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GTS stutters/buckles at idle and when giving quick full throttle.

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GTS stutters/buckles at idle and when giving quick full throttle.

 
Old 06-07-2019, 04:00 AM
  #136  
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Originally Posted by Arnoud View Post
After having passed the compulsory yearly inspection (as we have here in Finland, including full smog test) by the end of April, last month May turned out a very busy work month for me. So I was only able to order and receive PEMs from John Speake (thanks John!). I borrowed a Sharktuner2, so to get more data and insight of my root problem(s ?).

Finally had some time this week to put the PEMs into a spare set of EZK:


And into a spare LH (and yes: this still has the old hybrid circuit in there. My normal LH has that replaced with John Speake's excellent permanent solution).


Connected my WBO2 (which is in the right hand side of my Finnish developed X-pipe) via TechEdge 2J9 controller to the Sharktuner2, while - on advice from John Speake - kept the factory NBO2 (which is in the middle of my Finnish developed X-pipe) connected directly to the LH. The Sharktuner2 software started fine, and I loaded the default EPROM for a GTS into the PEM's:


I did not changed any of the default parameters:


I then started to drive around, while just data logging. Attached is one file: "Run 7-driving+accelerate-to-100km-row-2232-20190605.txt" , which has a total of 6820 rows (including the header row).
- Just before row 2232 I accelerated (not WOT, but close enough fast throttle) onto a highway towards 100km, and it can be seen that all eight (8) cylinders have knock-retard applied then. Is that a normal log for a GTS?
- It can also be seen in this log file, that my idle does drop every now and then below 600 rpm. Still do not understand why that is happening too...
- Note that I have by-passed the ICM "relay" module, and thus far have not had my engine going into total "crap running mode".

Any comments and feedback super appreciated (and I will drive and data log more in the days to come)!
Arnoud,

First of all if you are going too submit data it is better to prepare a graphical representation as most folks do not have the kit to analyse such an array.

I put your data into both ST2 data logging analysis and then into sharkplotter [that you possibly do not have if you are not registered user] to get a better idea of what is going on. Basically you only have one data point to all intents and purposes and that makes rather alarming reading at face value.

Your problems started when going to full load - i.e. value 3 in the throttle position column. The data tells us that your throttle position switch full load is working OK and at that point the the engine is being driven on the full load maps for both fuel and ignition. The AFR looks very decent [high 12's] and the advance applied looks stock value. Pretty much straight away all cylinders started knocking with up to 4 counts being registered during one sample interval. The sample interval is 1/10th of a second and at 5k rpms your motor will spin about 8 times or 4 firing cycles. That all the cylinders show a knock event taking place with retard around 6 degrees suggests you have an issue of some kind the more obvious one being fuel octane or more to the point a notable lack of it. What octane rating are you running? Was the engine making any funny noises [audibly detectable knocking] whilst this happened? Your motor really needs 98 RON and I have an empirical rule of thumb that suggests if the octane drops to 95 one needs to pull about 2 degrees of advance and if that relationship holds then pulling 6 degrees of advance might suggest an octane rating of 91 RON. Do you get your fuel from across the border in Russia by any chance?

With high compression pistons [10.5] the GTS is a bit more prone to knocking than the S4 motor but even then such a response should not occur. If it is not fuel related then the question becomes what else could cause this? AFR looks OK and in my experience that does not impact knock much at all providing the motor is running in the range it is.

Have you sorted the glowing cats issue yet? Did not pick up anything to suggest you have- apologies if I missed anything. Attached a couple of data plots I made in sharkplotter.
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Old 06-07-2019, 10:45 AM
  #137  
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Originally Posted by FredR View Post




Arnoud,

First of all if you are going too submit data it is better to prepare a graphical representation as most folks do not have the kit to analyse such an array.

I put your data into both ST2 data logging analysis and then into sharkplotter [that you possibly do not have if you are not registered user] to get a better idea of what is going on. Basically you only have one data point to all intents and purposes and that makes rather alarming reading at face value.

Your problems started when going to full load - i.e. value 3 in the throttle position column. The data tells us that your throttle position switch full load is working OK and at that point the the engine is being driven on the full load maps for both fuel and ignition. The AFR looks very decent [high 12's] and the advance applied looks stock value. Pretty much straight away all cylinders started knocking with up to 4 counts being registered during one sample interval. The sample interval is 1/10th of a second and at 5k rpms your motor will spin about 8 times or 4 firing cycles. That all the cylinders show a knock event taking place with retard around 6 degrees suggests you have an issue of some kind the more obvious one being fuel octane or more to the point a notable lack of it. What octane rating are you running? Was the engine making any funny noises [audibly detectable knocking] whilst this happened? Your motor really needs 98 RON and I have an empirical rule of thumb that suggests if the octane drops to 95 one needs to pull about 2 degrees of advance and if that relationship holds then pulling 6 degrees of advance might suggest an octane rating of 91 RON. Do you get your fuel from across the border in Russia by any chance?

With high compression pistons [10.5] the GTS is a bit more prone to knocking than the S4 motor but even then such a response should not occur. If it is not fuel related then the question becomes what else could cause this? AFR looks OK and in my experience that does not impact knock much at all providing the motor is running in the range it is.

