flying_solo

Basically my car hates starting in weather bellow about 40F which is no bueno around here.

I thought this may be related to a known vacuum leak I have with my Air Pump as this started by first acting up for about 30 seconds I suspect a loose old vacuum hose there. All other hoses look great as I checked them over this summer chasing down other Series I common gremlins.

First issue just started happening today. The video begins with the clutch in and the tach going crazy. Second issue is the constant one where with the clutch not engaged the car bounces it's idle from 1500-2000. It will do this till water temps reach at least 140f. This happens whenever the car is started and the initial temps are bellow 40f. If I depress the clutch the car holds an idle at 1500. The other solution is to just hold hide around 2300 till it warms up.

I don't think it's the common idle hunt problem solved with a new clutch sensor as it is definitely temperature related. What are some idea's folks have?

RIWWP

iTrader: (2)

Try disconnecting the battery and cleaning the grounds. Most wierd gauge cluster issues end up being a problem with poor electrical connections, usually at the battery.

flying_solo

The battery is only 4 mo old and I cleaned up the terminals when installing (not that there was any real corrosion). I haven't driven her much this winter except to hoon in the snow and the battery was dead from sitting so I had to jump her. Perhaps the tach was related to that. The bigger issue is the crazy idle.

RIWWP

iTrader: (2)

If it's a fixed RPM jump up and down to exact RPMs each time, then it's the neutral switch freezing up. If it's just the RPM jumping around completely randomly, it could be a number of different issues.

I'd still say to clean those battery terminals first. Free, easy, quick, and it will rule that out.

flying_solo

Roger that, I'll clean them again and need to pull the battery to put it on a trickle charger anyway.

So, I had ruled out the neutral switch as it seems related to temperature. But, it is indeed a fixed RPM. It just seems so odd it happens only in the cold. I'll see if I can find how to test the neutral switch.

flying_solo

well, crap. Easy enough if it's not snowing and cold out. I'll deal with this in the spring. I'll update the thread when I do have time & heat to test this.

https://www.rx8club.com/series-i-do-...switch-200453/

Thanks for the advice RIWWP!

RIWWP

iTrader: (2)

The tach dropping to 0 with the engine still running is definitely an electrical problem, likely a common grounding issue. If it was mechanical, it would only be the e-shaft sensor, but you would have a corresponding cut in fuel and ignition if it was the e-shaft signal dropping out.

If the RPM jumping only does it with cold ambient temps, I wouldn't worry about it personally. It will happen to pretty much every 8 out there at various cold temps. It was about 5F for my 8. I suspect it has to do with how thick the transmission fluid gets, and the neutral switch has problems making the electrical connection for the ECU to see it's status.

flying_solo

This was a Texas car, perhaps it's bitter I moved it up here?

Thanks!

nycgps

iTrader: (1)

Your ABS module is on it's way out.

RIWWP

iTrader: (2)

What makes you say that?

nycgps

iTrader: (1)

cuz I seen couple of them with the same thing, the pump will die eventually.

just yesterday I replaced a 8 with only 15K miles, yep, 15K miles, but it's a 04 car so the pump is at least 8-9 yrs old.

everything dies, just the matter of time, and as our car ages, more and more abs pump failure gonna show up, and it seems that, "not changing brake fluid" will accelerate this process (failure, duh, lol)

RIWWP

iTrader: (2)

Care to be more specific? "A tach problem at idle is a symptom of ABS module failure" is what you seem to be saying, which doesn't make much sense.

nycgps

iTrader: (1)

there is nothing wrong with IC's tach, the abs module is in the middle of CAN bus, it intercepts all wheel sensor signal and sends them to the IC and ECU, so if there is something wrong going on inside the module, well, the IC's tach gonna have this "wtf" jumping. mind you the tach actually still works, if u step on gas the tach will jump between the "actual" rpm and zero, cuz it's just giving the ECU all kinds of wtf signal and confuses the **** out of it, then u will see lots of Uxxxx code and Cxxxx code.

replace the ABS module will fix this, but requires a trip to dealership to get it programmed,

cuz when the ABS module came to this "wtf" state, IDS will not be able to get the As-Built data from it and it will not show any errors, your new(used) ABS module will still get an error of C1805 with it, just do a clean As-built input and it will work.

RIWWP

iTrader: (2)

I'm still a bit confused. The tach is run by the e-shaft sensor, not the wheel speed sensors. Does the ABS module intercept the e-shaft sensor signal too?


I've seen the jump tach first hand, and have remedied it with clean battery connections, so I know that is one possibility of the root cause. Perhaps with corroded grounding points, the ABS module also has problems, and that is where it's getting through to the tach?

nycgps

iTrader: (1)

there is probably an internal short or bad solder, giving lots of weird signal to ECU/IC, confused the **** outa it.

to op, if u see this Tach thing, turn car off, disconnect ABS connector and the pump motor connector behind(pull this straight out, it's hard/stuck at first), restart the car and the jumping idle should go away (ABS light will go on)

1.3_LittersOfFurry

iTrader: (4)

Whoa whoa whoa, This is interesting..

nycgps, do you remember any of the U codes it will pop? I keep getting "ESP U1900".

I get the jumping tack sometimes too! Battery terminals are new/clean. I noticed the op's DSC/TC lights are on (mine does not work). But my abs do work. Restarting the car seems to fix the problem if it doesn't fix itself while warming up.

I will definitely check the neutral safety switch either today or the following Sunday.

