Project Thread Crank no start, stumbling idle wont catch

[Melo]

Hey all, ive been researching and struggling to get my UZ running in my gutted 84 celica for quite some time now. I had made a previous post when first buying the UZ asking about fuel rail differences and trying to find more information on what engine I have - all is well and I have this information now:

basic engine components (block, heads, fuel rails, crank cam) all from a 93 SC400 (nonVVTI), I am however, running 96 LS400 electronics and sensors(, also to my knowledge, nonVVTI electronics). I had bought a standalone harness for the UZ from LexusV8 down in florida when they had still offered their standalone services to nonVVTI UZ's. There is NO EGR and NO AUTO TRANS. The only engine codes im getting from an OBD2 reader are for missing transmission solenoids, alas - crank no start and i suppose i have some questions for the gurus here.

Im using a second gen maf, the crank trigger wheel is the correct tooth number, crank and cam sensors tested correctly when doing a resistance test, TPS is set and within spec, IACV is within specification and correctly steps through positions (I have both kinds of IACV but am currently running 'later' of the two P/Ns, as im running the ecu that expects this control valve).

I am getting fuel pressure (i do NOT have a secondary pressure regulator, although my engine is utilizing UCF10 rails and i think this gen has a FPR built in? havent VERIFIED a hard number on FP, though i doubt this may be it).
I am getting spark on all 8 (tested by pulling plug wires and inserting plug into wire while cranking), have plugged all vacuum ports I am not using, and im at a loss of where to check next.

ECU toyo pn 89661-50303
I did just replace the capacitors within the ecu but fear i may have fried part of the board on one of the capacitor mounts, although after performing open brain surgery on it, the engine acts the exact same as it had prior to changing capacitors.

Would anyone happen to know if the ecu I have is supposed to be equipped with a matching immobilizer unit? -

Im asking this because theres nowhere else for me to look as to why this UZ isnt running. Im getting compression, Ive given it a full head tune-up (valve stem seals, lapped valves, headgasket changed) and reverified compression afterward.

So i have the basics > fuel, air, compression, spark

It seems to be backfiring through the intake occasionally, sputtering when cranking, sometimes cranking for a while without sparking, other times catching small attempts at an idle with the throttle all the way open. Ill include pictures and video if the site allows, just looking for any sort of direction from this post. TIA
- J Melo.

 

[P Bateman]

Sounds like it wants to start if you're getting backfiring and sputtering on crank.
I would be checking the timing

 

[blinkerfluid]

is the engine timed correctly? Have you the checked the timing belt marks?

 

[Melo]

is the engine timed correctly? Have you the checked the timing belt marks?

Engine is timed correctly as well, yes

 

[P Bateman]

If you have spark, compression, and the timing is correct, that only leaves fuel.

You post mentions that you have pressure - but how much? (measure with a gauge)
Are the injectors wired correctly? (check they all have 12v with IGN on one pin, and check continuity on the other back to the ECU)
Are the injectors pulsing? (noid light)
Are the injectors blocked? (get them tested, if not already)

Easy way to confirm is to spray some ether into the intake manifold and try to start it.
If it fires then you know what the problem is.
You seem to have all the other ingredients for combustion.

And just because you bought a standalone harness doesn't mean its wired correctly.

PB

 

[blinkerfluid]

Do you have good fuel pressure and / or good injectors?

 

[Melo]

Would anyone here have a pinout diagram for 89661-50303? Ive scoured the web for pinouts to no avail so far.

After testing the pinouts on my harness and cross comparing the repair manual i have, I found that my iacv grounds are wired incorrectly per my manual. However, my repair manual is for the ecu part number 89661-50304, and my ecu part number is 89661-50303.

I have yet to check fuel pressure as i pulled the engine and harness from the the car. I also had injector connectors 2&4 plugged to the incorrect injectors (swapped with eachother) on the engine, which are should now be corrected.

I double verified the wiring continuity acceptable resistance for the following sensors from connector to ecu;
Both knock sensors, both cam sensors, crank sensor, fuel injectors, iacv s1-s4.

