• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

4.0 carbon issues. any emission gurus out there?

Driftingrz said:
what should my cts read when engine is at running temp?

edit: im guessing from statement

". Resistance should be less than 1000 ohms with a WARM engine (examples = 212* would be about 185 ohms, 160* would be about 450 ohms, 100* (not warm enough) would be 1,600 ohms"

i should be finding around 1000 if i get a crazy number ill look for a bad ground or replace the sensor
Click to expand...

Look for 200 too 500 ohms with fully warmed up engine.

You might google youtube for videos on how to use a multi meter (ohm, volt test, meter, digital for key words search)
 
well the back end of the CTS was literally missing. the 2 connects were half exposed and when i took the plug off and attemped to measure the resistance between the 2 connectors i got nothing on my meter so im gonna replace that i guess
 
Make sure you had the probes in the right place on the meter side, and the meter dial set to test ohms, not volts. One of my meters, I have to swap the red probe to different hole going from volts to ohms, on top of switching the selector dial. Can be confusing for a newbie. Also, some meters have a range selector, so you need to adjust the range to get a proper reading. 0-2000 ohms would be the first range to try.

You say you got nothing, but what was nothing? Zero or infinite?

From the physical description it sounds like you found a problem sensor?
 
it was set to ohms and i tested it on other things and got readings but none on the sensor it self... now while im looking at sensors on line at advance auto parts or oreillys im realizing they look nothing like the sensor on the side of my block. different connector type completly. im pretty sure i checked the right one. only sensor on drivers side of block according to this diagram

Sensor_Coolant_For_ECU.jpg
 
Actually, there are two sensors on that side of the block. The lower one is the Knock sensor, and they are fragile, and easily damaged! The CTS is way up under the exhaust manifold, and has a 12-18" pigtail wire and connector on the CTS sensor itself. The Knock sensor does not have a pigtail wire and connector!!! I think you tested the wrong sensor.


Driftingrz said:
it was set to ohms and i tested it on other things and got readings but none on the sensor it self... now while im looking at sensors on line at advance auto parts or oreillys im realizing they look nothing like the sensor on the side of my block. different connector type completly. im pretty sure i checked the right one. only sensor on drivers side of block according to this diagram

Sensor_Coolant_For_ECU.jpg
Click to expand...
 
yea i just jumped back on here to say the same thing mike. i didnt see it. but the knock sensor was broken so ill see about replacing it. engine is warming back up and ill test the correct one this time
 
The bad knock sensor could have been part of the problem, but I doubt it was the biggest issue.

Pull the vacuum line on the fuel pressure regulator, engine running, see if you smell or see any gas, which would indicate a ruptured diaphragm in the regulator.

380 ohms is not way off, but it is not a hot engine reading either. For now call it OK, and move on to the O2 sensor, then test the MAP and MAT(IAT). If the engine is running cold, rich fuel op, 380 ohms might be right, as that is about 160 F IIRC, and a working O2 sensor system should over ride the CTS data and compensate to reach stoich operation, so I suspect an O2 problem running the engine rich and cooler, either a vacuum or exhaust leak, or no voltage to the O2 heater or a bad O2 sensor or wires.
 
Last edited:
did replace the o2 sensor, just replaced the MAP since i was seeing no change in voltage from ignition on.engine off to engine running . just got home put the new map on turned the key to start the truck and the key snapped in 2... was able to ge hte half of it out of ignition but i have no extra/spare key so no way to crank it now. gonna see about getting one made or just replace the ignition cylinder
 
if i havent fixed it something has changed drastically. with the engine running i just had my head in there listening to something. i listened and listened looking for exhaust leaks or vacuum. and i found what i think to be a problem. i dont have a manual or diagram but i got a few pictures of how it was and how it is now...

excuse the ignorance but the top vacuum line was just handing around disconnected. so i played with it and found a hole it liked (please correct me if im wrong) it slowed the idle down to a more calm running engine. so i took it for a ride and it was alot better not nearly as much black smoke. so i came home and there was one more port underneath and i put my finger over it to plug it since there was no hose (if its supposed to go somewhere please help me) but i made a plug for it put it on and drove to oreillys auto parts and it is not smoking at All. idles nearly perfect and no soot coming out of exhaust and it doesnt reak of gasoline

IMAG0394.gif


hooked up top one

IMAG0395.jpg
 
edit - stared at the vac diagram a bit more. The skinny line out of the top of that fitting goes to the fuel pressure regulator, so a big vacumn leak right below it could certainly explain running very rich. The one you hooked up is for the EGR valve.
 
Last edited:
so do i have it right currently? or.... should the bottom just be plugged up, or should it be running somewhere. anywhere i could find diagrams on the net?
 
There is a vacuum chart and pictures bouncing around here and there if you dig on the net. Sounds like your EGR is disabled, so you need to get a manual, even a Haynes manual as lousy as they are, would show the vacuum line routing, so you can fix the EGR set up.

This thread is a good start for you:

http://www.naxja.org/forum/showthread.php?t=1033466&page=8
 
Last edited:
i looked for one while i was at oreillys they had one that was like 20 years old covered in grease and missing pages. every other manual on the rack was new in wrapper... wtf haha. im gonna hit another parts store tomorrow and see what i can find. probably pick me up some hose to redo some of the vac lines that are cruddy
 
You must log in or register to reply here.

Similar threads

O
0331 Strikes Again...?
Replies
11
Views
367
Ol Blue
O
S
Issues flushing dirty coolant
2
Replies
29
Views
4K
fenns7
F
N
Severe stumble, misfire and no start issues
2
Replies
27
Views
4K
maxbraketorque
M
4
Emissions
2
Replies
29
Views
4K
wbnickens
W
T
1 Ton steering clearance issues
Replies
9
Views
934
XJChang
X
Back
Top