Build thread

[speedjunkie]

Something seems to be drawing hard on the battery when cranking. The ECU relay is only getting 6v under normal circumstances, and you have to pull the ACC relay for 12v to be restored. If the relay is only getting 6v, the car will not start unless external power is applied to it as well. It will still crank normally under any circumstance, so I believe the starter is still getting full power.

When I close the battery circuit breaker, the ECU relay will buzz for about a full second. When I insert the key into the ignition while the door is open, the ECU relay will buzz along with the beep for the key reminder. At this time, the top right terminal (and possibly the bottom right terminal as well) on the ECU relay is only getting 6v.

If you pull just the ECU relay and put it back in (with CB open or closed), nothing changes. If you pull the ECU relay and the ACC relay at the same time, the ECU relay will once again get 12v and if you put both relays back in while the circuit breaker is closed, there is no noise once you insert the key into the ignition again and you can start the car normally. If you open the circuit breaker to remove the relays and re-insert them, the problem persists once the relay is closed again.

In any of these cases, if you pull the key out of the ignition, the ECU relay buzzes and the problem will persist.

Pulling the ACC relay is the only thing that changes the voltage. Pulling any other relay changes nothing.

You can start the car normally with just the ECU relay inserted and the ACC relay removed, but it will idle very low. Once the ACC relay is inserted again, idle will bump up to normal.

The ECU relay is the only one getting voltage to both terminals on the right side, all the other relays are getting voltage on only the top right terminal.

2022-06-07_09-18-41 by Eric Jausel, on Flickr

[speedjunkie]

Chris remoted into the car yesterday and after we talked a bit he said the starting problem is due to the ECU as well. So I'm thinking about saving up my money and getting a Haltech Elite 2500 this next winter, and I might try to salvage the harness as much as possible since it's already done.

I also made a new battery hold down piece from a thick piece of aluminum I had, probably almost 1/4" thick so the sides don't pull down when it's tightened down like the last piece. I left a hole for the re-start button too.
2022-06-12_09-08-41 by Eric Jausel, on Flickr

[speedjunkie]

I got the other guy's ECU from Chris Friday night and tested it Saturday.

The first test was the AC. On my ECU, the AC compressor clutch engages immediately, so I tried it on the new ECU and it worked normally. SWEET! That's one indicator of a bad ECU.

Then I took the car out and put on a couple different fuel maps with different boost setups and tried different boost settings. First I put on an old map from before Joe changed the boost settings in the fuel map last June, and I tried the normal boost cals (10psi, 12, 14, 16, 18 w/ AI, etc). I hit boost cut in every single cal. Then I installed my current map and tried the first three cals (10, 14, and 20 I think, the only ones I've been using since Joe tuned it), and I hit a little under on each cal. So for 10psi setting I was hitting 5, for 14 I was hitting 10, etc. I was thinking maybe I have the hoses going to the boost solenoid hooked up incorrectly, but I found a pic online of how it's supposed to be and mine is the same. So the boost test was a little confusing.

I parked the car and let it cool down for a few hours before I put my ECU back in. I decided to check the AC compressor to see if the problem was still there (why wouldn't it be?), and it was operating normally. OK WTH. Then I realized I never connected the wiring for the AC compressor since it wasn't operating normally. So I have to connect that wire and try it again lol. Oof.

I also lowered the car about 1/2" on all corners since it was jacked up like a monster truck after adding preload to the springs. It looks super low now but I'm still not scraping the bumper. Weird.

We did 7s day yesterday and started in Colorado City and went to Bishop's Castle, Skyline Drive just west of Canon City, and finished the drive through the mountains through Divide and back down to C Springs and then did some go-karts at Overdrive Raceway. A really great day overall (aside from the oppressive heat) and pretty much no problems with any of the cars. No serious problems anyway.

[speedjunkie]

I just reconnected the AC compressor and tried Ricke's ECU again and it's doing the same thing mine does. Ugh. So that means it's something in my wiring, but I have no clue what it is.

[speedjunkie]

I did a little more testing with the AC. I changed the map to where the AC wouldn't come on at all just to verify it's a mechanical problem and the clutch still engaged.

