89 NA vert

Finally got my car running after a failed OMP and now it’s hitting a hard wall at around 6-6.5k.

I also cannot get my TPS to stay set, I’ve adjusted at exactly 180 degree coolant several times and after even a 5 minute drive it’s out of set again at exactly 180 degrees again.

My idle also bounces intermittently. It will be smooth for a little and then start to bounce then eventually smooth back out as the car heats up. Sometimes it will also bounce when the car is fully warmed up, sometimes not

Whats been done to the car over the last 3 months:

Cleaned and tested injectors
new fuel pump
New fuel filter
brand new TPS
New tps adjustment screw
oem S4 primary fuel rail the FPS block off
New OMP lines
New to me OMP
new to me ECU
New aftermarket radiator
E fan installed, stock fan and shroud removed
Coolant flush
Fuel Pump resistor relay delete (after 6500 issue started)
New alternator/water pump belt
cleaned ecu ground on UIM

All emissions have been deleted since before I bought the car, and it ran perfectly up until my OMP went out.

So a little background, a couple weekends ago I got the car out of limp mode and took it out for a drive. Well after the car being down most of the summer, I did what we all would and had a healthy high rpm drive up until my temps started to get hot. I thought I was just pushing too hard so tried to relax and make it home. Temps started getting up towards 215 so I pulled over and shut the car down. That’s when I realized there was steam from under the hood and after checking, my stock radiator had exploded and my alternator belt was shredded. The entire engine bay was covered in coolant.

I let the car sit for 30 minutes and limped it the last mile or so home, having the coolant buzzer screaming at me the whole time and having no temps because my coolant was no longer in the coolant system.

Everything in the list of things I’ve done were before this happened except the rad, belt and fan.

Aswell as deleting the fuel pump resistor relay in hopes of that being my issue (it was not)



So with that being said, I haven’t been able to compression test yet, but the car drives beautifully up until the hard wall so I think I managed to avoid destroying my engine. From other threads about this issue, i want to think this is an issue with my secondary injectors. I think the injectors themselves are not the issue since they were cleaned in the last few months. Would it be possible that the hot coolant the exploded have melted my injector wiring? Most of it landed on the passenger side of the engine bay so this is my working theory.

Im just not sure how to test the wiring if that is my issue


Then for my bouncing sometimes idle, it acts like a vacuum leak but if it was wouldn’t it be bouncing constantly and not smooth back out? I imagine it’s linked with my TPS refusing to stay set and I’m not sure how to fix it

Any help would be greatly appreciated, thank you

 

I have a couple of questions. Are you getting any codes?

Could you explain how it feels when you reach 6500rpm? It does sound fuel related at a glance.
Could you explain how you set your TPS?
Did your idle change when you omitted the fuel resistor relay?(I'd reinstall it to diagnose your issue).

No, your coolant leak could not melt your wires.

 

I also meant to ask if you still have your air pump.

 

If you're hitting a wall, it could be spark related.

 

Also, I don't think it's your secondaries as they kick in at like 3800rpm iirc. You'd feel the lack of power before 6500.

What kind of fuel pump did you install?

 

Codes:
25,30,33,38,40,41- These are all codes the car has had since i bought it and are caused by the emissions/rats nest delete. I'm sure none of the are my issues, just the car complaining about not having the solenoid valves anymore.

However, I have code
51 - Fuel pump resistor relay
73 - Injector (Rear secondary)

I had gotten code 51 intermittently before this had started which is why i deleted it, thinking that my have been my issue. Reinstalling it will be a pain because i used the method of cutting at the connector and splicing the power wires back into the the outputs. I don't think this is causing my issue though and is just one less factor to have to deal with. This also did not change my idle at all.

Now code 73 is new and gets me thinking that may be my issue. There is another thread on here of a guy with my same issue that ended up being his secondary's were having problems. I will link this if i can find it again.



I have been setting my TPS with a banzai test light, it had worked great for months up until recently. Now its like the vibrations from the engine is moving the screw. I tried fixing this with a new screw and a nut on the back with blue lock tight, however it is still able to move.


I do not have an air pump, the actuators are plugged in with vac lines and have been like this since i bought it. The car ran great like this for about a year before my OMP nuked itself.


The wall i hit feels like instant fuel cut. It does not matter if I'm WOT or slowly climb up the revs, it will hit the wall at the exact same spot no matter what, in every gear. (Have not tested this in 5th but i assume it would be the same)

There is no lack of power before 6500, however there is a secondary injector staging around 6-6.5k where they start reaching maximum duty cycle, it seems like this staging is not working for whatever reason.

The fuel pump i installed was an OEM S5 from atkins, which the car ran great on for one night until my Rad blew on me.

 

last time i had a n/a that wouldn't get past that point it wound up having a secondary injector wire issue. ohm test the secondary wires between the ECU and the injectors since they're easy enough to get to.
you can also load test the wire with a incandescent light bulb like a turn signal bulb. my fix was to overlay a single wire from the ECU to the injector rather than rip into the harness to find the source. this was an S5 non turbo and almost felt like a soft rev limiter around that same RPM.

the secondary injector wires are subjected to more heat since they sit right above the exhaust. pushed out pins in the injector clips is also a common problem. with a secondary injector offline the engine will still be able to rev somewhat smoothly up to that RPM level before it leans out and starts to buck and sometimes audibly ping from preignition due to being so lean.

manually testing the injectors with a 9 volt battery is also a good idea.

 

Here is a thread with my same issue, ended up being his TPS. I tried switching old TPS back on to see if that would help but same issue.
https://www.rx7club.com/2nd-generati...-668729/page2/

 

I hate to be this dumb, but could you explain or provide a link on how to test the wires properly. I can handle the mechanical stuff, but electrical still confuses me quite a bit

 

you'd need to access the ecu under the passenger side carpeting, then disconnect the ecu connector and find the 2 injector circuit wires, disconnect both secondaries and test the wires. here's a video describing how to ohm test and load test the wire to ensure they aren't corroded/broken and can carry enough amps to run the injectors:


i'll try to get a picture of the s5 n/a ecu pinout

 

here's the wiring diagram, just be sure the wire colors are the same at the ECU for the ones you need to test, light green/red and light green/white

 

you should also check the 12v circuit for the secondaries by checking the other side of the injector clip wires with the key on between black/yellow to ground. the power wires are simply brass crimped and those crimps can fail inside the harness, especially if coolant gets into the wiring. the driver wires are all singular, but it doesn't mean they can't snap due to heat and brittleness.

you will need a pin or needle and a length of wire about 10 feet long preferrably with an alligator clip to connect one end to. the needle needs to be not large enough that you need to force it into either side of the connector, spreading the terminals would create a new problem.

 

and here's a video on testing the secondary injectors. you do not need to remove them from the engine to do this test.

 

Code 73 is suspect. I would definitely start there.

 

a simpler test of the injectors is to just ohm test the secondaries, they should be around 15 ohms. if one somehow shorted or is open it should show up easily. the S4 injectors are lower impedence though, so anyone else who reads this and has an early model that number won't apply.

 

Here’s where I’m at

Load tester I made just didn’t want to work, not sure how I messed that up but I did.

Ohm test
Front secondary - 13.8
Rear Secondary - 13.7

Not sure if that’s too far off from 15 to cause my issue, but maybe



The LG/R wire connector on the injector itself has a slight bit of corrosion, gotta get some sand paper and try to clean that off, but it doesn’t look like enough to cause me any issues.

Voltage test came out good

LG/R wire atleast is somewhat connected. It does show continuity on the multi meter when both ends are connected

Im think about just saying screw it and putting a new wire in anyways. If I do, can I just cut and crimp onto the wire already in both connectors? And should I try and make it close to the same length or can I take a shortcut through the fire wall?

 

Also now realizing I completely forgot to test my injectors with a 9v battery. I’ll have to grab one on the way home tomorrow and will get back on that

 

I really depends on how damaged you wire is or where. Most will just find a pig tail and solider it on to the injector side, cutting back the harness until you find a good section of wire. If the wire is deteriorated in the middle, this doesn't work. Same if the damage is on the ECU side.

I really don't know the answer to this, though. As far as I can tell, the connectors like the injectors, BAC are far less prone to corrosion than the non sealed ones on the car. If there is damage in that connector, it is likely that the other connectors are in far worse shape than that one. Check as many other slip style connectors as you can, which are most without the metal clips, the circular ones are sealed, I think. On my car, the slip style lugs were way dirtier/corroded than the others. If that is the case with yours, you have a lot more work to do.

Also like the earlier poster mentioned, push backwards on the pin in the connector. If it moves backwards, you've found your issue. That little tang can break/corrode off, if so the tang can not lock the lug in place. Also, the plastic grabbing the tang can become brittle and break causing the same problem. At best, the lugs will just touch instead of interlocking.

 

~13.7 ohms is still acceptable for high impedence injectors. still need to physically test them with a battery to listen for the audible clicks to ensure one hasn't seized up, but it wouldn't set that code so i suspect there is a wiring issue.


i would suggest trying to clean any corrosion first, i've seen plenty of wiring repairs cause more issues than they solve.

to load test the wire it needs to be disconnected from the ECU and the injector. take the light green/red wire for example, jumper the injector pin with a length of wire to a light bulb holder with an incandescent bulb, attach the ECU wire to the negative post on the battery, attach the injector side to one wire on the bulb holder and the other wire off the bulb holder to positive. the light should be bright, if it is dim or flickers and the wire gets warm then the wiring is faulty.

 

So, passed the 9v test and the load test. Pushing on the pins, they feel solid with no movement at all. Cleaned corrosion off the injector connector and a good cleaning on the ECU ground.

The only thing that concerns me is looking at the pins in the connector. The B/Y wire (ground?) pin looks slightly off. Could this be my problem?


Pin on the left is to the black wire, right is the green wire

 

Just looking around the car for anything that might be off and found the nut on the CAS was very loose, is this something that could throw my timing off?


The nut in question

 

Not sure about the connector, it's in the middle. Not really clean but no green death.

One way to find out about the timing is to check with a timing light.

Everyone should do this anyway when checking a car. One good way is to adjust your idle speed is until the timing lines up. As long as the idle is fairly close to factory settings.
With yours being messed with, it will be a back and forth between adjusting idle and timing, many times over most likely.

You might need to reset your TPS afterwards as well. Setting and checking all three until after a few times around the block.

 

Timing light came in and I was way off. Cleaned up grounds, and got timing set back to as close as I possibly could. The timing mark wanted to jump around a bit, i assume it’s from having a street port so my idle didn’t want to sit exactly perfect at at such low rpm. But I no longer have the 6500 wall, cat revs put smoother than it ever has. I’m glad I saw that but before digging into my harness

Thank you for all the help and suggestions, moral of this is check everything you can before jumping to conclusions

 

That's good news. Did you disable all accessories when you timed your engine(grounding the orange wire next to leading coils)? Just wondering, cuz if you didn't, your car will need to be timed again.