— and they do match up to my repair manual (which, again is for a different ecu p/n)

Im going back out to verify the tps and maf against my repair manual pinout, but a correct pinout for 89661-50303 would be very much appreciated.

 

[Melo]

To clarify- My isc or iacv s1-s4 are pinned correctly regarding my manual for a 50304 ecu.

Connector pins B1 and B2 seem to have continuty through ecu connector E11 pin 22.... Which seems incorrect as this should be B+ per my manual, and B1/B2 should be pinned to ecu connector E12 pin 16....
Again, not sure if this is botched wiring or having the 'incorrect' repair manual pinout. Though this seems to be the only discrepancy with my repair manual for a 50304 ecu so far. I just got done checking the maf and tps, those have correct continuity from sensor connector to ecu connector per my 50304 manual as well as all the other sensors mentioned previously.

 

[P Bateman]

The images you posted shows the procedures for a (1) puse waveform test for the IAC and (2) a basic ECU voltage test, both with the wiring harness installed - they are not continuity tests.

• Symbols (Terminal No.) refers to the two terminals (connector - pin), between which you conduct the test
• Wiring Colour is wiring colour
• STD Voltage (V) is the range of acceptable results (in volts)
• Condition refers to the conditions under which the test is conducted

The only way you could get continuity between E11/22 and E12/16 is through the battery.

I have a stack of 1UZ diagrams from many different models and none of them mention terminals named B1 or B2... do you mean +B and +B1?
Unfortunately, none of them have no ECU part number references I'm afraid.


If the engine is sputtering and wanting to start, I refer to my earlier advice
Easy way to confirm is to spray some ether into the intake manifold and try to start it.
If it fires then you know what the problem is.
You seem to have all the other ingredients for combustion

Connect everything back up and get some ether spray.

 

[Melo]

View attachment 25898
View attachment 25896

The images you posted shows the procedures for a (1) puse waveform test for the IAC and (2) a basic ECU voltage test, both with the wiring harness installed - they are not continuity tests.

• Symbols (Terminal No.) refers to the two terminals (connector - pin), between which you conduct the test
• Wiring Colour is wiring colour
• STD Voltage (V) is the range of acceptable results (in volts)
• Condition refers to the conditions under which the test is conducted

The only way you could get continuity between E11/22 and E12/16 is through the battery.

I have a stack of 1UZ diagrams from many different models and none of them mention terminals named B1 or B2... do you mean +B and +B1?
Unfortunately, none of them have no ECU part number references I'm afraid.


If the engine is sputtering and wanting to start, I refer to my earlier advice
Easy way to confirm is to spray some ether into the intake manifold and try to start it.
If it fires then you know what the problem is.
You seem to have all the other ingredients for combustion

Connect everything back up and get some ether spray.

View attachment 25897

B1 B2 i referenced are the two middle pins on the iacv along with the outer 4 S1 - S4 pins. What you said about only getting continuity through the battery does make more sense now. Assuming 50303 and 50304 ecu's are wired the same the only thing thats messed up was myself plugging in the injectors wrong.

I plan on putting it all back together sometime this week, its hot here in the desert and i had pulled the engine out again to make new engine mounts, along with checking the wiring.

 

[Jay Purcival]

To clarify- My isc or iacv s1-s4 are pinned correctly regarding my manual for a 50304 ecu.

Connector pins B1 and B2 seem to have continuty through ecu connector E11 pin 22.... Which seems incorrect as this should be B+ per my manual, and B1/B2 should be pinned to ecu connector E12 pin 16....
Again, not sure if this is botched wiring or having the 'incorrect' repair manual pinout. Though this seems to be the only discrepancy with my repair manual for a 50304 ecu so far. I just got done checking the maf and tps, those have correct continuity from sensor connector to ecu connector per my 50304 manual as well as all the other sensors mentioned previously.

may i please ask for a link to this manual, It would benefit me greatly thank you, I have a similar issue to you, have no security light functionality or injector pulse so if either one of us figures it out, it may be a similar thing, my ecu part number is 89661-50390 and has separate immo ecu which i believe will disable injectors