Knock Retard Issues

[huntsg]

I recently installed my new scanmaster 2.1. I ran two WOT passes on February 16th and here are the results of the last pass.

O2 mV 289
Knock retard 16.6

Since I was running so lean I added a boost gauge, an O2 sensor, a MAF sensor, a Hotwire kit and an XP-Plus Fuel Pump. I did one pass and my O2 mV have come up to 722 but my Kr was still 16.5. This week I added 42.5 lbs injectors with matching 93 chip and a fuel pressure regulator. and here are the results:

O2 mV 781 WOT
Kr 14.8 WOT

At hot Idle:

O2 mV 100-750
Kr 0.0
AF 05
L8 32
Bat 13.9
Int130
BL 122
CLt 182
AtS 81
r 825-925
tps .46
IAC 44
cc 02-252
MAL 00

The car runs smooth with plenty of power and no misfires. I checked and found no vacuum leaks. I have a stock turbo and the boost was about 17 lbs. I set Fuel pressure at idle at 46 lbs (I don't have a gauge installed permanently). Any suggestions on what to look for next? I am at a loss... Thanks.

 

[datquick6]

ur numbers show that you are running a bit lean i think it a safe number would be in the low 800's
Bl should be closer to 128 maybe this is why its leanin out.
and the iac might be a bit high i think it should be below 30...
when i had this problem i was suggested to get a ttchip to add fuel...this would help with the lean out

 

[Onalky87]

Also. Get under the car and look under the hood. You could be getting false knock. Look for signs of ur dp or exhaust hitting something, or anything hitting anything for that matter. Also. Where u in OD when u kicked it down to wot?this could cause it too

 

[Turbo-Fun]

I have to agree it looks like false knock to me too. If it's possible to watch the scanmaster and see if it's a single occurrence and then clears it's probably false knock.

 

[berserker6]

or maybe get some race fuel in it. if you still have knock its probaly false.

 

[wbrophy]

Adjust your tps so it reads .42 at idle .46 is to high for idle. .44 is the max. at idle.

 

[bmackinnon]

14.8 KR ?

Dude! Turn the boost down before you grenade the thing figuring out what's going on!! It could be false knock, but if it's not just a KR spike that then decreases, rather it's hanging in there steady at wot, it probably isn't. It certainly isn't worth blowing the motor GUESSING it's false. Turn the boost down to 12-13psi and see if the knock goes away...

 

[krazy86t]

Let us know what you find

I sympathize cuz I've got a similar problem, although i'm not going that far into KR. Checking motor mounts, DP was re-welded to avoid firewall...However, wouldn't a mechanical vibration cause KR in park, neutral at 3-4k RPM? does the ECM know that you do not need KR when the trans is in park/neutral and engine load is zero?

In my case KR can be a few degrees from standing start with lots of throttle (not WOT - too afraid to hit WOT right now). If i slowly creep the boost up to 10-11 PSI on the highway, i get 1 degree constant KR at that boost level. I have to get out of the accelerator quickly if the boost goes to 15psi because there will be several degrees KR (5-7 deg); i only let this happen if testing to see if a change/tweak fixed the problem. I don't hear any load pinging, do you? One thing i do notice is the KR dials back engine performance pretty quickly once it sets in. In your case 14-15 deg of KR must really decrease performance.

My set-up:
-91 oct gas - TT chip is set-up for this fuel and 15-16 psi boost with my combo (3" DP, 42lb inj, pypes Exh, cold air filter, walbro 340 + hotwire).
-Fuel pressure looks good; I increased it to 45psi at idle without vac + 1psi for every psi boost.
-TPS is at 0.46, so supposedly the ECM is not actually in idle mode (need to adjust that); max TPS is 4.30V whith peddle mashed to floor.
-BL and int at idle are 128.
-Reman MAF seems to function - counts change with air flow.
-IAC = 0 but isn't supposed to be involved with engine performance outside of idle. IAC = 0 is probably because TPS is 0.46 and ECM is not in idle mode.

Good Luck!

