I put a 1988 engine into a 1989 and mis-positioned the flex plate. More on that below; two related questions 1st:

1. The CPS sensor reads what? In > 1 message here, there are comments about the CPS reading the tone ring and firing after it sees the place on the ring where a hole is missing. Is that correct?

2. Pins are for? The picture you see in Bentley, Haynes, here, elsewhere references the alignment of the "two pins" to (2 & 4 O'clock, crank at TDC, rotor pointed to cyl_1). Do these pins have any purpose other than alignment eg. balance, timing? I have flex plates and flywheels missing one or both pins.

2a. I have a pre- tone ring flywheel with 2 pins. Are they aligned to 2 & 4 O'clock for balance reasons?


Some comments and a cautionary note about flex-plate alignment.

I pulled a flex plate off the shelf to install on the pre-CPS 1988 engine. Search here was down and I thought I remembered how to align the plate; and I used the picture in the manual. I was wrong. Comments for those doing this the 1st time.

a. The ubiquitous picture you see shows the pins at 2 & 4 O'clock. The pins are on the block side of the plates that I have.

b. It also shows an arrow pointing to 3 O'clock. This arrow is imaginary - intended to show a level-line across the plate. There is an etched arrow on some plates but it is on the block side and it needs to be pointed towards the CPS bracket.

c. One message here has the comment that the "no hole" area on the tone ring needs to pointed up at the CPS bracket. That's wrong, at least for LH 2.4. The "no hole" space should be around the bottom of the starter hole.

For all Bentley's thoroughness, I'd think they'd have included the above info - especially the note about the alignment of the etched arrow. The manual says "Some plates have an arrow" and shows you a picture with an arrow at 3 O'clock.
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240 drivers / parts cars - JH, Ohio

2. Pins are for? The picture you see in Bentley, Haynes, here, elsewhere references the alignment of the "two pins" to (2 & 4 O'clock, crank at TDC, rotor pointed to cyl_1). Do these pins have any purpose other than alignment eg. balance, timing? I have flex plates and flywheels missing one or both pins.

2a. I have a pre- tone ring flywheel with 2 pins. Are they aligned to 2 & 4 O'clock for balance reasons?



Hey Jon, I think those pins are vestiges of the old Mono-tester days when Volvo shops used a proprietary multimeter to set timing electronically. You'll find the threaded hole still exists in the casting for the magnetic sensor which, in the olden days led to a test port up on the cam cover. The question comes up now and then when people start to pull apart their motors. Yes you could time the ignition without a light.

Not to worry about the EZ116K you are used to. There are only six ways you can put that flex plate on the crankshaft, and the one that puts the two blank spots at the starter (with #1 at TDC) is the one you want, if you only want to do it once. If you don't, you join a group of car hobbyists who have lost more hair than the average.
--
Art Benstein near Baltimore

We give dogs time we can spare, space we can spare and love we can spare.
And in return, dogs give us their all. It's the best deal man has ever made.
-M. Acklam

Thanks Art.

I've put the plate on wrong twice. Once when I didn't know any better; this time was just inattention and poor brain function.

I suspected right away what was wrong - the engine misfire when it tried to start was dramatic. The search function had come back up here and I realized how I should have done it. It runs as it should now.

Between the pins, arrow on the back, and blank spots it really should have been cake. I have two more to do. I'll use the tone rings with the missing pins and not worry about it.

Thanks again.
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240 drivers / parts cars - JH, Ohio

your questions/remarks come across as chaotic.

let me simplify this for you:

1. an 88 engine into an 89 car REQUIRES you use the 89-93 240 flex plate and bellhousing (or knock out the slot in the 88 bellhousing)for the crank sensor

2. the flexplate for an 89-93 automatic has 2 spaces on the window pane ring which are NOT cut out. no little squares for the cps to read as they spin.

3. the blank space on the tone ring needs to be centered over the starter motor opening or the car will not run or run like sh-t

4. you should discover that once you install the flex plate and rotate it so the blank space is centered over the starter hole the bolt holes to affix it to the block may require you to tweek the plate bit one way or the other so once you can get all bolts inserted the blank space on the ring will be centered properly

5. obviously you're transferring the cps bracket from the 89 engine to the back of the 88

Thanks for the reply but I know all that now. My mistake was not remembering your (3). I fixed it easily, it runs fine. My comments about the two repair manuals were just for ref. Sorry I wasn't clear. Again:

1. How does the CPS read the tone ring?

2. What are the two pins for on the flywheel or flex plate other than alignment?
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240 drivers / parts cars - JH, Ohio

the cps is a magnet as the tone ring spins magnetic contact is broken at specific intervals by the windows. this change in pulse of contact strength tells the ecu when to fire the plugs and when to squirt fuel.