Knock
- Thread starter bjzq8
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Quickstop [UK]
Combating adversyty.
Re: Knock
same thing applies though - if that sensor is wrong then you'll think you're at a pressure but not. Does that pressure provide infor for fuelling?
Are you saying you have the stock MAP sensor as well as another and they both correlate?
same thing applies though - if that sensor is wrong then you'll think you're at a pressure but not. Does that pressure provide infor for fuelling?
Are you saying you have the stock MAP sensor as well as another and they both correlate?
Try Me
New member
Re: Knock
Check your crank reference angle settings in the Operational Paramiters table in your FAST. Is this a bank-to-bank setup? If you havent yet, get a light and check the timing on the balancer and compare it to what the FAST is seeing at that same rpm. It almost sounds like the calibration is off in the FAST making it think you have 17 degrees when you're really getting more than that at the engine. I had that problem once on my old FAST system. Engine was getting 6-8 degrees more timing than the FAST thought it was.
My 4.3 had vortecs, 75lb injectors, built motor, and my T76 and I ran 18-20 lbs on 93 octane with a nice happy 11:1 a/f ratio and never had trouble with it pinging. I did have trouble with it lifting the heads though
How did the plugs look when you took them out? Any signs of detonation? You could also always go to a colder heat range plug. I ran champion RS9YC (if i recall correctly) which is a very cold plug compaired to what is called for stock (RS14YC or TR5). Also you may be blowing out the spark at that boost (wont cause knock i know but) I had that problem unless i gapped the plugs tighter (around 20 i think).
Check your crank reference angle settings in the Operational Paramiters table in your FAST. Is this a bank-to-bank setup? If you havent yet, get a light and check the timing on the balancer and compare it to what the FAST is seeing at that same rpm. It almost sounds like the calibration is off in the FAST making it think you have 17 degrees when you're really getting more than that at the engine. I had that problem once on my old FAST system. Engine was getting 6-8 degrees more timing than the FAST thought it was.
My 4.3 had vortecs, 75lb injectors, built motor, and my T76 and I ran 18-20 lbs on 93 octane with a nice happy 11:1 a/f ratio and never had trouble with it pinging. I did have trouble with it lifting the heads though
How did the plugs look when you took them out? Any signs of detonation? You could also always go to a colder heat range plug. I ran champion RS9YC (if i recall correctly) which is a very cold plug compaired to what is called for stock (RS14YC or TR5). Also you may be blowing out the spark at that boost (wont cause knock i know but) I had that problem unless i gapped the plugs tighter (around 20 i think).
bjzq8
New member
Re: Knock
I set the fast manually to 12 degrees of timing at idle, because that's where the end of the timing mark is. In fact I set a whole range of them around idle to 12, so it wouldn't be wandering into neighboring cells. With the timing light on it, it was sitting right at 12 degrees. I backed the timing to 0 in the spark table, and it backed the timing mark to 2 degrees on the balancer; just what FAST said in its data item. The crank reference angle is 10 degrees now, but it's been right on the balancer every time with what FAST was expecting.
I have NGK UR5 plugs in it, but I will definitely try a colder plug. They are gapped at .030 now, but I will knock them down to .020 and see what happens.
I set the fast manually to 12 degrees of timing at idle, because that's where the end of the timing mark is. In fact I set a whole range of them around idle to 12, so it wouldn't be wandering into neighboring cells. With the timing light on it, it was sitting right at 12 degrees. I backed the timing to 0 in the spark table, and it backed the timing mark to 2 degrees on the balancer; just what FAST said in its data item. The crank reference angle is 10 degrees now, but it's been right on the balancer every time with what FAST was expecting.
I have NGK UR5 plugs in it, but I will definitely try a colder plug. They are gapped at .030 now, but I will knock them down to .020 and see what happens.
1madgumby
New member
Re: Knock
This is what I have done no knock. 0.0 o2 correction I have F.A.S.T. also
1. change the fuel pump. USA made Walbro pump
2. get the racetronix fuel pump wiring harness.
3. put Autolite 103,s with A .35 gap. NGK plugs fowl out really quick
4. Set fuel psi at 55 psi no vac.
5. 100 octane or better fuel
6. change the knock sensor
Let me know if that help at all. If this is not all done just going to have the same problem. Start with the sensor first then start at #1 if that does not fix it.
This is what I have done no knock. 0.0 o2 correction I have F.A.S.T. also
1. change the fuel pump. USA made Walbro pump
2. get the racetronix fuel pump wiring harness.
