'07 died, now won't restart without pressing pedal

Duster

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OK so it's an '07. It cranked just fine, backed out of drive, all was fine. At the 3rd stop sign from home it died. A half mile drive from home. I am not 100% sure now, but I want to say it died just as I went to go. Wouldn't start back. I was on a slope and thankfully no one was behind me, so I let it roll back out of the way. It would sometimes start back but not really catch on and run. Kinda start stumble and die if it started at all. I thought oh boy. It usually starts really solid with a vroom. So I called my wife to come get me since the rain from he hurricane is starting to reach us.

I got home to round up some tools and it just started raining harder. So I made some calls and drove back up to have a look to see if I could figure out an easy way to give it a redneck tow home. Some time had passed so I decided to try to start it again and it really wasn't hitting until I took it to the old days and pushed the gas pedal. I figured out I could get it running and keep it running if I didn't try to let it idle. So I moved it around where I could get in and just go. Then I went home and got my wife to take me back so I could try to run it the half mile home so I could at least put up the tent to look at it without the soaking. It made it back, but the rain started getting worse and the wind wind started kicking up by the time I got the tent out of storage.

So I just gave up for now, which has me really stressed out. Can't even try to diagnose.

All I can tell you is that it is not setting a check engine light. No recent issues leading up to this. The only thing even relative to this I can think of is every once in a while over the past couple years, it will either seem to start and hit bit quick and run, or hit and immediately stumble and die. But only once. Never replicates. Its probably done both maybe 2 or 3 times in a couple years. So I had been just chalking that up to flukes of an aging Jeep. It's really a rare occurrence considering it's my work truck. I did 60 start/stops yesterday to put it in perspective. So I don't know if that info matters.

Any thoughts that might help me on this issue?

My mental check list so far is... vacuum related hoses, idle air control, throttle position sensor, MAP sensor, battery, fuel solenoid / filter / pump
 

lfhoward

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Your 07 has no IAC since it is an electronic throttle body (same as my 08). If the electronic throttle control was bad you’d have the lightning bolt symbol on the dash along with a check engine light. I am thinking fuel pump? Only gets enough fuel pressure when floored? How many miles on it?
 

DadOSix

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I would start with unplugging the MAF sensor on the hose from the air filter box to the throttle body. I’ve seen that gizmo do some weird stuff. The fact that it runs better at WOT (Wide Open Throttle) says the ECU sees something it doesn’t understand. I just watched a YT that had a car, don’t recall what, that wouldn‘t idle. the guy unplugged the MAF and it ran like it should. The MAF ‘weighs’ the air coming to the throttle body. Air calculation by ecu determines how much fuel the injectors squirt to get the right mixture to run. With a bad air calculation, the ECU cant figure out how much fuel to inject.

Just a SWAG, but it is cheap to test.
 

LibertyTC

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Any chance water in fuel?
At 240k, it could be the fuel pump. With a fuel pressure gauge, I'd want to know what the fuel psi readings are, key on reading- off for 15 min- & running psi.
 

Duster

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I wrote that mileage, then went and crawled in bed. I was laying there thinking and I heard the rain slack off. So I got up and went out to see what I could see. Did the below and wrote the below, but it did not post. Think the internet was flaky from the weather. Gonna post this then respond to more folks.

I don't see anything obvious. There is not a bunch of vacuum on these running all over. Just the PCV related stuff and the one line off the throttle body to the vapor canister thing by the battery. And a line off it that appears to go down by the firewall. I'm guessing that runs back to the fuel tank?

Hmmm, you know I did run over some brush/limbs on my last shift. I was going down an access trail. It was very windy and some limbs had broken out over the trail. Normally I would stop and clear that, but at the time I also had two Rottweilers trying to chew my tires off the rims. It wasn't real big stuff so I just eased on over and checked the mirrors for signs of dragging anything. I saw no sign and never even stopped to check after I got away from the dogs. I could have popped a line or snagged it and put it in a position to pop off. So I guess I should jack it up and inspect under there.

I would think something with that would throw a check engine light for evap or vac leak though? But then again, back when my PCV stuck and it sucked a hole in my PCV pipe elbow, it never threw a code. It just made a suction noise that took me a bit to find. I was lost until I pulled the dipstick while it was running and heard it suck air there too.

Oh and the battery was resting at 12.6v. I have seen some bad batteries show over 12v and be bad, but never seen one read 12.6 resting and be bad. But when I can I will hook to it and see what the reading is when it is cranked over. It's back to pouring. I'll have my wife crank it over while I watch the meter when I get a chance.
 

Duster

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I would start with unplugging the MAF sensor on the hose from the air filter box to the throttle body. I’ve seen that gizmo do some weird stuff. The fact that it runs better at WOT (Wide Open Throttle) says the ECU sees something it doesn’t understand. I just watched a YT that had a car, don’t recall what, that wouldn‘t idle. the guy unplugged the MAF and it ran like it should. The MAF ‘weighs’ the air coming to the throttle body. Air calculation by ecu determines how much fuel the injectors squirt to get the right mixture to run. With a bad air calculation, the ECU cant figure out how much fuel to inject.