Have you sorted the glowing cats issue yet? Did not pick up anything to suggest you have- apologies if I missed anything. Attached a couple of data plots I made in sharkplotter.
Fred: thanks for your detailed reply and follow up, including showing the data in SharkPlotter.
- Before this drive I tanked up fully with new 98-octane patrol fuel.
- And nope: that fuel does not come from Russia (to be exact: it comes from a Finnish fuel company, Neste Oyj . And quality control is rather good in general, in Finland, so this is really proper 98-octane patrol. And yep: I always tank with the same supplier while in Finland).
- It has 5% ethanol in it, and has such already for many, many years (the 95-octane fuel has 10% ethanol in it, which I never use for my 928).
- So indeed: if it is not the 98-octane fuel, then what else can cause this? I'm open for all suggestions!
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Old 06-07-2019, 12:03 PM
  #138  
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Did you solve the red hot cats issue?
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Old 06-28-2019, 09:49 AM
  #139  
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Originally Posted by FredR View Post
Did you solve the red hot cats issue?
No and yes: ever since I have bypassed the ICM "relay"/module with the 3-jumper wire several weeks ago, I have not had the engine going into the "runs like crap mode" - while having driven several 100's of kilometers now. Note that the cats only started to glow, when I totally deliberately kept on driving for a bit when the engine was in the "runs like crap mode"...
- This still puzzles me, because if it is/was the ICM "relay"/module switching 4 injectors off, I would NOT expect the cats to start glowing after a while...
- And the root cause problem is still not solved: my idle still goes under 600 rpm all the time (these logs show it clearly), which as from my very 1st post I have stated must be a clue of something...

I will try to test the ICM "relay"/module myself (I have an electronics + software background) in the weeks to come, because not at any time in the past did either of it's green or red warning LED's came on...I am aware that it might also be 1 or 2 of the thermocouple sensors and/or it's wiring (more likely to be dirty rather than faulty, because their impedance was about right when I measured and publish that here some time ago).
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Old 06-28-2019, 10:18 AM
  #140  
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Default More SharkTuner2 logs...

Did more driving and data logging last week, and hereby some raw data files + SharkPlotter graphs (thanks very much to Jim Corenman, for his permission to me for using his excellent software too). Note: all this driving was done in closed-loop mode, i.e. NBO2 sensor connected directly to LH (that sits in the middle of my X-pipe), and a separate WBO2 via TechEdge 2J9 connected to SharkTuner2 (that sits in the right hand PS of my X-pipe).

For Runs 8 + 9 + 10, I had modified the ignition EZK map, by having deducted 3 degrees from all default values for all RPM cells from loads 80% and higher (up to 100%). This in the hope it would produce a lot less knocks at fast and WOT throttle. But that did not really fixed that...

Mmm...somehow uploading pictures does not work for me at the moment, so will add the SharkPlotter graphs when I can so again onto this post.

[Edited a bit later today] And hereby several SharkPlotter graphs. First LH + EZK graphs from driving from idle and then the engine being warmed up, @5 samples/second for a total of 32+ minutes of driving. This included 1 quick acceleration, that obviously caused knock events.






Next SharkPlotter LH + EZK graphs are from a WOT from standstill with the automatic gear in "2", i.e. driving away in 1st gear (as it did) and then slow driving after that in that gear for 1+ minute. I.e. never up moving up in gear. Again: this caused knock events.




Last SharkPlotter LH + EZK graphs are from 40+ minutes driving. Before this, I had changed the EZK on the cruise map, for loads from 80% and up with all RPM ranges lowered with -3%. I hope that this would make the knocking at higher RPM's/quick accerlaeration a lot less to none, but it appeared not so much to be the case...




Constructive feedback/remarks/questions etc. - so to help me get this all better, and finding and fixing root problem #1 = idle still dipping all the time <600 rpm - much appreciated!

Last edited by Arnoud; 06-28-2019 at 02:41 PM.
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Old 06-28-2019, 02:42 PM
  #141  
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Run 3 data
Arnoud,

Your data logs did not contain ignition advance values. On run 3 at 23.2 seconds on the attached sharkplotter image you actually managed to get all 8 cylinders knocking with 7 & 8 the most severe and the question must be why. Your runs with 3 degrees taken out calmed things down by comparison but still some knocking going on.

Suggest you check which map is active on full throttle [Cats/non cats] and copy/report the advance values it is applying for the different rpm thresholds. Something very odd going on here I suspect either fuel is lousy, map is corrupted or something is causing combustion problems. If you have the kit to do it, take a photo of the piston crowns on cylinders 7&8.
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Old 07-11-2019, 01:55 PM
  #142  
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Originally Posted by FredR View Post
Run 3 data
Arnoud,

Your data logs did not contain ignition advance values. On run 3 at 23.2 seconds on the attached sharkplotter image you actually managed to get all 8 cylinders knocking with 7 & 8 the most severe and the question must be why. Your runs with 3 degrees taken out calmed things down by comparison but still some knocking going on.