3. put Autolite 103,s with A .35 gap. NGK plugs fowl out really quick
4. Set fuel psi at 55 psi no vac.
5. 100 octane or better fuel
6. change the knock sensor
Let me know if that help at all. If this is not all done just going to have the same problem. Start with the sensor first then start at #1 if that does not fix it.
bjzq8
New member
Re: Knock
1. change the fuel pump. USA made Walbro pump
I have a Walbro 255 high-pressure pump I bought in 2003 and installed in 2004...I assume this would be USA-made, but I don't have the original box for it any more.
2. get the racetronix fuel pump wiring harness.
I only have the original wiring harness, I can certainly try this.
3. put Autolite 103,s with A .35 gap. NGK plugs fowl out really quick
I will try these plugs.
4. Set fuel psi at 55 psi no vac.
No-vac fuel pressure was 50 when I checked last night, I will bump it up to 55.
5. 100 octane or better fuel
I don't have any 100-octane fuel within 30 miles of my house, but I have 5 E85 stations...I would convert my truck to E85 if I get to this point.
6. change the knock sensor
Does you have a part number for this unit?
Thank you for your help.
1. change the fuel pump. USA made Walbro pump
I have a Walbro 255 high-pressure pump I bought in 2003 and installed in 2004...I assume this would be USA-made, but I don't have the original box for it any more.
2. get the racetronix fuel pump wiring harness.
I only have the original wiring harness, I can certainly try this.
3. put Autolite 103,s with A .35 gap. NGK plugs fowl out really quick
I will try these plugs.
4. Set fuel psi at 55 psi no vac.
No-vac fuel pressure was 50 when I checked last night, I will bump it up to 55.
5. 100 octane or better fuel
I don't have any 100-octane fuel within 30 miles of my house, but I have 5 E85 stations...I would convert my truck to E85 if I get to this point.
6. change the knock sensor
Does you have a part number for this unit?
Thank you for your help.
bjzq8
New member
Re: Knock
Slight update...it rained a bunch last Friday, and I was busy helping people clean up their flooded basements all weekend. I noticed that the Autolite 103 plugs are MUCH longer than the NGK UR5 plugs, at least from the pictures I can get off of images.google.com.
Compare:
Autolite:
http://www.wbodystore.com/grandprix/images/autoliteplugs.jpg
NGK:
http://www.autoguide.net/apf/images/products/engineparts/u899962843mtp.jpg
By longer, I mean the threaded portion is TWICE as long on the 103s. I couldn't find a parts store here in West-Central Illinois that carried the 103s, so I ordered them. Could this be part of my problem? Is anyone else with Vortec heads running NGK UR5 plugs with any success? If not, I'm assuming that having the electrode recessed 3/8" into the head might have had some negative effects on my engine?
Slight update...it rained a bunch last Friday, and I was busy helping people clean up their flooded basements all weekend. I noticed that the Autolite 103 plugs are MUCH longer than the NGK UR5 plugs, at least from the pictures I can get off of images.google.com.
Compare:
Autolite:
http://www.wbodystore.com/grandprix/images/autoliteplugs.jpg
NGK:
http://www.autoguide.net/apf/images/products/engineparts/u899962843mtp.jpg
By longer, I mean the threaded portion is TWICE as long on the 103s. I couldn't find a parts store here in West-Central Illinois that carried the 103s, so I ordered them. Could this be part of my problem? Is anyone else with Vortec heads running NGK UR5 plugs with any success? If not, I'm assuming that having the electrode recessed 3/8" into the head might have had some negative effects on my engine?
dgoodhue
BuSTeD 4.3
Re: Knock
Vortec uses a longer plug, most people using NGK use part numbers TR5,TR55 or TR6.
Vortec uses a longer plug, most people using NGK use part numbers TR5,TR55 or TR6.
bjzq8
New member
Re: Knock
So without pulling off the cylinder heads, how can I tell that I actually have Vortec heads? I mean, the intake was modded (extended) and the original heads were re-drilled for the bolts...but I can't say that I've actually seen the underside of the combustion chamber. Will a Vortec-modded intake fit up to stock heads? Are there some numbers I can look for on the outside? Is there a freeze plug or something in a different location?
So without pulling off the cylinder heads, how can I tell that I actually have Vortec heads? I mean, the intake was modded (extended) and the original heads were re-drilled for the bolts...but I can't say that I've actually seen the underside of the combustion chamber. Will a Vortec-modded intake fit up to stock heads? Are there some numbers I can look for on the outside? Is there a freeze plug or something in a different location?
