Acceleration problems

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  #1  
Old 03-04-03, 10:14 AM
Ednerd
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Acceleration problems

I have a 1992 Dodge Caravan (3.0 liter V-6 w/ 3-speed) that has problems with acceleration. It first started in the cruise control, where it would drop off the set speed and surge back up. Then I lost the cruise, and it has started doing it when I cruise by foot on pedal, usually at 45mph and above.

I did have to change out the brake vacuum booster, so I might have screwed up a vacuum line somewhere. I also had the engine top partially torn down to replace the rear valve cover gasket, so I might have broken a vacuum line or electrical connector.

It’s usually okay when the car is cold, but starts jerking and losing speed when it warms up. I have to kick in hard acceleration to get up to speed, and it will let me “glide” there for a bit, then drop out as if I took my foot off the gas. Usually, after a while of highway driving, it will go back to normal, then it may drop out again. I thought I heard some backfire, which made me think of something in a vacuum or electronic ignition timing or advance module.

No vacuum hoses or electrical connectors are visibly broken or disconnected. Any advice on where else to start looking?

Ed
 
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  #2  
Old 03-04-03, 10:41 AM
Joe_F
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Start with the links and posts in my signature file below.
 
  #3  
Old 03-05-03, 10:10 AM
Ednerd
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>>Start with the links and posts in my signature file below.

>>Autolibrary Free Service manual info

This took me to a site selling Chilton Auto Repair manuals. I already have a Chilton and a Haynes specific to my vehicle.

>>-Check my post "The Basics" FIRST which can be found at:
>>The Basics by Joe_F

I did that before I made the first post. I did forget to mention the engine has 180k miles. I thought perhaps the electric fuel pump in a tank low on gas might be the problem, especially since it didn't act up one the way home yesterday (35 miles, most of it at 55-65 mph). Then it did it again on the way out to work this morning.

When it acts up, I have minimal acceleration, unless I put my foot in it and kick it into passing gear. Then it acts normal - until I hit my cruising speed and ease up on the accelerator to cruise. After a second or a minute, it drops out. Sometimes, if I just hold my foot steady, it surges back and forth, from no acceleration to full until it hits speed, then back down to nil.

Any suggestions are welcome.

Ed
 
  #4  
Old 03-05-03, 04:20 PM
Joe_F
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I'll go back to my first post "See the links and posts in my signature file".

Start with the basics. You have provided us very little to go on.

1) What is the regulated Fuel pressure as tested with a fuel pressure gauge? Rent one from Autozone.

2) What trouble codes if any are stored in the computer? Have AZ pull them and tell us what you find.

3) After the "rebuild" did the problem occur before or after that time?

4) What other repairs have been made to the vehicle?

etc, etc, etc, etc, etc, etc, etc..............

We need to know the basics and the answers for the same. Otherwise, you will be throwing more money at the problem than the van could ever be worth.

Autolibrary tends to be a bit better than Haynes or even the average Chilton. If neither help, you should consider an Alldata.com subscription or a OEM Chrysler manual.
 
  #5  
Old 03-06-03, 06:21 AM
Ednerd
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Once again, the first link in your signature doesn't work on my computer. It doesn't take me to Autolibrary with free information; it takes me to a cyperpartspro.com that wants to sell manuals, which I already have.

The problem was there before I changed the vacuum booster. It has steadily gotten worse. It was also there before I changed the rear valve cover gasket. No other repairs (other than front brake pads - but they're not connected, are they?? 8>p )

I didn't check fuel pressure because I didn't know if I should be looking for a fuel problem, a vacuum problem, an electrical problem, or a solenoid that is known to stick and cause these kinds of problems.

On checking the fuel pressure: the car runs fine first thing in the morning, then acts up after driving for a bit. By then, I'm running down the highway towards work. If I just check the pressure sitting in my driveway when it's running fine, is that going to be a valid piece of information?

And if the problem "resets" itself when the key is turned off, and reoccurs only after the car has been driven a bit (vice immediately after starting), am I looking at fuel pressure from the pump, or a pressure control device? If I can "kick it", and it drops into passing gear (as I mentioned) with full acceleration, I have done something that brings the car out of problem mode temporarily (apparently, anyway - it may just be fooling me because I feel acceleration) - but I don't know what this type of acceleration "over-rides", so I don't know what to look at (fuel, electric, vacuum, computer module, solenoid, new car, etc.).

Ed
 
  #6  
Old 03-06-03, 09:37 AM
Joe_F
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Something is wrong with your computer's setup. The site is free and DOES offer information. I use it all the time, as do other posters here.

Also, the links I provided DO give you a starting point. You must answer the questions I have presented in my "The Basics" or you won't solve a thing.
 
  #7  
Old 03-08-03, 11:27 AM
NLD1220
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Autolibrary link

Just to let you know that the Autolibrary link does not work for me either. I have used it in the past but now it redirects to a site selling manuals.
 
  #8  
Old 03-08-03, 04:48 PM
waaland
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The site didn't wor for me today either.

This also sounds very similar to what I have been experiencing with my Camaro.
 
  #9  
Old 03-09-03, 07:08 AM
Joe_F
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They may have disbanded the site----it was free after all .

All the more reason to hit the library for a service manual (still free), or $25 bucks for an Alldata.com subscription for a year. Can also find the OEM manuals used on the Internet which is the best resource.
 
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