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Knock Sensor Connection To Harness?


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during removal of he intake manifold it was noticed that the knock sensor was not connected to anything. after reassembly all connection were put back in their original places. this left no connectors empty. there was one single wire coming from the harness side. naturally i assume that this is it. most knock sensors i have dealt with in my career are single wire connections. at this point i g to my reference material (mitchell on demand & alldata pro) to verify this is the correct wire it should be connected to.. this is where my trouble started. wiring schematics show this sensor with a 2 prong connecter. from the harness side it shows a blk/red and a white wire. i found that connector but it plugs into what i imagine is a ground for he cooling system located on a bracket hung on the pipe to fill the cooling system. that sensor has the same appearance as the top of the knock sensor but does not mount in the block it only touches the bracket which hangs on the fill pipe. that sensor is however connected to the blk/red and white wire 2 prong connector. the schematics did not show this sensor or ground. the single wire coming out that has no connector just wire the same as the knock sensor is a blu/yel wire. i could not identify this wire as anything on the schematic except having a diode at the end. so does any one have any idea where this may connect? the wire coming out of the sensor is a single wire with a shielded ground and just as the blu/yel wire has no connector on it. if any one has info on this it would be greatly appreciated.. got the engine running but between the fouled plugs and the knock sensor it has a litte bit of a rough idle. I am even more amazed that after driving the car (10 mi. or so) and operating it to burp the cooling system no mil is on and there are no pending codes. i imagine the customer drove it this way with no cause for concern i can not send it on its way like this though

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The KLG4 knock sensor is a 2 wire sensor with 2 pin harness. In the diagrams it looks to go in the direction of the throttle body area.

Here are some scans from the 2001 manual. It's the closest I've got.

img-334355-1-01-40B-32.jpg

img-334355-2-01-40B-33.jpg

GL and get that 626 back on the road. :)

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Hmmm.

I just checked my 2000 V6. The wire from the knock sensor is a pair of wires (one red and one black, I think) that connect to a bracket bolted to the coolant filler on the passenger side. On the other side of that connector is a blk/red and white pair of wires, going into the loom.

My 94 MX6 V6 is totally different. The wire from the knock sensor (it looks like a single wire, but may be coaxial) goes to the driver's side, to a connector on the throttle body just below the tps.

I have a hunch that some previous owner replaced the original 98-02 KLG4 engine with a 93-97 KLDE engine (or maybe a KLZE Japanese domestic market).

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The engine code is always stamped on the block NickR. I don't remember exactly where it is on the V6 but you can do a search for that. Plenty of topics on how to spot the difference between a DE/ZE and the same probably applies for the G4.

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ok so there is a sensor on the coolant fill tube attached to a bracket. the sensor does have the same colored wires referenced for the knock sensor. so if that is the knock sensor what to do with this other knock sensor. the sensor i cant find the connection for threads into the center top of block under the intake and coolant pipes. the car is idling rough and clearly that is most likely the cause. however today i found out that the person who had originally owned the car had some how rigged the ecu or damaged the harness so that his o2 sensors would not operate so he could fool emissions. this was a horrible idea on his part. customer was bitching about having to buy new head bolts which list at 130 and i got for 80. i've got a disclaimer list a page long because instead of buying new necesary parts they wanted to reuse old ones. hence the reason i shelled 100 dollars for a new timing belt tensioner. some people just dont understand that by doing things this way they will find themselves right back on the side of the road. anyways, if you could maybe post a picture of yours. tomorrow i will post some pics of this mess. one thing that is good is it does not over heat and other then at idle the car (engine) seems to operate nicely. thanks for your help

PS

i will ask the customer of any known lower end swaps.

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@ monoxidechild: the sensor we are talking about does not go into the coolant pipe. to the left of the sensor that we are referring to is the coolant temp sensor and a ground. does your mazda have a sensor that is hung on a bracket right under the coolant pressure cap? this one does and it clearly is not a temp sensor seeing that it does not go into the cooling pipe or block to read coolant temp. thanks for your input though

@djdevon3: All other wire colors match up with what is referenced on the wiring schematic. so i'm thinking that what may have happened is the previous owner had a knock sensor failure and maybe he tried to modify it with a knock sensor set up from the other block configuration. seems like something he may have done seeing the way he tried to mess with the ecu to effect the o2 sensors trying to pass emissions.

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If he's trying to fool the 02 and mess with the knock sensor then you know that engine has some combustion issues. Bad gas? Unlikely if this is a prolonged issue. Might not be a bad idea to do a compression test and timing check. Whatever is causing his combustion issue seems to be the root cause for all of his issues. He's only made things worse by trying to cover it up.

Fellow 626 owners, please do not ever attempt to fool the ECU as a permanent solution. You might just as well shoot your car in the head like a lame horse. The end result for your engine will be the same. Please take it to a mechanic. Get the issue fixed properly and then get emissions tested.

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@djdevon3: so the timing is good. I am a mechanic and I just tore the car down to the heads. the only way the timing is off is if there is a undisclosed secret like on the pt cruisers where you set the cams off one tooth. I did not see any tsb on this and so i set it according to all timing marks. The car had sat for a couple months with blown heads. the spark plugs where the old plugs and where fouled. I have told the customer that many of these things can cause that rough idle. I have advised them that until they spend the money to fix these what could be small issues their vehicle would not operate at peak performance. So many little things like that which they have let go and now it is effecting the performance of the vehicle. there was no code for the knock sensor but an 02 code did come up, guess his tom foolery was unsuccessful. Had I known the real history of this car I probably would not have taken the job as I am not trying to marry or make a career out of this vehicle. I will check everything else. another thing noticed is not all injectors seemed to sound the same through the stethoscope. To many issues that it could be and with out them wanting to spend any more money I cant spend all the time going through it all. knowing that the head installation was performed correctly minus new parts they were advised to get and did not, due to funds. makes no sense to pay me all that money to put the new heads on and then not spend the lil bit extra to replace needed parts and give the vehicle a tune-up makes no sense. what do i know though. haha!

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j.tayorauto: any chance you could post a picture of that sensor, and how it is attached to the bracket near the coolant filler cap? Is that sensor just hanging there, dangling from the wire? This car sounds very strange.

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