Just a SWAG, but it is cheap to test.
Thank you for the suggestion. I will for sure try that.

First thing I am going to do is recreate the cold start from yesterday. But this time if it cranks normal I am not going to leave lol. Wait around and see if it dies when it gets up to full temp. Thant way I get an idea of it it is anything temperature related. If it don't crank then I will unplug that.

I appreciate the suggestion, name of part and location. I'm no mechanic but always end up being the one turning the wrenches and fixing things with the help of the crew here and the 2006 service manual also thanks to here. Need to look in that too and see if the 06 has the same throttle body etc as my 07 to see if it can help here too.
 

Duster

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Any chance water in fuel?
At 240k, it could be the fuel pump. With a fuel pressure gauge, I'd want to know what the fuel psi readings are, key on reading- off for 15 min- & running psi.
Yeah with today's fuel you can never rule out water in the gas.

I was also thinking fuel pump fuel filter or injector leak down. I've had to replace 2 of the 6 injectors along the way. The other two caused codes for misfire. But one could be going bad a different way than the previous two.

Also thanks for your old thread on cleaning the IAC. I can now recognize my throttle body is different from yours as Ifhoward pointed out. This has me wondering what can even be cleaned on mine.
 

klc

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Perhaps an fuel intake induction cleaning where they spray the stuff into the throttle body.
 

Duster

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OK, recreated the cold start from yesterday. It cranked right up normal. But as it warmed it started to idle rough which I didn't notice yesterday. At a touch of the pedal it died.

I was able to start it back like yesterday by throttling. I unhooked the MAP sensor once I was able to keep it idling long enough to get out and try it. It ran the same, but set a check engine light that stayed. I unhooked the battery for a while and checked underneath good and didn't find anything. The check engine light did clear after I got it back running again.

Well the light cleared until I started unhooking coils to see if I could find one that didn't produce a rougher idle. I really thought the first one I tired was the issue. It didn't seem to change so I pulled it and pulled the spark plug which looked ok. I replaced the coil, no change. After further messing with the coil unplugging it doesn't seem like most of them make much of a difference in how it runs. Typically one idling this bad will croak when you unplug a good cylinder. So I haven't bothered to check all the plugs and move coils around.

I took the intake tube off and took the throttle body loose. It was gunky in there. It looked mostly like oil gunk residue and buildup. I wiped out the throat and butterfly of the throttle body, and turned the MAP sensor and cleared it off with a q-tip since I didn't see an obvious way to remove it.Looks like it just pushes in pulls out? I wiped a little out of the intake riser tube before putting it all back. There's a coating all down in there which I assume comes from sucking oil and oil vapor in there through the PCV? And a lot lot of miles. I was afraid to try to remove the side cover on the throttle body to see if I could access anything more to clean. I really didn't want to screw it up and find out nothing is in there but electronics either.

I can hear the fuel pump priming. I do need to get it back running and see if I can hear it run like I do when I sometimes dont shut it off and work out of the back gate. I never went and listened. I'm not ruling it out but I don't know why it would crank fine cold if it is not holding pressure while off? And I don't know why it would idle rough but rev up fine if it was not maintaining pressure? Is there such thing as variable pressure based on throttle position.

I think I will pull all the spark plugs and just look at them next since I am out of ideas at the moment and just stewing. I don't think it is running bad on just one cylinder but I can have a look. See if one is oil or fuel fouled.

I also need to locate and name sensors I guess. I see the canister by the battery. I see what seems to be a coolant temp sensor front top center. Just behind it I see another sensor that seems to go in the plastic intake? Down the right side of the engine by the airbox I think I see another? Time to jump into the service manual too.

Thanks everyone
 

Duster

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Perhaps an fuel intake induction cleaning where they spray the stuff into the throttle body.
Yeah I would not disagree with that nor disassembly to flush it out in a parts cleaner. I don't think it is the run issue but it would not hurt on high mileage onto clean them. This may be why the PCV pipe design was changed and had me wondering when I replaced it some time ago. My stock one went under neath from the valve to the intake. Then new one from the dealer goes over.
 
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Duster

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Well I pulled all the plugs for a look and they all look OK to me. I smelled the darkest one of them which was not fouled. It honestly just smelled like a gas can you left pretty much empty for a year kinda dead gas smell. Could be bad gas but I burned a half a tank of it already and it's from the usual station.

I tried again unplugging the coils and I can hardly tell a difference. No difference unplugging map sensor or the purge valve. The only thing that seems to make any difference is creating a leak after the throttle body like the PCV hose or the purge valve hose. Doesn't cure it, but it's better and when you go to put it back it will kill it even if you try to do it really slow where it has time to adjust. Like if you put your hand over a small engine carb and starved it for air.

Exhaust seems to flow OK. Just smells smoggy, not raw gas not a sweet coolant smell.

I am stumped. Almost seems like its something going bad that isn't throwing a code yet but it's already badly effected. Something that delivers data that is ignored during cold start, or something that doesn't adjust out as it begins to warm.

Anyone have any other ideas? Anyone have any experience with this electronic throttle body. Anything more I can open up and clean?
 

