.

Trouble shooting should start with the simple things and as you rule them out you move to the more complex.  Based on my 10 plus years here I could tell you I suspect your tune or maybe the ECM as I have seen many time now those being the issue.  Given how much an ECM cost do you want to start there?  Given your reaction to my suggestion you buy a $5 tool I'm going to guess not.

Clearly you don't want my help but have you tried searching the forum for this issue?  I'm not saying you will find a definite solution but you might.

Try and remember we are here because most of us wanted to try and help each other out.

[MattM]

Bro, you should be getting codes I agree, but I have had blowout without throwing the CEL.  Have you done a bunch of WOT pulls without clearing the codes? Not saying you should hurt your car that's on you, just wondering haha maybe it will eventually set a code that would be super helpful so you can swap coils and then injectors to see if the code follows as usual if those things are flaking out or died.

Are all your coils plugged in and wiring is tip top?  Injector system wiring?  You are freaking out clearly, so at this point if I were in your shoes I'd be open to looking at stuff that sounds crazy especially if it's quick/dirty, the occurrence at the same engine speed is important but don't let it 'box you in'.

If you're feeling a torque loss then we can assume it's cylinder pressure dropping out, you ruled out traction control and you're the judge on mechanical feeling.  Then going down to 'tree level' inside the figurative forest of [cylinder pressure dropping out], I suggest looking at all things related to creating cylinder pressure consistently: spark, fuel, compression, or air and as you know each of them have their own system to consider.  What I am getting at here is it might not be throwing a misfire code but your descriptions sure makes it seem like your car is stumbling like it's misfiring (not creating cylinder pressure from combustion).


As far as your AFR and my LE5 tuning experience: I've not had misfire/blowout with my LE5 setup running 25+psi reaching down to 0.70 lambdas while I was tuning in the car.  0.70 lambda is 30% richer than stoich (stoich = 1.00).  If your stoich is 14.70 running pure gasoline, then 14.70 * 0.70 = 10.29:1

I'm targeting 0.78 right now and run richer, running big methanol is proving to make fueling difficult below top engine speed so I am on the rich side.  I have many things on the list before I start leaning it out. Anecdotally, I ran a small methanol jet in my Cruze 1.4T and caused blowout pretty easily, so I don't think methanol suppresses blowout if anything will cause it.

However it's possible your LNF doesn't like it that rich and being direct injected I would assume it can be leaner than low 11's to 1 AFR.  +1 for getting HPT or EFIlive so you can do advanced diag by recalibrating your car.

Its seriously whacked out!  This car is pissing me off!  So I have torque pro with one of the expensive dongles and it allows me to monitor in realtime (the datalog)  all misfire eve on each cylinder at all rpms in the datalog.  As I understand it there can be a pretty decent amount of misfired before it will throw a check engine light.

Hell it took 4 full seconds of me with the 2step limiting rpms at 4000 on the line at the dragstrips for the ecu to actual throw a check engine light.  Long story short I think you need very consistent misfires to throw a code.  That said,  I was sure that when I datalogged the cylinder misfire pids through the run that it would tell me I was at least getting some misfiring...No such luck..Its stupid as hell!  It's basically telling me that there is no misfire.....

[MattM]

DUDE DON'T BE A DOUCHE TO PEOPLE TRYING TO HELP

Seriously this is just a forum of people with a common interest trying to help each other out none of us are getting paid so if you act like a ungrateful no one is going to help you.

Your the one complaining about the feeler gauges, some of us were just trying off a simple solution.

Trouble shooting should start with the simple things and as you rule them out you move to the more complex.  Based on my 10 plus years here I could tell you I suspect your tune or maybe the ECM as I have seen many time now those being the issue.  Given how much an ECM cost do you want to start there?  Given your reaction to my suggestion you buy a $5 tool I'm going to guess not.

Clearly you don't want my help but have you tried searching the forum for this issue?  I'm not saying you will find a definite solution but you might.

Try and remember we are here because most of us wanted to try and help each other out.

Wait a minute here....Now....Twice I told you that ive tried many different and larger gaps.  On both occasions you still seemed to be fixated on the feeler gauge.  What does the feeler gauge have to do with my car hesitating?  If I've tried many larger gaps (.030/.032/.035) and had the same exact issue....why would my purchasing a new feeler gauge fix anything?

I wasn't frustrated after the first time, but the second time of you fixating on the feeler gauge seems uneccessary.  In any event I thank you for trying to help. 
With regard to whether Ive researched the problem....I have searched here, solsticeforum, skyroadster, and cobaltss.net.  so far the only thing that seems to match is a sky redline that was still under warrantee and GM replaced turbo, wiring harness, ecu, intake and a few other things but the problem never went away so they bought the car back.

Also, this car was doing this before the trifecta tune as well.

Now that I think about iit....I did seafome it through the intake vacuum which (I think) made it go away for a while...maybe I'll do that again...

[MattM]

Steelmesh, I did also think possibly fueling issues but the datalog shows it getting richer in that area.  My other thought was possibly fouling of the spark plugs as a result of the richer conditions but I pulled them after the runs and they still look fine...

This shit is unbelievable!!!! Stupid car is too damned complicated....

[MattM]

Can anyone with a Trifecta budget tune tell me if your boost starts at 23psi then around 5000rpms drops down to mid 20s to 21psi to redline? 

