No start question...cam sensor?

[TR6]

Hi all:

I have an 87 TR. It is virtually all stock, and typically runs great. It is a daily driver, and I have not really had any problems with it. I parked it for about 3 days last week to drive my wifes car because her car was having some problems I wanted to check out. Her car finally died Saturday, so we all hoped in the Buick to go to dinner, and no start. It was running fine when parked.

It cranks fine and has spark, but I am not getting injector pulse on a noid light. Fuel pump is working, but injectors are not getting signal to fire. I suspect the cam sensor, but am not certain. How can I check the sensor to confirm? I have read all the info on how to change the sensor, but have not seen anything on how to check it to confirm this is the problem.

Also, if this is the problem, can just the cap be replaced, or does the whole sensor need changed, and, will pulling it out and resetting it do the trick or are they just dead when they go?

Any ideas/info/how to check sensor would be appreciated.

Thanks all!

 

[superjaay]

Sounds like it could be the crank position sensor

 

[breiter]

I think your on the right track. Here is some detailed info on the cam sensor. Caspers or Kirbans (and others) sell new caps or the whole assembly. I think there is even a by-pass designed so you can "limp" it home. I would just by the new cap or sensor. I keep two spares.

Cam Sensor Information

 

[TR6]

Is there any info on how to test them? Like check for voltage on this wire or that one, and voltage out of spec is a bad sensor?

I was thinking/have read that the crank sensor is for spark, which I have, so I figure that is likely good. And I thought the cam sensor was more for fuel control. The pump is working, but no injector pulse from the ecm. Is there any way to test the cam sensor to verify this so I don't just replace it for fun? If I have a short somewhere else, I would rather just fix that than replace a working sensor and then find the wiring problem.

Has anyone else experienced this or know how to test the sensor?

 

[83ttypecooled]

cam sensor

Hi,
Using a digital graphing multimeter,you can get a picture of the sensor output. It should be a basic square wave,nice and clean, with no glitches. I know, you don't have such equipment. I think you have hit the nail on the head, though. Check for reference(5V) voltage to the sensor, and check it's ground. After that,you might put a noid light(tests the injector) on to each injector connector, but I think it is a forgone conclusion that the cam sensor took a s--t. Good luck with your issue.

 

[TR6]

You are right, I don't have a digital graphing multimeter, but I do have a DVOM. I could check for reference and ground. At that point, if the signal wire shows any voltage I can figure the sensor is working, and if no signal voltage I can figure sensor is no good? What voltage should I see on a volt meter from the signal wire? Is this voltage present with key on, or does it need to be cranking? Since it is not starting at all, it seems that a volt meter would be just as helpful as the graphing meter. Am I correct? If it was an intermitant problem, the scope pattern would show the issue, but since it is not working at all, wouldn't a volt meter be able to show that voltage is out of spec?

I had nothing on a noid light at the injector, but I only tried one injector. Is it worth checking them all? I figure if one is out they all are, or at least that if only one is out, the car would start and run like ass (maybe the same as having plug wires crossed)?

I appreciate the comments. If anyone has any specs or can tell me if my reasoning is on/off base, that would be great.

Thanks everyone!

 

[wbzautocustomiz]

this is de javu I just went thru the same thing no lite on noid lite check crank sensor at the harmonic balancer it has three wires two should show power with key on and the third wire you will need to put test lite to a power source and crank car (2 people?) and test lite should flash if it does crank sensor is fine so I did change the cam sensor and still no start (money down the drain ), so I got a loaner ecm from my buddy and sure enuff car started right up. So when I checked out my ecm ,the prong on the ecm where the orange (hot off batt) was broken off at the plug on ecm so for about $90 bucks at local a-parts store I can fix it new ecm. So check out the free info for the wiring diagrams also on this forum and keep asking one the GN old heads will help you get it right. PS check all fuses and power its a pain but good luck to you

 

[TR6]

I will check those things, thank you. Did your car crank? Mine cranks fine, and has spark, just no injector pulse. Thanks for the info, I will check these.

 

[TurboBuRick]

No diagnostic codes?

 

[wbzautocustomiz]

yes it did crank and had fire , what I did to try to figure the first part was I pulled the turbo pipe off plenum(was a pain to get back on) and I sprayed some 2+2 carb clean name brand ( dont use the cheap stuff and stay away from start fluid )and car would run so I new it was fuel prob. so if you try that that might help to the next step. After that I checked the crank sensor and that was fine so I shot the dice on cam sensor and I lost ,but maybe not you? but it did take me about 2 weeks to figure it out so try the spray first to see if it will run if so then it will be something that controls the injectors. The brown wire should be hot with key and the other wire should go to ground pulse that is when the noid lite comes handy,PS i think it doesn't matter if you check all inj. or just one. I do understand fustration so take time and do as much as you can because there aren't many mechanics that will know much about these Turbo Buicks and their labor rate will eat us up alive. so go luck, Jake

 

[johnnyttype]

perform this procedure and i believe it should tell u if the sensor is working correctly.

Cam Sensor Information

"The sensor is a hall effect device with a rotating metal ring that is driven from the front of the cam gear via a shaft (like a distributor). This ring passes thru a grooved sensor molded into the sensor cap. The metal ring has a notch or window cut out of it. When the window goes by the sensor, the voltage drops, which tells the ECM where #1 TDC is."

the middle wire "B" for the cam sensor is where u check for the voltage by backprobing it. hope this helps!

 

[TR6]

I did not have chance to do anything last night but check fuses. They are all good. Tonight I will check for codes, pull the cam cover and see if it spins (just read this in another post that if it spins the tab is broken), and check sensor signal, voltage, and ground. I can also check the computer terminals and see if anything is funny. ECM was replaced at some point before I got the car, so I don't suspect that is the problem. It sounds more and more like the cam sensor, but as some of you have pointed out, you have replaced that and did not fix the problem. I would rather put the $ into something else if the sensor is OK. I wil check these things and go from there. Feel free to chime in with any other ideas. I will post my results. Thanks.

What is the best place to get a cam sensor if I need one?

 

[TR6]

Forgot to report back...

No codes, cam sensor appears to have been replaced in the past and does not spin freely. Found a loose wire at ECM that was not putting power through to injectors. Thanks for the feedback and ideas everyone.