Duster

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OK, making a correction here. On the 07 the sensor in the intake tube that I cleaned with a Q-tip is the charge air temp sensor, not the MAP nor MAF sensor. Same one I unplugged which was no change and just a CEL.

The MAP sensor I am guessing is the one there by the coolant temp sensor that looks to bolt into the plastic intake manifold.

The part pictures are great here, diagrams for location are horrible though.


 

DadOSix

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OK, making a correction here. On the 07 the sensor in the intake tube that I cleaned with a Q-tip is the charge air temp sensor, not the MAP nor MAF sensor. Same one I unplugged which was no change and just a CEL.

The MAP sensor I am guessing is the one there by the coolant temp sensor that looks to bolt into the plastic intake manifold.

The part pictures are great here, diagrams for location are horrible though.


Can your scan tool read real time data?

If so, give a look at the fuel trims both short and long term.

—-

Running over some stuff in the past, i clipped the wiring for the left rear oxygen sensor. That did set a code only when the wire hit the exhsust and grounded it out.
 

Duster

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Can your scan tool read real time data?

If so, give a look at the fuel trims both short and long term.

—-

Running over some stuff in the past, i clipped the wiring for the left rear oxygen sensor. That did set a code only when the wire hit the exhsust and grounded it out.
Thank you. No unfortunately I don't have access to a scanner that can read real time data. That would be nice right now since there aren't any codes.

I went back under a second time and looked at things. Everything looks OK. All 4 wires to all four o2 sensors look OK. Majority of the underside lines are steel. I did get up under the tank and check all the hoses coming from the tank to the EVAP parts too.

If I were guessing here which I am still, I would suspect the coolant temp sensor because it starts OK cold. But I think my gauge is operating normally. So I don't think that is it.

So I now look to the crankshaft and camshaft position sensors. I think I have located them on the passenger side of the engine? Cam up higher in front of the exhaust manifold. Crank down lower to the rear near the exhaust coming down. Saw a sensor there looking at everything by the front passenger o2 sensor.

I think I will crank it up and try unplugging that MAP sensor behind the coolant temp sensor and see if it runs better in a limp mode or not. I think that is about all I can do. I assume if I unplug crank or cam sensors it wouldn't run at all? Or would it run in a limp mode with just one of them unplugged at a time?

Would be nice if I could unplug something and it run better in a limp mode to get a clue what part to throw at it since there's no codes to point to anything.
 

Thom2006kj

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My 07 would do that and not like starting hot, changed my fuel pump and it solved all my issues
 
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Duster

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That about had me whipped. It warmed up outside a bit more today and it seemed to run a little better a little longer.

I had kind of put the crank sensor and coolant sensor on the end of the list since the gauges seemed to be operating normally. And although my first thought was the coolant temp sensor I could not find a second one that might have ran the cluster guage.... and the sensor was indexed with the release clip towards the map sensor. So I couldn't figure out how to get it apart and once I did I was very uncomfortable trying to do it again with the engine running. But I finally managed.

It was missing and idling maybe 450 rpm. When I unplugged the coolant temp sensor the engine sprang to life. So I ran and got a temp sensor. If you ever have to change one you'll need a very deep 19mm or 3/4" socket. My spark plug one was not deep enough. I took the sensor to O'Reilly and their 1/2" drive 19mm was just deep enough.

So it was the coolant temp sensor. I would not have guessed it considering the guage clutster seemed to be operating normally. But I kept coming back to it. Apparently it was reacting to slowly or too quickly and really throwing off the air fuel ratio once the engine was warm.

I don't know why it didn't code? Maybe I didn't make it far enough for it to go into closed loop and throw all kinds of codes?
 

LibertyTC

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Good you found the culprit/ Temp Sensor.
I have no idea why so often the Kj's do not easily set codes for the sensors.
It's like the the computer is sound asleep zzzz..Snore or ignore mode !!;)
 

DadOSix

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That about had me whipped. It warmed up outside a bit more today and it seemed to run a little better a little longer.

I had kind of put the crank sensor and coolant sensor on the end of the list since the gauges seemed to be operating normally. And although my first thought was the coolant temp sensor I could not find a second one that might have ran the cluster guage.... and the sensor was indexed with the release clip towards the map sensor. So I couldn't figure out how to get it apart and once I did I was very uncomfortable trying to do it again with the engine running. But I finally managed.

It was missing and idling maybe 450 rpm. When I unplugged the coolant temp sensor the engine sprang to life. So I ran and got a temp sensor. If you ever have to change one you'll need a very deep 19mm or 3/4" socket. My spark plug one was not deep enough. I took the sensor to O'Reilly and their 1/2" drive 19mm was just deep enough.

So it was the coolant temp sensor. I would not have guessed it considering the guage clutster seemed to be operating normally. But I kept coming back to it. Apparently it was reacting to slowly or too quickly and really throwing off the air fuel ratio once the engine was warm.

I don't know why it didn't code? Maybe I didn't make it far enough for it to go into closed loop and throw all kinds of codes?
Great that you got it!
 
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