Author Topic: Low boost knock  (Read 5099 times)

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Offline larrym

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Low boost knock
« on: March 20 2015, 01:26:57 PM »
Been helping a buddy with his car, its running great WOT and putting around. But at part throttle he sees retard on the scan master that starts low and climbs if he maintains that speed.


Its a smaller BB turbo that spools insanely quick and it seems to be on boost with any load, this shows by the half empty ALKY tank after trying to tune this out.
 He says it starts as soon as it begins making boost 1-2 PSI and AF reads around 12.0 on the wide band he has a screw type boost controller and stock type waste gate.
TT chip 42lb injectors, EGR deleted, Razors Kit,


We have played with the gain knob on the ALKY, tried a different MAF with a translator no change, fuel pump is new same with filter, all sensors are set and double checked.


We are going to try a known good ignition module to see if that clears it up.


Are there any other things we should look at?


Its the old motor out of my car and its kinda tired but does not knock at WOT, I told him to just drive it with the throttle mashed  :rock:  its around town that makes it a pain....
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
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Offline good2win22

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Re: Low boost knock
« Reply #1 on: March 20 2015, 02:50:07 PM »
Can you put up a log?  I would be interested in seeing what the timing is doing right before the knock
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Offline larrym

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Low boost knock
« Reply #2 on: March 20 2015, 02:52:59 PM »
No power logger ....
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline larrym

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Low boost knock
« Reply #3 on: March 20 2015, 02:54:04 PM »
We did pull timing in 1-2 to try and eliminate it  did not do much.
« Last Edit: March 20 2015, 03:42:17 PM by larrym »
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline earlbrown

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Re: Low boost knock
« Reply #4 on: March 20 2015, 04:55:51 PM »
Flat spot with the TPS?
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Offline larrym

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Low boost knock
« Reply #5 on: March 20 2015, 05:48:26 PM »
Cool something else to try I have an extra we throw at it thanks Earl!
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline Scoobum

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Re: Low boost knock
« Reply #6 on: March 20 2015, 06:01:37 PM »
Put your PL on his car and make a log.
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Offline larrym

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Low boost knock
« Reply #7 on: March 20 2015, 06:10:50 PM »
Mine does not exist either.... I  have autoXray that will capture data but not timing.
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline Steve Wood

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Low boost knock
« Reply #8 on: March 20 2015, 07:51:32 PM »
What are the o2s during this?
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Offline larrym

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Low boost knock
« Reply #9 on: March 20 2015, 08:02:43 PM »
On the wide band they are about 12.0 did you want the narrow band readings?
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline Steve Wood

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Low boost knock
« Reply #10 on: March 20 2015, 09:58:10 PM »
That's OK.... I wondered if it was rich... But it looks pretty lean
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Offline larrym

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Low boost knock
« Reply #11 on: March 20 2015, 11:07:14 PM »
That's where it starts if he replicates the issue on a long hill and brings in some boost the ALKY starts to spray and you can see the WB start to drop into the 10s and the knock retard continues to climb until you let off or mat it. I don't hear any detonation.
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline Steve Wood

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Low boost knock
« Reply #12 on: March 20 2015, 11:29:52 PM »
If it's very far into the tens, you can get so called rich detonation which can trigger the knock sensor.  Is PE being commanded by the Ecm?
Steve Wood

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Offline larrym

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Low boost knock
« Reply #13 on: March 20 2015, 11:45:34 PM »
It's strange it will start just as it starts to build boost that's when the AF is around 12 if he tips in more bring on boost up to say 6 to 10 psi it continues to show retard and the AF drops as the ALKY comes in. Everything seems to be working like it should it is a challenge. I guess it could be engine noise this motor has been abused valve train is new cam lifters chain.
86 white T type with t tops and blackout trim. 60lb injectors Gen 2 with Extender Chip TR6 ignition 212/206 roller cam Turbonetics BB CPT 61 CAS V4 Intercooler Cobbled together Alky Injection 4 inch MAF pipe with integral sensor
2800 stall lots of fun with a little 6 banger!
Best ET 11.36

Offline Steve Wood

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Re: Low boost knock
« Reply #14 on: March 21 2015, 10:50:58 AM »
Does it seem to be prevalent at a given rpm range or does it occur anywhere in the band?
Steve Wood

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A lot of broken parts does not make you a racer; it makes you a slow learner.

 

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