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List of critical sensors

Slonopotam

Slonopotam

NAXJA Member #1358
Location
San Jose
Hi,

I have a 1996 Jeep Cherokee with inline 6 and manual transmission.
Does any body know where I could get a list of sensors engine could not run without ? I am a little lazy to go through FSM and compile the list myself, I could also miss something.

I just want to look at the list and buy everything on it, if it does not cost a fortune.

I've learned the hard way that the camshaft position sensor is definitely on the list. The engine died on the freeway in storm.

What are other sensors ?
 
Cam position sensor (probably inside the distributor.)

Crank Position Sensor (at 11:00 on the bellhousing, looking forward. This one drives fuel injection AND ignition timing - critical. Check here first if you have a "no-start" condition.)

MAP sensor - Manifold Absolute Pressure. Used to quantify air going into the engine for fuel mixture regulation.

IAT - Intake Air Temperature sensor. Probably in the intake plenum - likewise important to fuel metering.

Those are the big ones that I can think of. I'd start with the CPS first, and work outward from there. The CPS, due to location, is subject to an awful lot of heat - and the wiring often gets melted against the #6 exhuast pipe as well (which can be cut and spliced for replacement - I do it all the time.)

5-90
 
Gaseous Anomaly sensor in the passenger compartment. (Fart detector)

:laugh:
 
Sniggs said:
Gaseous Anomaly sensor in the passenger compartment. (Fart detector)

:laugh:
Click to expand...
It won't stall the engine. In my case it won't distract the driver either.
 
5-90 said:
Cam position sensor (probably inside the distributor.)

Crank Position Sensor (at 11:00 on the bellhousing, looking forward. This one drives fuel injection AND ignition timing - critical. Check here first if you have a "no-start" condition.)

MAP sensor - Manifold Absolute Pressure. Used to quantify air going into the engine for fuel mixture regulation.

IAT - Intake Air Temperature sensor. Probably in the intake plenum - likewise important to fuel metering.

Those are the big ones that I can think of. I'd start with the CPS first, and work outward from there. The CPS, due to location, is subject to an awful lot of heat - and the wiring often gets melted against the #6 exhuast pipe as well (which can be cut and spliced for replacement - I do it all the time.)

5-90
Click to expand...
I'll add to the above:

O2 sensor
Coolant temp sensor (in t-stat housing for your 96)
TPS- throttle position sensor

Kyung
 
corbinafly said:
I'll add to the above:

O2 sensor
Coolant temp sensor (in t-stat housing for your 96)
Click to expand...

Bad O2 sensor won't stall. The engine will go into open loop mode, I think.
I remember it was running ok without downstream O2, never tried it without upstream one.

Coolant temperature - if you disconnect this one it would probably let the engine overheat. It won't shut down right away. I am sure.
 
5-90 said:
Cam position sensor (probably inside the distributor.)
Crank Position Sensor
MAP sensor - Manifold Absolute Pressure. Used to quantify air going into the engine for fuel mixture regulation.
IAT - Intake Air Temperature sensor. Probably in the intake plenum - likewise important to fuel metering.

I'd start with the CPS first, and work outward from there. The CPS, due to location, is subject to an awful lot of heat - and the wiring often gets melted 5-90
Click to expand...

Thank you. Indeed, when my jeep stalled on a freeway it was due to CPS. I just checked, the wires on the old sensor were not melted though.

Will malfunction of MAP, IAT or TPS stall the engine ?
I can try starting the engine with them disconnected, if it's not going to hurt it. I am not going to Antarctica yet, just hate to be stranded.

You are right about all the locations.
 
TPS is off the list. The engine is somewhat hard to start without it, but then it runs ok.
 
it may start with a bad MAP sensor, but it will likely stall off idle and gernaerally be impossible to drive. Unplug the vaccum line to it with the engie running and you'll see what I mean.
IAT- Engine should run without it, it may just go into open loop, or it may run poorly, never had it disconnected to know.
TPS-If it's gone bad it will start and usually run, they usually develop a dead spot that causes the engine to buck. If it's totally bad and not sending voltage to the ECM then it may not start.
Te CPS is the most likely ad the most critical, I carry a spare one in the heep and about 30" of extensions to get to it.
 
87manche said:
TPS-If it's gone bad it will start and usually run, they usually develop a dead spot that causes the engine to buck. If it's totally bad and not sending voltage to the ECM then it may not start.
Te CPS is the most likely ad the most critical, I carry a spare one in the heep and about 30" of extensions to get to it.
Click to expand...

I understood about TPS on the road, sometimes it was giving just high voltage, in that case ECU did not see a problem and idle was erratic. When the output is above the acceptable range, ECU just ignores this input and the idle is good. When the sensor is disconnected, ECU receives input above the acceptable range again and disregards it. I've managed to start the engine, somewhat difficult, then pulled out of the parking space and back in.

Do I understand it correctly, one unbolts CPS from transmission side, not from the engine side, and 30" straight extension is all you need to get to it ?

Andrey
 
Yes, you unbolt the CPS from the transmision side.
You need to get around the curve of the bellhousing and between the floorpan, a straight extension wouldn't do it I don't think.
I have an 18" and a 12", a wobbly joint, and a wobbly socket to get at it. It's at the 11 o clock position on the back of the bellhousing.
and don't drop the bolts into the bellhousing
Don't drop the bolts into the bellhousing.
Yes, I said it twice, dropping the bolts into the bellhousing is a gigantic PITA.
 
Slonopotam said:
Coolant temperature - if you disconnect this one it would probably let the engine overheat. It won't shut down right away. I am sure.
Click to expand...

The engine will run , but like a complete bucket of ass, with a bad or disconnected coolant temp sensor. That sensor is key in determining A/F ratio. Unplug yours and see what happens ;)
 
anony91xj said:
Unplug yours and see what happens ;)
Click to expand...
I did. Looked fine, but never tried to drive it like that.
 
Is the Intake air temp sensor the same thing as a Air cleaner temp sensor?
Thaat is what they are calling it at the local parts store?
 
Well I'm still waiting for an awnser I guess lol
 
in some cases a TPS can cause a no start. if the tps is reading 5 volts at start up it may not alow the injectors to pulse. confirm this by holding your accelerator to the floor and try and start the engine. if u have a TPS thats faulty and reading 5 volts at start up and your jeep wont start, unplug the TPS and it should start.
 
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