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John, Master A.S.E Automotive technician
Category: Chevy
Satisfied Customers: 9176
Experience:  A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
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1999 Malibu: Crank Sensor, Cam Sensor..Injectors..Coil pack

Customer Question

I have a 1999 Malibu and 3.1 engine crapped out. I found a good 2005 Malibu engine, 3.5, but electronics are slightly different. I swapped the Harmonic Balancer and Crank Sensor, Cam Sensor, the TB and sensors, Injectors and Fuel rail, and the Coil pack. all the wiring matched up at this point. However the Crank Position Sensor in the middle of the block is totally different (much shorter and 3 wire instead of 2). I fashioned a spacer to hold the 1999 sensor the correct depth, but engine still will not start. Oh, forgot, the 3.5 does not have the Oil sensor in the pan. Any suggestions on why it will not fire (appear to have no spark). I would also like to know the difference in the CRANK between 3100 and 3500. the SPECs stated they share the same stroke, just different bore. So is the Harmonic balancers positioned the same on the crank. Why the huge difference in the Crank Position Sensor in the middle of engine, what is different about the notches or sensor wheel on the cranks. Thanks. Rick
Submitted: 7 years ago.
Category: Chevy
Expert:  John replied 7 years ago.


If you are going to use the 3.5 engine from a 2005 you will need the complete engine wiring harness & PCM from a 2005 model.

The balancers do not interchange & the engine electronic data sensors process info differently.
Customer: replied 7 years ago.

John, Thanks for the reply but the concern is I dont have the PCM or wiring and the apparently the way the TB is contolled by the pedals is drastically different. Being the core engine is basically the same 60degree V6, Same stroke (84MM) just different Bore, making it larger CID. I swapped all the electronics out but struggled with mid engine Crank position sensor. So I was trying to get more details on how this sensor is different between the two versions. The older 3100 uses a 7x configuration apparently. I have the engine apart and see the seven slots in the crankshaft wheel where the sensor runs. Is the 3500 similar or different. The sensor is shorter, indicating something is different :) I did swap the balancer out as the 3100 has the crank angle sensore as part of the balancer, but was not sure the slot position was the same on the crank, making sure it oriented correctly (TBD center is the same). I got a good deal on the engine and dont want to break it apart to investigate. the other difference is th location of the MAP sensor but I believe that is simple and would impact IDLE and driveability and will work on that one later, If can get it started. The other missing sensor if the OIL LEVEL sensor (3500 does not have one located in the pan like 3100) but from reading up it should not prevent starting, just light the dash light. Do you have links to details of the internal and electronic workings of the 3.5 / 3500.



Expert:  John replied 7 years ago.
Yes,I know the mechanical parts are very similar,but the logic of the electronics are different & not interchangeable.Either get the engine wiring harness & PCM or get a 3100 block.