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Discussion Starter · #1 ·
Going to start this as a new thread. May be helpful to anyone experiencing a rough idle.

Question:

if Crank mark is spot on, then piston (assuming the right stroke) should be at TDC, correct?
if Crank is spot on and piston is at TDC and cam index marks are aligned to the top of the cam housing, then cam should be timed correctly, right?

I looked into buying blocks from a long-time alfa mechanic and they told me not to bother, saying they stopped using them and simply slide a thin (very thin) feeler gauge under the cam cap to snug the cam in place once the mark on the end is lined up and that will hold.
They also told me the 24v cam marks are reliable.

So, if the crank position is right and TDC is right and the cam marks are correct and 4-6 rotations shows a steady tensioner space and no movement in the alignment marks, all should be good to go?

I have checked my cam marks 2-3 times and they are still spot-on but my rear bank plugs are damp and car feels rough although the rpm is steady but my exhaust is shaking.
No error codes. No jumping around at the timing belt tensioner (I have left it off for the test start to make sure there are no other leaks down there) and I can insert the pin into the T belt tension alignment hole while the engine is running!

All injectors seem to be clicking away.

If it were a vacuum leak at the manifold, from the intake or from the egr lines, I expect all cylinders and plugs would be uniformly affected.

I don't think all 3 plugs would go bad or all 3 igniters would go bad at once.

Will a poor sealing boot into the rear bank only affect that cylinder or will it throw off the entire bank?

I will be swapping ignition "modules"? later and checking wiring before I swap plugs and try again. Is this simply a "harness swap" or should I leave the harness connectors in place and swap the actual modules? Very tedious removing that intake manifold over and over again.

Thanks.:1eye:
 

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Discussion Starter · #3 ·
Re poor pattern

Injectors may be leaking or spraying a poor pattern.
Thanks. It's 30c in the GTA (greater Toronto area) today. How hot is it in Pensicola?

Re injectors, thought of that but would all 3 show the same symptom at the same time? Unless the rear bank is receiving a specific signal separate from the front bank, I don;t see how this can be the issue.
I don't know much about the fuel delivery system in this car. If the front and rear banks receive specific signals for fuel delivery, there may be an issue I can follow.
 

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164 ECU fires all six injectors at same time just one power wire with six legs and one trigger wire with six legs from ECU.
 

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I am very interested in the idea of using feeler gauges to lock the cams. Did you find it worked as well as expected? What thickness did you use? I am contemplating tackling the job on my GT 3.2 when the time comes in a year or so. I have never done one before, but I am comfortable doing the 12 valve ones now. It would save a lot of money if I can do it myself, but it is a bit daunting.
 

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Discussion Starter · #6 ·
Well, that narrows down the issues. Not the injectors.
I doubt I could have gotten injectors and ignition wires mixed up as they have been in place so long they have become fairly rigid in their paths.
Will swap the ignition modules and try again but is this simply a wiring swap or should I leave the wiring in place and switch the modules?
 

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Richard Jemison
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What?

Well, that narrows down the issues. Not the injectors.
How has anything posted below indicate to you that leaky injectors are not the issue?

What did I miss?
 

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Discussion Starter · #8 ·
Re leaky injectors

How has anything posted below indicate to you that leaky injectors are not the issue?

What did I miss?
Meaning that there are no separate pulses to front and rear (as in two control units) and all of the pulses come from one source. I don't think it is likely that all 3 injectors on one bank go wonky at the exact same time. if the front and rear banks had separate control units, then I could see one going faulty and affecting all 3 injectors on that unit, like the ignition control modules. Unless I am also missing something here.
 

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Discussion Starter · #9 ·
Re: no cam locks

I am very interested in the idea of using feeler gauges to lock the cams. Did you find it worked as well as expected? What thickness did you use? I am contemplating tackling the job on my GT 3.2 when the time comes in a year or so. I have never done one before, but I am comfortable doing the 12 valve ones now. It would save a lot of money if I can do it myself, but it is a bit daunting.
O.K. But please defer to any that have more experience than I do as this was my first 24v belt.