Suggest you check which map is active on full throttle [Cats/non cats] and copy/report the advance values it is applying for the different rpm thresholds. Something very odd going on here I suspect either fuel is lousy, map is corrupted or something is causing combustion problems. If you have the kit to do it, take a photo of the piston crowns on cylinders 7&8.
Fred: thanks for your comments and questions.
- The active maps are all based on Cats 98-octane, as per my coding plug.
- For the EZK, I have ticked the box: "Use cruise map also at WOT (do not use WOT map at all)".
- And yes, I agree with you: something very odd going on here, and it must be combustion problems. Because I know it is not the fuel (as we have proper stuff here in Finland), and I do not expect the map to be corrupt because I have had these problems now for 2+ years with different LH and EZK and without and with the SharkTuner2 - and which was the reason to park my car and start finding and fixing it, as what has now become this hugely long thread.

I will get/borrow a borescope, so to look better on the piston crowns in the days/week to come.
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Old 07-11-2019, 02:19 PM
  #143  
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Arnoud,

The ignition cruise map values are retarded a bit relative to the WOT map. Thus when using this feature one tends to dial in the advance one wants for full power based on what the system can take. In a perfect world this would be done on a dyno to be sure of obtaining the optimal timing given that too much advance is bad the engine and the big ends in particular.

If you are running stock timing maps on the cruise settings then something strange is for sure going on. I raised a potential known but rare issue in another thread to check for the possibility of the timing ring on the flywheel having slipped. To do this you would an appropriate timing light to check the timing at idle compared to what it shows in ST2. If you see a difference then this ring [an interference fit on the flywheel] would probably have slipped. I know it can happen albeit it is quite a rare phenomena and not the ind of thing one instinctively thinks to look for.
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Old 07-11-2019, 02:28 PM
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Default More SharkTuner2 logs, after coils swap + new 2nd stage ignition controllers...

What has happened in the past weeks:
- Swapped my old - original Bosch which are black colour coated, instead of the newer metal shiny ones - coils back in.
- And took out my still original 25 year old 2nd stage ignition controllers, and put in brand new Bosch units.
Why: because I wanted to make sure that everything ignition related is indeed not suspect, even though I have measured in the past that nothing seems to be wrong with those components either.

Taking out the original 25 year old 2nd stage ignition controllers (and it was me, who many years ago changed the original bolts to these inbus hex bolts):


And putting in brand new ones, including re-applying CPU-heatsink based paste:


And the result of all this was/is...main problems still there, as I was able to get the car going into "engine running like crap" mode again last weekend, while taking SharkTuner2 logs. So at least I know it is not any of these components, as well with the ICM bypass wires still in there/in place: nothing to do with that either (and most likely my ICM + it's thermo-couple sensors are working fine).

Attached six (6) SharkTuner2 log files, as well as a few plots from LH + EZK.

SharkTuner LH + EZK plots, from doing a WOT run in 1st gear from around 0-50km/h and then immediately after that the engine going into "crap mode": when revving it a little bit once in crap mode while parked, the load = 100% and a knck event occurs:



The following SharkTuner2 plots were made only minutes after the previous one: the transition from 87.30 to 87.40 looks strange to me: almost 2000 revs increase in 0.10 seconds, really? I was still parked, while doing this.



Final screenshot is from when I came back home, and engine went into "crap mode" while parked. It shows the idle revs going really low, being 481 rpm here, while the engine load shows 44% - while it should be very low at idle when parked...


Further help very much appreciated!
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Old 07-12-2019, 05:36 AM
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Originally Posted by FredR View Post
Arnoud,

The ignition cruise map values are retarded a bit relative to the WOT map. Thus when using this feature one tends to dial in the advance one wants for full power based on what the system can take. In a perfect world this would be done on a dyno to be sure of obtaining the optimal timing given that too much advance is bad the engine and the big ends in particular.

If you are running stock timing maps on the cruise settings then something strange is for sure going on. I raised a potential known but rare issue in another thread to check for the possibility of the timing ring on the flywheel having slipped. To do this you would an appropriate timing light to check the timing at idle compared to what it shows in ST2. If you see a difference then this ring [an interference fit on the flywheel] would probably have slipped. I know it can happen albeit it is quite a rare phenomena and not the ind of thing one instinctively thinks to look for.
Yesterday we were posting at almost the same time, so I only noticed your follow up reply now. Very good point made, and I will check and test this accordingly and post the results here once tested.

Another test I still need to perform, is the engine leak down test. I have the tools, just need some time to test it.
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Old 07-12-2019, 06:47 AM
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Originally Posted by Arnoud View Post
Yesterday we were posting at almost the same time, so I only noticed your follow up reply now. Very good point made, and I will check and test this accordingly and post the results here once tested.

Another test I still need to perform, is the engine leak down test. I have the tools, just need some time to test it.
Leakdown testing is always a good benchmark reference point but if you do have excessive leakage knock events are probably the least likely thing that is going to happen. Knock events are caused by either poor octane, too much advance or too much compression. GTS motors have been known to form carbon deposits on the pistons presumably from burning excessive oil with the residue building up on the piston crowns increasing the effective compression ratio. Remember the GTS has 10.5 to 1 pistons to start with.
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