Hesitation

I can make two suggestions. First, there could still be a diagnostic fault code stored in the Engine Computer. Only problems that could have an adverse effect on tail pipe emissions MUST turn the Check Engine light on. Other codes might not. Second, the Chrysler dealer has a mini scanner they can leave in the car while you drive it. You press the "record" button when the problem occurs, then they can play it back later and watch the sensor readings to look for clues. Because the data travels through the scanner's memory, the recording actually starts a few seconds before the button was pressed.

If you had to guess what would be your opnion be as to what might be the problem ?. So if I run the computer on a scaner I might see a fault code even without a check engine light on ? The crazy thing is that I never had the problem when I drive it. I take very good care of the car & everything under the hood looks fine hoses connections no leaks of any sort. Thanks for your help

I also found a recall I posted it below. Tell me what you think. Regards.
Recall Date:
NOV 09, 2006
Model Affected:
2005 Chrysler Pacifica
Summary:
ON CERTAIN PASSENGER VEHICLES, THE FUEL PUMP MODULE AND THE POWER TRAIN CONTROL MODULE (PCM) SOFTWARE MAY ALLOW THE ENGINE TO STALL UNDER CERTAIN OPERATING CONDITIONS.
Consequences:
THIS COULD CAUSE A CRASH TO OCCUR WITHOUT PRIOR WARNING.
Remedy:
DEALERS WILL REPROGRAM THE POWER TRAIN CONTROL MODULE. THE FUEL PUMP MODULE WILL ALSO BE REPLACED ON VEHICLES BUILT FROM AUGUST 1, 2004 THROUGH SEPTEMBER 30, 2004. THE RECALL BEGAN ON NOVEMBER 21, 2006. OWNERS MAY CONTACT DAIMLERCHRYSLER AT 1-800-853-1403.
Potential Units Affected:
127928
Notes:
DAIMLERCHRYSLER CORPORATION


Read more: http://www.motortrend.com/cars/2005/chrysler/pacifica/recalls/index.html#ixzz1FxuUIg1L

The only thing I'm sure of is any guess stands a 100 percent chance I'd be wrong. Anything you could see under the hood, such as loose vacuum hoses would typically cause a problem all the time. Intermittent problems, especially those that don't act up very often, are usually electrical in nature. Unlike GM fuel pumps, Chrysler pumps rarely quit while you're driving, however a poor connection in the pump's electrical connector would cause the pump to stop momentarily. A dropout of the signal from the crankshaft position sensor will cause the Engine Computer to turn off the automatic shutdown (ASD) relay. That will remove power from the ignition coils and injectors. The circuitry in the Engine Computer that drives the injectors and coils is high-current circuitry and as such is susceptible to failure. Even a little corrosion on one of the computer's electrical connector pins could cause a problem. Those are just a few examples of the types of things that might be found. As for the recall, it looks like your vehicle is too new to be included. You would have gotten a notice in the mail too.

I purchase it used 2 years ago I'll try the 800# to see if my Pacifica is part of the recall. Thanks for your insight you have been very helpful. Regards Phil Will run my computer scanner tommrrow. I'll shoot you an e-mail if I find any problems.

Thinking about a bad Crank position sensor on my Pacifica. My neighbor had a problem with his Chrysler regarding this part. Any input would be helpful. Hey Did I talk to regarding a 1988 Caravan about a week ago are you the same guy ?

Could be me. I have an '88 Grand Caravan, an '89 Grand Voyager, and a '95 Grand Caravan. The most common symptom of a failing crankshaft position sensor is it will stop generating a signal when it gets warm. With the loss of that signal, (or the signal from the camshaft position sensor), the Engine Computer thinks the engine stopped rotating so it turns off the automatic shutdown (ASD) relay which turns off the fuel pump, ignition coil(s), injectors, alternator field, and oxygen sensor heaters. After that sensor cools down, typically in 30 to 60 minutes, it will work again for a little while. It's less common but the sensor could suddenly fail completely. While momentary signal dropouts are a possibility too, loose connector pins would be a more likely cause of a brief stall or sputter that clears up almost right away.

Car has been fine for about a week (used scan tool as per your sugestion no codes & ran a scan & watched all vitals every thing was good ) she warmed up car for about 10min this AM drove approx 1/2 mile to drop off kids at school when she stoped it hesitated again then was ok. I drove it nothing , she then drove around town & the check engine light came on code p0132 O2 sensor bank 1 high voltage fault heated sensor. I reset it drove it all ok ?? Any ideas ??

Ran into something similar a week or two ago. The oxygen sensor only develops around 0.2 to 0.8 volts. It has to be at least 600 degrees though to work. To get it to that temperature faster they have heaters built in that are run on 12 volts. If the wire harness gets damaged that 12 volt wire can touch the sensor's signal wire. The fault code will be set when the Engine Computer sees that 12 volts on the signal wire. For the last person, the plastic clip was broken which allowed the harness to fall onto the hot exhaust manifold. The symptom was different because a wire was grounded instead of two wires touching. I suppose the sensor could be the cause of the fault code too but that wouldn't be very common. You might also check for corrosion between two pins in the electrical connector.

Ok I did a visual yesterday on the connectors but did not seperate them to look inside but would the condition you are talking about give me the hesitation that I have been getting. As far as tuning up the car what else has to be done except changing the plugs & keeping all the fluids changed & filter replaced. I feel like I am chasing down a ghost at this point. Again Thanks for your time much appreciated.

OK more info I warmed up car 5min this AM drove car approx 2 miles to coffee shop pulled into parking lot car stumbled caught itself then it surged 2 times. Then it was fine engine light came on same code P0132 checked connectors very clean no corosion ( very nice connectors buy the way ). Thanks thats all I got once again Thanks for your Patience any other suggestions will be greatly appreciated as always. Regards Phil

I really hate just throwing parts at a problem but sometimes that's what we resort to with intermittent problems. You might try replacing the front oxygen sensor. Normally the Engine Computer can only modify fuel metering by plus or minus 10 percent so it shouldn't be so noticeable when it makes an incorrect calculation but if it is reducing the amount of fuel for a long period of time I guess I could see where that might cause the symptoms you described.

Will do I will change the upstream 02 sensor it's a Bosch 15122 I can get for $26.60 that's no to bad. Thanks again. As far a tuning up the car what do you suggest I did the pulgs & all filters except the fuel filter. Thanks Again

Don't waste your time with the fuel filter on a Chrysler product except on diesel trucks. There isn't much else to do as far as a tune-up.

Hey Cardiodoc So the check engine light went out & the car has been running great took a 50 mile trip no issuess around town all good. Today wife went to store on the way back the check engine light came on. Car sat in drive way approx 15 min I went out side started it & the idel is teribble it drops then catches it self it dose not stall just up & down but if I rev it over 1500rpm it's fine. If I drive it a low speed it surges & when over 1500 2000 rpm it's OK. Any ideas dod not do a scan my neighbor borrowed the tool. As always thanks again. Regards Phil

See if you can get a code by cycling the ignition switch from "off" to "run" three times within five seconds, then watch for them to be displayed in the odometer display.

Very cool PO132 that was the only code & then it said done & went back the number of miles on the car ??
Some one suggested that since I changed the plugs one might be defective ? Spark plug wires ?

P0132 – Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 1).

Just had one with the same code. He found a broken ground wire for one of the oxygen sensors. When checked with a scanner to view live sensor data, he found 4 volts. The sensor can only develop between 0.2 and 0.8 volts on its own. The other things to look for are a wiring harness that fell down onto hot exhaust parts and two wires melted together, and possibly the heater circuit inside the sensor is shorted to the sensor element.

And this condition would give me the poor idle I described ??

This is the upstream sensor correct ?? Before Cat ??

Went outside to check for any wire problems did not find any ?? Talk to you tommrrow have a good night & thanks again. Regards Phil

The Engine Computer adjusts fuel metering plus or minus up to 10 percent based on what it sees from the front O2 sensors. Adding more fuel shouldn't cause an increase in engine speed unless there is also extra air to go with it. That could be coming from a vacuum leak. The clue that a defective O2 sensor is the CAUSE of the problem vs. it's just reporting the RESULTS of the problem is whether it occurs right after startup, although even that can be hard to tell on newer cars. O2 sensors do not work until they reach 600 degrees. Regardless of what is wrong with the sensor or its circuitry, the computer won't modify fuel metering, engine speed, or anything else based on that sensor until it reaches 600 degrees. That may never happen during prolonged periods of idle so there is a heater inside the sensor to get it to that temperature sooner.

If the engine speed surges right after start-up, the O2 sensor is most likely not the problem. If the surging starts a few minutes after starting the engine, the sensor might be suspect. By using a scanner to view live sensor data, you can see when the O2 sensors start working, (the system will go into "closed loop"), and you can read whether the sensors are switching properly between "rich" and "lean" a couple of times per second, or if one is staying at too high a voltage.

Came home today started car still running very poorly up & down idle. Unplugged the 02 sensor & it ran worse looked around can not find anything wrong. I reved the engine under the hood & it revs fine then I noticed the top radiator hose was collapsing as I reved the engine then it would return back to normal car is not over heating ????

The next step would be to connect a scanner to read live sensor data and hopefully find a clue. There will be some diagnostic fault codes from unplugging the O2 sensor. You'll have to just disregard any that are related to that.

One thing to look at is "idle steps". The Engine Computer will command the idle speed motor to one of 256 positions to control idle speed. You will typically find it at around step 32 when everything is working properly. If you find it going up and down a lot, say from 15 to 45, and engine speed isn't changing, suspect a defective automatic idle speed motor, or a plugged air passage, (very uncommon). If the step is staying low, typically from 0 to 20, the computer sees that idle speed is too high and is trying to bring it down, without success. Suspect a vacuum leak. Try pinching various vacuum hoses or unplug them and cap the ports. If you find one that steadies the idle speed, follow that hose until it branches into multiple lines and try that on each one.

Will do any idea about the top radiator hose collapsing when I rev the engine ?

Sounds like the water pump is pulling very nicely against the closed thermostat. Lower hoses actually have a wire spring inside to prevent them from doing that.

Ok so I got real busy at work & no time to work on car I dropped off to my mechanic he was not there today but on of his guys said they need another day he threw out it might be a head gasket but was not sure !!!??? The head mechanic yesterday said when I dropped it off was thinking intake leak. I do not see any antifreeze on the dip stick no sweet smell out the exhaust & no loss of collant does this sound right. Regards Phil

Very possibly. Everything so far sounds like a vacuum leak. I don't think there's coolant running through the intake, but even if there is, that doesn't mean it has to be leaking out where you can see it or into a cylinder. The leak could be a gasket that is cracked allowing air to enter from below the intake.

If your mechanic has a smoke machine that will help in identifying a leak. White smoke is injected into a vacuum hose at 2 psi, then you watch to see where it comes out. If the bottom of an intake gasket is leaking, the smoke will come out through the oil fill cap or the dipstick tube.

Thanks I will keep this info in my head when I talk to him. What would be the sign of a head gasket leak in the 3.8l motor ??

Not very common on this engine but a leaking head gasket will usually cause white smoke from the exhaust when coolant is burned. The engine will often overheat from the combustion gases forming air pockets in the cooling system that cause the thermostat to close.

Hey really starting to loose my mind with what could possibly be wrong with this car. I did alot of reading regarding bad head gaskets & what you are saying is correct but when I spoke to my mechanic today he said he needs to do more tests he did a smoke test & he said it was normal he removed the T-stat and he said the top hose was still collapsing. He said he was going to do a leak down test next. I questioned him regarding the oil being normal no coolant loss & no white smoke out the tail pipe . He said that this could be the start of the head gasket leaking hence the poor runing & the 02 sensor trouble code & that it is becoming a problem with the Pacifica's mine would be the 3rd one he has seen the head gasket go bad. Any comment would be appreciated. Thanks

I'm sensing some confusion on these gaskets because there are two totally different problems with the same terminology. The focus has shifted to leaking head gaskets. The most common symptom is white smoke from the tail pipe. That is from antifreeze being burned. Usually the combustion gases push into the cooling system, then the overflow reservoir and gives the appearance of overheating due to the bubbles. While an air pocket CAN cause the thermostat to close which leads to overheating, the clue most people miss is there is no steam associated with those bubbles in the reservoir. The coolant might even be cold, so the bubbles are from the leaking head gasket, not actual overheating.

There is a test that identifies combustion gases in the cooling system. Air is drawn from the radiator through a glass cylinder with two chambers partially filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.

Originally we were discussing a potential vacuum leak, and one of the possibilities is a leaking intake manifold gasket. Very few engines have coolant flowing through the intake manifold but some cylinder heads have passages that are blocked by the manifold. Those ports are only there as a result of the casting process, but they have to be blocked and the intake manifold and gaskets do that. That's why it is possible for coolant to leak from those gaskets. GM wrote the book on that problem with their trucks.

A vacuum leak at an intake manifold gasket is much more common than a coolant leak. The 3.3L / 3.8L engines have very little trouble with leaking head gaskets OR intake manifold gaskets, but when we're looking for something elusive that's where we look. One way to find a vacuum leak is by injecting a white, non-toxic smoke from a special machine that produces that smoke. These came about with the advent of fuel supply leak detection systems that are built into every vehicle since 1996. Tiny little pinhole leaks can be detected by the system, but they would be impossible to find without the smoke machine. The machine also works very nicely for finding vacuum leaks. A rare but possible place for that leak to occur is the bottom of the intake manifold gasket where it can't be seen. If it was on top, it could be found by spraying water on it while the engine is still cold. That wouldn't work if the leak was on the bottom where it can't be seen. It still wouldn't be able to be seen by injecting smoke, but the list of possible places to look would be narrowed down a whole bunch if it came out the oil cap or dipstick tube. When the smoke is pushed into a vacuum hose, it goes into the intake manifold, and there is no place for it to go accept through a leak or out the tail pipe if any cylinder has both valves partially open. If that happens, the tail pipe can be blocked to help a vacuum leak show up.

It may have seemed that I did not understand the difference between the Head & Manifold because I was all over the map trying to describe the issues with the car sorry about the confusion. Ok the mechanic called he had good news no Head gasket or manifold gasket leaks. He still has no idea about the colapsing top radiator hose but he said he will replace the cap ( the gasket at the t-stat had a drip when cold so there may be air stuck in the system ) . He wants to clean the fuel injection system & reboot the computer for some idle program. So once again any input would be great. Hope this thread helps other people. Thanks Phil

This is additional info to the April 01 post My mechanic did not do a smoke test for the intake manifold he said car is ruunning fine new O2 sensor installed & new spark plug wires as per my request. Top hose & bottom hose collapse when car is cold ( engine RPM is increased ) but ok when car is warm car never over heats he thinks there is an obstruction in the cooling system. Any input would be appreciated. Thanks Phil

Yes, there's an obstruction. It's called the thermostat and it's doing what it's supposed to do. I'm not convinced there is a problem unless there is some other objectionable symptom. You might want to check to see if the hose is mushy and should be replaced, or try a different radiator cap. There is a valve in it that lets coolant flow back in from the reservoir to prevent a vacuum when the coolant cools down. That should prevent the hose from collapsing.

Ok I try the cap . The top & bottom hoses are new & so is the T-stat. I have a Ford also with a 3.8l v6 & I never see the hoses collapse so to me in the Chrysler this did not seem like a normal condition. This happened about a year ago while on a long trip got a replacement cap at an auto parts store replaced it and all was fine then it started again. Is the OEM cap some sort of special cap as to an over the counter cap I would get at a local parts store. I know the t-stat was.

Nope. All radiator caps must have that vacuum valve to let coolant back in when it cools down.

Hey talked to the head mechanic today he drove car all over town & in heavy traffic on Friday with no issues temp was perfect on Sat morning cold start when the RPM is increased the both hoses flatten out (top one pretty bad ) but return to normal at idle. Ok I told him I was talking to a chrysler mechanic & he has spoken to a few chrysler mechanics who tell him this is not normal & a few of them said it might be a water pump issue or a lazy T-stat. Please note all hoses are new t-stat is new & they flushed the cooling system a second time & the rad cap is new. Any input would be appreciated. He said that if car was new & you checked for this condition you would not see this. Thanks again Phil

I agree it's not normal but unless you saw it while you were under the hood, I don't think you would even be aware of it. My first reaction is there is still an air pocket in there that allows the pump to push coolant against it and compress it. That would explain how the pump can move enough coolant to collapse the hose without moving other coolant from the engine back into the hose. I assume this doesn't happen if the cap is removed when the engine is still cool.

Eventually any air should work its way out if that was related to the problem.

I wonder if the thermostat is not fully opening. Also, any chance there is a kink in the hose going to the overflow reservoir? It's odd that the upper hose would collapse before coolant would be drawn back in from the reservoir.

No kinks he even made sure those lines going back to the overflow were clear & he even drove around with the heater on & that works fine also. I will pass along this info. Thank You one again.