Knock voltage less than 0.8 volts

[TopDollar69]

Here is a printout from my otc scanner. The knock active is on, but the voltage is less than 0.8 volts, which is what the Minimopar site says is the starting point for knock with Chrysler computers. The scanner is showing knock as being active, but I have no speckles on my plugs and the compression is still good in all four cylinders. The car is an 88 Lebaron running an 89 2.5L cal with a stock 2.5L TI thats intercooled with a garrett turbo. I am also running a G valve. Is the voltage actually lower than 0.8 volts to indicate knock?

Thanks,

Ben Huebner



CHRYSLER 1989 2.5 TURBO VIN J

FAULT CODES: 62

-- BASIC INFORMATION BLOCK --
ENGINE COOLANT TEMP 190 F
IDLE RPM X 10 095
INJ PULSE WIDTH 18.9 MS
MAP 48.1 IHG
O2 VOLTS 0.94 V
ENGINE RPM 3542
THROT POS SENS VOLTS 3.00 V
TPS MINIMUM 1.14 V

-- ENGINE INFORMATION BLOCK --
BARO PRESSURE 27.5 IHG
BARO PRESSURE VOLTS 2.34 V
BATTERY TEMP 060 F
BATTERY VOLTS 14.1 V
ELECTRONIC ADV/RET 007 DEG
KNOCK ACTIVE YES
KNOCK RETARD #1 000 DEG
KNOCK RETARD #2 000 DEG
KNOCK RETARD #3 004 DEG
KNOCK RETARD #4 000 DEG
KNOCK SENSOR VOLTS 0.72 V
MAP VOLTS 3.84 V
VEHICLE SPEED SENS 054 MPH

-- MISC. VEHICLE DATA INFO. --
ENGLISH/METRIC ENG

------ PRINTING COMPLETE ------

[MiniMopar]

At that RPM, knock voltage should be about 0.86V. The threshold varies across the RPM range and is tweaked from year to year. 1989 T1:

[TopDollar69]

Russ,

Is that a D cal parameter that can be adjusted?

[MiniMopar]

Yes, it is.

[Mysterio]

I know this is kinda off topic but how do you do a printout like that with your OTC? Connect it to your laptop?

[TopDollar69]

Yes, I made a cable to go from the round plug on the top of the scanner to a 9 pin serial connector. I then used HyperTerminal which is built into Windows to accept the info from my old OTC2000. You just do the print function on the scanner and it will come up on hyperterminal. You will need to set the baud rate on the scanner and in hyper terminal to match each other. I can't remember what the print function keys were, but I think it was 2 keys at the same time or something along those lines.

[TopDollar69]

Just another note, you will need to do this real time with a laptop. I have not been able to get an OTC2000 to store any info even with the pathfinder cartridge. I think it has something to do with the fact that the OTC2000 has no built in memory.

[Mysterio]

Just another note, you will need to do this real time with a laptop. I have not been able to get an OTC2000 to store any info even with the pathfinder cartridge. I think it has something to do with the fact that the OTC2000 has no built in memory.

Interesting, thanks for that info. Another question, how do you manage to actually drive the car on the road and realtime log those things( I see it says 54 mph) with the OTC hooked up? Since it has to be hooked up underneath the hood how do you connect it and have it running into the car without the hood closed or having the hood closed and possibly pinching/damaging the connection cable??

[TopDollar69]

I made the cable longer with some scrap wires i had out of an old engine harness I parted out. You only need to extend 3 of the wires. I ran the wires through the fender and then they are just run through the door frame. The door seal has enough give to let it pass through without pinching it.

[Mysterio]

I made the cable longer with some scrap wires i had out of an old engine harness I parted out. You only need to extend 3 of the wires. I ran the wires through the fender and then they are just run through the door frame. The door seal has enough give to let it pass through without pinching it.

Ok alright. I took a look at my scanner and it seems someone has already hooked up a serial cable in that spot by completely taking the scanner apart and connecting it on the inside. So I've got what looks to be a 3 or so foot cable w/ a serial cable. Maybe I'll look into hooking it up to my laptop if I ever fix my laptop lol. Thanks.