Wrong ECT readings - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
LinkBack Thread Tools
post #1 of 8 (permalink) Old 06-05-2019, 12:51 AM Thread Starter
Regular Member
 
RussianLT1's Avatar
 
Join Date: Jun 2019
Location: Russia, Pskov Province
Posts: 4
 
Wrong ECT readings

Hello, I'm from Russia, so don't be heavy on my grammar
My dad gave me his 1995 LT1 Camaro (obd1.5) as a gift.
There's no way to get obd1 scanner in my country, so i made my own. Initial problem was fans won't kick in. I checked everything, so I'm sure it's not the wires/relays/fuses. Recently i scanned car again and found one interesting detail, reading from ECT is off by like, 15c from cluster panel one. So, basically, PCM thinks that engine is still cold. I checked ECT sensor (not original) with ohmmeter and it's looks fine compared to shbox's table, might it be bad sensor, faulty PCM or bad ground? I checked every ground wires but the one from PCM to engine block, around starter.

Last edited by RussianLT1; 06-05-2019 at 12:00 PM.
RussianLT1 is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 06-05-2019, 04:24 AM Thread Starter
Regular Member
 
RussianLT1's Avatar
 
Join Date: Jun 2019
Location: Russia, Pskov Province
Posts: 4
 
So, i checked every ground aand.. nothing. My fix is simple, i flashed PCM with lower fans engage temps. I can give you some tips for lowcost 1995 PCM flashing.
RussianLT1 is offline  
post #3 of 8 (permalink) Old 06-05-2019, 06:38 AM
Global Moderator
 
cocobolo95's Avatar
 
Join Date: Sep 2008
Location: Fruitland Park,Florida
Posts: 12,822
 
Welcome to the forum.

Just in case you ever want to try it, here's a free pc based scan program that was made for our 4th gen cars. It's called "scan9495. It was written by our member GaryDoug. It scans for regular codes, ABS, & SIR codes. It does running sensor scans and will log data to a file for later review. Get it at the following link.
My Files

Get the newest version in the lt1 v8 folder. You will need Microsoft dotnet framework version 4.0 or newer to use scan9495. Get it on same site as program. Or at Microsoft site.

You will also need a cable to connect usb port of pc to aldl of car You can get the 16 pin obd 1 cable at OBD Diagnostics

Your English is very good.
cocobolo95 is online now  
Sponsored Links
Advertisement
 
post #4 of 8 (permalink) Old 06-05-2019, 12:00 PM Thread Starter
Regular Member
 
RussianLT1's Avatar
 
Join Date: Jun 2019
Location: Russia, Pskov Province
Posts: 4
 
Quote:
Originally Posted by cocobolo95 View Post
Welcome to the forum.

Just in case you ever want to try it, here's a free pc based scan program that was made for our 4th gen cars. It's called "scan9495. It was written by our member GaryDoug. It scans for regular codes, ABS, & SIR codes. It does running sensor scans and will log data to a file for later review. Get it at the following link.
My Files

Get the newest version in the lt1 v8 folder. You will need Microsoft dotnet framework version 4.0 or newer to use scan9495. Get it on same site as program. Or at Microsoft site.

You will also need a cable to connect usb port of pc to aldl of car You can get the 16 pin obd 1 cable at OBD Diagnostics

Your English is very good.
Thanks sir, but i already did a full scan, i used arduino as TTL to Serial for connecting PCM with my PC, using a program of Yours, thanks for it BTW, really great and easy to use tool. But, as i said before, i didn't find any major issue with anything, no DTC's, nothing. Might it be wiring problem? Or PCM gone bad? There's no original GM or ACDelco parts available, so i bought a closest match for original ECT sensor.
RussianLT1 is offline  
post #5 of 8 (permalink) Old 06-05-2019, 12:30 PM
Global Moderator
 
cocobolo95's Avatar
 
Join Date: Sep 2008
Location: Fruitland Park,Florida
Posts: 12,822
 
On a 24 year old car, wiring, connector pins, splices, & grounds, can all give trouble. The ect that you bought, which was a close replacement, will probably do the job. I thought that American auto parts companies shipped parts to Russia. Most of our members in other European countries have no trouble getting parts shipped from America.

