Knock sensor woes.

[moparman76_69]

I've been fighting an issue with the van ever since I got it together with the CE for knock flashing when I really shouldn't have knock. Right now I'm using stock fuel maps scaled to 40s and 3 bar with 5 degrees of timing pulled out of advancefromRPM2 and the voltage for knock turned up approx. 3 times stock and it still shows knock light anytime I get above 1/4 throttle even sitting still.
I'm assuming at this point I have either noisy injectors or lifters causing false knock. I've contemplated unplugging the sensor but I really don't want to chance it. I tried that with a different cal and broke a piston. I also thought about turning up the sensitivity until it goes away but at what point does real knock get covered up by the noise.
At the moment I'm "winging it" without the wideband in but it'll be in this week. But with stock fuel maps and stock boost I shouldn't have knock and I do.

Any advice on what I should do? Could it be a bad sensor or something? Right now the timing getting pulled makes the van real doggy and rich and it's slowing me down.

[raccoon]

got the exact same problem, i think its a loose bracket making a sound. but i cant find the source for the life of me. if the car is pointed down hill it works way better, night and day difference.

---------- Post added at 06:09 PM ---------- Previous post was at 06:07 PM ----------

we need to make some sort of vibrator. so you can zero in on sounds with the engine off.

[Force Fed Mopar]

I've had the same issue, and still do somewhat. I've tuned most of it out though. For one thing, my old sensor was bad. Put a new one in and started turning the timing down a bit. I set my cal the same as you, stock cal scaled for 40's and 3-bar and running at 15 psi, no wideband to check with. I don't get knock now at wot, but still get it at part-throttle in certain conditions. The warmer weather seems to have aggravated it too. I have a feeling that it's possible that the fuel now isn't as good as the fuel they had back when these were new. Most of it has ethanol in it now, I have a feeling they use ethanol to get the oct rating, meaning they can use a lower oct gas and boost the rating w/ the eth. Could be crazy though

FWIW I did add fuel to the part-throttle between 0-5 psi to fix a lean bog(FuelPartThrottle table), added a bit of fuel above 4500 (with the PumpEff table). I may need to add fuel in the PT table between 5-10 psi as that is where the main knock area seems to be now. However I get knock in vacuum sometimes too, like on hard decel, or cruising between 0-10" Hg, sometimes when I'm just barely touching the gas, about 19-20" Hg at 2k-2500. Thinking to maybe lower the timing in heavy vacuum some.

[Aries_Turbo]

id leave the timing in the AdvanceFromRPM2 table and just take it out at the boost level that you get the knock.

whats the distributor set at?

wanna send me the cal and take a look at it?

brian

[roachjuice]

I'm starting to think mine is false knock too. I checked the plugs and no salt and pepper.

[Aries_Turbo]

you know you dont have to guess if its knock or not.....

get a metal tube (1/2"-5/8"diameter, 4" long or so), smash the end flat and drill a hole in it and bolt it to the block. braze/solder/adapt it to a 3/8" hose barb and hook an air compressor hose to it.

run that hose into the passenger compartment. split it off into 2 hoses (t fitting) and drill some holes in earmuff hearing protectors so that the hose has to be pushed in tightly and seals well to the plastic shell of the earmuff and gets to where sound from it will emanate to your ear well.

get in the car and hammer it. if you can hear mechanical noises of the engine, youll be able to hear knock.

that way you can know if the sensor is picking up real or false stuff.

there are electronic methods too (turboshad did one on his shadow) but most folks here are more comfortable with hoses than wires alot of the time.

brian

[tryingbe]

Buy an OTC scanner. It'll tell you what the knock voltage is, plus it'll tell you which cylinders is the computer pulling timing on and it also supports data logging.

[moparman76_69]

FWIW I did add fuel to the part-throttle between 0-5 psi to fix a lean bog(FuelPartThrottle table), added a bit of fuel above 4500 (with the PumpEff table). I may need to add fuel in the PT table between 5-10 psi as that is where the main knock area seems to be now. However I get knock in vacuum sometimes too, like on hard decel, or cruising between 0-10" Hg, sometimes when I'm just barely touching the gas, about 19-20" Hg at 2k-2500. Thinking to maybe lower the timing in heavy vacuum some.

Sounds similar to me, on decel and anytime I'm over 1/4 throttle doesn't matter if I'm in boose or 10" of vac.

id leave the timing in the AdvanceFromRPM2 table and just take it out at the boost level that you get the knock.

whats the distributor set at?

wanna send me the cal and take a look at it?

brian

Distributor is set to 12 with the coolant sensor unplugged per FSM. I can send you the cal when I get home not that I'd think there's anything in there to see. I took it out based on RPM because it seems to be tied to RPM more than boost, it will knock with 10" of vac if I lean into it too hard.

I'm starting to think mine is false knock too. I checked the plugs and no salt and pepper.

