2.3L ('83-'97) Starts cold but not when hot except under WOT

[Alex_g]

I got a 1992 4x4 with a 2.3L 5speed Manuel the odometer reads 4685mi and I haven’t driven it enough to pay attention to see if it has rolled over or just stopped working.

The short
if it’s cold engine runs good. If it’s run for a minute or more under throttle it might return to idle fine or it might stutter or on occasion run on what sounds like 3 cylinders, generally happening after you let off the gas to shift or while coming to a stop.

The long
in general it has the average amount of power it should while your foot is on the gas. it lacks any kind of power at 500-1000 rpms compared to my 2wd 91 ranger with the same engine. Both are gutless but the 92 is far more prone to stall when you have low rpm’s.

when you step on the gas it seems to hesitate for just a second before revving. When it returns to idle it bogs/chugs/fires 3 cylinders. If you get back on the gas before it dies ,after a second or to of chugging like a train, it will even out as you pass 2k rpms.
If it dies after it’s warmed up you can only restart it by going WOT “which produces a blue puff of exhaust” and sounds like a Rotary engine starting or by giving it a shot of starter fluid or wait 2-5 minutes .

So far the tests I have tried are

1. Shot starter fluid into the intake while trying a hot start and it ran, so spark and air are ruled out
2. I tried priming the fuel pump 5 times before trying to hot start it and it didn’t start. So I think the fuel pump is ok/pressure is not the immediate problem?
3. Checked the fuel pressure regulator, no trace of gas and good amount of vacuum while engine was on. The regulator also looks newer than most of what is under the hood so previous owner must have changed it out.
4. Listened for vacuum leaks didn’t find any but I definitely have an exhaust leak somewhere I think it’s under the shielding on the exhaust manifold.

1st time I pulled the codes with the engine off and got

• 116 engine coolant temp higher or lower than expected during key off and engine running
• 224 erratic ignition diagnostic monitor input to sensor
• 122 Throttle position sensor circuit below minimum voltage

I replaced the spark plugs, leads and coils as well as put on a new MAF and did a coolant flush at this point then pulled codes again while waiting for more parts to arrive.

2nd time.

• 111 all clear, twice followed by
• 116 coolant temp sensor out of range twice.

Not sure why I got an all clear before the coolant temp code. Or what happened to my 122 tps code. I think the new coils cleared up the 224 because my tachometer started reading properly

I’m planning on replacing the coolant temp sensor and TPS
And I have already replaced the

1. Maf sensor
2. Air filter
3. Spark plugs, all 8 old ones were consistently a bit sooty but didn’t look terrible to me.

1. Spark plug leads
2. Both Ignition coils one was dead and the other was about half the ohms it should have been.
3. Fuel filter

At this point I think my main problem is either the tps or maybe injectors
Any thing else I should check or tests I should run?

 

[Uncle Gump]

With the Coolant temp sensor code...I wouldn't do much more until you can eliminate that code. Replace the CTS and see if it clears the code and how it runs. With it being out of range... your fuel system will never be right.

 

[scotts90ranger]

yeah, if the computer thinks the coolant temp is like -40 when it's 60F outside it's going to be giving it a lot of fuel on startup, and when you go to WOT it disables the injectors to "clear flood" which could definitely be caused by the coolant temp sensor... definitely look into that before injectors, $20 part versus like $200...

 

[Alex_g]

Thanks for the replies. I ordered a new temp sensor now just gotta wait for it to get here. I didn’t know a temperature sensor could mess up your fuel system is so bad.

 

[Alex_g]

I got the new temp sensor installed and it runs pretty decent now.

 

[Dirtman]

Cold engines need more fuel to run. (Think of a choke on a carburetor). the coolant sensor tells the computer to "choke" the engine when its cold. Which simply richens the fuel mix until it warms up. Like mentioned, if its stuck reading cold its gonna constantly choke the engine and dump a ton of fuel just like trying to run your lawnmower on a 100 degree day with the choke on. Anytime you have a situation with a fuel injected engine where it functions great at one temp but poorly at another you should always look at the temp sensor first.

Glad you got it fixed.