z24i no spark after engine rebuild

[Bludacious]

Had the motor out to rebuild it, ran fine before I pulled it. Reconnected everything and now I have no spark from the coils. ECM shows code 44 all normal, there is 12v & ground to the CAS & 12v to both coils. Also checked the CAS 0 / 180 rotation signals at the ECU per the FSM. Tried with another set of coils and amplifiers pulled off an 80k mile truck, no change. I did unbolt the big yellow and black ground cable but forgot where it grounded to at the end so I stuck it on the water neck bolt of the intake manifold. The only other clue I have is it looks like the potting compound from inside the little brown 2-terminal condenser has melted out since I last looked at it. Would this be a cause for the problem?

 

Alternately, is there a way to swap to the older mechanical distributor but keep the fuel injection? I hate carbs.

[Bludacious]

Just noticed it doesn't seem to be firing the injector either. Has anybody had one of these computers diagnose itself as fine when they're actually badly damaged?

[datzenmike]

Remove the condenser and see if that helps.

 

Pull CAS out and look to see if spindle is turning while trying to start.

 

 

[Bludacious]

Worked on it 'til 11pm with the old man & it started firing, but fireballs out the exhaust when we tried to run it on ether. ECU threw code 11 CAS error so swapped it back to the original dizzy that I'd swapped out for the donor's during troubleshooting. Checked the timing both cam & distributor a bunch of times (including making sure it's not 180 off), tried different coils / amplifiers & tried it at crazy advanced & retarded settings and still it keeps sporadically firing out the intake or much more often the exhaust. I'm not sure what else would cause this besides a damaged computer electronically adjusting the timing incorrectly? I ordered a new condenser as well.

 

When you say the spindle, do you mean there's a spindle on the distributor? And can the coils fire properly with the condenser removed?

 

Also like I was asking before. Is there a way to swap to a mechanical distributor while keeping the TBI? I know it'd still need to know where the crank is, could I possibly condition the tach signal with an arduino program & multiply it by 2 to get a faux 0/180 degree signal? Is there a simpler way to accomplish that?

[datzenmike]

There is a drive spindle run off the front of the crankshaft that turns the oil pump on the bottom and the distributor on top. It has to be inserted properly for the correct cylinder to fire and the rotors pointing to the correct cylinder.

 

The CAS requires a splined end to fit the mate on the end of the distributor.

 

 

 

Realize that I have only worked with the regular Z24 distributors and when the engine is precisely at TDC on #1 if the distributor is removed and you stand at the driver's side fender and look down into the hole with front of truck to your left, you will see this...

 

 

The spindle top is much different but there is a noticeable large and small half moon shape and a screwdriver blade shape in the middle. The blade should be in this position about 11:28.

 

See if the CAS spindle top can be oriented to this position. When the distributor is installed the rotor(s) should be pointing to the intake and exhaust on the #1 cylinder.

 

The firing order is 1342 in a counter clockwise direction....

 

 

At TDC note that the Intake 1 and Exhaust 1 are at 9:00 o'clock and 5 o'clock as viewed from the driver's fender.As stated I haven't worked with the CAS much but I don't see why Nissan would change this set up from the original.

 

To adjust the drive spindle the oil pump must be dropped out holding the spindle and turned. Align the two dots on spindle and oil pump. Possibly this can help...

 

 

 

52 minutes ago, Bludacious said:

 

 

And can the coils fire properly with the condenser removed?

 

Also like I was asking before. Is there a way to swap to a mechanical distributor while keeping the TBI? I know it'd still need to know where the crank is, could I possibly condition the tach signal with an arduino program & multiply it by 2 to get a faux 0/180 degree signal? Is there a simpler way to accomplish that?

 

The condenser is probably for noise suppression for the radio. Has no effect on running.

 

Can you get it to run on the old distributor? I don't know. The CAS tells the ECU where the crankshaft is the regular distributor won't. 

[Bludacious]

 

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See if the CAS spindle top can be oriented to this position. When the distributor is installed the rotor(s) should be pointing to the intake and exhaust on the #1 cylinder.

I already stabbed the distributor in at TDC on the splined shaft. Weirdly despite the manual making reference to a punched mark for the oil pump & the drive gear neither motor's oil pump or drive gear seem to have these marks anywhere on them 🙁. I will check one more time but I swear I never saw them while examining them.

 

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Can you get it to run on the old distributor? I don't know. The CAS tells the ECU where the crankshaft is the regular distributor won't. 

In the scenario where I swap to the older ignition the TBI will be going too so the computer won't need to know anything, it'll be in a junk drawer somewhere 'til I can revisit it. Trying to get this truck going since I really need it for work, if I have to ditch EFI temporarily to make it run I will.

 

Mike, would you happen to have one of the old style drive shafts I'd need to convert to the HEI distributor? Only other option seems to be cutting the other drive spindle & welding a bolt shank to it above where it passes thru the timing cover & hope it doesn't shatter or bend since loss of temper from welding will be above all stress points, but that's still a risky endeavor.

 

[datzenmike]

Get rid of Throttle body EFI?????? That's a lot of swapping.

 

Need Z24 drive spindle and distributor.

Need Z24 intake and carburetor with air filter housing. In a pinch a Z20 or Z22 intake and carburetor would do. May need throttle cable too.

Disconnect the high pressure in tank fuel pump and get 4-5 PSI electric inline fuel pump.

You'll need a power wire from a switched source for the choke heater and idle cut solenoid.

 

[Bludacious]

Update, I didn't fully comprehend that there are 2 electrodes on this rotor. I had it set in perfect time but with exhaust electrode at TDC, not intake. As for the TB, I completely forgot the regulator on these trucks is on the return line, not the feed line. Had them backwards. Gave it a quick start this morning before work and it runs okayish, I'll have to dial in the fine timing with a light.

 

On the bright side, I did find out how to turn the dizzy drive gear by yourself near-effortlessly. By putting the long oil pump bolts into the short holes threaded in only a few turns, I was able to disengage the OP from the crank gear, spin the half-shaft topside with a 6mm socket on an extension, then slide it back in where the 2 bolts keep it tracked so it always slots in perfectly. Wish I'd figured that out before! 😑

 

Now, another problem. The starter is clipping the flexplate in 1 spot every rotation. This is the same starter & flexplate used previously without issue, but I lost the starter bolts so used some others that fit that didn't have a home elsewhere when I was all done. Do the OG starter bolts have thicker shoulders? Can I shim the starter (equally on both sides) using a few auto body U-shims?

 

Also, would you happen to know the thread size for the two emissions / backfire valve holes into the exhaust manifold? I need to order some plugs.

[datzenmike]

I would get the correct starter bolts as this may affect the starter gear engagement to the flywheel teeth wearing them out.

 

The holes in the exhaust are for the air injection system (AIS) and use one way reed valves in the air filter to block the exhaust pressure wave but allow the vacuum pulses to draw filtered air down into the exhaust pipe. The oxygen rich air helps the catalytic converter burn off hydrocarbon emissions.  It is absolutely benign on operation and if working, can and should be left alone as it does no harm and has zero effect on running.

 

Probably metric pipe plugs will fit. 

[Bludacious]

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The holes in the exhaust are for the air injection system (AIS) and use one way reed valves in the air filter to block the exhaust pressure wave but allow the vacuum pulses to draw filtered air down into the exhaust pipe. The oxygen rich air helps the catalytic converter burn off hydrocarbon emissions.  It is absolutely benign on operation and if working, can and should be left alone as it does no harm and has zero effect on running.

Well aware of their purpose, PO ripped it all out thinking it was smog equipment including removing what I later realized was the barb fitting / hose for the crank ventilator tube & blocking it off with a bolt (was confused for a while as to why the air cleaner was always filling with oil). The truck I parted amazingly only had 84k clocked & had every single bit of original NAPZ equipment except the cat. I just want both of them plugged for now so I can do basic tuning & test runs without excessive noise or me inhaling fumes.

 

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Probably metric pipe plugs will fit. 

 

Rats, was hoping you knew the size. I'm in the states which means I'll have to order several sizes online to see what fits, metric hardware selection in stores here still sucks. Sigh....