 

[bmackinnon]

However, wouldn't a mechanical vibration cause KR in park, neutral at 3-4k RPM? does the ECM know that you do not need KR when the trans is in park/neutral and engine load is zero?

Yes, mech vibe can cause KR in P, N... no the ecm doesn't disregard KR in P/N/no load... Knock picked up on in the sensor triggers timing retard.... would be a good idea for you to verify proper knock sensor torque setting... definitely can make a difference if an ape installed it, as it affects the frequency response of the knock sensor... factory spec. is 14 ft-lbs., dry. Pull 14 ft-lbs. with a trq wrench on a random bolt to 'calibrate' your arm, and then duplicate that trq on the knock sensor with a wrench... close enough is, well, close enough...

In my case KR can be a few degrees from standing start with lots of throttle (not WOT - too afraid to hit WOT right now). If i slowly creep the boost up to 10-11 PSI on the highway, i get 1 degree constant KR at that boost level. I have to get out of the accelerator quickly if the boost goes to 15psi because there will be several degrees KR (5-7 deg); i only let this happen if testing to see if a change/tweak fixed the problem. I don't hear any load pinging, do you?

What are the o2's during the hi-mid acceleration? Will the (reman) maf get close to maxing out (255 g/s) when you are getting on it? They won't max out at 11-12 lbs of boost, but should still hit 200+ or so g/s at high load at that level. I'm suspicious of the reman maf, cause if the mid-flow calibration is off, and the reman mafs are notorious for crap calibration, you can see where it could easily cause a lean condition in that flow range. Note the maf # on a hard pull and also look at the lv8... lv8 should definitely go 255 on a hard pull... does it? If the maf numbers look good, smooth, and logical, then pull a degree or 2 of timing from the tt chip across the board via the user adjustments and see if the KR goes back to zero... a deg. or two at a shift or at the naildown is not cause for concern... lingering KR is..... you should have enough fuel press at 45 psi..... shatt gas (91) sucks!

Just to be clear, damage can/is already happening before you hear the audible pinging.... but your numbers aren't damage inducing... like op's!

One thing i do notice is the KR dials back engine performance pretty quickly once it sets in. In your case 14-15 deg of KR must really decrease performance.

My set-up:
-91 oct gas - TT chip is set-up for this fuel and 15-16 psi boost with my combo (3" DP, 42lb inj, pypes Exh, cold air filter, walbro 340 + hotwire).
-Fuel pressure looks good; I increased it to 45psi at idle without vac + 1psi for every psi boost.
-TPS is at 0.46, so supposedly the ECM is not actually in idle mode (need to adjust that); max TPS is 4.30V whith peddle mashed to floor.
-BL and int at idle are 128.
-Reman MAF seems to function - counts change with air flow.
-IAC = 0 but isn't supposed to be involved with engine performance outside of idle. IAC = 0 is probably because TPS is 0.46 and ECM is not in idle mode.

Obviously, be glad you notice the dial back with KR... shows the system is functioning as designed..:smile:

TPS=0.46 is not a problem... if you are anal like me, then adjust it, but it's not causing a problem... neither is 4.3V wot... but since we're anal, i'd fix that too... gnttype.org has a nice little detailed write up on how to maximize the tps range... ie. 0.42 idle/4.5+ wot... but again, 4.3 v wot is not a problem, as long as the ecm is going into power enrichment (PE)...

IAC=0 usually indicates a vacuum leak and is definitely not due to TPS=0.46. Go to the vortex buick site or gnttype.org and do the full monte on the tps/iac juggle... it may take 2-3 iterations... if the iac won't come up, assuming the iac is functional, start looking for a large vac leak... how's it idle?

All this crap should get you heading in the right direction... you're not too far off... just need a little tweakin'!

 

[SCOOBY DOO]

With your 02's at 781, the KR your seeing isn't real...it's a metallic sound the knock sensor is hearing. Could be the DP hitting the frame etc...find out what it is.

