Timing is 35-40 BTDC. Can't figure it out.

[Ace2cool]

Got my engine all back together. Total, 100% rebuild. Pistons, rods, and everything else except lifters, valves, and cams. Starts and runs, but is certainly not happy. Gotta feather the throttle to get it started and to keep it running for the first 20 seconds or so, sputtering, missing and smoking unburnt fuel. After that, it'll even out, stop smoking, and maintain a somewhat decent idle. Any throttle input will cause it to chug, and then it'll rev. Check the timing, running between 35 and 40 degrees BTDC. Brand new wiring specialties harness, and they even included an inductive loop near the PTU, where I'm taking my timing readings from. Rev the engine, timing mark disappears to the left, and as it settles, comes back to 20, and then rebounds to 35-40. Verified with 2 different timing lights.

Figured I'd jumped a tooth on install somehow, so bit the bullet and pulled everything apart and re-did the timing belt. Double, triple, quadruple checked all the marks on the belt with the marks on the gears and the backplates. Followed the procedure in the FSM, turned the engine to take the slack out. Waited a few hours, and tensioner was still right at 4mm. Buttoned it back up, exact same issue. Down to the chugging and feathering the throttle. Timing still exactly the same at 35-40 BTDC. Starts chugging when CAS is retarded past where it currently is. CAS was indexed and reinstalled in same orientation when I reassembled everything.

Click for video:
video-1529807062 by theaaronparris, on Flickr

Deleted everything there is to delete except PRVR. 740cc injectors and dual MAF, with a proper chip from Z1. As mentioned, brand new harness. Upgraded piping and exhaust. Auto to manual conversion with the conversion harness from Z1.

I'm out of ideas. Is it possible the new ECU chip has a bad timing map in it? How can I verify that? Is it possible my pickup isn't working correctly and is showing far before the actual plug is firing and I've actually got a different problem? Could it be a CAS issue, even though the CAS seems to be adjusting correctly? Help me out guys.

[itsa300zx]

Have you tried a different pickup point for the light; I've never had any luck with the loop that is built into the harness. The timing always seems to jump around using the loop on several vehicles. I recently asked SZ during our recent dyno tune and they also use the wires from the coil pack connector; much more reliable and stable.
I use the wires to the #1 coil pack or and extension of the COP to the plug. Just another thought.

[NolimitZ32]

I've never noticed a difference between the loop and #1 coil wire but I mostly use the #1 coil wire NOT the loop. Does the engine sound like its 30 degrees off?

[Ace2cool]

Oh yeah. And chugs hard with throttle input, as you can see in the video. And that's why I wanna get the Conzult hooked up so I can see what the engine is calling for.

[itsa300zx]

Base mechanical timing can only be done using a timing light. You ca not adjust the timing based off consult/conzult which measure the adjusted timing by the ECU for various conditions. Silly question but; Is the car warmed up before checking timing?


Quoted from Z32 wiki bold sentence

"Other Methods to Read Timing
There are a few other methods often used and recommended for setting the timing.
Using the coilpack connector as an inductive pickup. Many timing lights have difficulty picking up a signal from the coilpack connector, as they're designed for high-tension wires. Many have experienced inaccurate readings from this method, and this author has seen a 10 degree discrepancy.
Using a PTU wire/loop as a connector. This often causes the same problems as the above method. The black loop on the PTU subharness is a ground and will cause the light to flash for EVERY cylinder firing.
Using Consult alone to check timing (no!). A common misconception is that this eliminates the need to check timing with a timing light. The reality is, checking the timing with a computer is a great way to see what the ECU is timing for, but that doesn't affect the physical timing. The ECU adjusts ignition timing constantly depending on various conditions, but it does so assuming that it's getting an accurate reading on the position of the engine. Using a timing light is the only way to ensure that the ECU is seeing an accurate reading on the engine's position, but it's good practice to do this in addition to checking the timing with Consult to ensure the ECU is timing for 15°."

[Ace2cool]

I'm aware that base mechanical timing can only be set with a light. I also need to see what the ECU is calling for, because ECU timing and base mechanical need to match up. If the ECU is calling for 35*, then I need to find out why.

[itsa300zx]

Ahh, I see, good luck with the trouble shooting.

[NolimitZ32]

Silly question, have you tried reverting back to single MAF? Longshot but its a pretty easy test.

[itsa300zx]

What is the selin translator set to, ADD or AVE?

[DCaff300ZX]

What is the selin translator set to, ADD or AVE?

Aw crap, forgot about that one- my Z ran just like yours until changed to the correct AVG setting, since ADD is for custom tuning. HOPEFULLY it's that easy for you!

[Ace2cool]

I would like to, but when I ordered my chip, I specified dual MAF. I mean, maybe they put the wrong tune on it and it needs to set to AVG, but I'm pretty sure if the tune is for dual, it's supposed to be in ADD. Hell, it's worth a shot.

[Ace2cool]

I guess they sent me a single MAF tune, cause it's running way better on AVG. Whatever. Onward to further troubleshooting.

[NolimitZ32]

As it was explained to me the dual Maf and single Maf tunes do not affect the K-value (when using a Selin or SAFC to blend the signals), they do something (I don't remember what) to the way the throttle response and some other factors interact but the only time the k-value is affected is if you get a "Dummy MAF" tune.

[itsa300zx]

FYI for future searcher on how the Selin translator works; good info posted by SZ:

http://twinturbo.net/net/viewmsg.aspx?f ... dtSearch=7