Same here.

there are electronic methods too (turboshad did one on his shadow) but most folks here are more comfortable with hoses than wires alot of the time.

brian

I'll have to look into that.

Buy an OTC scanner. It'll tell you what the knock voltage is, plus it'll tell you which cylinders is the computer pulling timing on and it also supports data logging.

Yeah that would help.

On another note I'm mainly trying to get this combo sorted out for SDAC so I can drag it if it's running good. By the end of the year it'll be a 2.4/420a combo.

[Stinkbox]

I don't have a cel knock flash but awhile ago I turned my ignition adv down to 8 degs and the car runs so much better. Way more power. Not sure what is tripping my sensor out but obviously it is something.

[Force Fed Mopar]

What template are you using? What is the engine combo (2.5 w/ a g-head, or ...)?

[moparman76_69]

2.5 swirl head using the B151 2.5 MTX stock template. Only thing not stock is the 40s 3-bar FMIC and stock T2 garret

[wallace]

Check your alternator bushings. I've bot a Boost Button cal with the cel flash on knock. Recently it would flash on decel and light throttle. I was working on the A/C and found both bushings completely worn out and one of the inner sleeves had pushed all the way through. Replaced the bushings with good used ones from the jy and my "knock" issues are gone. HTH.

[Force Fed Mopar]

Check your alternator bushings. I've bot a Boost Button cal with the cel flash on knock. Recently it would flash on decel and light throttle. I was working on the A/C and found both bushings completely worn out and one of the inner sleeves had pushed all the way through. Replaced the bushings with good used ones from the jy and my "knock" issues are gone. HTH.

Now that's weird I've been wondering about the splash tray under my valve cover (TBI VC), it is missing the little rubber pads that the VC is supposed to squish down on to hold it in place good. It could be rattling at certain rpms or load conditions.

[wallace]

Now that's weird I've been wondering about the splash tray under my valve cover (TBI VC), it is missing the little rubber pads that the VC is supposed to squish down on to hold it in place good. It could be rattling at certain rpms or load conditions.

I would say that missing those pads could definitely cause an issue. How do you like that valve cover setup? I'm going to use the sheet metal one with the shroud on the engine for my Horizon it's got the crankcase vent in the right place for me. I couldn't hear the noise but the knock sensor could. Pretty neat how good that knock sensor actually works if everything is in working order. Weird thing is if I laid into it no cel light at all I would think hammering on it would make that faulty mount buzz quite a bit.

[Force Fed Mopar]

Yeah mine is the same way, no knock at WOT but PT has it all over randomly.

I have the late-model aluminum cover and I like it. The only downside to it I've found is the air intake sucks more oil as there is no baffle inside the cover to stop the oil vapor from escaping. It's not much, I lose maybe a half a quart in a month of daily driving. But it's got my IC plumbing kinda oily inside, and it gets blown into the engine compartment through the BOV. I think a catch can w/ a drain to the pan would probably stop all that though. Or possibly even a filter on the inside of the cover, like what they used to use on carburated air cleaners for the crank vent hose.

Speaking of oil, would sucking oil vapor cause the knock sensor to go off? I don't if oil quenches or aggravates knock.

[moparman76_69]

Don't run the catch can drain to the pan as water vapor collects in there also. I built mine using pvc and steel wool and seems to works ok, a catch can I bought on ebay didn't work and i ended up with oil all in my IC piping.

[wallace]

What does the late model aluminum cover look like? I've only seen the stamped steel ones on TBI cars. Oil vapor will definitely reduce the octane and could cause detonation problems.

[moparman76_69]

It's a cast al cover that has ribs on the top like the old stamped ones but has two nipples on the back and uses a separate baffle like the older ones. Uses the one piece gasket also.

[Force Fed Mopar]

Don't run the catch can drain to the pan as water vapor collects in there also. I built mine using pvc and steel wool and seems to works ok, a catch can I bought on ebay didn't work and i ended up with oil all in my IC piping.

So I guess the factory was retarded for letting it drain into the pan? I've been through this discussion before

What does the late model aluminum cover look like? I've only seen the stamped steel ones on TBI cars. Oil vapor will definitely reduce the octane and could cause detonation problems.

Looks just like the stamped one, but uses the 1-piece gasket like the later turbo covers use. Has 2 outlets in the same positions as the stamped. I believe the finish is powdercoated on the aluminum ones, seems to be more durable.

[moparman76_69]

So I guess the factory was retarded for letting it drain into the pan? I've been through this discussion before

One of the purposes of the PCV system is to pull all the vapor out of the crankcase so condensation doesn't occur. Water in oil even in small amounts can ruin a bearing.


On a side note I'm pretty sure I found the source of my false knock. I was parking next to a building where I could hear the engine sounds reflected back to me and my throwout bearing rattles while the clutch is engaged. Sounds just like a rod knock but goes away when I press in the clutch pedal.