theres a power wire from the ecu that hits most of those sensors, a 5v reference one. probe the wires on the map sensor, find a 5v ref?

 

it could be the 5v ref but it can also be the ground loop, both are important for all those sensors to function. the ECU generally only throws codes for an open loop or short to ground, i would suspect it to be a ground issue since it needs to see a certain resistance reading from the sensors/solenoids.

 

I found it, brown/white is at 4.97v

I also found something else very curious. I unplugged my aftermarket alarm main harness, cleared the codes, took the car to run errands. Recheck the codes and they have changed.

13 - Pressure Sensor
3 - CAS G signal
33 - Port Air Bypass
38 - AWS

Although to be fair I had the pressure sensor unplugged when I checked codes, realized it was unplugged and plugged it back in and rechecked. I did not clear the ECU codes before rechecking with pressure sensor plugged in.

I'm planning on putting in some time tomorrow. Pull the UIM check my grounds, etc.

While I'm looking for any and every little thing. A couple days ago I noticed an oddity with my AEM analog boost gauge. It has been consistently making little 3 inhg bumps for no apparent reason. For instance, I'll nudge the gas pedal, boost gauge jumps a little bit and when it comes back down to a resting vac reading, it then jumps 3 degree upwards. Or if I hold push the throttle and hold it, the boost gauge reading rises and even though throttle has not changed and is being held constant, the boost gauge does the same little 3 degree bump. I did not look for it today while running errands, but up until today it has consistently been doing this. Per my AEM manual, voltage at -30 inhg = .5v up to 35psi=4.5v I do not have a restrictor pill for my boost gauge, but I don't think this consistent fluctuation is due to that.

 

I've started going through my grounds and wiring and started in the cockpit of the car. A lot of the gauges, senders, stereo, etc I installed 3 years ago so I don't remember specifically how I wired them in. So I'm simply going through and check the work I did.

Today I re-grounded my 3 Prosport gauges (water and oil temps, and pressure) along with my antenna relay and headunit as a common ground under one of the shifter boot bracket bolts.

Regrounded my AEM boost gauge as well as my aftermarket alarm cpu and door actuator relay. Those are all grounded behind the driver side kick panel. Though I've disconnected the alarm CPU. I'm very suspicious of the alarm wiring because the alarm siren went off when I disconnected and reconnnected my negative battery terminal wiring...even though I had constant + to the alarm disconnected from the battery.

I created a common ground for the ECU grounding upgrade/mod. 3A,3B,3C,3D are grounded on one of the ECU bolts.

I cleared my ECU, started up the engine and after it ran for a little bit I pulled the codes.

30 - Split Air Bypass (I was incorrect about the 3 code, it's a 30)
33 - Port Air Bypass
38 - AWS

These codes make sense as I've got a JDM engine with no AWS and I've got emissions deleted.

Two things I've noticed

1. My remote on OEM wiring for amplifiers does not work and was working sporadically. I hadn't been concerned about it because I hadn't been playing the stereo and figured I'd get around to less important things when I had time. I tapped into the existing wiring after the harness and ran my remote wire to my amp. When I connected my remote on from the headunit directly to my remote wire to my amp it came on no problem.
   
2. My dome light does not work. I thought I had a burned out bulb but that is not the case.

Tomorrow I'll pull the UIM and go from there.

 

Well, I regrounded just about everything. Cleaned and regrounded on top of my keg, both the OEM harness ground as well as my two 4ga grounds on the firewall. Cleaned up and regrounded the ground under the trailing coil. Regrounded everything in the cockpit (headunit, gauges, antenna relay). I yanked out the aftermarket alarm CPU to eliminate any complications it might be causing.

What is this set of grounds to the left of the ECU? I previously had an 89 convertible, now have a 90 convertible. I don't remember my 89 having this strip of grounds and haven't found it in the FSM. The wires follow the dash harness up behind the stereo and logicon.


After regrounding I checked TPS on voltage and checked timing. Trailing is still off by the same amount.

I've noticed 3 things (so far) that should not be.

1. My alarm siren was going off when I took negative battery terminal wires off and also when I put them back on....even though my constant power for the alarm was not connected to the battery.
   
