CarmonColvin

Guys,
Basics out of the way first, '86 N/A, NEW NEW NEW motor (0 miles) heavily ported. Was running with a low compression engine 2 days before install was started. All emessions (stuff) removed (and running that way with old motor), full road race exhaust, large radiator, stock ECU, original wiring harnes, bla bal bal)
This one is killing me. I finally installed my ported motor earlier this week. I spent all day Friday trying to get it to start. I could never get it to catch on its own for more than a few seconds and that was ONLY after it had sat for a while or if I pulled the plugs out (they were almost always dry).
I assumed it was a timing issue (I had tripple-tripple checked to make sure I was getting spark). So after 100 + times removing and re-installing the CAS I gave up that it was a timing issue. So I moved to trying to diagnose a possible fuel problem. The pump was workng and I had primed the system and I know I had good pressure so that seemed out of the question.
After a bit more playing I sprayed some starting fluid into the intake pipe and the car started right up. But it sounded like it was running on only one rotor and I had to keep spraying the air filter with the starting fluid to keep it running.
The third start like this I was holding the throttle cable open and it was running with out me spraying the air filter. It still sounded like crap but I was excited to finally see the car running (almost) on its own. According to my helper I was letting the engine sit at around 4000 rpm, almost anything lower than that and the engine would try to die. It was running like that for about one minute. A quick glance down at the exhaust header let me know something was terribly wrong. The front rotor's exhaust header was glowing BRIGHT red. I immedietly let the car die. I knew at that point I had a fuel issue.
Telling by the heat on the headers only the front was actually firing (rear rotor exhaust was able to be touched by hand while the front was glowing). The only thing I could figure out was that only the secondary injector on the front rotor was firing. The starting fluid gave enough fuel to get the motor turning and over the 3500 secondary injector limit and beyond that it was only running on the front rotor and just the secondary injector for that rotor was not giving enough fuel to give a proper mix (thus the running lean and cherry header!).
Hours later I have done the following:

rigged up my own injector test stand (holding the injectors to the rail off the intake manifold with the air flow meter jacked open to simulate air flow. Neither of the primary injectors are working at starter speed.)

checked the resistance of all injectors
check the continunity (sp) of the wires from the ECU to each injector

checked the continunity of the wires from each injector to the resistor pack

checked the continunity of the CAS wires and the resistance of the CAS.

All of this checks out according to the Haynes manual (yea yea.. throw a rock at me for not owning a factory shop manual).

Any ideas?

B. Carmon Colvin
'86 Base
Yea I sold ThePartsTrader.com

HAILERS

I think your concept about secondary injectors is not quite right. The secondary injectors do come online at somewhere b/t 3500 and 3800 rpm, but only if there is a load on the engine sensed by the boost/pressure sensor. In other word you would have to be driving the car. You can fool the system and take the vac hose off the boost/sensor and then they will come on line, but thats trickery and not the way the car is supposed to work.
So, when everything is connected up, and you take the small plug off the ECU, do you have 12v on the primary injector wires (key turned to on)? Those would be the light green wire and the light green and black wires? You ohm'd the primary injectors and they are approx 2ohms?(the ones under the dynamic chamber). The reason I mentioned this, is your test procedure for testing the primaries indicated that you might be looking at the secondaries that are easily accessible without taking the dymanic chamber off.

CarmonColvin

So with the car sitting in neutral here is no way that the secondary injectors should/would be firing?
That does blow away my theory that only the secondary injector on the one rotor is working. But what explains it not running at all under ~3500 rpm?


At the time I tested the injectors under pressure had the upper intake manifold removed and I was using the upper/secondary fuel rail but I had pulled the wires going to the primary injectors to test with. And just incase the system needed a complete circuit I plugged the secondary injector plugs to the primary injectors still bolted to the block.

After a sleepless night thinking about it I have decided that just because all of the wires check out does not mean the injectors are getting a good connection because of the 15 year old connectors. One of them is cracked but the others look good. But it is hard to tell if they are getting a good connection once snapped into place.

Today I am goign to put it all back together and test a few more connections. If I don't get it running today I will take the injectors to a local turbo/injection shop and see if they can test the injectors and sell me some new snap on connectors for them.

Any more ideas or input would be appreaciated.


B. Carmon Colvin
'86 Base
Yea I sold ThePartsTrader.com!

HAILERS

If you have everything connected up, and go to the ECU, the small plug, and check to see if there is 12v on each injector wire, then the circuitry is good. Its the ECU that pulsates a ground to each wire that opens and shuts the injector. Not the 12v. The 12v is there anytime the key is on. The injector is just looking for the ECU to put a ground on it so it can open. Yeah. I now see how you checked the injectors. Frankly the wires for my primariy injectors will not come close to reaching the secondary fuel rail. Good for you that yours do. Any chance you have the primary and secondary connectors going to the wrong injectors????? Like I say, my primary connectors won't stretch to the secondary rail. If Ive misunderstood how you did the check......just disregard what I just wrote. Darn, I mean my primary connectors just barely reach the primary rail. Obviously I misread.

CarmonColvin

I had the fuel rail in my hand and not bolted down, the metal vacuum spider on top of the motor is gone. It was easy to push the secondary (larger) fuel rail down over the engine (with injectors facing me, over the passenger side fender) so that the primary injector plugs would reach. And at the time the full engine harness was out of place because I had been playing with it.

I am positive I don't have the injector plugs running to the wrong injectors. There is only one possible way it could fit. Here is my best to describe it from memory.

from the huge rubber thing at the firewall it goes down to the passenger side shock tower. It splits off and has wires that run down to the AFM, injector resistor, boost sensor and other stuff.
The main line continues to the motor behind the water fill neck. It has a few loose connectors that went to the air pump (no longer needed) and has a split that goes to the secondary injectors (on top of upper intake manifold. It is impossible to get these crossed between front and rear because of their lengths. The main line continues behind the alternator and has a plug there, it bends around the front/drivers side corner of the motor where it has the 4 or 5 colored plugs for the air actuators (no longer on car). It then bends back towards the passenger side under the intake manifold where it has the two primary injectors, it is obvious which one goes to the front and rear rotor because the front rotor line has an extra connector on it that goes to the temp sensor on back of filler neck.
I know I did not mention the TPS, oil pressure, etc. etc. but those are all plugged in too.

HAILERS

Sorry I doubted you. I see now how the harness reached the secondary rail. The rail was moved to the primary plugs. Almost sounds like a dead ECU. It does not sound like its pulsating a ground to the primary injectors. You sure you got 12v at the ECU? Small plug. Light green/black wire and plain light green wire? If you do and its not squiting fuel when you crank the engine, then me thinks the ECU isn't pulsing the ground to the primary injectors. The secondary injectors can be fooled into opening in your driveway by disconnecting the vac hose from the pressure sensor. But then you still need the 3800 rpm to make them come online. Why do your injectors not fire when starting? Either there is no 12v constantly at the injectors when the key is to on or the ECU is not pulsating a ground signal to the injectors. That ground signal is what makes them work, providing there is 12v sitting at the injectors. Just turn the key to on and put your meter on the injector plugs and see if one pin of each has 12volts. P.S I see now how you have things wired. I don't doubt you have things rigged right.

HAILERS

Here's a jpg of a schematic from a 87 N/A model. Might help some. If you got spark you should have injectors pulsating. The way I understand the way things work is that the ECU looks at the signal from the cas to determine when to spark and when to inject. Your car sparks, so why isn't it injecting? Really got me there.

HAILERS

Here's the other half of the schematic. Also if you do not have the 12v at the injectors, this jpg shows it comes from the 40a fuse in the engine bay thru the Main Relay. This is for a 87 N/A. 88 similar.

CarmonColvin

My father suggested that it was a bad ECU.. I know anything can happen with electronics so the only rebutal I have to that arguement is that the car was running fine with a perfect idle just 2 days before I started this motor swap. And the VERY first thing I did was remove the battery so shorting out is not an issue. I am going to spend the rest of my Sunday putting it back together to test the voltage at the injectors and to check some of the grounds around the ECU.

If the ECU was completely bad wouldn't it effect the spark too?


Thanks for the pics of the schematics.. I am sure they will come in handy later today.

HAILERS

Are you using the same injectors that were in the old engine, or did the new motor come with injectors???? The 86=87 and a half used low resistance injectors of approx 2ohms value. The ones in the newer cars use 12ohm injectors. Is it possible that you have 12ohm injectors in the car now?????? Could be a possible problem if the new engine came with 12ohm injectors.

HAILERS

Another thing: I am a big fan of using starter fluid to prove whether or not the engine is having a spark or a fuel problem. You really should try to avoid sustained spraying of the starter fluid to keep the engine running though. It caused detonation which isn't all that good a thing. Just to get the thing running I'm one hundred percent for. But for sustained running....try not to do that. One thing you might try.....pull the top plugs out and all plugs off. Have someone crank the engine with a fresh battery. Look a the top holes. Do you see a spray of fuel coming out of both or just one hole?????? If both holes, then maybe the problem lies elsewhere. Your battery must be taking a beating with this non starting engine. By the way, I've rebuilt a few engines and most were prone to flooding until the apex seals decided to get about their job of sealing. Usually there is low compression until this happens which results in a flooding situation until the engine gets a few hours on it. In case I didn't mention it, you can check for the 12v at the injector plugs with just the key turned on. No cranking needed. Check all those fuses in the engine bay, especially the two outboard ones. Then in the cabin check the forth row from the bottom, third fuse from your left. Also the the third row from the bottom, I forget which fuse on that row. The one on the forth row is identified as *Engine*. Press on. You'll find the gremlin.

HAILERS

The red hot exaust caught my eye. Does not seem right to me. A really badly retarded engine might do that. The way the manual installs the cas ........well lets say I disagree with their metod. I'm all for the putting the crank pulley on the yellow mark and then aligning the two indentations on the cas itself prior to installation. Like a number of people, another step should be taken. The black plate on top should be removed and with the indentations at the bottom of the cas aligned, one should look at the rotating parts in the top vs the stationary parts, and when installing the cas fully in the hole, make sure the parts you took note of in the top of the cas, align perfectly before cinching the cas in place. I'm just writing this in case it turns out not to be a fuel injector problem. Same in the post above. Just rambling. Hard to fix engines from a computer.

CarmonColvin

I am using the same injectors from the old motor. I was able to check them again and when manually putting power and ground to them they clicked as I expected them to. (did not have them attached to fuel rail at the time)

I know that a glowing exhaust can be caused by retarded timing. But it would make sence that it would happen to both rotors and not just one of them. Some other testing today lead me to believe that the injector harness plugs are in such bad condition that they are not getting a good connection. I ran out of time today to fully test this idea but tomorrow I am going to a local injector shop to see if they can sell me just the injector plugs that I can replace on my wiring harness. That will completely eliminate that as a possible problem.

Thanks for all of your input.

CarmonColvin

Last night I replaced all 4 injector plugs with new ones. I also replaced ALL 0-rings, grommets and insulators on all the injectors. I am in much better shape than I was 2 days ago but I think I opened up a new can of worms.

Now the car will fire up after trying to start for just a few seconds (4 or 5?). But when it fires it revs up to around 1500 rpm and dies. Most of the time it backfires as the RPM's fall.

If I try to start the car while pressing the gas pedal it will not start but as soon as I let off the gas it will fire up, rev to 1500 rpm and die.

Once it has started (during the rev to 1500 rpm) I can feather the gas a bit and get it to rev higher in short bursts (backfiring on the way down). Doing this the longest I have been able to keep it running has been around 20-25 seconds before it dies.

But then as soon as I hit the key again it will start back up and do the same thing. Any ideas of this new can of worms?

blu_gxl

sounds like a vacume leak. that's exactly what my car did when i had a wire harness stuck inbetween the upper intake manifold and the lower intake manifold. spray some starter fluid around to see if it makes the engine rev up it will be hard since you can't get the enging to sustain itself even with pressing the gas pedal. also look at your silinoid rack mine had a crack from when we were taking off the dynamic chamber and it would start but would not stay running for very long almost like yours. check around and don't lose faith.

james

HAILERS

Big *** air leak or.....jumper the yellow fuel jumper near the right strut tower and try again. Its possible that afm micro switch isn't making contact and not letting the fuel pump run. The jumper plug overcomes this possibility. When you turn the key to start, it energizes the fuel pump as long as the key is to start. When the key is returned to on, the micro switch in the afm is supposed to make the fuel pump circuit. The jumper of the yellow plug overcomes this possibility.

hekso

hey in had the same problem with my 86 rx7 after i swapped the motor out iunhooked the bat i unplugged the ecu checked all of my connections on the entire harness under the hood and i even replaced all of my intake gaskets it turned out that i had put the injector ground in a bad place not good enough ground point hope this help's