I've been slowly hunting down the problem to my DSC/TC not working since the end on 2011. I have already cleaned every damn plug I can reach in the engine bay. Along with the list here https://www.rx8club.com/series-i-tro...taying-202843/ . Any other signs that the abs module is failing without throwing a code?

nycgps

iTrader: (1)

U0073-FF- (EPS) - (CAN) communication bus fault - No Status Available for this (DTC)
U1900-FF- (EPS) - (CAN) Communication Bus Fault - Receive Error - No Status Available for this (DTC)
U2023-FF- (EPS) - Fault Received from External Node - No Status Available for this (DTC)
U1900-FF- (IC) - Missing the CAN message from PCM - No Status Available for this (DTC)
U2516-FF- (IC) - (CAN) Bus Off - Transmit Error - No Status Available for this (DTC)
U1900-FF- (RKE) - (CAN) Communication Bus Fault - Receive Error - No Status Available for this (DTC)
U0073-FF- (PCM) - (CAN) communication bus fault - No Status Available for this (DTC)
U0121-FF- (PCM) - Lost Communication With The (ABS) Control Module - No Status Available for this (DTC)
U0155-FF- (PCM) - Lost Communication With The Instrument Panel Cluster Control Module - No Status Available for this (DTC)
U1900-FF- (SASM) - Missing the CAN message from PCM - No Status Available for this (DTC)
U2516-FF- (SASM) - (CAN) communication bus fault - No Status Available for this (DTC)

Copied from IDS log, some U code repeated because every single failed communication error will give u these codes.

U1900 alone is already telling ya that something IS FAILING. as our car ages, more and more of these electronic related issues gonna show up.

why is ur DSC/tSC light does not work ?

RIWWP

iTrader: (2)

Most OBD2 code readers will give you 1 or more U codes normally, just because they are generic and don't communicate with all the RX-8 modules successfully. So don't assume you have a module failure just because you have a U code, make sure you have something else to back up the diagnosis of a module failure.

nycgps

iTrader: (1)

You are right, most CHEAP OBD readers will give you some weird code. even some Bluetooth adapters cause that.

what I was saying is if you didn't plug anything in , CEL turns on and u see U1900 (or whatever U related), then I got some bad news for you.

I already seen couple of failed ABS module with the same error, replaced and everything good as new.

1.3_LittersOfFurry

iTrader: (4)

No CEL, for ESP U1900. Cobb is pulling that code up.

Coincidence? Today when I got in, there was a CEL and a few codes... (First time I get these codes)
U0155 (<-- This one triggered the CEL)
U1900
U2516
U0073

Cleared the codes, haven't come back yet.
This sucks.. Like chasing a damn ghost..


I have no idea why the DSC/TC stopped working, the car was stock at the time minus being lowered by a previous owner. I went to work one morning in the rain, when I got to my exit I turned on the DSC, began braking, next time I looked at the dash the light was flashing at me. When I left work later that day it worked for like 3 mins? Then never worked again since. Then from that point code U1900 has always popped up.

I have made many attempts at fixing it...
-Brake pads
-Unstuck calipers
-Flushed brake fluid
-New shocks
-Replaced DSC button
-Alignment
-Ohm checked all wheel sensors
-Cleaned/repaired EPS connections
-Brake switch
-Cleaned all bulb connections
-Replaced all rear bulbs & plugs
-Cleaned all electrical connection
-New Tires
-Tested steering angle sensor
-Replaced one rear wheel sensor (I damaged it)
-Checked all fuses
-Removed ECU/ESP/noisefilter cleaned all connections

There is probably more I'm just forgetting....

Things I know still need to be replaced..

-Front rotors, inside worn down from sicking calipers
-New springs, sagging
-Sway bar end links, all bad
-Replace a rear wheel stud


Is this just one of those things I need the dealer to figure out? I mean I honestly only want it fixed cause the flashing light drives me crazy.

Oh and DSC button does not light up unless headlights are on, not sure if that's normal or not, just throwing that out there.

ABS, Cruise and auto aiming head lights work.

Thanks, Shawn.

flying_solo

So, I did pull the battery and checked the terminals. They are not corroded, but the battery had been drained. I have an ultraguage 2 reader and it seems to drain batteries in the winter. I had forgot to unplug it after my last "neighborhood ice rally."

so nycgps to recap, you think the weird idle and sudden tach dancing are related to the ABS module? How much does that cost me as this thing has nickel and dimed me to death enough this year. I'll pull the ABS motor as you say and test tomorrow night.

nycgps

iTrader: (1)

the one I replaced yesterday has intermediate issue, 30% the car works perfectly fine, while others will just have ABS/Traction light on with tach dancing, when this happen, I turn the car off, unplug ABS harness, car start, everything back to normal, plug in, jumps again, unplug, works again, plug the the new(used) module, no jump, does that tell me something? I think so

replaced, programmed, and it hasn't come back, and of course not even any of the Uxxxx/Cxxxx codes that's almost always stuck in his ECU as pending codes.

ESP code will show IF you press and hold DSC button for more than 5 seconds, which what you usually do

you can always get a used ABS module first, when the tach jumps on you, turn it off, plug in the new(used) module leave it hanging, jump back into the car see if the tach still go nuts.

You can wait until it's completely dead.

how much? a used one can go as little as 40 bux shipped, a new one is about 1600~ ish bucks. and you HAVE to let dealership program it, otherwise you will always have a CEL of C1805

flying_solo

Just threw a p0850 today. Guess that solves my mystery idle issues. Gonna replace it sometime in the next month and report back.

flying_solo

As promised I would confirm the fix. Replacing the neutral switch fixed all my issues.

ChaunceysRX8

U2023 and U1900 C2778 C1306 came up on my OBD2. my dsc light started flashing and traction control came on while driving. my OBD2 came in the next day and these are the codes I got. Would this be abs failure?