2.3L ('83-'97) Idles high, runs decent, sometimes stalls when starting from a dead stop, when it stalls refuses to start by cranking with the key

[FatPipeLife]

Things I've replaced off of others' spitballing ideas and OBD codes

• ICM
• Idle air control valve
• crankshaft position sensor
• TPS
• EGR Pressure sensor

These are all of the things that I have replaced FOLLOWING having a pretty reputable mechanic rebuild the engine 3 years ago. I had a few strange issues like idle surging (idle going really high, thn really low, then back to high, then dropping again). Replacing the IAC managed to fix this. It ran decent for awhile, but now I'm running into a strange issue where, no matter how careful I am starting from a dead stop, the engine just stalls. Once it dies I can crank the key, but it runst cranks and cranks... Refuses to actually fire and start... but if I get her rolling and pop the clutch in second.. She comes back to life. This is why I recently changed the TPS and the crankshaft position sensor. To no avail, though. Same issue persists. I'm at a loss folks. Please help.

 

[scotts90ranger]

Sounds like a voltage to the computer problem, either power or ground, the voltage drop when cranking is too much, there's probably a wire that's nearly breaking somewhere...

 

[Mechrick]

Check the harness that runs from the crankshaft sensor up the left side of the engine. I've seen these get oil-soaked and fall apart. In general, get it running and wiggle harnesses to see if you can get it to stall. It sounds like the rock of the engine starting out is disturbing something...

 

[55trucker]

No.1 stop throwing money at the problem hoping you'll hit on the answer
Get the engine on a scanner (OBD1)

What's the AFR doing while all this nonsense is happening? it it stable or is it all over the place?
What's the IPW doing while all this nonsense is happening?
What's the MAP reading doing while all this nonsense is happening?

The ECM cannot dictate a proper air/fuel ratio if it doesn't know what the barometric pressure is.....that's what the MAP supplies
It also won't be able to control the idle, the idle will fluctuate, the engine will stall repeatedly, the engine will crank & crank without firing.

 

[RonD]

Something to look for when cranking
The CEL(check engine light) comes on when key is on and engine is off(not turning), this means computer is ON
In a 1994 the crank sensor is connected to the ICM and then the ICM sends the crank sensor"pulse" to the computer(which operates the CEL)

As soon as engine starts to turn(cranking) the crank sensor sends its "pulse" to ICM to start spark and ICM sends it to computer for injector timing, and CEL should go OFF, this mean computer IS getting a good pulse/timing signal from ICM
So if CEL goes off timing is at the ICM and at the computer
(same applies to 1995 and up, just no ICM in the middle, CEL going OFF mean crank sensor is working)
If CEL stays ON when cranking then computer will not open injectors, so no start

Even if there are OBD Codes in Computer Memeory, the CEL will still go OFF when cranking, it will just come back on after start up to notify driver that there are codes available

4cyl engine warm idle should be no lower than 750rpm, 800-850 in an automatic

Stall when pressing gas pedal at warm idle could have been TPS issue
TPS gives the computer an instant "heads up" to add more fuel, its much faster than a MAF(or MAP) sensor could react
One of the main reasons for a TPS, instant throttle response

I assume the stalling only occurs after engine is warm and idle is lower?

After warm up and with engine idling, what happens when you unplug the 2 wire IAC Valve connector?
Idle should drop or engine may stall, either is good it means no vacuum leaks


How old are the O2 sensors?
These are the only sensors that wear out, 100k miles or 12 years and they need to be changed
1994 2.3l probably has only 1 O2 so not a big expense to change it if you don't know the age of it
And no, there are no codes when an O2 gets old, computer has nothing to compare it to so engine just runs richer than it should and MPG slowly goes down costing you $$$ in wasted fuel

 

[racsan]

Id check fuel pressure, I had a similar issue with mine, except for your high idle which sounds to me like a vacuum leak.