Knock Retard
- Thread starter dgoodhue
- Start date
dgoodhue
BuSTeD 4.3
Re: Knock Retard
Today, I tried testing the truck again with another degree of timing pulled out at 4400 rpm (and 2 degrees out at 4800, which is 11 and 12 degree retarded), not so much success. I am try to eliminate the 4.4 degree spike of Knock retard at approx 4500 rpm just before shifts.
I tried it once and I saw I had some knock retard but the scan tool computer lost power and I wasn't able to look at it. I tried again and left it in 2nd gear accidently, so I ran it up to 4900rpm in 2nd gear. At about 4600 rpm the knock counts went crazy :banghead: It said I had 18.1 degree of knock retard, that is on top of the 12 degree already taken out in my chip burning. I have a feeling the ECM can only pull so much timing (maybe not past 0 degrees). Since I am only runing 2-4 degree of timing in the chip table. I think maybe I need to physically retard the timing instead.
Today, I tried testing the truck again with another degree of timing pulled out at 4400 rpm (and 2 degrees out at 4800, which is 11 and 12 degree retarded), not so much success. I am try to eliminate the 4.4 degree spike of Knock retard at approx 4500 rpm just before shifts.
I tried it once and I saw I had some knock retard but the scan tool computer lost power and I wasn't able to look at it. I tried again and left it in 2nd gear accidently, so I ran it up to 4900rpm in 2nd gear. At about 4600 rpm the knock counts went crazy :banghead: It said I had 18.1 degree of knock retard, that is on top of the 12 degree already taken out in my chip burning. I have a feeling the ECM can only pull so much timing (maybe not past 0 degrees). Since I am only runing 2-4 degree of timing in the chip table. I think maybe I need to physically retard the timing instead.
SeattleSy#1255
Category 5 Conservative
Re: Knock Retard
You know Dave, I have heard that our head design can actually cause some detonation...being mass produced, you never know...all i can say is i feel your pain, been trying to hunt it down forever and i just concluded that it's not going to be fixed with the time/money i have at this time.
You know Dave, I have heard that our head design can actually cause some detonation...being mass produced, you never know...all i can say is i feel your pain, been trying to hunt it down forever and i just concluded that it's not going to be fixed with the time/money i have at this time.
cheatham2492
New member
Re: Knock Retard
Dave Sound like it is not going so good. I had the exact same problem........ Fought it forever...........
It was my EGR valve. It was leaking exhaust gas into the intake so it would cause a hot lean condition that would go away some when I used the race fuel to supress it. the exhaust temps are much colder band aid more or less. I didnt read that you have one"EGR" or not I bought a new one but now using the GM block off plate.9 bucks from GM.Take a look it might be the answer you are looking for.
HTH
Danny Cheatham
Dave Sound like it is not going so good. I had the exact same problem........ Fought it forever...........
It was my EGR valve. It was leaking exhaust gas into the intake so it would cause a hot lean condition that would go away some when I used the race fuel to supress it. the exhaust temps are much colder band aid more or less. I didnt read that you have one"EGR" or not I bought a new one but now using the GM block off plate.9 bucks from GM.Take a look it might be the answer you are looking for.
HTH
Danny Cheatham
Re: Knock Retard
I think we all feel your pain. I have spent the better part of the last year-and-a-half chasing the knock in my truck. I admire you for your persistence and tenacity.
Cheatham2492, do you have a part number for the Block off plate from GM. This is about the only thing that I have not changed on my truck as well.
Thanks.
I think we all feel your pain. I have spent the better part of the last year-and-a-half chasing the knock in my truck. I admire you for your persistence and tenacity.
Cheatham2492, do you have a part number for the Block off plate from GM. This is about the only thing that I have not changed on my truck as well.
Thanks.
ed hess
race or get outta the way
Re: Knock Retard
i've had this theory for a long time that i kinda proved to my self .
theory = most people here with knock have lots of miles on their truck.
we all know oil lowers octane.
lots of miles means worn rings and valve seals = egual lowering octane.
i had lots of knock on my original motor i couldnt get rid of.
when i did my 1st motor ( the one we raced all last year) i reused every sensor, igniton wire, etc.... everything but the old plugs on the new motor.
guess what with the motor being fresh i had zero knock using only an ultimate chip.
so thats my theory.
if youve been through all the usual items to replace to get rid of knock then look at the age of the motor.
but hey what do i know....
then to i dont usually see anyone say how many miles are on the motor they are having knock problems with.
ed
i've had this theory for a long time that i kinda proved to my self .
theory = most people here with knock have lots of miles on their truck.
we all know oil lowers octane.
lots of miles means worn rings and valve seals = egual lowering octane.
i had lots of knock on my original motor i couldnt get rid of.
when i did my 1st motor ( the one we raced all last year) i reused every sensor, igniton wire, etc.... everything but the old plugs on the new motor.
guess what with the motor being fresh i had zero knock using only an ultimate chip.
so thats my theory.
if youve been through all the usual items to replace to get rid of knock then look at the age of the motor.
but hey what do i know....
then to i dont usually see anyone say how many miles are on the motor they are having knock problems with.
ed
dgoodhue
BuSTeD 4.3
Re: Knock Retard
I will try checking EGR, I still have the stock EGR valve in place, but disabled.
I have noticed my truck has been running rich at idle which it never has in the past. I have been looking at that lately. I have looked at my plugs (I was trying to see if one my injector is leaking creating a rich condition), they are all tan,but some have different degrees of black on top. I assume that is detonation. Is it normal to see a variance? I would say 2 look perfect, 2 have black on top of the electrode (it looks dirty, but not oily, rest of the electode is tan) and 2 are inbetween, is that due the air distribution variance?
cheatham2492 said:
I will try checking EGR, I still have the stock EGR valve in place, but disabled.
I have noticed my truck has been running rich at idle which it never has in the past. I have been looking at that lately. I have looked at my plugs (I was trying to see if one my injector is leaking creating a rich condition), they are all tan,but some have different degrees of black on top. I assume that is detonation. Is it normal to see a variance? I would say 2 look perfect, 2 have black on top of the electrode (it looks dirty, but not oily, rest of the electode is tan) and 2 are inbetween, is that due the air distribution variance?
cheatham2492
New member
Re: Knock Retard
Yea I would just get the block off plate. Looks much cleaner and easier to work around. The plate is kind of archeic but dose the job. it's about a 3/8 inch thick plain steel. Part #10054880 EGR cover.
Later
Dan
Yea I would just get the block off plate. Looks much cleaner and easier to work around. The plate is kind of archeic but dose the job. it's about a 3/8 inch thick plain steel. Part #10054880 EGR cover.
Later
Dan
bezerk
New member
cheatham2492
New member
Re: Knock Retard
That was a great chart to use very helpfull. How ever never sine most of those.
Nice chart thanks
Dan
That was a great chart to use very helpfull. How ever never sine most of those.
Nice chart thanks
Dan
dgoodhue
BuSTeD 4.3
Re: Knock Retard
I haven't really made much progress. My truck started running really bad and rich after fooling with the timing. I think I have narrowed it down to a bad a fuel injector. I hope to install them this weekend see if that helps, I haven't gone WOT in a month
VermontTy said:
I haven't really made much progress. My truck started running really bad and rich after fooling with the timing. I think I have narrowed it down to a bad a fuel injector. I hope to install them this weekend see if that helps, I haven't gone WOT in a month
VermontTy
Support Our Troops
Re: Knock Retard
That gets me thinking a bit....my new build is very hard to start when cold; it cranks cranks cranks, sputters, coughs, catches, then chugs some more, then it runs fine and the idle smooths out. After its been started and warmed up, it'll start okay. It also runs rich as heck, not eye-watering like yours though. The plastic cup bottom on several injectors were cracked, which I was told would cause no issue. I like the reasoning though; good excuse to get 50's.
That gets me thinking a bit....my new build is very hard to start when cold; it cranks cranks cranks, sputters, coughs, catches, then chugs some more, then it runs fine and the idle smooths out. After its been started and warmed up, it'll start okay. It also runs rich as heck, not eye-watering like yours though. The plastic cup bottom on several injectors were cracked, which I was told would cause no issue. I like the reasoning though; good excuse to get 50's.
dgoodhue
BuSTeD 4.3
Re: Knock Retard
Mine is very hard to start when cold; it cranks cranks cranks, sputters, coughs, catches, andstalls. I restart it and the engine catches imediately and seem to run fine but stalls out sometime if I put into gear to quickly. It also sometimes sputters when cold and driving. I haven't timed it completely but I lose all my fuel pressure in atleast 3 hours. In the past, I used to hold fuel pressure for days. So it leaking down some where (fuel pump, regulator or injectors)
VermontTy said:
Mine is very hard to start when cold; it cranks cranks cranks, sputters, coughs, catches, andstalls. I restart it and the engine catches imediately and seem to run fine but stalls out sometime if I put into gear to quickly. It also sometimes sputters when cold and driving. I haven't timed it completely but I lose all my fuel pressure in atleast 3 hours. In the past, I used to hold fuel pressure for days. So it leaking down some where (fuel pump, regulator or injectors)
dgoodhue
BuSTeD 4.3
Re: Knock Retard
I replaced the injectors yesterday and it seems to have fixed the problem. I did run into a small snag. I thought I just could rescale the F28 table and compensate the Injector pulsewith and it would run. :rotf: That was a joke. After fooling around with it and realizing the 50# injector must not share the same fueling curve as the stock ones (ie they aren't linear in relation to each other), I ended up copying a 50# injector fueling curve to my chip program. I couldn't easily just run the 50# program because I need the boost control from my stock turbo and my tweaks I already have made (mostly for electric fans, lower timing to save my motor.) Those fueling tables changed quite a bit.
It now starts up the first try when cold and my eyes have stopped watering. I haven't had a chance to do any Diacom runs to see how it affects the knock retard issues. I won't be able to do any testing for a while because its supose to rain for next 4 or 5 days.
I replaced the injectors yesterday and it seems to have fixed the problem. I did run into a small snag. I thought I just could rescale the F28 table and compensate the Injector pulsewith and it would run. :rotf: That was a joke. After fooling around with it and realizing the 50# injector must not share the same fueling curve as the stock ones (ie they aren't linear in relation to each other), I ended up copying a 50# injector fueling curve to my chip program. I couldn't easily just run the 50# program because I need the boost control from my stock turbo and my tweaks I already have made (mostly for electric fans, lower timing to save my motor.) Those fueling tables changed quite a bit.
It now starts up the first try when cold and my eyes have stopped watering. I haven't had a chance to do any Diacom runs to see how it affects the knock retard issues. I won't be able to do any testing for a while because its supose to rain for next 4 or 5 days.