SikVSix
New member
Re: Knock
easiest way I know of is an extra bolt hole above the exhaust manifold bolts for vortecs. I believe its the drivers side front of the engine and pass side rear, should be an empty hole about an inch above the end bolt where the manifold bolts to the head. And the 103's are what I'm running on mine. (or 104's, cant remember now)
easiest way I know of is an extra bolt hole above the exhaust manifold bolts for vortecs. I believe its the drivers side front of the engine and pass side rear, should be an empty hole about an inch above the end bolt where the manifold bolts to the head. And the 103's are what I'm running on mine. (or 104's, cant remember now)
bezerk
New member
Re: Knock
oildipstick is not being screwed onto the head. or with an aftermarket bracket.
take off valvecover and check numbers under there.
oildipstick is not being screwed onto the head. or with an aftermarket bracket.
take off valvecover and check numbers under there.
Maxtor
New member
Re: Knock
AFR is 11.6 to 1, pretty sure you aren't running out of fuel. What was your injector duty cycle when the knock happened? Keep with one thing at a time. If you can hear audible knock you are hitting it hard, even with forged parts it can only take so much.
Wrong plugs definitely for Vortec heads. Put in the 103's and report back. If you want to be extra safe turn the engine over by hand to make sure there are no clearance issues with the longer plug. Sounds like you def. have Vortecs, I'm surprised it even ran with the shorter plug.
Where are you located?
AFR is 11.6 to 1, pretty sure you aren't running out of fuel. What was your injector duty cycle when the knock happened? Keep with one thing at a time. If you can hear audible knock you are hitting it hard, even with forged parts it can only take so much.
Wrong plugs definitely for Vortec heads. Put in the 103's and report back. If you want to be extra safe turn the engine over by hand to make sure there are no clearance issues with the longer plug. Sounds like you def. have Vortecs, I'm surprised it even ran with the shorter plug.
Where are you located?
bjzq8
New member
Re: Knock
My highest injector duty cycle during the high-ping runs, at 11:1 A/F, was 85.1%.
When I was running too much fuel (9:1 A/F) I saw 99.5% DC a few times...but I've never seen it run lean. I am logging it with FAST almost every time.
Every time I plant my foot to the floor I cringe. I know every part in that motor is screaming for mercy...and I'm always sure that the next test run will end with something flying through my hood or embedding itself in the pavement.
BTW, I'm in west-central Illinois, about an hour west of Peoria. Thanks to everyone that has provided input! The 103s should be here any day, I'll post again.
My highest injector duty cycle during the high-ping runs, at 11:1 A/F, was 85.1%.
When I was running too much fuel (9:1 A/F) I saw 99.5% DC a few times...but I've never seen it run lean. I am logging it with FAST almost every time.
Every time I plant my foot to the floor I cringe. I know every part in that motor is screaming for mercy...and I'm always sure that the next test run will end with something flying through my hood or embedding itself in the pavement.
BTW, I'm in west-central Illinois, about an hour west of Peoria. Thanks to everyone that has provided input! The 103s should be here any day, I'll post again.
SikVSix
New member
Re: Knock
Just to clarify in case others are looking at this as reference, this is not the third bolt hole in line with the other manifold bolts at the very front but a smaller bolt hole ABOVE that. Our stockers have the 3 bolt holes all in line also.
Just to clarify in case others are looking at this as reference, this is not the third bolt hole in line with the other manifold bolts at the very front but a smaller bolt hole ABOVE that. Our stockers have the 3 bolt holes all in line also.
bjzq8
New member
Re: Knock
Just got the Autolite 103 plugs in, gapped at .028.
I took it out for a short spin, and the pinging isn't improved. It is certainly a warmer day than last time, but it pings at 12psi, and pings more at 15psi. I tried it without methanol at first, and methanol cured the 12psi ping, but not 15psi.
I'm really just about to give up on it permanently. I can't seem to make anything run right on this truck, and as it sits now, it's slower than stock.
Just got the Autolite 103 plugs in, gapped at .028.
I took it out for a short spin, and the pinging isn't improved. It is certainly a warmer day than last time, but it pings at 12psi, and pings more at 15psi. I tried it without methanol at first, and methanol cured the 12psi ping, but not 15psi.
I'm really just about to give up on it permanently. I can't seem to make anything run right on this truck, and as it sits now, it's slower than stock.