Also, for Trifecta Budget tunes....does anyone know if their Air Fuel Ratios richen up to mid to low 11s at 5000rpms and above?

[LatinVenom]

I have not seen him on this forum for a while, but you may want to PM Bill from Canada on the Solstice forum, he experience the hesitation you are describing. It was solved after multiples logs he exchanged with the Trifecta developer.

[MattM]

I have not seen him on this forum for a while, but you may want to PM Bill from Canada on the Solstice forum, he experience the hesitation you are describing. It was solved after multiples logs he exchanged with the Trifecta developer.

Thank you!  I'll try to locate him there.

[elff]

The reason people were fixated on the feeler gauge is because you said you did not have one that could guarantee the gap you want is the gap you set.
So verifying that, with a cheap ass part, would be something I personally would want to do.
I had spark blow out on a tune at one point, that was 100% spark plug gap.  I went back to .028 and it went away.

I asked in another thread if you were re-tuned after adding the new downpipe.   Now that you have stated you have the budget tune, numerous times, my advice is simple.  You need a retune.   

The budget tune is for stock hardware.  You no longer have stock hardware and you no longer have stock airflow and your AFR, IMHO is off.
The following quote from LatinVenom is a paraphrase of what I just stated.

I have not seen him on this forum for a while, but you may want to PM Bill from Canada on the Solstice forum, he experience the hesitation you are describing. It was solved after multiples logs he exchanged with the Trifecta developer.

You need to log your car, send those logs to the tuner, and have him adjust the tune.
This is probably not going to be a one time deal.   It can take multiple logs and multiple adjustments to get a tune just right.  I am pretty sure that is not included in the budget tune pricing, so you may have to pay for this service. 

[Gentleman Jack]

Just getting back from vacation - so I'm getting caught up.  I just read this thread.  Here is my take:

1. Get a new feeler gauge.  These cars, especially with a tune, are very finicky about plug gap.  Many folks here fixated on that BECAUSE we have all dealt with issues and learned from it.  Heck, walk in to an auto parts store with your four plugs in your hand and gap them at the counter.  Just make sure the gap is right.  Too big - blow out.  Too small - blow out.  You trying 5 gaps larger than recommended and having the same problem does not eliminate this as a POTENTIAL issue.    Take a breath, understand you are likely right, and check them anyway.  I give the same advice on boost leaks and those codes. 

2. Get an update to your tune.  You need to log a bunch of runs and send them to trifecta.  The budget tune is fine on a stock car.  Any modifications and you need to step up to a custom tune.  The good news is - you'll get a bit more power out of it too! 

3. Worriesome bit added halfway through - the car was doing this before the tune?  Tell me more about it.  What has been done to the car so far?  How many miles?  Have you pulled the intake?  Oil in the intake tube? PCV gone bad? Carbon build up?

4. Do you have access to HP Tuners to do logging with so we can look at the logs with you?

GJ

[MattM]

Thanks for the reply Gentleman Jack.  So, when I first bought the car (it now has 70,000 miles on it) I would floor it in any gear and around 5500 rpms and up it felt to me like it was hitting the rev limiter.  I posted about it all on skyroadster.com.  Anyway, I seafoamed it then changed spark plugs (for the 4th time) and gapped them and the issue seemed to go away from early 2018 on.  Now, I don't drive the car too too much and after I got the downpipe installed I've started trying to get on it so I can make sure it's ready for the track. 

Well, now, that hesistation issue is back (albeit not nearly as bad).  I switched out the NGKs I had in it (mind you they only had about 3,000 miles on them) with AC Delco 41-108s thinking this would be the issue again, but, apparently not.

Oh, also, I posted a thread on skyroadster in 2017 asking if the Trifecta tune would stop my ecu from hitting the "rev limiter" early, but obviously, it didn't.  I'm just trying to remember all the things I did to the car that finally caused it to run better....Unfortunately, aside from the spark plugs, better fuel, tune, and seafoam there isn't much else. 

Oh, I also took off the EGT line that goes from the valve cover to the intake, and capped that hole and put a filter on the opening of the egr port, but I don't think that was what fixed it (since it's happening a little again)

[Steelmesh]

Throwing this out there 

This condition might cause performance issues being direct injected:

[MattM]

So....Last month I replaced the spark plugs and air filter, and recall driving it some, and still getting some of the hesitation I described.  Well I've been busy the last three weeks or so, and haven't even been able to start the car.

Well this morning I decided I would drive it to work.  I let it heat up to normal temp start driving it...even put the Trifecta tune on.  I floor it through 2nd...Didn't feel the hesitation....Do a test in 3rd.....Might have felt a SLIGHT catch at around 5200 rpms (maybe) but that was it.  Then decide to try it in 4th and floored it all the way through fourth (up to 105mph) to get through those RPMs and I didn't really feel much (if any) of the hesitation I described earlier. 

It really has me shaking my head, and I'm sure I'll go out after work and test it again and the hesitation will be back, but GOD do I hate intermittent issues!!! 

The only other thing I think could have happened is that I didn't drive it around enough after the new air filter for the ecu to get the tune back right (i'm just grasping at straws there though).

[Johnny_gxp]

Your hesitation is a lean condition in your tune. The car is retarding itself due to knock. Take it from me. I had this issue to a T. I’m saving you $2500 and hours of frustrating replacing the engine that you will soon blow the rings out of. Run a log and send it to the tuner.