Tempermental Cam Sensors

[spf_lexus]

Im out of ideas. I have searched and searched for info on UZ cam sensors and a solid way to solder cut lines but no luck. I have had 2 incidents where my serpentine belt jumps an idler and cuts 1 or both sensors. I have since replaced 1 of the 2 sensors with a used one but I cannot simply swap the driver side sensor. I actually cut a couple wires with tin snips by accident when I was trimming away some plastic loom casing in roder to make room for my supercharger bracket. The cut is AFTER the cam connector so its officially part of the engine harness. I soldered the line and used heat shrink on 1 wire and the second I had to use an extra piece of wire to gain enough room so make the connection. I must add that I used generic 14 gauge speaker wire, not official auto specific wiring but I assumed it would not make a difference. Both are copper of the same gauge with similar jacket thicknesses. Anyway I have made an improvement where the car will not die at idle and wont stumble as wasily but no matter what, at 60mph+ the car jumps like a bucking bronco until I either slow down to 50mph, or floor the gas. I know its my cam sensors because before I touched this used engine in its N/A form, it ran perfectly at all rpms and loads.

If anyone has a similar story or any insight/reccomendations please let me know. Any info is appreciated,

Sean

 

[cribbj]

Sean, for sensor signals such as cam, crank & knock, I would use only shielded cable, making sure that the shield is continuous and grounded only on one end, not both.

 

[spf_lexus]

Thanks John. Do you know the name of the ty pe of cable and where its readily available? I was told by my electrical teacher to just wrap each linbe with tin foil and then ele. tape each but something tells me there is a more professional way to do this.

I just wrapped the line with electrical tape and so far no change. I am goin to try and removing the section that I added and then solder the original 2 ends so I know the section is sound and then i can rest easier knowing I have 1 connection versus 2.



Just out of curiousity bit if i cure the cam sensor issue, could this type of ignition miss be caused my bent pass. side o2 sensor? I would assume that a faulty o2 would show issues within the entire rpm range but you never know. It almost feels like belt slip but every now and then it misses down low. Its a vary harsh bam... bam...bam... that goes on only over a certain speed and load. downhill cruising over 60mph wont miss nearly as often versus flat or incline so its load dependant. Im pretty sure the cam sensors trigger the ignition timing and this would make snense when at 60mph, I have a lot of air being channeled w/ minimal tps input, which would mean very little dwell time per coil?

 

[xspsi6]

You need to use rca cables to get the job done and same goes for knock sensors.

Just buy a cheap set of rca's that you can cut up and use for this.

 

[sideshow]

the insides of rca cables are very thin same goes with anything to do with tv or steroe electronics

the best shielded cable is found in automotive wiring
ive looked for years trying to find shielded 3 or 4 core wire and only way ive found it is
in facotry japanese car wiring

so if your after a short bit goto your local wrecking yards and cut some wire out
this way the wire will actually be decent thickness and not snap off easily

 

[xspsi6]

I have used rca's for many years with no ill effect fwiw.

 

[spf_lexus]

Thanks for the top Sideshow. I am pretty sure my cam sensor is the issue after addressing several possibilites. Yesterday I simply wiggled a solder connection that I made and afterwards its cutting out all over the place.

I am having a hard time tracing this wire down as its part of the engine loom and not stictly the cam sensor (after connector). The wire is white with green tracer located at the loom that runs in front of the driver side cam cover. I remember soldering it and I did a half-ass job (no r/f shielding and too much solder) but after inspecting Lex's wiring diagrams I cannot get a solid tracing. The 1996 wiring diagrams show this wire connecting 2 cam sensor wires but the 1992 diagrams do not show any white/green wires anywhere near the cam sensors.

 

[spf_lexus]

I have been reading the 92 wiring diagrams this morning and I think i understand how this works. G1, G2 and N2 are cam1, cam2 and crank. The ECU has a seperate positive 5v source for each sensor but what i found interesting is that all 3 sensor grounds seem to be joined together before returning to the ecu, where then they are split up again for each sensor's ground return for the ecu.

I know I am babbling a little bit but im currently sick, and on strong meds so I cannot find garage time this weekend. I would feel much more confident if i could decipher the madness behine this diagram. I am thinking that if i had a cold solder joint or too much sodler, the ground returns for all 3 sensors will show a low return voltage to the ecu due to excessive solder ressitance.

http://lextreme.com/PDF/scecu1.pdf

Whats confusing is that G2 is labeled green from the ecu, and labeled white at the sensor, yet there are no connectors labeled in between. Should I interpret this as green/white tracer? If so this is the cut wire in question.

 

[spf_lexus]

FOUND IT!!


I re-soldered both severed sensors with minimal solder, then shrink-tubes, then wrapped in tin foil, and then wrapped in electrical tape. No change. I had not occured to me but I never tried ruling out my MAF sensor. Inspected it and zero visual oil contamination so I test drove with it unplugged an all studdering/misfires disappeared! very happy right now. Safe to say the MAF is the cause? I figured that faulty cam/crank sensors wont allow the engine to rev/run properly regardless of loop.