Help / Input Appreciated - No Spark Issue 93 1FZ-FE (2 Viewers)

[Spdstr280Z]

OK, finally find myself begging for help...

93 80 Series, US market 1FZ-FE OBD1

Essentially the vehicle has been completely apart. Engine has been removed, fresh rebuild, all engine bay wiring has been removed, as has the majority of the in vehicle wiring, dash, ECU, everything has been out.... Wiring harnesses have been inspected, rewrapped, new conduit where needed, broken connectors replaced, cleaned, etc. Point being, there are a LOT of opportunities for something to have been put back in the wrong place, missed, etc.

With most everything reassembled and back in place, went for first start. I was not initially successful, and did feel I was chasing a no spark issue at that time. Checked the initial items, verified connectors, coil wire, fuses, etc. Then, it starts right up, and runs perfectly. Idle was a bit high, around 1,100 RPM, good oil pressure, ran without a hiccup for say 3 minutes or so until I shut it off. Checked oil, coolant, trans and PS levels and left it for a few hours. Later when I was ready to finish filling coolant it would not start again, and has not since.

I have verified fuel / fuel pump, and this is a no spark issue.

NO SPARK when testing coil wire against any grounded surface

I first assumed it was a loose connection or ground issue. The ground in the footwell beside the ECU was NOT tight, so I assumed that was it. Tightened, but nope....

I have followed the no spark troubleshooting process, from memory...

I DO ALWAYS have a check engine light when the ignition is on. The ECU is getting power and working at least well enough to show ready.
I DO have 12V at the coil
Coil (which is new) checks OK on both hi and low (resistance check)
Distributor pick ups test OK (resistance check)
Coil wire tests OK (resistance check)
Ignitor has ground (continuity checked from case to bracket and fender)
All related relays, fuses and fusible links are new.
Distributor connector has been checked multiple times. I had actually replaced this connector housing as it was broken.

Based on multiple threads of "trust me, it's the fusible links" I replaced the already new fusible links with new fusible links.

All that lead to "check ignitor by replacing", so I installed a new ignitor, no change.

Only things left on the troubleshooting path are verify the IG signal from the ECU (which I need to find how to do) and replace ECU.

I would easily believe something was not reassembled correctly, but it started and ran PERFECTLY once.

Same for the ECU, might be bad, but I have a CEL with ignition on, and it ran perfectly once.

Open to, and appreciate, any thoughts and experience.

Thanks !

Jason

 

[shocktower]

Sounds dumb but check the plugs on your ECU they can look ok but not plugged in all the way and it will give you head aches also put your old igniter and coil back in just in case I know they are new but I have seen new parts not functioning

 

[Spdstr280Z]

Sounds dumb but check the plugs on your ECU they can look ok but not plugged in all the way and it will give you head aches also put your old igniter and coil back in just in case I know they are new but I have seen new parts not functioning

Thanks, i have made sure the ECU plugs are tight, but i have not pulled and reseated. Agree with the idea to switch back to known previously working parts, but I have been working on this thing for a long time, and well... I can't find the old coil, I may have tossed it. I may be buying another. FWIW, all new parts mentioned are Toyota, well except for the ATC fuses which are Bussman...

Thanks again, I'll try reseating the ECU plugs this evening.

Jason

 

[Spdstr280Z]

Found the old coil, cleaned and reinstalled, no change. Removed ECU, checked connectors, pins and wires, plugged back in with a firm satisfying click. No change...

Also verified correct wiring at the distributor connector since the housing had been replaced. All good there.

Guess I'll start chasing wiring. I pulled the engine wiring harness apart and checked the known problem areas (EGR area) previously. Insulation was crispy, but wires seemed fine. Spark / starting and running were not among the many issues it had before I tore it apart.

Also I'll verify the "air gap" in the distributor. I had pulled the cap and checked visually but couldn't find feeler gauges. Picked up another set yesterday.

Still open to any ideas. May be looking for a known good ECU.

Thanks,

Jason

 

[zapatius]

Check and clean NSS sensor?

 

[Spdstr280Z]

Check and clean NSS sensor?

New NSS, but I DO still have an issue in the connector as my PRNDL lights are intermittent. My understanding though is that the NSS only prevents CRANKING, (starter turning the engine over) which it will do all day long. Can it also affect spark ? If so, that is probably the issue.

Thanks,

Jason

 

[gummycarbs]

Are the grounds between the body, block, and head all tight with good continuity?

Did you verify fuel pressure while cranking, since the ECU doesn't power the fuel pump until oil pressure is established?

 

[Spdstr280Z]

Are the grounds between the body, block, and head all tight with good continuity?

Did you verify fuel pressure while cranking, since the ECU doesn't power the fuel pump until oil pressure is established?

I haven't put a meter on them to verify continuity, but all are tight, battery to block, bat to fender, cowl to head and body to transfer case are all new and heavy duty. Lifting lug to inner fender / coil bracket / intake is factory and there.

I have a mechanical oil pressure gauge on it, and am getting around 20 lbs cranking. Have not tested for fuel pressure, but I smell fuel in the exhaust when cranking.

Jason

 

[Spdstr280Z]

No joy so far, this is becoming my own wits' end situation... But, updates anyway.

All engine bay grounds checked for continuity, they all seem solid.

Traced and tested (voltage or continuity) all igniter and distributor wiring. Documented here in case it helps me, or anyone in the future...

