How can I test the crank/Cam sensor? I know theres a sticky, but the diagram for the PCM wouldnt come up on my computer. I tried testing my injectors while someone cranked the engine, and i got some wierd readings, the highest the voltage fluctuated was to 1.4 volts. I also could bearly hear them clicking while listening with an stethoscope. ANy ideas? thank you!
still no start
- Thread starter nickd2689
- Start date
Injectors
Testing injector voltage with a voltmeter will be tricky. It is switching between 0 and 12 volts very, very fast. Normally, you should see about 4-6 volts as the voltmeter displays an average voltage because it is switching so fast.
Checked fuel pressure (bad fp regulator returning all your gas to the tank)
Checked for spark (bad crank sensor / coil pack / control module / esc module-rarely ever fail)
Injector timing (bad cam sensor)
About the only way to check for bad crank and cam sensors ON THE VEHICLE is with an ocilloscope. You can watch for the switch in voltage when the hall effect switches are opened and closed.
You can also test the sensor by powering up the sensor with a 6volt lantern battery. Run a jumper from + of battery to the 5V input wire of crank sensor. The - of battery will go to ground wire of sensor. Put your volt meter + lead on the signal wire coming from the crank sensor. Will have to ground your voltmeter to battery - as well. Pass a metal object (screwdriver, razor blade) through the crank sensor gate and watch the voltage on the meter. Should change theoretically from battery voltage (5V) to 0V. If not, check wiring for fault or sensor bad.
Same thing goes for the cam sensor, just have to know the pin outs for plugs. You would only have to take the top of the cam sensor out to do the test.
You may want to check that the cam sensor ring spins when the motor is spinning. May have a sheared roll pin on the cam sensor gear.
Do the injectors continue to click or do they click once and that is it?
Does the car start on ether / starting fluid? You will have to take the black snorkel off, open the throttle blade and spray the ether in past the throttle blade. Then fairly quickly reinstall the snorkel, and try to fire it.
That will keep you busy for a while. By the way I have done all of these procedures on one of our vehicles trying to figure out a weird miss / shake at idle. Didnt figure anything out.
Good luck,
Jerry jr.
Testing injector voltage with a voltmeter will be tricky. It is switching between 0 and 12 volts very, very fast. Normally, you should see about 4-6 volts as the voltmeter displays an average voltage because it is switching so fast.
Checked fuel pressure (bad fp regulator returning all your gas to the tank)
Checked for spark (bad crank sensor / coil pack / control module / esc module-rarely ever fail)
Injector timing (bad cam sensor)
About the only way to check for bad crank and cam sensors ON THE VEHICLE is with an ocilloscope. You can watch for the switch in voltage when the hall effect switches are opened and closed.
You can also test the sensor by powering up the sensor with a 6volt lantern battery. Run a jumper from + of battery to the 5V input wire of crank sensor. The - of battery will go to ground wire of sensor. Put your volt meter + lead on the signal wire coming from the crank sensor. Will have to ground your voltmeter to battery - as well. Pass a metal object (screwdriver, razor blade) through the crank sensor gate and watch the voltage on the meter. Should change theoretically from battery voltage (5V) to 0V. If not, check wiring for fault or sensor bad.
Same thing goes for the cam sensor, just have to know the pin outs for plugs. You would only have to take the top of the cam sensor out to do the test.
You may want to check that the cam sensor ring spins when the motor is spinning. May have a sheared roll pin on the cam sensor gear.
Do the injectors continue to click or do they click once and that is it?
Does the car start on ether / starting fluid? You will have to take the black snorkel off, open the throttle blade and spray the ether in past the throttle blade. Then fairly quickly reinstall the snorkel, and try to fire it.
That will keep you busy for a while. By the way I have done all of these procedures on one of our vehicles trying to figure out a weird miss / shake at idle. Didnt figure anything out.
Good luck,
Jerry jr.
Boostnitup
Member
- Joined
- Feb 20, 2002
Casper's electronics...
They sell a great tool... Camshaft Sensor setting tool.
It makes it easy to determine the hardest part of the equation. Setting the camshaft sensor.
The crank sensor is easily set with a matchbook cover and some lying on the back time on a cold garage floor.
Once these hurdles are known then you get into areas like the ecm, control module, and coil pack.
I recall the first time I couldn't get spark on the '84 GN... a rock (or other debris) had taken out my crankshaft sensor... what a pain. The moderator of this arena spent several minutes on the phone from Utah assisting me figure it all out.
They sell a great tool... Camshaft Sensor setting tool.
It makes it easy to determine the hardest part of the equation. Setting the camshaft sensor.
The crank sensor is easily set with a matchbook cover and some lying on the back time on a cold garage floor.
Once these hurdles are known then you get into areas like the ecm, control module, and coil pack.