The pcm in these cars, unlike many other computers, are rugged & don't go bad very often.

Last edited by cocobolo95; 06-05-2019 at 12:32 PM.
cocobolo95 is online now  
post #6 of 8 (permalink) Old 06-05-2019, 01:44 PM
Regular Member
 
Join Date: Dec 2018
Posts: 9
 
The ground (black wire, PCM Ground) on the ETC comes from PCM pin B6 it is the same ground used by the Throttle Position Sensor and Automatic Transmission. There is a 3-way splice (S122) on the black wire coming out of the PCM pin B6 25cm from the PCM in the harness. There is a possibility you have a defective splice causing a resistance in the ground wire to the ETC. The Yellow wire on PCM pin C25 goes directly to the ETC (called a Home Run) no splices or connections. Checking resistance on Shbox's page with PCM disconnected on the cable connectors C25 to B6 should be very close to resistance you observed when checking at the sensor on the water pump. If not suspect the splice, I had a similar problem on a ground splice connection to one O2 heater circuit that drove me crazy. Good luck .. Bob

I'm Bob 1994 Z28, A4, cam, 1.6 RR's CAI, LT's, stall, cat back. Custom tuned. 2007 GMC Envoy, tuned. 2015 Kia Sorento, bone stock.
bobdec01 is offline  
post #7 of 8 (permalink) Old 06-05-2019, 03:14 PM Thread Starter
Regular Member
 
RussianLT1's Avatar
 
Join Date: Jun 2019
Location: Russia, Pskov Province
Posts: 4
 
Thanks everyone for replies! Correct, they sure do send parts to Russia, but cost+shipment is way higher that i want to spend anyway. Bob, if we're on the same wave, i'm almost sure i checked wires from PCM connector to the ECT connector with ohmmeter and also continuity checked them, without ECT R was 0 Ohm. Also i forgot to mention, car wasn't moving for like, 6 or so years, after i started it, i noticed that readings on cluster panel is somewhat wrong, RPM is 800-900 and scanner tells me RPM is 650 +- 50, Oil pressure is around 100 psi, when i switch ignition off, fuel, temp and pressure needles shows last readings. I'm not sure what can cause this, all i know, previous owner talked about 340 horsepowers he made at rw, PCM was tuned before, O2 and Cat was removed, i'm not sure you can do this on LT1 without any bolt ons and fully stock internals.
RussianLT1 is offline  
post #8 of 8 (permalink) Old 06-08-2019, 11:12 AM
Regular Member
 
Join Date: Dec 2018
Posts: 9
 
1- Fuel, temperature and oil gauges stay at the last reading in my car also. Voltage, speed and tac go to bottom of gauge, tac should read 0 with key on, if I can remember I think it's actually near 10 RPM w/key on engine off on scan data due to digital to analog conversion in PCM..

2- 650 RPM is close to stock idle setting.

3- I think the oil sensor is left top of engine behind the EGR valve (see shbox site for exact location). Pull the wire off, and observe pressure, then short wire to ground gauge should move between 0 and high reading, my US gauge reads 0 lb to 80lb yours at 100 must be metric KPA. Could be the sensor is plugged up with dry oil. I searched but could not find what the correct ohms-to-pressure resistance range of the oil sensor should be. 650 Idle should be 10-40 lbs (us readings) of cold oil pressure depending on how old engine is.

4- I don't think stock with just a tune and cat removed will make 340 HP at rear wheels, stock is around 275-280, maybe 300 w/a good tune unless other work was done to it.

I'm Bob 1994 Z28, A4, cam, 1.6 RR's CAI, LT's, stall, cat back. Custom tuned. 2007 GMC Envoy, tuned. 2015 Kia Sorento, bone stock.

Last edited by bobdec01; 06-08-2019 at 11:16 AM.
bobdec01 is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome