So I've had this issue for a couple years, ever since swapping a new engine into my 89 teg (like-for-like D16A1 replacement, albeit way newer). The last one was eaten by the timing belt snapping.

So anyhow, ever since the new engine was put in, Code 9. Cylinder Sensor, little doohickey next to the distributor sitting on the end of the exhaust cam. Detects the position of the #1 cylinder to give the ECU accurate info on fuel injection timing.

Stuff done:

The entire factory service manual procedure on troubleshooting Code 9
Resistances across wires were checked multiple times from multiple locations. Everything nicely in spec. Replaced the engine wiring harness anyhow (it was in horrible shape; this was not a bad thing to do).

Verified timing multiple times.

Replaced the cylinder sensor anyhow.

Replaced the ECU.

None of this fixed it. I was stumped for a while, and also had another car to drive so it was lightly used (it runs like *** with the ECU in its derpy default mode).

Recently, I'm going to sell the car to my roommate/friend on the cheap. He's going to (and already has) put some other work into it and we're trying to get this sorted out. So I'm back at this.

After a bit of research online, I read an instance where replacing the distributor fixed this problem, despite the fact that it's not part of the standard procedure for this. Fine, whatever, I'll give it a shot, for $65 a dizzy was worth trying.

The distributor I was sent--and I knew it was going to be aftermarket, mind--well, the best I can put it is it looks like someone took an OBD1 TD43U or similar and wired it for the TD03U's connectors. I'm currently working with the reseller to explain to them why this isn't going to work, such as differences in the ignition coil specs, ignition module and so on, but... well, that's another story.

I did pull both the old distributor and the new distributor apart to compare them, though (to see if I could interchange -any- parts--the answer to that was no) and mostly to get sufficient documentation to give the reseller of the distributor the business. Part of that was comparing resistances for the ignition coils. The ignition coil in the new TD43U (or whatever the hell it is) passed appropriate resistances for most of the early 90s/OBD1 dizzies. On the other hand, something about the resistances in the ignition coil for the original distributor seemed off.

I checked the FSM and.. yea, they're out of spec, however slightly. Secondary is fine, but the primary is off... should be testing 0.3-0.5, and it's testing 0.6 to 0.7. Well, that's good to know.

It also raises an interesting question--could the ignition coil being just barely out of spec be enough to throw that cylinder sensor for a loop and generate a code 9? It makes a certain amount of sense to me, anyhow--the Cylinder sensor is basically supposed to verify the position of the #1 cylinder sensor for fuel injection timing so the ECU can cross reference that information with the info coming from the dizzy sensors for accurate fuel injection timing. The ignition coil being slightly out of whack could cause minute timing/firing issues, which could maaaaybe trip that sensor?

As far as other symptons of a bad coil, at first it hadn't occurred to me--I had thought they were symptomatic of the ECU running in derp mode and a bad IACV, but here's some additional info:

Idle gets a bit low/rough, and occasionally when stopping the car stalls out altogether (moreso in cold weather) or gets damned close to it. We just cleaned the bejeezus out of the IACV, and it tests in spec electrically, but it's not exactly new.

Very occasionally, and moreso in cold weather, I've had a backfire or what feels like a miss from the engine, especially when revved a bit. This was rare enough I hadn't thought anything of it before (other than relating it to the CEL problem), but that's something that can certainly be symptomatic of ignition coil issues.

Also occasionally, and more often than the misses/backfires, it'll bog when stepping on the accelerator for a few moments before it decides it wants to get up and go like it should. Another thing that can be symptomatic of the ignition coil.

Now obviously, the coil is testing out of spec and I've got some related issues, so the damn thing needs to be replaced. My question now is that if this is the possible cause of that code 9, or failing that, if there's anything else I should check. I know this was a bit of a long read but I wanted to accurately cover everything I've been over.

Thanks!

 

The coil being bad will have no effect on the cylinder sensor. Remember it is basically a magnetic pick-up/trigger and only signals the ECU twice every rotation of the exhaust cam.