2. My OEM remote on wire for stereo was working sporadically and then not at all.
   
3. My AEM gauge is occasionally showing more vac/boost than normal. I assume since it uses voltage to show readings on the gauge that is is occasionally seeing more voltage than it should.

 

i have never seen that ground junction before so you got me there.

for the split, you also got me. i have never had a car refuse to go into the proper 15 degree split at idle. i'm assuming the main pulley is still OEM, since you said it is a narrow split and most pulleys are stamped in 10 degree increments based off of TDC and not the 5/20atdc markings.

only thing to be sure about is that you're using #1 lead plug wire, sometimes using the #2 wire it will bounce around a bit with the timing light and appear more retarded than off the #1 plug.

 

It's the same pulley I had always been using. I have a spare S5 pulley that I could compare marks with, but I have no reason to believe it's a S4.

I'm sure it's lead #1

Something you said on the other forum is starting to seem accurate. The engine may not be settling down into idle mode. I noticed it today while checking timing. The engine never really hit that idle sound, even though I had to raise the idle a little to get it above 500RPM. It was sitting under 1k, but never really sounded like it went into idle mode.

As I'm starting to simply take stabs in the dark. I have a modded alternator. I may pull that and take it to be tested. Other than that I guess I can start testing voltage at the ECU pins and testing all the sensor/senders: thermoswitch, AFM, IAT.

I can periodically check my CELs. See if I get another of those where ALL my major sensor/senders threw a code. I had not cleared any codes after first installing the engine and first start up. Those codes might have all been something residual, but if they all popped up again I'd have to think there is a short.

I wish there was a quality rotary tech near me, I'm at the point where I'd pay someone to figure it out. BUT no one in my town will touch a rotary, especially not a modded rotary.

 

thinking about it i would probably check the inputs to the ECU for the clutch switch and also the gear selector. those may be making the ECU think you are sitting at a stop with the clutch in, in gear getting ready to accelerate and taking it out of idle mode.

 

I have a 1990 vert and have that grounding block. Don't think it's your problem, just saying...

 

You know, I pulled the clutch switch when I thought I was having starter issues before I even got the engine to fire up. I checked it for resistance and it failed continuity, but yet still allowed the starter to engage. Well so long as I tested the clutch switch and not the cruise control switch. FSM showed the one on the front of clutch pedal, not the back was clutch switch and that's what I tested.

 

yeah, one is for starter cut and the other is the signal for the ECU, i believe the second will pull it out of idle mode once you step on the clutch versus the transmission gear select switch but it could be both, but neither seem to fail in the closed position otherwise i would probably see this problem more often than not.

 

I started going through my ECU pins looking at voltage, but in perfect irony my DMM batteries went dead and I had no others. I got to 1R before I had to stop.

As a general rule should I be worried about mV variations where I should be seeing 0V? Just about anytime I was supposed to be seeing 0V I would instead see some very small voltage always in mV. For instance pin 1G Ignition Coil Trailing with ignition to On should read 0V and I had 11.2mV

I created a spreadsheet and unfortunately I can't upload spreadsheets. I'd be happy to email it to anyone who wants to look it over. Toss me some info. That being said...
The big things that were off were:
clutch switchneutral switch (IIRC my JDM transmission did not have a neutral switch and is not plugged in)A/C RelayA/C Switch

 

Interesting, I had been told and never bothered to confirm that one of the switches on the clutch was for cruise control.

 

When checking the Clutch Switch one side should have a ground to it. When the clutch is depressed this ground (that would be the Black wire) passes through the switch onto the other wire. If this doesn't occur then chances are it's the switch

 

I'm a little confused, but I think I'm understanding you. Check the switch and make sure it's grounded?

Can that switch keep the engine from dropping into idle mode and thus keep my timing off?

 

There are only two wires to the switch, one is Black this is a constant ground wire. The other wire in the switch receives this ground signal when you press on the clutch pedal. This is how the pin related to this switch receives the less than 2 volt signal it needs. The ECU then makes some type of internal adjustment.

