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88 FC3S Barely starts and runs - need help troubleshooting!
Hey guys, Long time rx7 enthusiast here, thanks for trying to help.
Real quick about the car:
88' FC3S with a rebuilt S5T JDM Engine
RTek 2.1 ECU, 750cc RC Inj. Pri & Sec
K&N FPIK intake
T4 Garret turbo
3 inch exh to a "can" muffler
What happened. So the problem first presented itself in the dead of winter this past Jan. I tried to start the car and the RPM Gauge died, the starter seemed to stay engaged after I started it and it blew the starter. replaced the starter and the weather warmed up. I was able to push start it and get her home a few weeks later. Fast forward now its warmer and sometimes the car is okay sometimes not (Mid Feb). I hear the fuel pump relay in the front right of the car clicking like crazy so I start to suspect it. At this point I can get the car running well and then at times it will start but run super rough, Like very very rich. It is also violently flooding, Like to where I stall it at a stop light and cant start it for hours after. I thought I had an injector stuck open so I ordered all new ones from RCengineering and at the same time sent my ecu in for the Rtek 2.1 upgrade.
When I uninstall my ecu to ship it in for the upgrade I already had my emissions harness disconnected, The injectors plug and the other one. It was when I took off the final plug, (the one that connects to the FR Harness I believe) that I found a bunch of green corrosion that may or may not be related to this incident. So I began investigating. Maybe I had a short somewhere? Where the battery goes I do not have a battery tray. It was sold off before I was able to rescue my 88 Shell during its part out by the previous owner. Under my battery I noticed I started to eat through a section of the FR Harness. I cut it open and fixed some smashed wires. Did not look to bad.
Where I did find noticeable heat was within my emissions harness. I went through the entire harness, took out what I am not using (Actually depinning the wires and removed them) and so I have now minimal stuff up there. I rewired my fuel pump properly using write ups found online here, Using the original fuel pump circuit(deleted the FP resistor) to run the relay that has a fused power lead from the main breaker box. I have a new FD pump/w/sock in there, new filter, Plugs and wires (Maybe I should ohm out my new SP wires).
So the latest is this. I swapped out the AFM with the one from my NA and was able to get it to run on what seems like one rotor. It wouldn't even fire up with the orig. in there. I also put some fresh gas in there. I did pour a bit of MMO in the tank to try and clean the injectors I thought were giving me the problem. I have good fuel pressure, and I wired in an led to one of my injectors on both primary and secondary circuits. The one primary (I believe I have it on the rear for both) blinks when starting, then once it catches and starts to turn over I notice the blinking stops. then it kicks back in again.. sometimes. It did when I had the NA AFM on, when I had the s5 turbo afm on it seemed to cut off after the starting which is what made me think, hey its not seeing incoming air so that's why the injectors are not firing, or am I losing the fuel pump signal because the afm is not seeing incoming air?
So there was... As I write this I am thinking that maybe I should change this back but.. There was a shielded wire that the shield was not connected to anything and just the center was with a butt splice connector. It looked suspect because the shields could touch the insides of the butt connector if jammed in there right. I redid the connector and spliced the shield together and the cores together and taped it all up.. Unlike before where the shield just had its break in it and may or may not have been touching the center conductor. Maybe I need to take that back out however it was not correct in the first place it looks like. That shield does connect to one of the ground loops. My harness was chopped right down the middle at one point which is how those (Coaxial?) Shielded cables got cut. I wish I could tell you exactly what cable it is, I can once I get home. The last time it ran correctly was after I got it home back in Jan-Feb. I hopped in to take it to the casino and half way there it started running stupid rich, I had to hold the gas pedal down as it was choking and drowning in itself to get it home. Once home it died and floods out every time.
Now as far as my ecu is concerned I have not been able to set it up yet to recognize the 720 cc injectors, Apparently I need to find an older version of windows or a driver, something to get the palm software working correctly and I am working on that. this problem however seems bigger then that plus this was going on before the ecu came back. I was sure it was an injector problem. I can record the way it is running now if that will help.
So right now with the na afm installed: It will idle but only with no gas pedal pushed and it seems like it runs on one rotor or only one side is getting fire, or fuel, or something. If I try to rev it up it chokes out, and seems like the actual injector stops firing. I should probably hook that other LED up to my other Primary injector to see how it is firing too. Did I burn up an injector driver? I am at a loss! I've been messing with these 7's for a long time and can usually get them going again but right now I am at month 5 and still no luck... so it is to you that I reach out. I know if I had someone with alittle more tech knowledge they could figure it out while it was running. Can I check the amps through the spark plug wires to be sure they are firing correctly? I did buy a fuel pressure regulator but I guess watching the voltage going to my fuel pump relay a1-a2 will let me know that my fuel pump is staying on (Maybe I Should have just installed a switch?) Did I ,mess something up with that, like does the ecu need to see something that says the fuel pump is running or does it just do the output?
I probably need to do some more testing and get some solid results for better help. I've been trying just about everything lately.
It sounds to me like you may have a few problems intermingled... Starting with the basics as it were (if you already know what I'm talking about just ignore it. I write more than is strictly necessary as this is a publicly searchable forum)...
An internal combustion engine requires fuel, air, compression, spark/ignition source, and timing to run. If I read it right you said your motor last ran in the middle of winter time frame after an issue with a stuck starter.
As you addressed the starter issue I would move into a compression test. This does several things but primarily it tells you the motor is either fucked and the little things aren't worth doing at this point in time or that it is some other thing. Turn the engine over a few times to ensure there isn't any residual fluid in the chambers. If there is, do check to see what came out.
If you are dead set on checking your injectors then you need to check that the injectors work, the wiring to them works, and that they flow.
To do the first, quickly applying a direct 12v source should allow you to hear a "click". Do NOT hold the 12v source to it and do NOT apply it to where the connector connects. Make some flying leads to do this.
The second can be done with a NOID light (or faked with a DVOM). It is essentially an LED and lights up briefly when the injector would be pulsed. Buy or DIY one.
The third requires the injectors be off the car. I don't recommend this one until you've checked the others and perhaps a few other items as it requires a certain amount of time and in general is an annoying test to do.
Check spark. There are a variety of ways to do so. I prefer the - pull plug - flying lead from plug to bare block (aware from electronics/sensors) - have someone crank car and look for spark - method
That one AFM will allow the car to sort of run implies a few things, some are checked by the compression check, others are things like what tune you have, condition of various electronics, etc.
Not lastly or least (but where I'm stopping) is to check your intake tract and ensure no small animals have made nests in there. Oh yeah, also make sure you're not making matters worse by trying to turn the car over, i.e. look for things like bare or melted wires and trace/repair them.
One of the first things I did was a compression check. It is even on all faces, about 30 PSI Each. I could only get about 75PSI out of it cold on both front and back. I think I have what you described with the LED's on the Injector leads. I will go ahead and install the other LED on my other primary injector. I am also going to look at the splice I performed on the coaxial cable. I removed the entire em harness and went through every wire, hence the picture there. I did have some extra wires in there that look like they got shorted out at some point.
I need to read advice from people that know what they are talking about please. 30 PSI on each face is good. My compression is fine. I am using a piston engine tester. Also this engine has about 10K miles.
The FSM has sections to test each component individually. I'd say that since it's this far torn apart, that rather than putting it all together and playing electrical whack-a-mole, go through the FSM piece by piece and verify each component, and then verify continuity in your harness. It'll be tedious, but at this point, it'll be the only way to eliminate issues.
Something we have to do in blasting is also check cross-continuity. Sometimes in old wiring, the insulation on wires becomes weak or cracked and you get electrical gremlins going places they shouldn't. Checking and making sure the signals aren't crossing would probably be in your best interest too.
Is there some commonality to your problems, like the ignition switch or grounds? If you can find a single point of failure, that would be the best case scenario. If not, you're going to have to procedurally test everything.
I need to read advice from people that know what they are talking about please. 30 PSI on each face is good. My compression is fine. I am using a piston engine tester. Also this engine has about 10K miles.
If you don't like suggestions given to you, then why ask?
30 psi per face is not good, whether it be a 500 mile rebuild or 10K mile rebuild, things don't last forever. Some things less then others
Being that said, have fun, i've said my peace and tried to help, i won't be surprised to see an engine teardown thread from you soon
The FSM has sections to test each component individually. I'd say that since it's this far torn apart, that rather than putting it all together and playing electrical whack-a-mole, go through the FSM piece by piece and verify each component, and then verify continuity in your harness. It'll be tedious, but at this point, it'll be the only way to eliminate issues.
Something we have to do in blasting is also check cross-continuity. Sometimes in old wiring, the insulation on wires becomes weak or cracked and you get electrical gremlins going places they shouldn't. Checking and making sure the signals aren't crossing would probably be in your best interest too.
Is there some commonality to your problems, like the ignition switch or grounds? If you can find a single point of failure, that would be the best case scenario. If not, you're going to have to procedurally test everything.
Roger that Pro Pyro. That's what I tried to do when I went through the EM harness, I dissected it, ohmed everything and it was all good but I will uninstall and check it again. I need to investigate those shielded wires as those were the only things I changed. Going to start with testing out that ground the shield went on. I definitely get a small shock from the frame when I hook the battery up. I am also going to tear open the harness where the battery was sitting on it and inspect it again. Aside from that I guess after I get it running I can see if the other injector is firing and be sure I am getting the spark signal from both front and back leading. I could swap to coils from the NA but like you say, its easier at this point to check the system vs swapping out components. Thanks for your help and motivation!
Alright, I'm a wee bit confused here... your compression is only 30psi per face, but you're expecting the car to run ? If you utilized a standard compression tester the right way for use with a rotary engine, your numbers won't be too far off from reality.
Enlighten us, rather than making a statement like someone pissed in your cereal bowl this morning.
Alright, I'm a wee bit confused here... your compression is only 30psi per face, but you're expecting the car to run ? If you utilized a standard compression tester the right way for use with a rotary engine, your numbers won't be too far off from reality.
Enlighten us, rather than making a statement like someone pissed in your cereal bowl this morning.
What are your actual compression test results ?
Just as I said, 30 on each face.. No one pissed in my cereal, just do not want to be debating something that is common knowledge instead of actually getting help. I understand people like to think they can solve issues, and I know its fun to imagine "Oh the guy blew his engine, I know he did because I know my stuff and thank god I was able to tell him that and solve his issue." but when I come back to say hey this is not it and this is why... suddenly I am being a dick and someone pissed in my corn flakes.
Lets just skip all that, what do you say RX7Club?
30 psi on each face... Each rotor has 3 faces, each with shared and their own seals. Checking in this way tells you more then what you can read with just one number so that is the way I do it. That comes to about 90 psi on both housings. In addition this engine has only 10K on it. If I had low compression it would be a seal broken and one, possibly two faces (If it were an apex seal) would have lost compression, not the entire thing wearing out evenly to render a small number.
If 90 psi on each housing, (30 per face) is not good enough to run then what are numbers on a cold engine which allow it to run.
This was my daily before these electrical issues started. I hope we can be over the compression test debate and move on. I will update my findings soon.
30 psi on each face... Each rotor has 3 faces, each with shared and their own seals. Checking in this way tells you more then what you can read with just one number so that is the way I do it. That comes to about 90 psi on both housings. In addition this engine has only 10K on it. If I had low compression it would be a seal broken and one, possibly two faces (If it were an apex seal) would have lost compression, not the entire thing wearing out evenly to render a small number.
If 90 psi on each housing, (30 per face) is not good enough to run then what are numbers on a cold engine which allow it to run.
I'm far from an expert, but I do believe you re supposed to get 3 even bounces of 90PSI per rotor. 30 is unbelievably low. So low, in fact, that you probably did something wrong when you performed the test leading to artificially poor results.
no worries, I have pretty much the same setup, same injectors. I have the BNR turbo instead, but same size exhaust, etc with factory computer. My harness is out of a wrecked car, so every time I work on it, I go the full gambit and solder, heatshrink, and re-test my connections.
I have the same injectors in my car, and I remembered a problem I had with them. I couldn't get them to seal very well on the bottom and it made a weird boost/vac leak. Caused shaking, etc. What I ended up doing to fix it was get the Mazda lower grommets and then use a couple fuel injector o-rings to take out the slack between the injector nozzle and the grommet. Those don't have pintle caps on them, so there was some wiggle room on mine for air to bypass. While you're there, it might be worth checking out.
I'm far from an expert, but I do believe you re supposed to get 3 even bounces of 90PSI per rotor. 30 is unbelievably low. So low, in fact, that you probably did something wrong when you performed the test leading to artificially poor results.
You should probably test it again.
I feel like I'm on the funny farm right now. A rotor is shaped like a triangle. Each triangle has three faces. Each face reads 30 psi. 30+30+30 = 90 total for the housing.
I feel like I'm on the funny farm right now. A rotor is shaped like a triangle. Each triangle has three faces. Each face reads 30 psi. 30+30+30 = 90 total for the housing.
"Piston compression gauge with the Schrader Valve removed
3 even bounces of 85 PSI or above is GOOD. Readings above 110 PSI is GREAT!
3 even bounces of less than 85 PSI: indicates that motor is tired, and indicates engine should be rebuilt before causing damage to rotors or rotor housings.
2 high and 1 low: indicates problem with side seal (stuck, cracked, broken, etc.) Engine needs to be rebuilt.
1 high and 2 low: indicates problem with apex seal (stuck, cracked, broken, etc.) Engine needs to be rebuilt.
NO bounces: either incorrectly installed gauge or destroyed rotor and housing."
"... relatively even pulses around 75-80 psi ... Minimum spec in the manual is something like 85 psi, but there will be some variation between gauges."
"You want to see 3 even bounces. Looking at the psi, 115 psi is like a brand new motor, 100s-90s is acceptable, anything lower than ~80 psi needs to be rebuilt soon"
For some reason my last quote is incorrect. It appears correctly in the editor, but renders incorrectly on my screen. Not sure if problem is same for everyone else. If not, apologies for the double post.
Ya he doesn't quite get how a compression tester works, the OP and me have been PM'ing, and I think I described it the best I could for him how it works, we'll see in time
All I can say is I've been using the same crappy harbor freight compression tester for quite a few years now. I've gone through and re-built six engines. When I use the tester I hold down the button and I get 30 on each face if everything's good. I can usually get 90 if I let the valve closed. It's the same way rotary resurrection tells you to do it on his website. It's common knowledge if you look it up. This is why I'm at such a loss and why you guys don't understand what the hell I'm talking about. In any event the compression is fine. My tester, Who knows.
the way rotary resurrection lists the test procedure on his site is an antiquated and poor way of performing the test, it's actually quite simply the lazy way of performing a compression test.
remove the schraeder valve from the hose to the gauge and do not hold the relief button. this method will give you a more accurate peak bounce with closer to accurate resolution.
even a cracked side or corner seal will cause an engine to run like garbage but only result in something like a 90/90/60 test result and potential hard starting and flooding issues. which is not so easy to read when you are seeing the needle only reach a peak of 30/30/20 which might even appear like 3 even bounces of near 30.
and why i say that test sucks, is the difference between 25 and 30psi is passing or failing for an engine's health.
hell, even manual gauges are antique now in a world of digital compression testers that offer sub 1psi incremental readings that you can correct for RPM and altitude. so i consider the revised method i wrote just now to be the most basic method. if anyone is still using kevin's method they should abandon it unless you are trying to verify the engine doesn't have 0 compression net, but for a running engine and diagnostics, it just doesn't work. he should revise it or take it down, because the only place it might be beneficial is if you are in a field with a compression tester without a removable schraeder and no hand tools.
Last edited by insightful; Jun 13, 2017 at 09:14 PM.
All I can say is I've been using the same crappy harbor freight compression tester for quite a few years now. I've gone through and re-built six engines. When I use the tester I hold down the button and I get 30 on each face if everything's good. I can usually get 90 if I let the valve closed. It's the same way rotary resurrection tells you to do it on his website. It's common knowledge if you look it up. This is why I'm at such a loss and why you guys don't understand what the hell I'm talking about. In any event the compression is fine. My tester, Who knows.
Let's say for the sake of argument you had a side seal blown (theoretically, of course). You put your tester in and do it as outlined in the steps above. Your peak on two faces is say, 90 psi. So when you look for a "total" compression value, as you call it, this test returns a good result. Then you look to see if the bounces are "even", and you perform it your way, but because the tester only returns maximum values of 30PSI in this configuration, you conclude you have three good faces. However, maybe one face is actually 55PSI, and your test method won't show this. Or perhaps your tester returns bounces of 30,. 30, and 27, and you conclude that the lower value is simply an acceptable margin of error.
And then you waste lots of money and time addressing other components in your engine setup that aren't the problem.
Unless I'm horribly misunderstanding the workings of a compression tester, that scenario is not impossible.
Are you done stroking each other now? Are we through giving bullshit solutions to problems that I don't ******* have? You guys want to fight over the same **** some more and waste more time? I knew that this forum had gone downhill over the past couple years but I figured there was still a few people out there that werent damn fools without real world experience.
You know what? Keep this post up so that other people can read all this bullshit and know not to try and get help from you self-absorbed ******.
When I figure out my solution I'll post it somewhere else and maybe some other place so that it actually helps somebody instead of wasting everybody's time like this **** has.
88 FC3S Barely starts and runs - need help troubleshooting!
