RHD fd3s not starting after rebuild
 

I have recently done a rebuild on my 93 RHD, using Atkins rotary rebuild kit. The engine seems close to turning over but never does until I put a little oil in the lower spark plug holes, it will turn over but instantly wants to die . I tested the compression before I tried to start the car and got 90 psi on both rotors cold. I have also put in new spark plugs. my injector were fine before I parked the car for rebuild. Could the issue be timing related? I thought the ECU controls timing. I have been pulling the plugs and cranking as I go so it isn't flooded. The spark wires are on the correct plug, the fuel lines are in correct order, injector plugs are correct.

There are a million possibilities in a situation like this. Map sensor, swapped fuel lines, poor or not attached grounds, mismatched plugs on the injectors or water/fuel temp sensor, swapped plugs on the cas, plug wires in the wrong spots, plugs on the coils in the wrong spot......

It can go deep. You need to troubleshoot one thing at a time and rule it out. Dont pigeon your possibilities to a mechanical issue with the motor itself.

The engine only needs four things to run: Compression, Air, Fuel, and a correctly-timed Spark. You've already checked compression. To check for air, make sure there aren't any rags blocking the intake manifold or intercooler or charge piping. A quick and dirty check for fuel might be to pull a spark plug after cranking and smell if it smells like gasoline, more thorough test would be to add a fuel pressure gauge or fuel pressure sensor to the feed line. To check for spark, the very basic is usually called the 'screwdriver check for spark' where you move the spark plug wire to a screwdriver and hold that near chassis ground to see if any spark is happening at all. Careful not to zap yourself. The more in-depth spark check needs a timing light like is common in communities that use distributors such as old-school hot rods. Ideally you want a timing light without the dialback function, just a strobe that flashes when the spark event occurs. The service manual shows there is a small notch on the CAS trigger wheel, the spark for the front trailing coil should flash within 1 or 2 teeth of that small notch. If the front trailing fires 6 teeth away from that notch you have the trailing coil wires switched around. The factory leading setup is hard to get wrong, fortunately. The timing light is mostly confirming there is a spark, you don't have the ability to change much besides maybe swapping the two CAS connectors in the wiring harness.

And make sure the battery is fully charged in case you need to spin the engine on the starter for a long time. I would swap in fresh spark plugs in case yours are fouled from assembly lube. And I would check that you've got oil pressure before giving the engine fuel or spark, since insufficient oiling is the quickest way to hurt an engine. You also may need to hold the throttle around 10-20% to keep the engine running if it sounds like it's trying but not quite starting or staying running.

thank you, I will try things that you said

Start with running codes if you still have stock ecu. Takes about 5 minutes to learn how to do.

RHD do not have a check engine light. If you do not have the specialized JDM codereader (nobody does), you can run codes with an LED light and a jumper wire.

Learn to do this and start with a code reading session each time you have a problem.

There is up to 75 faults the codes can tell you about.

Check all (ALL) your grounds.

The codes will not tell you about vacuum/air pressure leaks.

Find a shop which will run a "smoke test" for you.

Random note: For RHD 16 bit systems (Version 4, 5 &6) the location of the coils were switched around. If you use the USDM FSM as a guide to hook up the leads you may be hooking them up wrong.

Thanks for the input!

On one of my builds the harness leading to one of the ignition coils was shorting out somewhere. The car would run then randomly shut off, maybe restart and then shut off again. It took me 2 weeks to discover after chasing fuel lines, dropping and cleaning the tank, replacing plugs/wire, and double checking all the other grounds and connections.

I just so happened to crank it long enough one time that it shorted out enough to produce a stream of smoke that I could follow.

The short harness to the coils from the "engine (starter) harness" is also different on Versions 4, 5 &6.

https://cimg9.ibsrv.net/gimg/www.rx7...671d22cc24.jpg
I have tried get a code, but the light will not come on, even after I turn the key to the on position. I have flipped the bulb around, but no light.

I think the LED light needs some sort of resistor. Does you light have it? I think ebay has the led light with the needed resistor.

My friend bought about 50 of these for $10 on amazon. Delivery was next day.

https://cimg9.ibsrv.net/gimg/www.rx7...bcbaf6f053.jpg

Okay will get those.

Do you really expect the ecu to give you fault codes?sorry but that is a false hope.
the procedure is simple.
Check for ignition. Lisle makes a very nice spark tester.
https://www.lislecorp.com/specialty-...e-spark-tester

check for fuel pressure

since this is a fresh rebuild make sure you didnt leave anything unconnected. You ll be surprised how often that happens…

i am assuming you are running a stock ecu?

try starter fluid in the intake and see if that’s firing.

these cars are so incredibly simple when it comes to actual diagnosis.

The code tests are the first thing you should do before screwing around.

I disagree 100%.

Certainly codes are not the sole resort.

But a huge portion of the troubleshooting section of the FSM is predicated on reading codes and following steps to seek remedies to the issue they identify.

Why preclude this tool?

Recently I have tested the fuel pressure(reading 40 psi), as well as checking codes. I have trouble code 9 and only 9, which is coolant temp sensor. I have found out I have a broken thermo switch connector, could this get in the way of starting the engine? Doesn't really make sense to me.

The fan thermo switch is what triggers the fans with a factory ecu. If the connector is broken then you need to fix it. This sensor is on the back of the filler neck and has 1 wire.

The coolant temp sensor can keep the car from starting yes. When they fail the ecu will think the coolant temp is -40c and it just DUMPS fuel. This sensor is also on the back and has 2 wires..

The wire from the thermo switch has likely rubbed off. The wire is part of the emissions harness. The circuit runs through the emissions harness, the dash harness and back out to the fan relay through the front harness. Ironically the thermo switch is actually only about 5" away from the relay.

Congratualtions on running codes! How easy was it?

All things considered you might consider yourself lucky if this indeed fixes your issues.

( I believe later versions of FD did away with the thermoswitch and the ecu relied on the temperature sensor.)

Realistically, most owners give up on trying to preserve the stock set up. Too many components aging out at once.

In the end, although robust, the circuit boards in the ecu are 30 years old.

Perhaps begin planning for undertaking the "reliability mod" route.

This invariably leads to an aftermarket ecu and substantial deletions of the emissions and sequential turbo set-up.

Although considered antiquated, the Apexi Power FC is a common fall back.

There is lots of support and modernized analysis software available.

(Importantly you can preserve your air conditioning.)

Thank you for the help!, I am happy it is a easy fix. I plan on selling my current car, for the quest of finding a real j9 CYM. so I won't do anything else to my current car. The ability to read codes is nice for the future though.:)

After finally getting to install the theromswitch sensor, the car still wont start . There are no fault codes, and the car wont turn over at all. I have pulled the plugs and saw fuel mist when cranking, so I have fuel. I am using valvoline vr1 20w-50 which is synthetic, I have heard synthetic is bad for start up, is this true? I know it is harder on the OMP. I have no clue where to go now! :mad:

1. You said the engine has fuel, did you check for spark?
2. Have you swapped fresh spark plugs in case the old ones were fouled out during previous attempts?
3. Are you holding the throttle partly open so there is enough air for the engine to fire up and stay idling easily?
4. Is the battery fully charged and spinning the starter nice and fast, or have you drained the battery by cranking it dozens of times without putting it on a charger?

yes, everything you said I have done, with new spark plugs, and starting fluid

It is cranking. Therefore it is turning over. The issue is it is not firing? At all? Or is it trying to fire but not catching and therefore dying?

20W-50 is pretty heavy.

My car will flood very easy if it does not catch after a few cranks.

There are several procedures to follow to try to overcome the flooding.

But invariably I have to remove the spark plugs and let the combustion chamber air out.

The owners manual will tell you the procedure for a flooded engine is to crank while holding the throttle to the floor.

Holding the throttle to the floor is supposed to cut off the fuel..

It has only worked a couple times for me.

To avoid flooding I always start without touching the throttle at all. My car is that sensitive to flooding.

There are procedures to clear the engine of excess fuel by disabling the fuel pump.

You'd have to see if someone has explained how to do that on here somewhere.

All that said it seems more likely that you are not getting spark.

If it is not even cranking then there are likely issues with the starter. Does the starter just "click". If so it may not be getting enough power (or grounds are loose). Or it is just wore out. Working used starters can be found for $100.

Early LHD have a starter interrupter switch on the clutch. This ensures the clutch must be depressed for the car to start. If this is defective it may cut power from the ignition to the starter.

I am not sure if JDM had such switch. Later JDM did not.

Check to see if there are issues with either of your two crank position sensors.

These can easily get bumped when taking the motor in and out.

Also there may be issues with your TPS (throttle position sensor).

Follow procedures to check it.

Mind the screw heads strip easy. Use a small ratchet with a phillips head bit. (don't drop the screws).

SO the car is cranking strongly, I have been pulling the fuel pump fuse and the spark plugs to clear the engine before start up. I use 20w-50 because I live in an area that sees over 95 degrees Fahrenheit. I am not getting a code for CAS and both plugs are clipped in all the way as well as in the correct order with grey clip on top . I will try to check TPS. I have tested the spark by holding the spark plug(connected to the wire) near metal and saw I have spark on all four, is there a better way to do this?

the white plug goes on top, grey on the bottom

sorry, that is what I meant, had to look at the car and check

During your process was the ecu removed, unplugged, replugged? Was the harness pulled through the fire wall, or did someone share the firewall opening with other wires (such as after market gauges).

Harness could be damaged at the firewall.

Pins on the connectors to the ecu can get bent.

Are the circuit boards in the ecu clean. Not water damage or blown transistors or capacitors?

These things happen.

Back to square one with the OEM diagnostics? WOW what a shocker. I am so surprised it did not tell you exactly what is causing your issue.... :bigeyes:

I don't know why your being a dick, I am trying anything to figure this out, I have even done the things you said! :suspect:

The ECU was removed, stored in my house. Everything seemed just like it was when I took it out, I did not see any damage on connectors or plugs.
I did remove harness from fire wall
I also did dual throttle delete as There was a broken solenoid that controlled it. I have filled/blocked the hole for the rod that the butterfly valves sit on, I am wondering if I need to tune/ adjust anything for it. I have looked it up and I couldn't find anything on it.

Rather than pulling the fuel pump fuse, there is another procedures that, I believe, cuts out the injectors. Some have said this is better than just pulling the fuel pump fuse.

90 is fairly low compression. I don't know how it relates to the engine being cold or not.

The early USDM manuals quote 85 psi as the lower acceptable limit. This may be a printer error.

Every other manual says 100 psi at 250 rpm at sea-level.

I would expect compression to greaten with thermal expansion, as well as the need for fresh seals to seat in which would cause higher compression. I Had someone crank the car( gas pedal to the ground) while I was under it with plugs out, there is only a mist spraying but no liquid leaking out of the plug holes

i was not referring to you actually but ok

as a summary the oem diagnostics suck as i have mentioned above.

also compression is perfectly fine. The motor will break in . It hasnt even started yet

I just got it to run with oil in the spark plug holes and starting fluid, once running it wanted to die. after 45 seconds I started to see a lot of smoke coming from underneath the UIM as well as around the belt and pulley area. I felt the main pulley and it was hot after lest than 50 seconds of run time, I wonder if I did something wrong when putting on the bearings after bolting on the stationary gear or something with the thermal pellet. Is it normal that the belt slips when wrenching on the alternator pulley and will not move main pulley?

no...

take the belts off and spin the motor. it should be as smooth as it was when you rotated it after it was stacked. spin the accessories individually as well and make sure none of them are locked up

it is spinning fine, the other pulleys are too, and the end play was fine when I put the front cover was on as well, so it probably isn't that.

Here is the video of how close it is, https://www.youtube.com/shorts/QkHjLTV4nr0

Try giving it a bit of throttle?
This always seems to work for me when it gets a bit flooded and sounds like your engine. Just add more air and compression.
Not too much, though. On and off.

Also, maybe absolutely sure that your big fat block ground wire is properly installed. A bad ground can cause all sorts of problems.

In the video I was off and on the throttle a little bit. By block ground do you mean the ground that bolts the metal piece of the rats nest or the ground under the a fuse box a few inches away from the power steering. Both of those I have checked and are good.

The main engine ground, which (at least on my car) bolts onto the front iron (near where the AC compressor used to be).

Mine was loose when I bought the car, which made the engine sound like a lawnmower.

Try some starter fluid? You've already got the elbow off, anyway.

https://cimg2.ibsrv.net/gimg/www.rx7...77ea0ebeb9.jpg
Both of these are tight and have a solid ground. I cant get the car running with just starting fluid

https://cimg0.ibsrv.net/gimg/www.rx7...030d10d186.jpg
it looks like I need something here I can find a picture or remember what it is


To be clear trailing plugs have two blue lines on them, correct?

I just want to see what it does when you use it.

What do you mean use it ?? starting fluid ?

Yes. Also, how old is the gas in your tank?

I will make a video with start fluid. The gas is fresh as I emptied it out as well as the fuel lines , with no premix either, pure fresh fuel

WOW, it actually started this time with out oil in spark holes, The car sill wanted to die though . I didn't show in the video, but my coolant light and oil pressure light started

flashing which leads me to believe there is a problem with he ECU or wring. The buzzing noise is the air pump line detached from the exhaust as the previous owner

pugged exhaust for some reason, I know the car can run like this thought.

I watched the video. This makes me think you are not getting enough fuel. Get someone to actually spray it directly in as you start the car.

What *exactly* is happening with your oil pressure and the coolant level light?

Are you getting oil pressure as you crank it? Is the needle moving? How does the low oil pressure light come on?

If you are getting oil pressure, open the throttle enough to keep it running as you long as you can, unless it's a crazy amount of throttle. Or does it just die after a few seconds no matter what?

Make sure that your coolant level sensor is actually covered in coolant and that the wire isn't broken. It's pretty easy to break. I had to replace them on both of my RX-7s...


Also, have you checked that you don't have a massive vacuum leak somewhere?

I have had someone spray it while I cranked and it didn't want to start. while it was running I notice the lights flashing, but I didn't check what the gauge was reading

before it died. The lights; coolant oil and battery where all flashing when running, when attempting to start the lights come on and stay on all solid/ not blinking. I am not

getting response from any gauge except for RMP. The car only runs when I am on throttle but can also die , MY coolant sensor has been replaced/ water it topped up to

cap. I haven't done a smoke test, but I have replaced almost all lines when reassembling. I will try to get it running and make a video of the gauges

tomorrow.