Need some help with my knock sensors!!!!!! [Archive] - Cherokee SRT8 Forum

: Need some help with my knock sensors!!!!!!


UDLOSE
05-15-2007, 08:36 PM
I was wondering what voltage my knock senors should run at idle.....I am getting .5 all the way up to 5 on both sensors and its not constant either goes back and forth never sitting still.I know this is killing my
ET's by retarding my motor.How do I fix it??????

timster
05-15-2007, 09:45 PM
you should be getting no readings from the knock sensors, Idle or otherwise. The knock sensors should only go off if there is a problem with pinging, or if the sensors are bad. Seeing that both of the sensors are picking up knocking, I would take it to the dealer.

I have a similar problem with my truck, but it is only on one of the two sensors. My PCM retards timing via knock retard consistantly when I start the car first thing in the morning. I have found that if I start the jeep, let it idle for about a minute, and then restart the truck, the knock retard goes away, even though one of the knock sensors still indicates knocking.

I plan on taking mine to the dealer sometime this week. I'll post my results when I get the truck back.

UDLOSE
05-17-2007, 02:29 PM
dealer won't help without charging??

timster
05-17-2007, 05:58 PM
hopefully it is covered under warranty. I didn't buy the truck to perform at non optimal conditions

pjvreede
05-17-2007, 07:38 PM
I was wondering what voltage my knock senors should run at idle.....I am getting .5 all the way up to 5 on both sensors and its not constant either goes back and forth never sitting still.I know this is killing my
ET's by retarding my motor.How do I fix it??????

Out of curiousity, does your Dashhawk show "Ignition RTD" #'s above 0.0 with these elevated knock sensor voltages? I don't follow the knock sensor voltages, but rather the "Ignition RTD", which rarely reads anything but "0.0".
I could set up my Dashhawk to follow all three of these parameters if that would help you answer your question.

FastSRT8GC
05-17-2007, 08:38 PM
This will be one of the fields I put in my dashhawk once i get it back. Seems to be a problem.


Inferno what is yours reading? You seem to have the strongest truck here!!!

UDLOSE
05-19-2007, 09:02 PM
The volts are always running .49 all the way up to 4.9.

I am getting a stage 2 Heads and cam package from HHP on june 11th.
They said if they are broke they would fix them.

If I am right this is the reason all the jeeps run different ET'S.
Very simple car to drive:)

Can't wait to run low 12's or high 11's:) :) :)

Inferno SRT8
05-19-2007, 09:04 PM
This will be one of the fields I put in my dashhawk once i get it back. Seems to be a problem.


Inferno what is yours reading? You seem to have the strongest truck here!!!


I have not looked but I will and let you know!

UDLOSE
05-19-2007, 09:07 PM
Yeah man let us know:)

Inferno SRT8
05-20-2007, 11:54 AM
Ok just ran some tests at idle im at 0.072 bouncing up and down no higher, at WOT the highest it went was 1.335, both sensors are pretty close in voltage output after WOT and just cruising both stay around 0.480-0.700 and just bounce up and down normally, not once did I see any of the knock sensors go to 5.00 volts.

Grip Grip
05-20-2007, 08:02 PM
I was wondering what voltage my knock senors should run at idle.....I am getting .5 all the way up to 5 on both sensors and its not constant either goes back and forth never sitting still.I know this is killing my
ET's by retarding my motor.How do I fix it??????

I just got my Dashhawk and confirmed over the weekend that I'm getting the exact same readings. Also I confirmed that my timing is in fact being retarded.

Let me know what you find out. I suspect it has something to do with the loudness of the headers. I may try wrapping them. On second thought, that's too much work, I don't know what's next.

Anthony

Inferno SRT8
05-20-2007, 08:08 PM
I just got my Dashhawk and confirmed over the weekend that I'm getting the exact same readings. Also I confirmed that my timings is in fact being retarded.

Let me know what you find out. I suspect it has something to do with the loudness of the headers. I may try wrapping them. On second thought, that's too much work, I don't know what's next.

Anthony


Anthony your getting 5.0 volts readings on the Dashhawk? We have the same set up and im not seeing anywhere near 5.0 volts.

Whats going on?

Grip Grip
05-20-2007, 09:54 PM
Anthony your getting 5.0 volts readings on the Dashhawk? We have the same set up and im not seeing anywhere near 5.0 volts.

Whats going on?


Got me. Any ideas on a way of confirming whether the sensors are actually identifying knock or giving me false positives?

I'll probably be driving my Jeep down to Florida for work in the next couple months. I think I'll drop it off at KRC and see if Marty can figure it out.