Igniter -

1 Black / Green - IGF to ECU Plug E10 position 17 through connector IH1 (behind glove box) position 17. (Continuity at ECU plug)
2 Black / Light Green - IGT (signal from ECU) to ECU Plug E10 position 23 through connector IH1 (behind glove box) position 16. (Continuity at ECU plug)
3 Black / Green - Battery + from Ignition Switch. (12V when ignition on)
4 Black - IG- to Data Connector, Tach and Noise Filter. (Continuity at Data Connector and Noise Filter Plug (Black))
5 Black / White - To Coil Negative through connector EA2 position 8. (Continuity at Coil Negative)

Coil -

1 White - NE to ECU connector E8 position 12. (Continuity at ECU plug)
2 Red - G1 to ECU connector E8 position 11. (Continuity at ECU plug)
3 Green - G2 to ECU connector E8 position 10. (Continuity at ECU plug)
4 Blue - G- to ECU connector E8 position 6. (Continuity at ECU plug)

I also found that after cranking the engine over with the distributor unplugged, I had a code 12 for no RPM signal. That does not happen with the distributor plugged in, so it seems the ECU is seeing the distributor signal and processing it. Is it possible that the ECU has an issue firing IGT, but it fine otherwise ?

On the plus side, I did find that I have a 60221 ECU even though I have a fairly early 93.

Jason

 

[Spdstr280Z]

New NSS, but I DO still have an issue in the connector as my PRNDL lights are intermittent. My understanding though is that the NSS only prevents CRANKING, (starter turning the engine over) which it will do all day long. Can it also affect spark ? If so, that is probably the issue.

Thanks,

Jason

Looking through the EWD, the ECU does have an input from the NSS, but it prevents starts outside park or neutral by interrupting the starter and circuit opening relay (fuel pump). I have starter and fuel, so I think I am good there, even though I do not have transmission indicator lights.

Thanks,

Jason

 

[Spdstr280Z]

FINALLY ! Got it started again just now. Haven't spent a ton of time on it, but finally figured it out. Painfully simple once found. It was indeed a loose connection, just a lot sneakier that expected. I'll document the rest of the story in case anyone else finds this thread having the same problems.

As mentioned previously, I had checked all the individual components, everything I could test tested good, and following the FSM (maybe a little too blindly) I replaced the "can't be tested"' igniter with new. With no joy there, I kept digging. I had tested all the wiring by checking continuity from the ECU plugs to / between the igniter and distributor plugs. Everything tested good, and I was down to thinking it was bad distributor pick ups (despite testing good) or a bad ECU. I hit up @slow95z who had a distributor in may hand in a few days (we're practically neighbors). Unfortunately no surprise, it didn't help. I'm a pretty experienced shade tree mechanic, but this thing had me confused for a while. I hit up every resource I could find, read through every schematic in the EWD, and eventually ran in to a couple of YouTube videos on testing ignition systems, one using an LS400 and on using a 94 Celica. I learned you CAN test the igniter, and expanding on that the whole igniter side of the circuit in car. The IGT wire which signals the ignitor to fire the coil is pin 23 on the large ECU connector. After reconnecting the coil and igniter plugs and unplugging the ECU, you can trigger the ignitor by hand with a low amp / voltage signal. I used the test lamp as a power probe trick that I had learned a long time ago, but had totally forgotten until seeing the videos mentioned above. With the coil wire laying on the manifold, I had a strong spark every time I triggered IGT. I was also able verify the tach needle moving (tach is driven by IG- off the igniter just like an old MSD box), and using a logic probe also verified that the IGF signal (confirmation of trigger from the igniter to ECU) on pin 17 of the same connector was being sent. Relatively simple test confirmed that the igniter, igniter wiring, coil and coil wiring were all good. Done with the output side of the equation. So that left me with the input (coil pickups) or ECU as the problem, and I had already replaced the distributor. Crap, looking like an ECU, since I had already tested all that wiring, even though it shows ready with the CEL and otherwise seems fine. Since I had the tools out and the ECU unplugged anyway though, it made sense to take it one more step before dropping the cash on an ECU. I tested the distributor and wiring together by checking resistance of the pick ups from the ECU pins. G1 to G- and G2 to G- were both good and matched up with what I had tested on the old distributer, but.... NE to G- was open. Wait, what ? Surely @slow95z hadn't sold me a bad distributor, he seemed like a nice guy, I hadn't even bothered to test it, crap.. Nope, it tests fine at the distributor, WTH. Wait, let's try to move this connector pin around a little and relieve the stress on that wire.... NOW it tests good, is this it ? Dare I hope ? Reconnect ECU and turn it over... Coil wire (still on the manifold is firing ! Back in the distributer and... IT RUNS ! Loose pin in the distributor connector the entire time.

Seems a lot of this is already out there in @jonheld 's troubleshooting guide, but the links I found to it no longer work. Some of the threads were still helpful though.

Some visual reference material...

 

[slow95z]

Man you had one hell of run around. If you end up not needing the dizzy I will gladly take it back and refund your money.

 

[Spdstr280Z]

Man you had one hell of run around. If you end up not needing the dizzy I will gladly take it back and refund your money.

No worries man, I knew it was a gamble when I bought it, and I'm good having a spare. I replaced a ton of stuff while I was in there, but the distributor and igniter weren't done as they are not cheap, and are relatively easy to replace. The igniter is done now, and it's not impossible I'll end up with a new distributor anyway while they are still available. If I end up with two spares, I'll let you know.

Thanks again for your help and generous offer to come down to troubleshoot. I have a feeing I'll see you with a shopping list in hand in the not too distant future.

Jason