 

[krazy86t]

What are the o2's during the hi-mid acceleration? Will the (reman) maf get close to maxing out (255 g/s) when you are getting on it? They won't max out at 11-12 lbs of boost, but should still hit 200+ or so g/s at high load at that level. I'm suspicious of the reman maf, cause if the mid-flow calibration is off, and the reman mafs are notorious for crap calibration, you can see where it could easily cause a lean condition in that flow range. Note the maf # on a hard pull and also look at the lv8... lv8 should definitely go 255 on a hard pull... does it?

from standing start to WOT: MAF is 210-235 (did not see 255); LV8 was 255; O2 about 790-810. However, doing these tests had be nervous because in addition to a few deg KR, i hear buzzing sound from driver's side firewall. Is that the detonation sound these cars produce?

 

[wbrophy]

I have not read all of the replies since I posted but 05 af at idle is quite normal/good. Set the tps than if you still are reading 0 on iac than adjust that so you get a reading, 10/30 is fine warmed up and in park; than adjust the tps again. 780/800+ is good at WOT usually but if you are getting knock you need to turn the boost down as suggested in another post and see if it goes away, if it does than leave the boost at a level that does not knock or increase your octane to get the boost higher. I hope that sound you hear is nothing to worry about.

PS: a degree or two of knock on a shift is quite normal and it goes away in the next reading or two. Always lift if the readings go up on the next frame or two.

"Standard Brand" MAF sensors I have found are the best rebuilt ones that are usually calibrated correctly and I have tried a few! Hell I have went 10.15 at 21 psi on a Standard Brand and it is still going strong after many years.

 

[TrAb]

Yeah i just started reading my scanmaster last night. I upped the boost a little, somewhere around 15lbs. My boost gauge isnt the best i dont think so probably 16-17lbs on 93. I get 1.2 knock retard around 60mph then it goes away around 70mph. Then at like 90-100 i start getting like 3.5kr or so. Im goinng to tune it down just a little more and see how it goes tonight.

I do have a question, is there a method to calculate how many counts of knock im really getting from the readings the scanmaster gives me, from the timing retard?

 

[it's just a six]

Yeah i just started reading my scanmaster last night. I upped the boost a little, somewhere around 15lbs. My boost gauge isnt the best i dont think so probably 16-17lbs on 93. I get 1.2 knock retard around 60mph then it goes away around 70mph. Then at like 90-100 i start getting like 3.5kr or so. Im goinng to tune it down just a little more and see how it goes tonight.

I do have a question, is there a method to calculate how many counts of knock im really getting from the readings the scanmaster gives me, from the timing retard?

No meth injection?

 

[TrAb]

No i dont have meth on this car, i just wanted to bump up the power just a tad

 

[bmackinnon]

I do have a question, is there a method to calculate how many counts of knock im really getting from the readings the scanmaster gives me, from the timing retard?

I don't think the SM will display the knock 'counts'.... the old Turbolink software would... I use DirectScan, and can't remember if it displays or not... I think it does..... don't know about Powerlogger.... but in any case, the number of counts is rather irrelevent... the KR number is the important one to tune by... I suspect the algorithm used by the ecm to determine the amount of timing retard to apply from knock counts received would be a bit complex....

 

[TrAb]

I don't think the SM will display the knock 'counts'.... the old Turbolink software would... I use DirectScan, and can't remember if it displays or not... I think it does..... don't know about Powerlogger.... but in any case, the number of counts is rather irrelevent... the KR number is the important one to tune by... I suspect the algorithm used by the ecm to determine the amount of timing retard to apply from knock counts received would be a bit complex....

I dont think it would be anymore complicated then using the word algorithm

 

[wbrophy]

Believe it or not!!

"Over boost" is one of the "main causes" of poor performance!!!!

 

[TrAb]

Yeah, i have a buddy who CANNOT understand that more boost does not automatically mean more power. Trying to tell him timing retard makes it like im not getting that extra boost.

OOOO i dont wanna make another thread, what temp should my car be at normally? After driving a little my scanmaster said my car was around 214-215 is that normal or is it about to catch on fire and explode??? Thanks

 

[bmackinnon]

I dont think it would be anymore complicated then using the word algorithm

big words = small brain... :tongue: