Injector Heat Soak Symptoms

Tob

Tob

Paint-Matched Bezels Club
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What are all the symptoms of injector heat soak? Does it only cause rough startup? Or are there other issues associated with it?

I've observed that after a 6 hr interstate drive pushing 70-75 mph, I've got a rough idle and it wants to stall. But after a while in stop and go traffic, or when left idling too long, there's a sort of 'rev float'. Is that from injector heat soak or a different problem entirely?
 
Rev float would most likely be a vacuum leak. Only symptoms of the heat soak problem would be a rough idle for about a minute or so (tops) after starting when warm.
 
jodomcfrodo said:
Rev float would most likely be a vacuum leak. Only symptoms of the heat soak problem would be a rough idle for about a minute or so (tops) after starting when warm.
Click to expand...
So it's possible that I have a vacuum leak that only shows up in certain conditions?
 
There’s a decent explanation and solution of heat soak in this TSB.
 

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Posting here, rather than starting a new thread -
My daughter's 02 TJ 4.0 AT is having intermittent (crank / no start) issues when recently running (already warm)
We let the Jeep sit for a while, maybe overnight, and it starts right up, no issue. This is very occasional, but yesterday it also happen to stall while driving. Now, we live in a small town, it takes about 15 minutes top to go across town. It's 5 minutes to her school or the gym. I know she will sometimes lets it run while parking in the parking lot waiting to meet up with friends, so that's where I come here to discuss - Heat soak. Thoughts?
By the way - when it stalled, she opened the hood to let it cool, turned on the heater to blow the hot air through, waited 5-10 minutes and it started up.
Another side issue I'm also dealing with is the throttle valve cable connection broke at the throttle body end, the plastic connector busted... so I'm waiting for that part to arrive.
 
Alaska Nate said:
Posting here, rather than starting a new thread -
My daughter's 02 TJ 4.0 AT is having intermittent (crank / no start) issues when recently running (already warm)
We let the Jeep sit for a while, maybe overnight, and it starts right up, no issue. This is very occasional, but yesterday it also happen to stall while driving. Now, we live in a small town, it takes about 15 minutes top to go across town. It's 5 minutes to her school or the gym. I know she will sometimes lets it run while parking in the parking lot waiting to meet up with friends, so that's where I come here to discuss - Heat soak. Thoughts?
By the way - when it stalled, she opened the hood to let it cool, turned on the heater to blow the hot air through, waited 5-10 minutes and it started up.
Another side issue I'm also dealing with is the throttle valve cable connection broke at the throttle body end, the plastic connector busted... so I'm waiting for that part to arrive.
Click to expand...
I can’t imagine you would experience injector heat soak in Alaska. The only time I ever had it happen to me was a 6-hr interstate drive in over 90 degree weather.

How exactly does it “stall while driving?” Is it that it gets weak and sputtery when you come to a stop?
 
Fair, but I can’t figure out why I have this intermittent fail to start.
It cranks no problem. Battery is holding 12.6 volts starter engaged..
just no fire. I’m not sure how to test the the fuel system, but perhaps a sensor of some type?
 
Alaska Nate said:
Fair, but I can’t figure out why I have this intermittent fail to start.
It cranks no problem. Battery is holding 12.6 volts starter engaged..
just no fire. I’m not sure how to test the the fuel system, but perhaps a sensor of some type?
Click to expand...

I'm having this exact issue. I've done a few things based in engine codes I was getting and tips from mechanics I was recieving. I had the exact same symptoms. Sputter while driving, rev float and or sputter at idle after the jeep is up to operating temp. Hard start in certain conditions. Here's what I've done:

-Replaced Camshaft Position Sensor
-Replaced Crankshaft Position Sensor
-Replaced OPDA
-Replaced Intake Air Temp Sensor
-Cleaned Idle Air Control Valve
-Cleaned Throttle Body


It runs much better than it did now, however it still stumbles on occasion after being driven for a while. I'm still trying to sort it out, but all the work I've done (which isn't much and can be done with basic tools in a driveway) has eliminated small parts of the problem as a whole. (ie: check engine loght stays off now, it doesn't stumble while driving anymore (only at idle and rather infrequently), and it starts in all conditions now.
 
Not too sure if this will help but I had a similar issue with my 99 TJ AT stalling while driving and taking a moment to start back up. I replaced the distributor cap, rotor and Distributor Ignition Pickup (this is if you have the distributor and not the coil pack). Try this. Part number at advance is # MEA2262. I couldn't find the part number when I needed it or the name of the part at the time so I ordered a whole distributor from rock auto and took the parts I needed at the time.
 
I had (and may still have) injector heat soak. It's not a no start issue. Fires right up but will run with a lumpy idle that clears in less than fifteen seconds. No issues with stalling or no starts. No rev float.

I did the Design Engineering 010378 Fuel Rail and Injector Cover Kit a few months ago. The rough idle has re-occurred only once since installing the kit on March 9th, but the proof will be later in the summer as ambient temps rise.
 
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