Inferno SRT8
05-20-2007, 09:56 PM
Got me. Any ideas on a way of confirming whether the sensors are actually identifying knock or giving me false positives?

I'll probably be driving my Jeep down to Florida for work in the next couple months. I think I'll drop it off at KRC and see if Marty can figure it out.


The knock sensors have a foam protector on them, make sure that there on both sensors, the knock sensors have to be removed during header install. Never know.

Good luck

UDLOSE
05-20-2007, 10:16 PM
Man these jeeps are to smart for their own good:)

rainmaker
05-20-2007, 11:21 PM
Got me. Any ideas on a way of confirming whether the sensors are actually identifying knock or giving me false positives?

I'll probably be driving my Jeep down to Florida for work in the next couple months. I think I'll drop it off at KRC and see if Marty can figure it out.

Grip,

try some higher octane... Do you have access to 100 octane in your area? I think it's false knock, but higher octane will help point you in the right direction. False knock can still effect performance, but doesn't mean the engine is killing itself....probably something rattling around that the sensors are reading as engine knock. Don't use any Octane booster and don't go above 100 octane. Heck you probably only need a couple gallons to be sure....

The best way to tell is use some sort of data logger to watch the voltage of the sensors, compared to the o2 milivolts. A wideband would help too, but not really needed. The dashhawk has some primitive data logging built into it. I'd log Knock Retard, and one of the primary o2's (since it only gives you two PID's)... the sensors voltage can be erratic like you're seeing, but unless it's triggering the PCM to back off timing it's really not a concern. The only way to tell if it's really effecting you is to data log Knock Retard, and record a couple WOT runs. If you're getting more than 1-2 degrees of KR, then something is fishy. A little KR once in a while is normal especially between shifts.

Post back here with results, and good luck!!

Blown7
05-21-2007, 04:27 AM
There was a old mechanics trick, where you could check the knock retard on GM engines. Hold the engine at 3K RPM and tap the block with a big screwdriver handle. The engine timing should retard just by doing that.



Jeff

SpeedRacer333
06-08-2007, 07:01 PM
Any updates on this??? I just got my dashhawk and took some readings today. Knock sensor 1 always reads exactly 0.4375, and 2 reads 0.0000.

It was a horrible 95 degree humid day, and my knock retard never read anything over 0.0. That has got to be a dashhawk/CAN issue only with some vehicles?

Blown7
06-08-2007, 07:55 PM
Any updates on this??? I just got my dashhawk and took some readings today. Knock sensor 1 always reads exactly 0.4375, and 2 reads 0.0000.

It was a horrible 95 degree humid day, and my knock retard never read anything over 0.0. That has got to be a dashhawk/CAN issue only with some vehicles?

Seems like your fine, the lower the voltage the less the timing retard. So if one is at .4 and the other at 0 you have the best timing advance you could ask for.

Jeff

SpeedRacer333
06-08-2007, 08:58 PM
Seems like your fine, the lower the voltage the less the timing retard. So if one is at .4 and the other at 0 you have the best timing advance you could ask for.

Jeff

I can agree with that - it just seems like that fact it was giving that same reading at idle, cruise, WOT, whatever, it never changed? I woud expect we all should be reading how Tony's reads. I guess I'll give it the "tap" test tomorrow.

Inferno SRT8
06-08-2007, 08:59 PM
I can agree with that - it just seems like that fact it was giving that same reading at idle, cruise, WOT, whatever, it never changed? I woud expect we all should be reading how Tony's reads. I guess I'll give it the "tap" test tomorrow.


Got to love my 2006! :D

timster
06-08-2007, 09:02 PM
Any updates on this??? I just got my dashhawk and took some readings today. Knock sensor 1 always reads exactly 0.4375, and 2 reads 0.0000.

It was a horrible 95 degree humid day, and my knock retard never read anything over 0.0. That has got to be a dashhawk/CAN issue only with some vehicles?

I have the exact same readings as you...wtf??

Inferno SRT8
06-08-2007, 09:07 PM
I have the exact same readings as you...wtf??


Seems the 2007 are electricaly different in some ways, both my knock sensors read the almost the same, damn I love this Dashhawk.

timster
06-08-2007, 10:18 PM
yeah, the DashHawk's awesome

UDLOSE
06-09-2007, 10:47 AM
Yes it is:D :D

SpeedRacer333
06-11-2007, 03:58 PM
Hopefully,
This is issue is a minor fix through a future dashhawk firmware update...
http://www.msdignition.com/forum/showthread.php?p=37791&posted=1#post37791