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Caravan runs rough or quits, Intermittent!

9K views 7 replies 4 participants last post by  98Dodge 
#1 ·
Hi folks... I am a "newbie" here, so if this has been covered, I would appreciate it if you could at least point me to the thread.

First of all, It is not really a Caravan, but a 97 T/C LXI with a 3.8L. (I hope this is OK!)

It is a daily driver for my wife. It has 135 K miles on it, and most often runs perfect, regularly gets 24 MPG, and we are very happy with it.

That being said, within the last month it has developed a problem where it will idle rough, and sometimes quit running when she stops at an intersection. It had not set any codes. I took it into an established auto / electronics shop in Fargo, and they replaced the air idle motor and cleaned the throttle body. They also replaced the plugs, wires, and PCV valve. They tested the fuel pressure, and had 50 PSI at the rail.

A few days later, the same symptoms appeared again. I called and they said they thought my fuel pump may have an intermittent problem. I replaced the FP myself, and the filter at the same time. The problem was gone for a couple of days.

Earlier this past week it started it again! We have discovered that the problem only appears when it is very cold outside (like below 10 degrees) and seems to disappear as the weather warms up. I took it back into the shop today, and the tech drove it for a half hour, and it ran perfect. He drove it off and on all day, and of course it would not act up. The temps were in the high 30's today. They hooked up the computer again, and of course no codes. No surprise to me, as the check engine light has never come on.

I left a little disgusted, but I understand that they can't fix it when they have no idea what is wrong. I don't want to throw a bunch of high priced parts at it! I am going to bring it back to them during the next cold spell, if the problem persists. They are more than willing to keep working with me. They did tell me that they checked all of the electrical connections under the hood, and they did find that one of the battery cables was "a little loose" but they couldn't imagine that this would cause the problem.

Does anyone have any suggestions?

I am enjoying the forum. My ride is a 98.5 Dodge 2500 4X4 Laramie with a 24V Cummins. I was actually researching an issue with that when I found this forum!

Thanks!

Mark
 
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#2 · (Edited)
Did the genuis at the shop who checked your van, take the time to check the oxygen sensor(s)? Check them before you go and throw anymore money away. A bad fuel pump will not cause what you decribed, it will just stop working and leave you stranded.

A plugged fuel filter, bad fuel pressure regulator, bad MAP sensor and bad oxygen sensors can cause these running problems.

I believe the 3.8 has 2 and upflow and a downflow. get them to do a voltage switch test on both sensors, if the voltage doesn't change as the sensor heats up its gone bad. Also all modern oxygen sensors have a heating element to heat the sensor up quickly, sometimes this heating element goes bad.

Oxygen sensors won't always set a trouble code when they go bad and they cause all kinds of running problems such as what you decribed.

Regards
Chet.
 
#3 · (Edited)
running problems

Some vehicles as they get older have problems with the winter formulations of gas they use . i have a 96 3.0 that has this problem . What I have found is to dump a bottle of isopropol gas line antifreeze into every tank and this has gotten rid of the problems I was having . Where you are getting your gas may also have a higher water content and this could cause your problem , anyway it a cheap try , run a couple of tanks with the antifreeze in your gas and see what happens . Make sure it is of the isopropol variety not methanol . Also you might want to try getting your gas from a different supplier for a few weeks.
 
#4 ·
Thanks for the replys.

FYI... I didn't have to buy the fuel pump. I had an extra here that I knew was a good pump. I would not have spent $175 for a fuel pump on a guess. I did buy a new filter, but that was needed anyway.

I will relay the suggestions about the MAP and Oxygen sensors to the mechanics involved. They are nice folks down there, and are not charging me for the "follow up" trips. The only expense has been the initial diagnosis, (or lack thereof) and for the work I approved of the first visit. The plugs and wires were due as they were original (130,000 miles) The plugs were toast! I should have done that myself, but I didn't miss trying to get at the back 3 plugs.

As far as the fuel blend, we have tried "Heat" (iso) in the tank, and that did nothing. Good idea though... It was my first hope!

I will watch this thread for additional thoughts, and will post a reply when I get it figured out! I owe the group that!
 
#5 ·
I had a problem with stalling before the engine came up to operating temperature. I did a lot of parts swapping and cleaning, and nothing worked. Then, after a while, my power brake booster failed. As soon as I replaced the booster, my stalling problem went away. If you hear a hissing when you step on the brake, in addition to the rough idle/stalling, I'd look at the vacuum lines and the booster.

Rick
 
#6 ·
As promised, here is the latest update on my van.

It has been very warm for this time of year here in ND, so the van has not acted up for weeks. Then, out of the blue, on Monday my wife called me (very concerned) because the "Service Engine Soon" light came on! I said... "It's about time!" and after I explained to her why this was a good thing, I had her take it to the service center that has been working on it. As luck would have it, she was only a few blocks away.

They put the code reader on it, and it had set a faulty EGR valve code. I took it in on Tuesday, and they replaced the EGR valve, and so far, so good. I am not going to get my hopes up just yet, as the problem had previously only presented itself in colder weather, an again, it has been warm here, like in the 20's and 30's!

The service center sold me the EGR valve for 48 bucks. I had done my homework, and the best deal I could find in town was average $80. I had put some pressure on them as it was my opinion that they had put the idle motor in for no reason, as it had not solved the problem.

I will post here again if my stalling problem comes back, but I did want to update you all as I promised I would!

Thanks for your advice!
 
#8 ·
gas28man said:
But a faulty EGR also would have dropped your gas mileage by about 20 percent. Did you notice anything like that?


Rick
Not right away Rick, but I did take a 400 mile trip the weekend previous to the EGR valve failing and I was down to 20 MPG on the highway. This would be a 17% drop from my average 24 Hwy! :tup: Very good!

I'll let you know if it acts up again.
 
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