I recall the first time I couldn't get spark on the '84 GN... a rock (or other debris) had taken out my crankshaft sensor... what a pain. The moderator of this arena spent several minutes on the phone from Utah assisting me figure it all out.
who sells the tool? that sounds helpful, even when it ran it ran like crap so im wondering if the crank/cam sensor isnt just a little off. but yea we have matco, snap on, and mac tool reps that come to work through out the week so that would be convenient if they made it
Thanks!just got mine back up
Replaced Module and coil pack unecessarily. One issue I had was the connector going into the module had weak connections allowing voltage to go up and down. Other issue was crank sensor was just barely making contact with vanes on back of damper. Dont know which caused the stumble I had and when but after chasing many ghosts car runs really well with crank sensor being biggest issue. I used caspers harness to upgrade to the more easily found 87 sensor. Mine would have no spark. I think the other issues I had were causing similar problems but were unrelated. I had to replace fuel lines and the aforementioned wiring issues. I pulled down the harness and traced all of it after I found the weak connectors. Runs good now!!
Replaced Module and coil pack unecessarily. One issue I had was the connector going into the module had weak connections allowing voltage to go up and down. Other issue was crank sensor was just barely making contact with vanes on back of damper. Dont know which caused the stumble I had and when but after chasing many ghosts car runs really well with crank sensor being biggest issue. I used caspers harness to upgrade to the more easily found 87 sensor. Mine would have no spark. I think the other issues I had were causing similar problems but were unrelated. I had to replace fuel lines and the aforementioned wiring issues. I pulled down the harness and traced all of it after I found the weak connectors. Runs good now!!
I actually got it running briefly today, I was checking for spark again, and felt that it was a little weak, so I changed the plugs, and sure enough it ran. I guess I gotta learn to "Keep it Simple". however the car stalled after a few minutes, the plugs were fouled out again. Not sure what Im going to do about this.
Testing procedure
I knew it was a 12v signal from the car. I was referring to the test battery when I said battery voltage. You should still see it switch with 6 volts right?
Sounds like really weak spark, bad cables, injectors hung open flooding the car and fouling the plugs.
Jerry jr.
I knew it was a 12v signal from the car. I was referring to the test battery when I said battery voltage. You should still see it switch with 6 volts right?
Sounds like really weak spark, bad cables, injectors hung open flooding the car and fouling the plugs.
Jerry jr.
Do you have a chip burned for those?
If the chip isn't burned for those injectors, the ECM will try to run those injectors like the stock ones, which I think would make it idle kinda funny. Is the fuel pressure regulator adjustable? You can rent the fuel pressure checker from Autozone or oreilys and check pressure at the schrader valve on the fuel rail.
Could also be a problem with the injector harness trying to ground itself out which would flood the motor.
Jerry jr.
If the chip isn't burned for those injectors, the ECM will try to run those injectors like the stock ones, which I think would make it idle kinda funny. Is the fuel pressure regulator adjustable? You can rent the fuel pressure checker from Autozone or oreilys and check pressure at the schrader valve on the fuel rail.
Could also be a problem with the injector harness trying to ground itself out which would flood the motor.
Jerry jr.
yes, I did have a chip burned for all my mods from poston, and the FPR is adjustable, I have a fuel pressure guage already, but Im not sure what I should set the fuel pressure for optimum performance. 42.5 injectors warlboro 340 Fuel pump (hotwired), only running 94 Octane, adjustable FPR from poston, T33 Turbo, 160 degree thermostat.
I cant even set the fuel pressure though because I cant get the damn thing to start. It fired up for a few seconds the other day (running like junk) and then stalled, but I cant get it to actually run, It wont give me any codes besides 12, which is supposed to be there, and I have fuel and spark. I do know that the TPS is reading the voltages backwards again. 4.8 V @ closed and .7-8 V @ WOT. It did this before and I replaced it, but it wasnt preventing it from running. Sorry, I know this is the same as the posts Ive dont before, but here is absolutely everything about my car: 94 octane with chip from poston, also from poston: adjustable FPR, warlbro 340 FP, Hotwire kit, 42.5 injectors, T33 turbo. Parts replaced: Plugs, wires, 86/87 coil pack, battery, fuel filter, intake gasket, vacuum lines (double and tripple checked correct routing). I know I have fuel and spark, so what would your next move be? Compression? timing? Thanks alot everyone, without this forum, I would have just sold the car to a junk yard and cut my losses.
if the tps is reading 4.8v with the throttle closed that needs to be corrected i believe that above 4.somthing (dont remember) the ecm goes into clear flood mode and it wont spray fuel
as far as setting the static fuel pressure you can do that with the car off just jumper the fuel pump relay so it stays running and set your pressure (86/87s have a termnial near the alternator on the left side of the engine to kick on fuel pump don't know if the 84/85s do) anyhow if they dont just jump the relay
get that tps problem worked out first
I believe the clear flood mode is correct
it thinks you're holding own the pedal to clear a flooded condition and will not spray gas.
I dont know if it goes into limp home mode if the tps is unplugged or not.
One of the "experts" would have to say yes or no to that. You may try to run the car with the tps unplugged just to see if it starts.
If it does you know where the problem is.
May be that the tps 5V source wire and the signal wire are shorted together and doing funny things. May look at the wires to make sure they never touched the header on the driver's side.
Jerry jr.
it thinks you're holding own the pedal to clear a flooded condition and will not spray gas.
I dont know if it goes into limp home mode if the tps is unplugged or not.
One of the "experts" would have to say yes or no to that. You may try to run the car with the tps unplugged just to see if it starts.
If it does you know where the problem is.
May be that the tps 5V source wire and the signal wire are shorted together and doing funny things. May look at the wires to make sure they never touched the header on the driver's side.
Jerry jr.
