Slightly off topic, but...KS bypass

[squeefoo]

I asked this in the Maxima section but so far no takers... and I trust you guys My Mom has a '94 Maxima with a bad det sensor (code 34), so I went and bought some 470K resistors to by-pass it with. I hooked the resistor up between the connector to the ECM and a ground.....and before I hear about melted/punctured pistons, I can't get a sensor until Wed. next week.She is getting 11MPG (!?) and has to drive around this weekend "visiting" so this an emergency and it really runs like crap.

It seems like the only way, normally I hate doing stuff this way

Is this how I hook it up to bypass the KS? TIA

[Q451990]

As a temporary solution - I think this should work. I'm not sure exactly how the connection should be... is the harness using the sensor's physical connection to the engine block for ground? Did it clear the code?

Heath

[99q45t_vl]

I'm not sure it's going to work. Please correct me if I'm wrong, the ECU is checking for both resistance and the voltage in the correct range from the sensor expecting to hear the sound of the engine at normal RPMs and speeds. The first part of the equation is there, but the second one is not.

[squeefoo]

I'm not sure it's going to work. Please correct me if I'm wrong, the ECU is checking for both resistance and the voltage in the correct range from the sensor expecting to hear the sound of the engine at normal RPMs and speeds. The first part of the equation is there, but the second one is not.

I agree... that's why I asked. This seems to be common out there for all the kids who put on S/C and turbos.

It does put out a .001 - .002 ? AC voltage from the vibrating crystal, so I'm not sure how this is resolves that either. Anyone????

[squeefoo]

As a temporary solution - I think this should work. I'm not sure exactly how the connection should be... is the harness using the sensor's physical connection to the engine block for ground? Did it clear the code?

Heath

That's what I assumed (ground through block). Didn't start it yet since I wanted to see what the consensus was, I cleared it at the ECU. Thanks Heath.

[elwesso]

most times KS dont cause such bad gas mileage.. on my Q with bad KS, i still got 20ish MPG.

[squeefoo]

She said she was getting ~ 28 before. (????)My KS were bad and just turned my Q into a total dog. I've spent hours on the internet searching for this, it's like it's some big secret

[Q45tech]

The problem is the KS [harness/connector] also contains the wiring for ecu coolant temp sensor...............................it's some big secret

[RobertsnewQ]

You need a 550k resistor between the center wire of the KS harness and ground (to the engine block). The other wire should also be grounded.

Works great. On the Q you will get MORE power and no pinging if you only use premium. Probably the same on the Max. Out here in CA you'll get pinging on a hot day with 91 octane and the stock ECU, but everywhere else should be OK.

Oh, and even OBD-II does not listen for engine noises - Ideally it won't hear any in normal cases!

The resistor trick is well-known in Nissan circles.

[squeefoo]

The problem is the KS [harness/connector] also contains the wiring for ecu coolant temp sensor...............................it's some big secret

With all due respect... this is a 1994 Nissan Maxima, not a 1990 Infiniti Q45. This has a single wire with one (1) connection in a double connector. Isn't it too early to be drinking <j/k>

You need a 550k resistor between the center wire of the KS harness and ground (to the engine block). The other wire should also be grounded.

The resistor trick is well-known in Nissan circles.

Thanks Robert, there is only one wire on this thing, it appears to be working after two heat cycles = no codes.

I think it's funny that it's mentioned many times on the internet, but no one ever actually tells how to do it, or gives any specs. I spent a lot of time yesterday trying to find out how to do it.I only found 470K resistors at Radio Shack, and the spec for the KS is/are 500 - 620.... it seems to be working for now... thanks all !!

[Q45tech]

560k is the closes more common resistor value............resistors come in +- 10%, +-5%, +-2%, +-1% of labeled [color coded] values and off course wattage rating 1/4,1/2, 1, and 2 watts...5 watts all the way up to hundreds of watts.....................obviously at high ohms and low volts even 1/4 will do. but 1/2 watt has bigger thicker leads that bend better without breaking.

The KS has one terminal grounded via the mounting bolt and the other connection is shielded thus 2 wires except the sheild stops short of the actual KS..........that ground goes nowhere.

Why you must ground [engine block] one side of resistor and connect other side to center conductor of KS wiring harness...............unless you just bypass the whole harness at ecu or intermediate point.

Most ethical people try to protect the non automotive engineers from themselves but we change engines for a living so.............why not try we can always replace your engine for a fee.

In other words any use of the above is purely and soley at your own risk and I won't shed a tear or lose any sleep about the results.

I have made some lovely [from old KS harnesses] tester that emulate the KS and the 174F voltage from coolant temp sensor [thermistor].

Can't be used to cold crank or warmup but swapped in when engine is hot to show prospect what will happen when new KS and Harness are installed....dramatic increase in power that even an owner can feel.

Of course we know KS are bad from Consult so this would be a shot in dark diagnostic aid without knowing. Guess you could ohm test first then confim with emulation.

I have even made a coolant temp fine tuning box that shows what happens when you lower a real 210F COOLANT TO 174F [indicated] and how with good enough fuel the 4 degrees of ignition advance you gain back is noticeable.............to sell radiators, cooling fans, and cleanout condenser/leaves, etc.

[Q45tech]

Lots of these diagnostic tools are dangerous in the hands of people who would use them to avoid fixing the real problem...................why the software is there in the first place to increase engine reliability when things are not as new.

You can have someone sign a document that they take all responsibility then turn around and sue you claiming they didn't understand or you should have warned them better..............why people avoid discussing these things.

I remember the case of one such owner who said [in court] we should have refused to give him his car back if [since] the water pump was leaking since he didn't understand that a leak could destroy his engine if he ignored the temperature rise.

BYPASSING KNOCK SENSORS [or fooling ecu in other ways] CAN DESTROY YOU ENGINE IF the engine knocks [you may not be able to hear the knocks] and thus are unaware that the damage is occuring!

[squeefoo]

Thanks for the info.

I've ordered a new KS but won't be here until Wed., then it will be immediately installed since I don't like it either.

Mom says it runs alot better, and Merry Christmas !!