Engine Stalling

I have a 2005 Jeep Liberty, I was at work tonight and when I got off work my car just started fine. I drove it just a block away from the mall and it locked up and died. I tried starting it and it will crank over but not start. The engine light came on but that is it. I have gas in the car and it has never done this before. Can you please let me know what could be wrong. I am a woman and I don't know anything about cars at all. Thank you so much.

My car has recently had some issues starting. It will start, but as soon as I shift into reverse, it will stall. I need to keep the foot on the brake to slightly rev the engine. Once the car is moving, I have no stalling problems at all - no stalling at lights or anywhere else. This stalling issue also doesn't happen all the time. It also is not idling nor running roughly. WHat could be causing this?

My Jeep has developed an unusual set of symptoms over the last 3 weeks. Primarily, it stalls a lot. About every 2 minutes (roughly, and not consistently) it stalls. If I'm at idle, it quits. If I'm driving, it picks right back up and drives like normal for a bit. Sometimes, the gages don't even dip, there's just a quick grab.

Ok, now the background. I moved the Jeep to Minnesota from Hawaii. No problems in Hawaii. Before shipping, I did a basic tuneup (oil, filters, spark plugs). When I did this, I replaced the stock filter for a K&N. I also replaced a small section of vacuum hose that had a big crack along the bottom of it. This hose came down from the throttle body and T'd into a line coming from the purge solenoid (80% sure that's what the thing mounted off the relay box is that clicks sometimes.)

For the first several weeks, there were no engine codes. I hooked it up to an OBDII reader and verified there were no codes. There were 4 lights flashing on the reader: O2, CAT, EVA, HTR. Now, I get an engine light when I start the Jeep, until it does it's first stall, then the light check engine light goes away.

When my wife picked the Jeep up from the shipper, they drove it up to the pickup area, turned it off, and it wouldn't start again. All the stall symptoms started about a week after this. The shipper had a couple guys look at the Jeep and mess with it until they could get it started. Ever since, the alarm system hasn't worked the same. Not sure if the pickup from the shipper is important, but you never know.

Lasts week, I changed out the K&N for a paper filter to see if there was any change. It went a whole day of driving without stalling, but then went back to stalling again. I disconnected the battery, cycled the key, and let it sit overnight to reset the computer. I started it up the next day and started getting incredible gas mileage, though it was still stalling. Gas mileage in Hawaii was 13.4 avg over 4 years. Gas mileage went up after fixing vacuum leak, to about 16 mpg. Ever since resetting the computer, it's been averaging over 18.5 mpg.

After resetting the computer and driving it for a couple days, I took the airbox off and visually inspected the throttlebody. I started the Jeep and watched and noticed the throttle plate wasn't moving to adjust the throttle plate and the idle. So, I think the engine is starving of air because the IAC isn't working and the throttle plate stays closed for some reason. With the vacuum leak, it could have been drawing air in through the vacuum line via the suction drawn behind the throttle plate. With the vacuum leak fixed, there's no source of air. That means the problem could have existed in Hawaii and been part of the gas mileage problem.

But, I'm not ready to change out the IAC. It makes sense that some signal may not be telling it to open.

So, I took the Jeep to hook up an OBDII reader again with the check engine light in, and it returned a code 0601 checksum code, again with the same 4 flashing indicators (O2, EVA, HTR, CAT.)

When I had the airbox off and was watching it idle, about halfway between the time I would restart it and the time it would stall, there was a clicking that would start. I traced it to a thing that has 2 vacuum lines and an electrical connection to/from it. I believe it's a purge solenoid related to the emissions system. So, once it starts clicking audibly (about 2 clicks per second), the Jeep soon stalls.

I've been to the forums, but most help there is "Replace your PCM and see what happens." I don't like the "replace some expensive part and see what happens" style of troubleshooting that happens all to often - even at dealerships. So, I'm hoping for some insight into this complicated picture of electronics, emissions, vacuum lines, sensors, etc. That can relate these symptoms to a common component.

Thanks for your time. Jason

So. Replace the PCM?

Ok. You're validating that there isn't likely to be something else wrong that's causing the PCM error? It sounds like that's what the code is saying.

Thanks for posting the detailed info on the 0601 error. Hopefully it's related to the stalling problem. I only recently started getting the code, but it's been stalling for weeks.

Could it be that something else is causing the stalling, which has resulted in the internal checksum error? And it still doesn't make sense that it goes away as soon as it stalls the first time after starting.

In fact, I tested it last night by starting the Jeep - verified I had check engine light - checked the code, it was 0601 - covered the throttle body to cut off air and stall the Jeep. It stalled. I restarted it and the check engine light was out.

I'm glad I didn't go and replace the IAC. I took resistance readings on it and got 53 ohms from outside pin to outside pin. I also got 53 ohms between the two inside pins. Any other combination resulted in OL. However, the signals coming to the IAC didn't make sense. The pin resistance combination didn't match. I got 23K ohms from pin 1 to pin 3, and same from pin 2 to pin 4. Going outside to outside, like on the IAC, resulted in OL.

Without any reference on correct readings, I don't know how else to verify the IAC is working other than visually. It drives out, but I could not get it to drive in.

I'll start looking for a PCM. I just want to eliminate other (cheaper) possibilities first.

Thanks for the reply. Jason.

I checked all the wires I could get to. There's a bunch in the loom that are wrapped pretty good, but anything accessible I checked. Everything going into the PCM looks good.

I messed with the Jeep some more last night. When I unconnect the vacuum line that I fixed and leave it unconnected then there's no check engine light when I start the Jeep. It doesn't stall. It just seems to run fine. So, the PCM still appears to be working. I just don't understand it.

Thanks for your previous answers, it s was helpful for me,

The Engine now start normaly but when I'm driving, sometimes the engine stop abrutly itself. I can start again the engine normaly and continue to drive.

Help me please, I'm worry about this, I want to sell the car

It's the vacuum line that comes down from the throttle body and T's into the bottom line from the purge solenoid.

The purge solenoid has 2 vacuum lines and an electrical connector.

When I leave all vacuum lines plugged in, but disconnect electrical connector, Jeep still stalls.

When I reconnect electrical connector but disconnect bottom vacuum line, letting more air get to throttle body, then the Jeep runs fine with no codes. No engine light. No stumbles. Just runs.

So for some reason, it runs fine with a vacuum leak, with air getting sucked into throttle body, but will stall and get PCM code if I fix vacuum leak.

Just doesn't make sense.

Purge Solenoid. Part of the emissions system. The vacuum line that had the leak I fixed T'd into the bottom one on this solenoid.

This is the section of hose I replaced. When I found the leak, the hose piece that was there was split lengthwise and wrapped around the two connections. Now that I've fixed the vacuum leak, the Jeep gets great gas mileage but I have this stalling problem.

This is where the line goes into the throttle body. When I disconnect it, the Jeep runs fine, idles a tad high, sucks a LOT of air in through here, but runs fine with no codes.

Picture of Purge Solenoid in foreground and line going to T with section of hose I replaced.

Ok. I hadn't thought of that.

Do you have a recommendation on how to check those?

As soon as I disconnect anything to check, it will lose vacuum. I don't have any kind of vacuum tester.

I didn't realize there were check valves in the system.

Now that I think about it, when the Jeep stalls out, or I shut it off, there's a hissing sound - like it's losing its vacuum - for about 2 to 3 seconds. I can't identify where it's drawing in the air, but it sounds like it's breaking vacuum through the air intake. I thought that might be normal.

Hmmm. Ok. I'll see if I can figure out how to test those check valves and the solenoid.

I have problem with my jeep liberty, the engine refuse to start for 3 or 4 days, sometimes it's start and after 5 - 10 min, it's stop.

I check with the chek engine and the error code is P1282, it show problem in Fuel Pompe relay Control Circuit, I want to know where this part is located? And is there difference between fuel pompe relais and Fuel Pompe relay Control Circuit

thanks

Sweet. I'll do that. Give me a couple days to get the tester and get that done. I'll let you know what I find out as soon as I do.

Thanks again. Jason