Knock when starting from a stop

[Bouche Dag]

Car is a 92 AWD. Mods as follows: JDM EVO 1 RS engine with 16g turbo, 510cc injectors, 90 ECU (with pins swapped), BSE, o2 sensor is good, 3in. GM MAF w/translator, FMIC with dejon tool piping, -6an fuel feed line/custom fuel feed line fitting, summit racing high flow fuel filter with male -6an fittings on both sides (about the size of a co2 cartridge), -6an return line, wally 190, bored throttle body w/half shaft mod.

The Problem: When I am starting off from a stop (not hard launching, just DDing) I get 4-9 counts of knock. I run 93 octane and my timing is set at 5*BTDC.

Any ideas? Should I try to adjust the mid knob on my maft?

 

[Bouche Dag]

I am going to replace the plugs to BPR7ES (currently running BPR6ES) to see if one step colder will help with the knock. I also need to replace the plug wires. I will report back my findings.

 

[Bouche Dag]

So far so good... The new magnecor wires and 1 step colder plugs have brought my knock down to 1-2 counts here and there with 1 count MAX when taking off from a dead stop. I've only put 10 miles on the new setup so far so I'll have to give it a few more days to make sure.

 

[97gsxIA]

If its under 3k rpm it is most likely phantom knock. Could be motor mounts or an old knock sensor getting gummy

 

[Bouche Dag]

If its under 3k rpm it is most likely phantom knock. Could be motor mounts or an old knock sensor getting gummy

Well that's a relief! I'd hate to be damaging my precious EVO1 engine!

I made motor mount inserts per the VFAQ using a hard cutting board and my knock sensor was untouched. I am 95% sure it's the OE sensor off of the EVO donor... I didn't bother changing it because it still had the black goo in the back and it hadn't leaked out.

 

[jmartinez1228]

I say get rid of that maf translator, get a dsmlink and call it a day. I had the same exact problem when i was running a maft.

 

[97gsxIA]

Well that's a relief! I'd hate to be damaging my precious EVO1 engine!

I made motor mount inserts per the VFAQ using a hard cutting board and my knock sensor was untouched. I am 95% sure it's the OE sensor off of the EVO donor... I didn't bother changing it because it still had the black goo in the back and it hadn't leaked out.

Get ecmlink sooner than later. Also, do some searching on here about phantom knock and you can try tracking it down if you want.

What are you using for datalogging?

 

[jed344]

knock sensors can be very sensitive id guess its phantom knock and not worry especially if its really low amounts of knock.

 

[Bouche Dag]

I'm taking everyone's advice and bought dsmlink.

I was using mmcd to datalog. Link will be here Friday.

 

[anchew02]

I was getting the same issue right from a start. My knock gauge would max out and if i let off the gas it would drop and then and only then could i step on the gas again and get going. I have been fighting my pk issue for awhile and i have finally found that it is my turbo. When i would step on the gas there was excessive shaft play so it would vibrate due to an imbalance in the housing and the sensor would pick it up and then pull timing.

 

[crazyquik22023]

Most likely your knock sensor is loose or is very dirty. Maybe try to tighten it down some more or take it out and clean it. Either way though its more than likely nothing to worry about. If your sensor checks out good and you still get knock its probably phantom knock. I would only worry about it if you see high knock counts when under a lot of load.

 

[turboglenn]

You've got nothing to worry about really. Even on my still fairly fresh wiseco 9:1/eagle H-beam engine that's built to rather tight specs as far as piston to wall and such there's noise that even my expensive J&S stand alone knock sensing system picks up any time i jab the throttle from dead close.. more so cold than hot but really anytime i want to make sure the display is working and it's picking up correctly i'll just give it a sharp jab of the pedal (mostly in neutral from idle) and i'll see around 2-3* being pulled from a cylinder or two (J&S retards eacy cylinder on it's own by counting what cylinder is firing or has fired when the knock was detected and displays how many cylinders it's taking timing from and how much it's taking, as well as showing you how fast it can feed it back if it's able to)

I've even had my system sent back in and calibrated (algorythim changed a little) to compensatew for teh forged pistons and other common 4g63 noises that cause PK. NO matter how much i even dial down the sensitivity on the use controllable setting any sudden jab of the throttle especiallyu in neutral or with the clutch in will generate and pick up some pistpon slap

I also got this same slap on the stock blocks I've ran in the past, and the more milage the more wear/clearance and slap you're liable to get, it's nothing to really worry about though

One thing that can REALLY cause someknock sensor activity is to be WOT, let offand re-gun it while staying in the same gear.. (when i granny shift the J&S is turned off below a TPS reading of 1.75volts to it sorta resets for each gear change unless i flat shift the car)

and when you say "1 count of knock" do you mean actually "one count" or "one degree pulled"?? thjere's a difference, it takes a certain amount of counts of knock to pull each degree of timing so i thought i'd clue you in on that if you didn't know

There's a lot of fear of knock in the DSM community, but if you read up much on detonation and pre-ignition you'll find that tuning to completely avoid any knock at all is leaving a lot of power ojn the table, a knock sensotr is nice, but tuning just to make it never go off is tuning like a mitsu engineer (meaning more to avoid warranty claims and keep power under a certain level compared to making the best power you can safely)

I wish i bookmarked some of the stuff i'veread in the past but i'll find you 2 links i know off right off the bat here real fast

This one is 8 pages long, look for the "next" link at the bottom of the last paragraph on the left side of said paragraph
Engine Basics: Detonation and Pre-Ignition: Streetrod Stuff

here's another good one
Pelican's Perch #43:<br>Detonation Myths

and here's some reading on the J&S unit and knock theory and such
J&S Electronics • Tech Articles

 

[mschlanglv]

I had knock from a start that was worse when cold, better when things warmed up. During a recent rebuild I found the coolant pipe and alt mount had loose bolts. I imagine a little clutch shudder from a stop and those parts probably started rattling around triggering the knock sensor. Haven't fired the new engine, but I can't imagine those loose parts were helping anything.