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I know this is a worn out subject, but I still dont understand KR, why its caused, and how to get rid of it. My scanner dosent have a measurment for KR, so is there another way to know how much I have?
 

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KR is known as "knock retard". Generally, when the fuel mixture in the cylinder of an engine is not burning the proper way,( flame propagation) as in a smove wave front from the igniter(spark plug), the cylinder will "ring". The improper wave front ignites too quickly, or another source in the cylinder,such as a "hot spot" ignites instead of the spark plug upon compression resulting in detonation.

The PCM (powertraind control module or "brain") registers the "ringing" through knock sensors on the engine. When it is detected, the PCM reducing the timing (retards timing) to prevent or reduce the "ringing" in the effected cylinder. If enough "ringing" or detonation occurs, catastrophic engine damage likely will be the result. Sometimes extreme heat will melt the piston or burn a hole in through the piston from a "too lean" condition. Other times i am sure it would break chunks off the piston due to extreme ringing or detonation. A hot spot in the cylinder such as excessive carbon or metal burring could induce this condition. There are other conditions that may initiate this as well.
Superchargers on our engines doe produce heat. Using an intercooler reduces the incoming air temperature, resulting in a denser mixture in the cylinders, helping to ensure a smooth wave front of burning when initiated by the spark plug. Higher octane gas allows the mixture to burn more slowly, and increases power because more timing can be added and more compression in the cylinder.

I have seen more than one engine destructed from detonation. My friend asked me to bring over a scan gauge because he said his 3800SC was "missing". When I saw the dipstick pulled out about 3 inches and engine oil sprayed on the engine, I knew exactly what happened. He detonated a cylinder, mushed a piston, and the blow by gases increased the pressure in the crankcase and oil shot out of the dipstick tube.

There is a lot more to KR, but I hope this gives you the basics for why we want to keep KR as low as possible.......CHeers KEV
 

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I do not believe you can detect KR without a scan gauge. If you are hearing engine "pinging" it may already be too late. I would not suggest modifying
a 3800 without using a scan gauge. I have done it in the early days with mild mods, but it is definitely risky...

Maybe another member can discuss reducing KR through mods. A lengthy enough subject.....cheers KEV
 

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ELM323 and ELM327 Scanners suck, the ELM323 is even too slow to be very useful at all, they work, but they are some of the poorest performance scanners out there.

I use EFILive to scan, awesome tool. I have used HPTuners scan a little, I like EFILive better, but I didn't have it long enough to really get everything setup. It wasn't as easy to setup as EFILive. Palmer software scan tools are like EFILive. You can find Autotap with EFILive and that is a great deal, but only available used. You get the latest EFILive with it (scan only) and AutoTap 3.1 (old, but works, has a lot of features), but is is only RS232 based IIRC. FTDI USB to RS232 adapters work fine.

You can get ScanTool 425801 OBDLink SX OBD-II Scan Tool USB Interface with OBDwiz Diagnostic Software : Amazon.com : Automotive this one, it works pretty well and the software, free OBDWiz with purchase, is decent. The OBDLink is NOT ELM327 based, it is STN1110 based and much much much faster.
 

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I use Autotap with an EFIlive registration key.
Basically just lets you use EFILive scantool without the box.
I generally just use the Atap software though,mainly due to familiarity.
I am starting to use the EFIlive scantool though. Been thinking of getting rid of the Atap for ECMpro when I save a few more dollars.

Just don't know anyone with ECMpro so haven't seen alot of info on it.
 

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Guess I'm spoiled as well as the GM guys. We use diagnostic scanners. Gm uses tech II(but they are only good on GM). Being an independent shop, I have 2 Snap On scanners that pretty much work on everything(although I have not purchased the European software). I can see everything and have bi-directional controls for pin point component testing. Another nice feature of professional scanners is many can record a movie of data which can be viewed after a test drive looking at 1 frame of info at a time and see all info during each frame to better isolate a problem or performance issue.

It would be interesting to see a HP tuner in action to see if these could fit into a general repair shops daily activity and be of benefit for general diagnostics.....

Jake L

PS, I've had a few burned pistons and scored cylinder walls from KR/detonation. DO NOT MESS AROUND WITH THIS UNLESS YOU HAVE DEEP POCKETS FULL OF $$$
 

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Lol,I was thinking about just laptop software since most scantools don't have a good datalog option for tuning.
When i'm looking over datalogs I like to see lines of data,when i'm diag'ing for repair I lean more toward standalone.
As far as a good scantool definately pick up a good one if you can.
In my personal shop I also have vetronix,snapon and OTC scantools.
Really depends what your use is for it,no sense spending hundreds/thousands on a scantool if you won't utilize all the functions.
However,if you got the cash to throw down than for diag I like standalone pro scanners better like jake mentioned.

Jake,not sure about hptuner but while working at Ford dealer it was generally easier to use a generic tool than my EFIlive,Atap or other software/laptop scanners.
We didn't get alot of call there for gm specific stuff,but it was nice to be able to set cmp retard,perorm crank relearn etc.. If we did happen to take in a gm or work on a trade-in.
I would not want to mess with it daily though,standalone is less time consuming imo. And it's all about saving time at the shop right!
 

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If you have seen EFILive scan, you have seen ECMPro, very similar when it comes to the scanning part. I suspect EFILive bought part of it from Palmer.

And if you have used MXScan and HPTuners scan, again similarities are striking. And if you dig around the author or MXScan was involved with HPTuners....
 

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Discussion Starter #10
ELM323 and ELM327 Scanners suck, the ELM323 is even too slow to be very useful at all, they work, but they are some of the poorest performance scanners out there.

I use EFILive to scan, awesome tool. I have used HPTuners scan a little, I like EFILive better, but I didn't have it long enough to really get everything setup. It wasn't as easy to setup as EFILive. Palmer software scan tools are like EFILive. You can find Autotap with EFILive and that is a great deal, but only available used. You get the latest EFILive with it (scan only) and AutoTap 3.1 (old, but works, has a lot of features), but is is only RS232 based IIRC. FTDI USB to RS232 adapters work fine.

You can get ScanTool 425801 OBDLink SX OBD-II Scan Tool USB Interface with OBDwiz Diagnostic Software : Amazon.com : Automotive this one, it works pretty well and the software, free OBDWiz with purchase, is decent. The OBDLink is NOT ELM327 based, it is STN1110 based and much much much faster.
I purchased the scanner off of amazon and I have it installed, where do I look for KR, Im just not seeing it.
 
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