Used the thinnest gauge I had. Basically, I was told to:
Line up TDC.
Hold the cam in place using the flat portion with a suitable open wrench (perhaps have someone hold it as the cam can slip) and loosen one cap, place the gauge underneath and snug it down, being careful not to strip the threads in the head.
Loosen the cam pulley (again, always have that wrench in place as a precaution and use that as a counter lever against the torque wrench)
Still with wrench in place, loosen cap enough to slide out feeler, adjust the position of the cam, place feeler back in, snug cap, tighten your pulley back to the right torque (this is why t's good to keep the wrench in place so you have a counter lever and don't spin the cam while torquing).
Check your marks.
Still with wrench in place, loosen cap, remove feeler, tighten cap to proper torque.
Check marks again to make sure nothing moved. If belt is in place and properly tensioned, you should be able to rotate your engine clockwise 2 times and everything should still be in place.

I think there are a few threads in the forum that mention timing cams without the blocks.

I would have used them if available but another 2 weeks waiting plus the $$$ and advice from an ultra-experienced alfa dealer that stopped using the blocks and doesn't even sell them anymore left me fairly comfortable with the procedure.

Mind you, my rear bank is a bit off so perhaps I wasn't as exact as I thought I was.

DO AT OWN RISK, EH!
 

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Do one thing at a time and check results.
simple things first
if the rear bank is misbehaving the chances are, the belt slipped a couple of teeth, and the rear exhaust cam is out of whack.
a compression test will show an even and lower compression that front bank. EG. if front bank is 220 across the the board, the rear bank should be giving you same result. If, however, the rear bank compression is down to say 180 0r 160 then suspect a belt slip. the drop in compression will be even across the three rear pots.

first, as Del and others have suggested, unplug the modules and switch connections, now try. if rear is still the issue, then please confirm that belt has not slipped. The cam pulleys should have synch marks on them, to allow for quick identification. there are other threads on this but read this one....I went through a similar experience a few years ago.......

http://www.alfabb.com/bb/forums/164-168-1991-1995/32341-24v-cam-cover-removed.html

good luck
 

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O.K. But please defer to any that have more experience than I do as this was my first 24v belt.
DO AT OWN RISK, EH!
Very interesting. Thanks for that.
 

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just swap the connectors on the ignition modules. leave the modules in place; they are exactly the same

answer to your question above is yes, if crank at tdc, and cam marks lined up then mechanical timing is good
 

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Discussion Starter · #13 ·
Re cam timing, noted below:

Do one thing at a time and check results.
simple things first
if the rear bank is misbehaving the chances are, the belt slipped a couple of teeth, and the rear exhaust cam is out of whack.
a compression test will show an even and lower compression that front bank. EG. if front bank is 220 across the the board, the rear bank should be giving you same result. If, however, the rear bank compression is down to say 180 0r 160 then suspect a belt slip. the drop in compression will be even across the three rear pots.

Thanks Luigi. I confirmed the TDC, Crank point and cam marks 2-3 times before putting the covers back on and again when I was starting to diagnose rough idle and fouled plugs. No changes to cam position was done and the 2nd time around, plugs are cleaner but still damp. So, timing seems to mechanically spot-on.
A quick (dry) compression test shows 180-190 all around (except #6 is around 170) but I cranked 6 times so there may be more room.
I will try again after I charge up my battery.

first, as Del and others have suggested, unplug the modules and switch connections, now try. if rear is still the issue, then please confirm that belt has not slipped. The cam pulleys should have synch marks on them, to allow for quick identification. there are other threads on this but read this one....I went through a similar experience a few years ago.......

I believe that if the belt does slip a tooth it will retard the cam action so if I open it up again, a slipped tooth will show a cam with an alignment mark that is before (early) the alignment point on the head. Hate pull the covers again but maybe the next best way to confirm as putting it together and finding it is NOT the igniter will simply result in removing the plenum yet again. Frustrating.

http://www.alfabb.com/bb/forums/164-168-1991-1995/32341-24v-cam-cover-removed.html

good luck
Thanks.
 

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Discussion Starter · #14 ·
Following up on cam timing 24v

Removed the rear cover yet again. Turned crank to TDC and back-forth just a tooth or two to confirm TDC.
The cam marks are lined up o.k. (at most, the exhaust is above the head alignment spot by the thickness of the scribe mark and the inlet is above by no more than the same amount, facing eachother, meaning that the exhaust is late by that fraction and the inlet would be early by the same amount ,I think).

The mark on the flywheel and bell housing are not 100% lined up. Seem to be about 2mm after the bell housing mark but hard to line up visually. Don't know why this would be or if is an issue or how to adjust that.
 
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