Hi, my engine started to smoke, compression test shows 10.1-8.5-9.0-9.7, then removed head and now is all clear. Pistons (forged Wiseco's) nr. 2 and 3 are completly melted. All injectors are tested and are ok, ran with wideband of curse, no lean runs... Is it only a spark problem ?? (too much advance, too much heat ) ???
But why only cylinders 2-3 which are firing (spark) together ???
(http://mervart.eu/C20XE/kompkos.jpg)
(http://mervart.eu/C20XE/wisecokos.jpg)
(http://mervart.eu/C20XE/wisecoko1s.jpg)
What about spark plugs? Color?
Last couple of km was totaly black, because oil was leaking... anyway I have posted here a photo of my spark plugs in may...
http://195.159.109.134/vemsuk/forum/index.php/topic,850.0.html
what primary trigger settings you have?
I found that 2.0 16v has two types of trigger wheel, 6deg difference between them.
Yes, I checked with the timing light, that 68deg is my trigger settings. Before I have set 74deg (so smallar advance) for a longer period ( A few runs were with 64deg.....
It's strange, the spark plugs are in good condition (imho), no heat marks etc. ......
I think my shi.y spark map is the key for this 700Euro unsucessful story :/
Pls does anybody have the original stock C20LET spark map, or some proven one for this engine ? I can pay something for this, still better than another 700E for new Wiseco's....
(http://mervart.eu/vems.spark.LET.JPG)
Have you tuned your ignition map on rolls or road w/detcans?
We run about 13 deg at 210 kpa with Yb cosworths, (cr about 8.5:1). But I am interested in too oem spark map...
Another tip - I don't know which was your max pressure - but put the max kPa bin much bigger, because Ecu can run out from the bin and interpolate bad.
Another question what about on the 55-140 kPa / 700-1200rpm area? Why is this ?
No, I was preparing to go for dyno tuning in a few days.... The engine, until now, wasn't under heavy load for a long time (only a few,5- 6,1/4m sprints).
Hmm, my max boost was sometimes higher then 220kPa, maximum was 230-235kPa, but as I have said, only for a few seconds on the highway on VI gear.
Quote from: max on September 17, 2009, 03:38:01 PM
Have you tuned your ignition map on rolls or road w/detcans?
Quote from: z0tya on September 17, 2009, 03:45:51 PM
Another question what about on the 55-140 kPa / 700-1200rpm area? Why is this ?
I took some ign map for C20LET from another Vems user (from user pages) ........cause didn't have any another starting point to tune ign map...
As much as I understand, I think thats why this has happend. Next time you MUST tune your cars ignition and only then drive with boost. Detonation will destroy your engine quickly. You should be lucky that only two pistions are dead.
Yea, but why only pistons 2-3 ?? 1-4 are hitted to, but absolutely not so much like 2-3.
Dunno, maybe pros have answer to this.
I've heard that if intake mainfold is wrong made, it can have uneven flows to each cylinder so its leaner/richer mixture to some cylinders. Theoretically it can start to det.
As just stated you probably have unbalanced air flow to your cylinders.
this causes varying mixture between them and some can be to lean, that also does look like a little to advance
What is the compression ratio of this engine?
Those black dots on the ceramic on the spark plug is a sign of detonation.
Hmmm, don't think, cause I am using a stock C20LET manifold from factory...
These Wiseco's were 8.5:1, low temp thermostat (82C) and 100 octane fuel.....
It is not considerable as "conservative" map. It is weird map - retarded, where it can be safe at almost any advance and advanced in dangerous area. If your engine was not tuned, result is as it should be. Some seconds with hard knocking and - done. Also you use original hot spark plugs. IMO it is not a safe way. Black dots on isolator was months ago. Usually it is from knocking.
It is rare when all pistons are melted.
Gints
I'm looking at this:
(http://mervart.eu/C20XE/wisecokos.jpg)
What is the deck surface like between 2&3 especially in the area where those two black half moons are?
They look as if they might be pitted.
Also can you raise the pistons so that we can see the crowns more clearly?
your map is very bad, probaly knock at 3000rpm. At high rpms you need more advance, no less.
here is little retarded map for c20let 8.5:1, safe map(not for max power).
http://img263.imageshack.us/img263/5743/mssparkv2set3.jpg
btw opel c20let stock exhaust mainfold is crap, cly 2 and 3 have many better flow.
what is your trigger tooth and rising or falling?
Quote from: MWfire on September 17, 2009, 08:19:44 PM
your map is very bad, probaly knock at 3000rpm. At high rpms you need more advance, no less.
here is little retarded map for c20let 8.5:1, safe map(not for max power).
http://img263.imageshack.us/img263/5743/mssparkv2set3.jpg
btw opel c20let stock exhaust mainfold is crap, cly 2 and 3 have many better flow.
what is your trigger tooth and rising or falling?
Thanks,
my trigger tooth is 8, trigger angle 68 (was 74), rising edge.
Here are detail pics of piston 2 and 3 + head is destroyed too :(
(http://www.mervart.eu/C20XE/p2ko.jpg)
(http://www.mervart.eu/C20XE/p3ko.jpg)
(http://www.mervart.eu/C20XE/h1ko.jpg)
That last picture is a perfect example of detonation.
That doesn't look like an overly aggressive timing table @ all...
It doesn't have to be aggressive to get detonation.
If the inlet temperatures are too high, or the octane too low (I know that this was running 100octane fuel) then detonation can occur.
In this case it may be possible that the timing was out on cylinders 2 and 3, or it could be that the water flow was not right and the middle cylinders overheated and that this started the detonation.
i take a look to my c20xe settings, and i have trigger tooth 9 and 69deg.
So 9*6+69=123deg, and you have 116, so you have 7 deg advance more than me. My setup is 100% correct for that type c20xe. So scope your engine again.
I have 6*9+63=117
::)
Thanks, I'll check it, asap I get some new pistons and head....
Here is detail of one melted piston, I must say, the most upper ring was very strong to hold together....
(http://www.mervart.eu/C20XE/p2kout1.jpg)
Quote from: GintsK on September 19, 2009, 08:21:47 PM
I have 6*9+63=117
::)
as i sad, i saw two types of trigger wheel on c20xe(123 deg is from one c20xe with motronic 2.8. That c20xe has heavier flywheel and blue injectors(241cc)). Difference is 6deg. So you can't only copy config for c20xe.
So far did 4 c20xe and 2 c20let, and two have 123 deg, 4 have 117deg.
Ah, remembered: "LET" was builded from XE !
So the engine is running again and I have really 117deg version, so now I have trigger tooth 6 and 81deg angle, checked with timing light. Thanks.
And remember that you shouldnt drag-race before you your car is correctly mapped ;)
Yea, you are bloody right ;D
But now I have inside the block old XE machined Mahles with new rings, CR aprox 9.5:1. So I am planning to tune the engine on slight boost (max 0.6-0.8bar) with knock control. And then, if all will be fine I re-bore the block for my new set of JE pistons. I am starting with this spark table now (max boost is now 0.25-0.3bar).
(http://www.mervart.eu/vems/c20let/c20let_spark_start.JPG)
you have to much rumping up with rpms(difrent from 7000 and 3000rpm). Usually 6-7deg difrent.
BTW MBT on c20let is before knock on good fuel.
Hi all, I would like to ask someone about injector/spark fire sequence. When I am looking around user pages, forum etc. I am more and more confused if I have set the right inj/ign sequence. So I found on Peter Jensen user page (VW Corrado G60, 1-3-4-2 engine) this timing picture (http://www.vems.hu/wiki/index.php?page=MembersPage%2FPeterJenseninjector original page)
(http://www.mervart.eu/vems/corrado_diagran.jpg)
From this timing diagram I'm reading:
1-3-4-2 - spark
4-2-1-3 - inj
For Vems it means:
h[0] = 04 01 02 08 .. (Pre_Inj00 - cyl1, Inj01 - cyl2, Inj02 - cyl3, Inj03-cyl4)
h[2] = 40 50 40 50 .. (Wasted Spark: 1&4 or 4&1 on Ign259-channel 5, 2&3 or 3&2 on channel 4)
This sequence looking good for my engine (now without cam sync). Idle is nice and smooth, then it pulls in any RPM range well.
But then when I switch second (CAM trigger) on, engine will not start. (I have 2-nd trigger set to raw 24, it means
it reacts on falling edge of CAM pulse ('cause rising edge - raw 25, is near my primary trigger).
I tried to change h[0] and h[2]
h[0] = 01 02 04 08 .. (it means 4-3-2-1 inj sequence)
h[2] = 50 40 50 40 .. ( 3&2-4&1-2&3-1&4 spark)
With this setting engine idling nicely (2nd trigger still active), but after 3000RPM there are missfires or what, and it's running bad.
My wiring is checked twice, inj0 is realy in cyl 1, inj1-cyl2 etc. so I am really confused how to set up, or what is the right setting for this C20LET (XE) engine. Thanks for any help.
Little up, I have changed trigger tooth to 12 (TDC atfer...then 45) and it seems it works well. Plugs have quite good color, haven't ?
(http://www.mervart.eu/C20XE/sparks_ago1s.jpg)
Quote from: Pet on September 17, 2009, 04:03:25 PM
Yea, but why only pistons 2-3 ?? 1-4 are hitted to, but absolutely not so much like 2-3.
Only just picked up on this.
I suffered plug failure on cylinders 2 and 3 on Nitrous. I spoke to the experts as to why only 2/3 failed when they were fed with nitrous on oposite sides of the distribution block. Their answer is that the middle two cylinders combustion temperature will always be higher as those cylinders are surounded by other cylinders on each side, where as 1/4 are only surrounded by one cylinder on one side. The other contributing factor was the amount of advance I ran, and I would tend to agree with them on that one, as Even though the engine was not knocking, the advance was most likely beyond MBT, even after pulling 2 degrees out on Nitrous. Basicaly the peak cylinder pressure was happening early which raises combustion temps.
Quote from: Pet on December 07, 2009, 02:09:30 PM
Little up, I have changed trigger tooth to 12 (TDC atfer...then 45) and it seems it works well. Plugs have quite good color, haven't ?
(http://www.mervart.eu/C20XE/sparks_ago1s.jpg)
Have you checked the TDC after Trigger value with a timing light? Plug colour looks good. maybe a little lean, or it could be a temperature of the plug. perhaps try a #8 plug and check the difference?
Yes, it was checked at 0deg and 30deg advance during idling; I have marks on the flywheel, all was absolutely in one line. Under boost (0.6bar) I have it very rich, around AFR 11, in atmo area around 14.7.