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Drp6982

What I Think Is False Kr

56 posts in this topic

To be honest, I didnt think this issue was a mechanical one, thats why you might just be hearing about this Scott :)   figured it was either tuning or nature of the beast

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To be honest, I didnt think this issue was a mechanical one, thats why you might just be hearing about this Scott :)   figured it was either tuning or nature of the beast

 

You actually sent me a link when I was out of town at a wedding last week.  But I just got a chance to read the symptoms..And put a little thought into it.   When you come to the shop next I will start my car, you will hear a little piston slap then it will go away after a few minutes.

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You actually sent me a link when I was out of town at a wedding last week.  But I just got a chance to read the symptoms..And put a little thought into it.   When you come to the shop next I will start my car, you will hear a little piston slap then it will go away after a few minutes.

 

That being the case, have you ever logged the car when cold to see if its detecting any knock due to that ?

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My car?  No.. Never had the need to..

 

 

Well, time to plug in your trinity.....   If there is some piston noise, I would be curious to see if its registering on your motor

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4032 pistons run much tighter clearance than a 2618 piston. Even though its forged, it expands less with heat and doesnt need the excessive clearance so it should not be the piston making the noise IMO.

 

Dan, you did say your AFR was in the 10's during open loop but my guess is that its only that rich because of all the KR and not vice versa. Too much fuel can cause knock and pull timing, but I don't think that's the case here, Is it possible to remove the supercharger belt and run the car cold to see if the KR is still there without the blower turning? That would pin-point the blower if that's the issue.

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I spoke with Johan today and he sent me another tune revision he wants me to try specifically on the cold start so I will throw the tune in and will datalog on the way into work tomorrow.

 

 

4032 pistons run much tighter clearance than a 2618 piston. Even though its forged, it expands less with heat and doesnt need the excessive clearance so it should not be the piston making the noise IMO.

 

Dan, you did say your AFR was in the 10's during open loop but my guess is that its only that rich because of all the KR and not vice versa. Too much fuel can cause knock and pull timing, but I don't think that's the case here, Is it possible to remove the supercharger belt and run the car cold to see if the KR is still there without the blower turning? That would pin-point the blower if that's the issue.

 

Well based on the last fuel revisions my AF is actually spot on when cold, hot, idle or Part throttle.  If I am accelerating for any long period of time (in 4th or 5th building boost at low RPMS) I can see the AF mixture richen after about 4-5 seconds... it dips which I assumed is more of a safety precaution but not richer then WOT, it will get in the 12s....

 

 

When this KR occurs, I will be at part throttle with a small amount of acceleration (Maybe 10-20% pedal) and it will start knocking but my AF gauge shows 14.3:1 


Edit: When I said previously the AF goes very rich, it does if I stay in the pedal and try to accelerated through the KR.... if I stay in it for too long (4-5 seconds) like I do on the highway, the AF gauge goes way rich but I assumed it did that in attempt to try and eliminate the KR......

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I spoke with Johan today and he sent me another tune revision he wants me to try specifically on the cold start so I will throw the tune in and will datalog on the way into work tomorrow.

 

 

 

Well based on the last fuel revisions my AF is actually spot on when cold, hot, idle or Part throttle.  If I am accelerating for any long period of time (in 4th or 5th building boost at low RPMS) I can see the AF mixture richen after about 4-5 seconds... it dips which I assumed is more of a safety precaution but not richer then WOT, it will get in the 12s....

 

 

When this KR occurs, I will be at part throttle with a small amount of acceleration (Maybe 10-20% pedal) and it will start knocking but my AF gauge shows 14.3:1 

Edit: When I said previously the AF goes very rich, it does if I stay in the pedal and try to accelerated through the KR.... if I stay in it for too long (4-5 seconds) like I do on the highway, the AF gauge goes way rich but I assumed it did that in attempt to try and eliminate the KR......

Its going rich because of the KR. You can leave AFR alone and remove timing and it will richen up. You can add timing and it will lean out. Not talking a lot but measurable. 12 degrees of KR will surely richen the AFR as a result of not enough timing in the engine. At least thats my understanding.

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Its going rich because of the KR. You can leave AFR alone and remove timing and it will richen up. You can add timing and it will lean out. Not talking a lot but measurable. 12 degrees of KR will surely richen the AFR as a result of not enough timing in the engine. At least thats my understanding.

 

 

Well, leave it to me to have some of the more interesting problems :)

 

I'll be at AMP on 9/20... we'll take a look. I might try to get there earlier and let the car sit, and hopefully it will be long enough where Johan finishes tuning he can drive the car

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Well, leave it to me to have some of the more interesting problems :)

 

I'll be at AMP on 9/20... we'll take a look. I might try to get there earlier and let the car sit, and hopefully it will be long enough where Johan finishes tuning he can drive the car

What will Johan be tuning?  FIrst Ive heard of this?  Have him call me please.

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What will Johan be tuning?  FIrst Ive heard of this?  Have him call me please.

 

 

lol...  It seems like Johan is tuning cars for you guys every weekend. I dont know he will be there. I just figured there would be a good chance :)

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Oh  I actually have the dyno rented out that day  hence my confusion..

 

Oh lol....  sorry about that. It just seems you guys pump out cars and Johan is there every Saturday......

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Well, just a little bit of an update, Johan sent me a revision yesterday which he had been fiddling with the cold start fuel enrichment.... Not sure specifically what he did but this AM on the way to work the car "felt" ALOT better. She seemed almost perfect in the manorisms. I will pull the log tonight and see if the KR is still spiking but I would doubt it based on how she felt. Might not be perfect but a huge step in the right direction

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 FYI, Im running the newer Modern Muscle 4032 material pistons.

 

 

 

These are 2618's FYI....

 

 

You telling me or Dan?

 

 

Dan, pay attention. You have 2618 pistons not 4032. :)

 

 

 

Modern Muscle also calls them 4032

 

http://www.modernmuscleperformance.com/product/SRT-64L-392-Drop-In-Forged-Pi

 

 

Does he have a 2618 offering now? I see they offer a rod/piston combo in 2618. Is that what Dan has?

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