The really strange part is what it did when I jumped the connector to bypass the switch. Just to refresh, the clutch will engage automatically when the car is started, and even if the pressure switch is disconnected, it will somehow still get 12v to engage. The only way to disengage the clutch is to jump the connector to bypass the pressure switch, which is exactly opposite of the way it should be. Now the weird part is that when I jumped that connector, the engine bogged down as if AC kicked on, but the clutch disengaged.

[speedjunkie]

I put the multimeter on the wire to the compressor to check for voltage.

Key to accessory - 0v
Running but no AC - 14v
Running with AC - 14v

I also tested with the pressure switch disconnected and the wire to the switch jumped.

Disconnected - 14v
Jumped - 0v

So it confirms the way the compressor has been acting. I pulled the AC fuse in the relay box and it killed voltage to it as well. I want to pull the AC relay but I need to remove the bumper to do that where I have the box mounted, so I'll do that another day. I checked the pressure switch and it's open, which I suppose is normal since there is no pressure. The wiring diagram shows it closed, but I guess that's indicating the system is operating, IDK. I'm going to pull that out and use compressed air to see if it closes.

[speedjunkie]

I think I'm on the right track now. After talking it over with Brett, we stumbled on what we think is going on. And considering I discovered this problem a couple years ago and forgot about it lol, I'm pretty sure this is it. I didn't think it through while looking at the wiring diagram back then, but it makes sense now. First I had to determine if I had the 93 or 94 wiring. My car is an early 94, so I figured it could be either one. But I determined it's for sure 94 wiring, first by the colors of the wires, but also by verifying that the wiring from the pressure switch doesn't go directly to the compressor like in the 93 wiring.

2022-07-30_12-02-42 by Eric Jausel, on Flickr
The red line is grounding out automatically, which would explain why the change of ECUs didn't affect it. It's bypassing the ECU altogether and providing a ground for the relay and sending power to the compressor. I was going through old emails with Chris Ludwig and noticed that two years ago I determined it was only grounding after starting the car, and while that makes sense with regard to the compressor clutch only getting power once the car is started, I'm trying to figure out WHY it's only after the car starts. If the wire is making contact with the chassis, it should have continuity with ground even with the car off. So I'm wondering if that wire is making contact with another wire that gets ground only when the car is started. I pulled that wire from the connector at the ECU (1L in the stock ECU connector) and it's not getting ground with the key on, but I'll test again tomorrow to verify it's happening with the car running.

Now to the pressure switch. With the switch connected OR disconnected, power still gets to the compressor clutch because the wire from the AC relay to 1L at the ECU is already grounded, thus bypassing this part of the circuit completely. This would make sense because the switch is apparently open if the system is undercharged or overcharged (it was open when I tested it the other night, as there is no pressure in the system), so the circuit is incomplete in both instances. If I jump the wires together (the yellow line), bypassing the switch, it completes the circuit and the system acts normally, the same way it would if the system is charged and the switch is closed. Jumping the wires with the system discharged (or overcharged) kills the power to the clutch, while the system being charged and the switch closed gives power to the clutch like normal. I'm still not sure I understand why jumping the wires kills the power to the clutch when the system is discharged, but Brett understands why and it seems to be the case either way.

Now I just need to figure out what is supplying ground to the AC relay.

[speedjunkie]

Well, that idea is a bust lol.

I checked for continuity to ground from that wire 1L with the key off and got 5 kiloohms, but as soon as I turned the key to on and start, I got no continuity at all.
20220730_095332 by Eric Jausel, on Flickr
20220730_095324 by Eric Jausel, on Flickr

Now for the weird part. I had removed the leads and when I put them back on, I put the black lead on the wire and the red lead on the ground, and it read full continuity with the car running. Then I swapped the leads back to red on the wire and black on ground and I got no continuity again. Ugh.

With that wire disconnected from the ECU still, I checked for power to the compressor clutch and got 0.012v. So that means that wire must not be grounding to the chassis or anywhere else.
20220730_102043 by Eric Jausel, on Flickr

Then I checked to see if the ECU was providing the ground. I disconnected the wire to the stock connector to isolate it just in case, and put a needle lead through the back into the ECU. I got 121 ohms. Not crazy high, but enough I guess. Then I jumped the pressure switch connector and lost continuity, until I turned on the fans and AC button and got continuity back, 121 ohms again.
20220730_113845 by Eric Jausel, on Flickr
20220730_113842 by Eric Jausel, on Flickr

So maybe it's the ECU afterall? Although the new ECU didn't change anything, so maybe it's the map? I thought maybe it was the thermoswitch since it's the only other thing in line before the ECU, but all that does is complete the circuit or not.

[speedjunkie]

Chris wanted me to do some testing on the AC.

"1. Disconnect the ECU and check for continuity to ground and voltage on ECU connector 1E with the key on and the blower switch in all positions and AC switch on and off. The GY/R wire.
2. With the ECU disconnected, check for continuity to ground on ECU connector 1L with the key on and off. The Y/B wire.

Those two tests will tell me if it's in the chassis or the ECU. I think we had some issues with the fan relays when I had the car. I can see where one of the relays, if faulty, could backfeed positive voltage into the sensor circuits all the time and cause an always on condition. Let me know what you find."

For these tests I just disconnected the two wires from the Syvecs connector, but all the other connectors and wires were plugged in.

I ran the tests the first time but didn't have the 15a fuse in the relay box, but I put the fuse back in and tested everything again and got the same results. For the test on 1E, continuity to ground, I got open on all settings (with the fans on and the AC on and off). For voltage, I got .005v on all fan speeds with the AC off, and .003v with the fans on and AC on.

For 1L with no fuse, key on and continuity to ground, I got no continuity, and with the key off was the same, no continuity. I put the 15a fuse back in and checked this again, and got no continuity with the key off but with the key on I got continuity with ground. I had the black lead on the wire and the red lead on the ground. I swapped them, and got no continuity. I swapped them back and got continuity again.

I might borrow a Fluke from work and check this again tomorrow.

[speedjunkie]

I forgot to post this Friday night.

Chris filled me in a little more in my language on how it works haha, so I did some testing again.

"The AC button and the fan speed switch are both in the 1E circuit. The AC button just opens and closes the circuit. The fan speed button will close to ground in the off position and close to positive voltage when it’s in the 1-4 positions. It pulls to 12v but has the resistors to create variable voltage for each speed. But we set the ECU up to turn the AC on when it sees any voltage. So, with the AC button on and the fan speed off, you should continuity to ground. With AC button on and fan speed at 1-4 there should be 3-4v. With the AC button off it should be an open circuit. "

I tested again with my multimeter just to verify, and I got the same results.

AC button on and fan speed off, open circuit.
AC button off, open circuit.
AC button on and fan speed on, no voltage.

I tried something else too though. 1E disconnected and 1L connected, I get 14v to the compressor. So the ECU is getting no voltage to tell it to provide a ground, and it's still providing a ground to the relay.

With 1L disconnected, I get no voltage to the compressor. So that means it's not grounding out anywhere, and it also means the AC relay isn't stuck closed.

I was still confused about not getting voltage on 1E though, then I remembered. The system isn't charged, so the pressure switch is open and not providing voltage. I jumped the pressure switch and got different results.

Whether the AC button is pressed or not, it sees full 14v with the fan speed off. With the AC button on and fan speed one I get 1.6v, fan speed two I get 2.7v, fan speed 3 I get 3.3v, and fan speed 4 actually dropped down to 3.1v. So if Chris is correct, I still have an issue with it getting 14v instead of continuity to ground with the AC button on and the fan speed off. Then again, jumping the pressure switch connector makes the system operate normally, or so it seems.

And tonight, I changed the output (ECU to AC relay) from A4 to A19, one of the fuel outputs, at Chris' suggestion. He remoted in and changed the settings and we tested everything and it worked like it was supposed to, although that's with the pressure switch connector jumped, which I already knew operated normally before when it's configured that way. After we got off the phone I tested it again the way I know it has an issue and the issue is still there. I'm going to verify tomorrow night with the multimeter at the back of the ECU that the output wire is still providing ground at all times with the car running.

[speedjunkie]

I hooked up a relay and wiring external to the stock wiring and AC relay, but I must be missing something else because this time it didn't come on automatically, but it didn't come on at all with the pressure switch jumped and the AC turned on. I even tapped off where the power actually comes from. I bought a new relay from Ray Crowe and pinned out the stock wiring to make absolutely sure all the wires were going to the exact pins they do with the stock wiring so I can test it again.

20220820_093219 by Eric Jausel, on Flickr
20220820_093343 by Eric Jausel, on Flickr
20220820_090116 by Eric Jausel, on Flickr
20220820_090059 by Eric Jausel, on Flickr
20220820_090107 by Eric Jausel, on Flickr
20220820_090153 by Eric Jausel, on Flickr
20220820_090209 by Eric Jausel, on Flickr
20220820_090215 by Eric Jausel, on Flickr
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[FDEEZ]

Eric... after 6 years overseas, I'm finally back on the mainland. Unfortunately I have zero updates on my FD since it's been in storage the entire time. But I just viewed your build, and OMG... you've been through a lot. I admire your courage and persistence on building your dream car, especially with all the adversity you've been through.

Regarding your a/c issue, have you tried replacing your blower resistor or checked the resistor wiring? With our car's age, these typically go bad. If the resistor is shot or if there's a short in the resistor wiring, you won't get a ground signal to your AC switch and it won't function in any of the 4 positions.

Btw, I love your seats!!! The color, stitching, and material is well designed. Looks OEM.

Good luck, and never give up on your dreams!
FDEEZ

[speedjunkie]

Eric... after 6 years overseas, I'm finally back on the mainland. Unfortunately I have zero updates on my FD since it's been in storage the entire time. But I just viewed your build, and OMG... you've been through a lot. I admire your courage and persistence on building your dream car, especially with all the adversity you've been through.

Regarding your a/c issue, have you tried replacing your blower resistor or checked the resistor wiring? With our car's age, these typically go bad. If the resistor is shot or if there's a short in the resistor wiring, you won't get a ground signal to your AC switch and it won't function in any of the 4 positions.

Btw, I love your seats!!! The color, stitching, and material is well designed. Looks OEM.

Good luck, and never give up on your dreams!
FDEEZ

Holy crap, I was wondering what happened to you lol. Welcome back! How much time do you have left before you have your freedom? Where are you now? In CO again?

Thanks! I forget all the things I've done to it, so it doesn't seem so bad. Especially since I haven't had to replace the engine since 2014, knock on wood haha. But this AC issue is really kicking my butt.

Well, I don't think that's where the problem is because all that works just fine. The blower works on all speeds, although speeds 3 and 4 seem to be the same if just going by the voltage readings, so I could swap the resistor pack and see if that fixes anything. The problem seems to be in the circuit between the ECU and the compressor, or just the ECU itself. I'm still waiting on the new relay so I can try it on the external wiring I have and verify whether it's that stock wiring causing issues. Do you think the resistor wiring or resistors could be causing issues in the other wiring somehow, or maybe giving the ECU a false reading to tell it to turn on AC right away?

Thanks! The seats have been a long time coming. Although they still sit a little high haha. I've been thinking about pulling the seat covers out and trying some foam with adhesive backing and cut little pieces to put on the seat and see if that gets me sitting just a bit lower AND further back in the seat. Overall it's not bad, especially just for driving around town. I haven't tried a long distance drive to verify comfort over a long drive or a track day to see how well I fit with a helmet in actual track conditions. I've also never been crazy about how the seat covers look on them, specifically how the edge of it is kinda loose on the sides and back of the seat, but that's not a deal breaker. If you're here in town, stop by and have a sit in them haha. Or come out to a meet again.

[FDEEZ]

My mistake on the blower resistor. I misread your post and thought you couldn't get your a/c to work due to no ground. Instead, it's the complete opposite... my bad.

Here's my 2 cents:

I'm not too familiar with Syvecs, but I assume you're using some sort of standalone ECU to control the engine & a/c system. If this is true, then your ECU should only have a few inputs/outputs to control your a/c.

First, the output. Is your ECU supplying ground to the a/c relay (through the y/b wire you circled RED) when the engine is on? You can confirm through a test light. If your ECU is not supplying ground, then your relay is probably bad.

Second, is the input. If your ECU is supplying ground, then we need to check why your ECU thinks it's ok to do so. What input is it receiving? I assume it's through 1L. You should only get ground from 1L if all these conditions are met:
1. A/C switch is pressed.
2. Blower switch is in positions 1, 2, 3, or 4
3. Thermo-switch closed
4. Refrigerant Pressure Switch closed (this is interesting, because on '93 Rx7s this is after the a/c relay before the compressor).

If all these conditions are true, then you should get ground through 1L. Once your ECU detects ground from this input, it should think it's ok to supply ground to the a/c relay. If all conditions in 1-4 are NOT met and you're still receiving ground to the ECU, then you might have a short somewhere. A test light can also confirm if you're getting constant ground from 1L.

Last, is on the software side of the ECU.
a. Is your a/c input really from 1L? It's possible you could be supplying a constant ground (wire connected to chassis ground) to the input side of the ECU. In other words, try to double check the pinouts of your ECU inputs to ensure 1L is correctly mapped in the ECU.
b. Through the same token, it's possible your ECU's output could be mapped to supply constant ground to the a/c relay wire INSTEAD of waiting on certain conditions to be met (e.g. for 1L to be grounded).
c. What logic do you have programmed in the ECU to supply ground to the a/c relay?
- Is it set to wait on a ground signal from 1L, on a certain engine rpm, etc?
- Once set, are your radiator fans also programmed to turn on at full blast?

Anyway, I hope that helps. For me, I have about 1 more year before I'm eligible to retire. If I stay in or get promoted, then I'm due to deploy again next summer :-( I'm currently stationed in the national capital region... but I wish I was back in the Springs.

Btw, if you're super bothered by seat height, one option is to completely cut out the metal under the seat area and replace it with welded-in flat sheet metal. It's a little extreme, but you'll be able to lay your seat closer down (using more conventional seat brackets) by removing those protruding seat bracket humps.

[speedjunkie]

Yeah the Syvecs is the standalone ECU. I've thought about swapping a stock ECU and harness back in but there is a ridiculous amount of work involved to make that happen. The ECU has the normal input and output to control AC.

Yes, the ECU supplies ground through 1L immediately upon starting the car. That's even with AC off, and only when the system is either not charged or overcharged. If the system is charged (or if the pressure switch is jumped/bypassed), the system works normally.

Input comes through 1E, and it's voltage actually. At least that's what I'm getting and Chris says that's correct lol. Supposedly the ECU is getting the correct input, but it supplies a ground to the relay regardless of what input it's getting or isn't getting. With the Y/B wire disconnected, the compressor gets no power, so I know that wire isn't grounded to the chassis (which was my theory at one point). I don't remember if I disconnected 1E going into the ECU to see if it still provides a ground, but I think I did. Regarding the difference in wiring between 93 and 94, I initially thought mine was wired like a 93 and that's why I jumped the pressure switch connector to verify the refrigerant had leaked out. But when I pulled the jumper out, the compressor stayed on. OOPS! lol

Anyway, all the troubleshooting results lead me to believe the ECU is the problem, but swapping in the other ECU has the same result, so it makes me think maybe the tune is the problem.
a. The input is from 1E. Chris is the one that handles all the tuning part, so I can't verify myself. I have changed the output (and possibly the input, I don't remember) more than once with the same result.
b and c. No idea haha. Chris handles all that. The radiator fans do turn on, but I'm not sure if they're full blast.

Sweet! Not too much longer for you then. Sucks to be in that region though haha. Considering housing prices, traffic, etc.

The seats are pretty good. With no or very little foam in the bottom, my eyes are at the top of the steering wheel. With the seat cover, I can still fit with a helmet, I just wish I was a tad bit lower. I don't have it in me to do all that work on the floor lol.