 

Gotcha, for some reason I was thinking you might have been saying to ground the switch for testing voltage at the ECU....similar to how 1I needs to tested grounded and not grounded.

 

As far as the trailing firing at the same time as the leading, you are sure you are putting the clamp on the trailing wire, right? I think I know someone, who glanced quickly as to what wire to put the clamp on... stumped me for a while.

I don't think its overly hard to do sometimes, especially with aftermarket wires that are a little bit longer.

 

Jeff,

We had the clutch switch wired in for the starter safety switch. So you couldn't start it without pressing in the clutch.

While the car ran fine (I don't know that I've ever checked trailing) we had problems with it dying rolling to stop signs & lights. So we switched the clutch switch to signal the ECU and that fixed the dying at stoplights problem.

I know in your initial post you don't mention if you're having actually running/driveability problems or if the trailing being off is a purely academic question. But we ran the car for YEARS - even driving from TX to IL several times without issue - with the ECU completely oblivious to the state of the clutch pedal or neutral safetey switch states.

Thought that may be of help.

Jim

 

while it could be ignored it is going to be nearly impossible to properly time the engine if it isn't idling down properly to set the timing. i figured with the coupler set it should regardless but apparently these ECUs are still too dumb to chew gum and walk at the same time.

if the timing was never touched i would say just forget it and move on.

 

Well, the idle doesn't "sound right", it's pootier than it should be, but this is the first home rebuild I've driven. I'm told the pootiness should settle down as the seals wear in. That being said. I am having some other symptoms. Since I put the new (to me)TPS on and re-set timing the idle on first start up has gotten lower than it was or should be. Until the engine warms up it sits at barely above stalling. It didn't used to be that way a week or two ago. Previously the idle speed was solid from first start up and through warming up to temp. I'm also seeing something strange going on with my electronic boost gauge. It is sporadically seeing higher readings than it should. It's an AEM and I looked through the owners manual and it breaks down voltage it is seeing and the equivalent psi/inhg it will show. It's looking like I have an overall electrical problem of some sort. Maybe these are all related or maybe each one is independent.

 

HAHA, yes I thought of that and I'm sure I'm hooking the timing light up to the correct coil/plug wire

Well I pulled the front clutch switch off the pedal and tested it for resistance and it showed no change from depressed and released. This was before I even got the engine started for the first time. I mounted it back up and plugged it back in and I'm betting that's the same one that is showing no difference at the ECU. From what I read in this thread there are two different switches, one for the starter and one that sends signal to the ECU.

I have/had plans to test the rest of the ECU pins for voltage and check that switch....but my back is bothering me and I'm procrastinating lying upside down in my cockpit. It might happen tomorrow, or after I've had a couple beers :P

See the post above about driveability. The exhaust/engine doesn't sound like it should, but I also only have between 300-400 miles on the fresh rebuild. While I have time I want to get as much done as possible and eliminate as many future headaches as possible. I'm starting a new job soon and also am in school full-time. While I have time I wanna get as much off my to-do list as possible :P

 

Got my clutch switch ordered from dealership ($15 or so), it will be here Weds.

I did more testing today, the most curious is my TPS pins at the ECU. Narrow is way off and full range is a little off.
2F TPS Narrow Range
OEM specs:My specs:2G TPS Full Range
OEM specsMy specsI had previously set the TPS using voltage to really close to 1V. It was something like 1.03V. I'll check voltage on it again. But can there be a voltage problem causing a difference between what my TPS is reading at it's harness and what the ECU reads?

Also my O2 sensor was way off, though I did actually driving. I simply reved the engine.
2C
OEM specsMy specs

 

I just checked my TPS voltage at the TPS harness. Engine warmed up, IGN switch to ON and I'm seeing 1.005V

But the other day I test voltage at the ECU pins and it's way off on narrow range and not even ranging when throttle is pressed.

Can anyone offer some advice what is going on here?

Bad TPS even though it's set correctly?
Short in the engine harness or bad ground
ECU bad?

 

I put a new clutch switch on with not much change in results. Voltage at the ECU pin remained the same regardless of clutch being released or depressed. Before it changed by a little bit. With the brand new part on voltage never changed. It's was 12.somethingV.