Alfa Romeo Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
I just recently replaced my Flywheel and some other items and my mechanic has informed me that the cam sensor wiring harness is completely shredded and cannot be used and that is causing my 'NO SPARK" problem. I am in need of a good used or new cam sensor harness (AKA Pigtail) if anyone knows where I may source one. I live in Massachusetts and would appreciate any direction that can be provided. You guys helped me source the flywheel but that guy is out of harnesses at the moment. I have been able to drive this beauty only once since the day I bought it. It's been all redone inside and out and only experiencing a couple of snafus but I am at the end and after many $$$'s spent on the flywheel I would like to complete this vehicle and get it ready for spring outings.

thanks,

jeff
 

·
Administrator
Joined
·
16,423 Posts
I think you may need a new mechanic. The camshaft does not have a 'sensor'. The camshaft has a solenoid operated VVT (Variable Valve Timing) device. The VVT solenoid has nothing to do with spark.

There are two sensors in the bellhousing that are aimed at the flywheel. These sense position (timing) and speed (rpm). The flywheel has a small pip for one of the sensors. The flywheel can be installed in six positions but only one is correct. I'd not sure if an incorrectly installed flywheel would lead to a no spark condition but it would certainly lead to an incorrect timing problem (and the engine wouldn't run).

The most common reason for a no spark/no start condition is low system voltage. The computers need ~ 10.5V to power up. It can sound like it is cranking over fine but if the available voltage drops below that threshold the computers won't send the 'make spark/squirt fuel' signals. Connect a voltmeter to the battery. With everything off a good battery should show ~ 12.6V. Now see what it reads as you try to start the engine. If the voltage drops below 10.5V then the battery is weak. (our '84 Spider reads ~ 11.6 - 11.8V during cranking)

See the link in my signature to a page of info about the L-jet system in our cars.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #3
Eric -
I have been told the very same thing about the two sensors and would be willing to replace those too but he specifically said there is a pigtail type harness that is in pieces due to someone leaning on it when the starter or something else was put in. He said he set the flywheel up correctly and the car did fire but when he was holding this harness which attaches electricity to the cam sensor it started but kept cutting out due to bad connection. I will pass along that link but even a guy who sourced me the flywheel told me there is a small footlong harness that attaches and it is nicknamed a pigtail due its closeness in image to one. Thank you for your reply and please let me know where I could find those other two bell housing sensors as I'm sure those can be replaced too.

thanks,

jeff
 

·
Registered
Joined
·
7,317 Posts
as you might want to get a VVT working again (it does make a difference when driving - but nothing to do with no spark as Eric rightly says) you sometimes see them on Ebay.
Here is one for instance, though rather expensive imo. (edit: seller says good up to MY 94, but that is wrong....good to MY 89 with L-Jet and in fact only the L-Jet with electronic VVT, early S3 had centrifugal VVT)
Alfa Romeo Spider VVT Solenoid Plug 83-94 | eBay

there is also a workaround solution for this for about 10$, if you are not too worried about originality, posted by Rich:)
maybe try that first.....
http://www.alfabb.com/bb/forums/spider-1966-up/361529-replacement-electronic-vvt-harness.html
 

·
Administrator
Joined
·
16,423 Posts
...let me know where I could find those other two bell housing sensors as I'm sure those can be replaced too.
Before replacing them try testing them. Info is in the L-jet diagnosis page. And make sure they are connected to the wire harness correctly. The two sensors are identical but must be connected correctly.

Do the system voltage test - make sure your battery is in good condition.
 

·
Registered
Joined
·
276 Posts
eric is pretty much on the money. the flywheel has to be put on in correct orientation for the flywheel sensors to work properly. if it is not, the timing sensor is not going to send its signal at the correct time.. spark will not have any effect. as eric said, 6 bolts means can be put on incorrectly 5 ways. 1 bolt off is crank timing 60' off. i will in fact start (very hard) and run there - sort of. if off by more, then no chance. if your mechanic is not an alfa guy (and sounds like he is not), is easy to miss. flywheel has a stamped mark to mark TDC. there is an inspection window in bell housing at back of block. at #1 TDC/compression, the flywheel mark should be visible. if not, timing is off.
flywheel sensors are identical, connectors are identical. their function is not. believe the upper sensor is for rpm and goes to black cable. the lower is for timing and goes to gray cable. if they are hooked up wrong, ecu will not send out signal for spark or fuel.
i cannot remember a pigtail cable coming off bell housing sensors, but ok if you say so.
there is no cam sensor in the system. the pig tail coming out of the cam cover ("cam sensor") drives the VVT solenoid on the cam. all the solenoid does is advance cam above ~ 1600rpm. should be repaired for proper function but in no way will contribute to a no spark/no start condition.
battery voltage and grounds are key. ecu needs to see > 10.5V or will shut down sending no spark or fuel signals. grounds are bane of the system - and there are a lot of them. all need to be clean and tight or no start/run like crap.
 

·
Registered
Joined
·
1,306 Posts
MY 86 ran for a few years with out VVT, until I finally reworked the fuse holder. It doesn't impede the car's ignition at all, and it can only be used once the car is warm enough anyway. The throttle position switch actuates the VVT, what you are calling the cam sensor, at mostly open throttle, when working properly.
 

·
Premium Member
Joined
·
1,910 Posts
Certainly follow the instructions of the others and check the voltage during cranking and resistance of the sensors.
Maybe even go have a look at the part he is referring to and snap and post pics of it on here for us to see.

The sensors look like this. It has a permanently attached cable, that if damaged the whole sensor needs replacing. They are flywheel sensors although some sites may call them crank position sensors.
https://www.amazon.com/Bosch-0261210001-Crank-Position-Sensor/dp/B0018DMENO

Just a heads up... new sensors don't come with a new aluminium spacer block. You need to reuse the ones you have.

The sensors plug into connectors like this which are part of the cars wiring harness. If they are damaged, they need to be cut out and spliced in. I'd refer to them as a 3 pin bosch connector.
https://www.amazon.com/Airtex-1P1421-Connector/dp/B002M1PIL6

Note- this may not be the exact part number, but more or less what it looks like. Just need to confirm correct part number via Alfa parts suppliers, Bosch website, etc. or take the mangled one with you to a parts store and match it up.

Like already said, if he's referring to the vvt harness, that is a separate issue that doesn't impact spark.

Mike
 

·
Administrator
Joined
·
16,423 Posts
Just a random thought - I am not sure if this would be true or not - wondering if perhaps the frayed wires to the VVT solenoid might be shorting out. Would that somehow prevent spark - perhaps if the short caused system voltage to drop below the computer's threshold.

Since the engine should start & idle fine without activation of the VVT, it might be a good idea to remove the damaged wiring to the solenoid.
 
1 - 9 of 9 Posts
Top