Replacing the coil may well improve/fix some of the throttle input and driveiaility issues, but it won't fix the Code 9.

First, un-pin the two wires from the plug connection of the engine harness and cylinder sensor, invert them, and re-install (the male pin side is easier). Clear the code and crank the car. If the code returns, switch them back. Next, check continuity between the wires at the cylinder sensor and their respective positions at the ECU. OHM resistance should be minimal from end to end... no more than say .005 volts. If you get a significantly higher number, run a pair of test wires outside the car (out under hood, through window and down to floor to ECU) to rule out a short in the original wiring. Test, if code returns, consider trying a known good ECU. This may be difficult since so few of these cars remain on the road today...

Good luck.

 

Thanks for the feedback. Unfortunately, that has all been done, part of why I'm grasping at off the wall ideas to find a solution to this. To clarify:

2 ECUs tested, both known good, and both give the exact same result.

2 Cylinder sensors tested, one of them brand new. Continuity and grounding checks on both of them and both of them show good, consistent results/no open ground both when the engine is warm and cold.

2 wiring harnesses and self-made bypasses tested; all 3 gave solid results--resistances well within acceptable parameters, no open ground, and readings very similar both directly at the cylinder sensor connects clear back to the ECU harness. ECU's cleared in all instances. Voltages show consistent as well.

Timing checked and rechecked, vigorously. I do know that the timing being off can cause this code.

And that pretty much covers the book on Code 9s on that engine/OBD0. I do know of an instance where replacing the dizzy on that engine fixed a code 9 where it by all means shouldn't, the distributor has the TDC sensor and crank sensors which throw codes 4 and 8 when they're issue. Just in case, I've checked wiring/continuity/etc on those as well and they test good as well. The distributor isn't that old and is in good shape, mechanically.

The only other things in the distributor that could maybe cause an issue and maybe not trip a code are the ignition coil and ICM. Hence my postulation that maybe if there's a 'barely there' problem with the ignition coil (and/or ICM?) it might be screwing with timing/cylinder firing just enough to give the ECU unexpected results from the cylinder sensor but not enough to cause notably significant issues. I'm kinda running dry on 'things that shouldn't cause this issue to happen but could cause this issue to happen' and have thoroughly ruled out the 'book' causes.

 

And of course this thread dies... This is literally the same issue I'm having. Can figure it out for the life of me. I did end up getting the different dizzy from the online guys(stay away from parts geek). Any closure on this? Im about ready to just dump a few extendo clips in it...

 

I feel your pain. I actually just solved my own issue with this recently getting the car ready for a friend. My case was exceptionally weird... The motor was rebuilt ages ago, the rebuilder used a pulley from a different (sohc) d series motor. So the ignition timing was right by the pulley marks, but not by the ECU.

For you, first off, the dizzy shouldn't have anything to do with this. Code 9 on a DOHC d16 points to the exhaust cam, and the little sensor that sits on the end of it. You'll get code 9 if there's a timing related issue or issue related to that sensor.

For this issue, I'd go with this troubleshooting order:

1) Double and triple check your ignition timing.
2) Test the sensor as per the fsm. I'll drop a link in here later. If the sensor tests bad, replace.
3) Test the wiring for said sensor per the fsm. If the wiring is bad, repair
4) Double and triple check your mechanical timing. A tooth jump isn't unheard of, and all it takes is the exhaust cam being off a tooth and it'll throw the code, but still run well enough to drive
5) If you're absolutely sure the wiring, sensor, ignition timing, and mechanical timing are good, then it might be the ECU.

Very unlikely it's an issue with a cylinder firing, vacuum issue, etc, as those will likely trip codes elsewhere first/at the same time. Code 9 is very particular on these motors. Basically, that little sensor (the CYP) is using the exhaust cam to check the position of the #1 cylinder to help with fuel injection timing precision. If the cylinder (or exhaust cam, usually) isn't positioned where the ECU expects it to be according to that sensor, then it throws the code (or if the sensor isn't reading right, obviously).

Good luck;