00 Poor Acceleration

[bigb6456]

Vehicle: 2000 Jimmy 4x4
Millage: 89,000
Engine: 4.3
Trans: Auto

I am experiencing acceleration problems, on a cold start the truck will bog out while the RPM's will race. This also happens hot or cold from a stop, from the stop the RPM's race but the truck has no acceleration. Once moving this is not a problem but the acceleration is still week and it takes some effort to get to passing speed.

Then sometimes I have no problems at all.

Along with this the a/c & heater have issues also. I know that the climate control (analog) has a vacuum leak coming from the selector dial (if you turn it a defrost it just continues to blow through the vents). If I turn off the a/c the acceleration is slightly better but even off the a/c will still blow very lightly.

I am pretty sure this is not a catalytic converter problem, I have experienced them before and this is not the same.

I still get decent millage around 16 so I am pretty sure this IS NOT A FUEL PROBLEM.

I had one person tell me it is the vacuum leak that is causing this problem.

And yes my gas gauge does not work just like ever Jimmy out there.

Please DO NOT reply asking what codes it is throwing because I don't have a scanner nor do I have access to one.

Thanx.

 

[bigb6456]

Anyone have any idea?

 

[Molson02536]

Vehicle: 2000 Jimmy 4x4
Millage: 89,000
Engine: 4.3
Trans: Auto

I am experiencing acceleration problems, on a cold start the truck will bog out while the RPM's will race. This also happens hot or cold from a stop, from the stop the RPM's race but the truck has no acceleration. Once moving this is not a problem but the acceleration is still week and it takes some effort to get to passing speed.

Then sometimes I have no problems at all.

Along with this the a/c & heater have issues also. I know that the climate control (analog) has a vacuum leak coming from the selector dial (if you turn it a defrost it just continues to blow through the vents). If I turn off the a/c the acceleration is slightly better but even off the a/c will still blow very lightly.

I am pretty sure this is not a catalytic converter problem, I have experienced them before and this is not the same.

I still get decent millage around 16 so I am pretty sure this IS NOT A FUEL PROBLEM.

I had one person tell me it is the vacuum leak that is causing this problem.

And yes my gas gauge does not work just like ever Jimmy out there.

Please DO NOT reply asking what codes it is throwing because I don't have a scanner nor do I have access to one.

Thanx.

Check your vacuum lines from the drivers side of the engine to the vacuum canister to the drivers side fender. The vacuum lines will run across the brake booster, follow the lines and replace any that are cracked and damaged. There common to go bad from the heat of the engine or from transmission fluid from a bad 4wd vacuum switch on top of the transfer case.

You may also want to clean out your throttle body, and pay attention to cleaning out your IAC. Keep us posted and you should be getting better gas mileage then that. 18 to 19 MPG on the highway with average speed of 72 mph. I'm getting almost 23 with my 96 Jimmy turned.

 

[bigb6456]

Sorry for the long period of time to get back to this.

I did replace the TC switch & I cleaned out the throttle body.

I still have the acceleration problem. When I start the car and press the accelerator any thing more then a soft acceleration the car bogs out & I sear I hear a quite pop/ping. I am not sure what is going on but I have to get this fixed.

Also I still have not solved the issue with the heat only coming from the dash & not switching to the defrost or floor when selected.


Any help here would be appreciated, it is getting cold her in Detroit & driving with cold feet while unable to see out of the windshield makes for a even more dangerous commute then usual.

 

[ashorn]

have you tried cleaning your MAF sensor? I had the same problem with mine and I cleaned the MAF the Intake really well and it made a huuuge difference. I've been told by a couple service techs that they have been replacing and cleaning MAF's on these trucks for the last couple of months and that has fixed any accel. problems people have been having. Hope this helps u!

 

[bigb6456]

I took a look at it & it didn't look dirty at all, I hope I don't have to replace it. I will double check it again.

 

[ashorn]

I had thought the same thing too when I first looked at it, the wires are supposed to be very clean silvery looking. They are a little over 200$ new so I can see why u wouldnt wanna get a new one. If you cant get MAF cleaner most brake cleaner will work too. Just be sure to clean the entire wire and give it a little while to dry before you hook everything back up, I'd be surprised if this didnt solve it because what you are describing sounds just like how my truck was. Good Luck!

 

[Molson02536]

Sorry for the long period of time to get back to this.

I did replace the TC switch & I cleaned out the throttle body.

I still have the acceleration problem. When I start the car and press the accelerator any thing more then a soft acceleration the car bogs out & I sear I hear a quite pop/ping. I am not sure what is going on but I have to get this fixed.

Also I still have not solved the issue with the heat only coming from the dash & not switching to the defrost or floor when selected.


Any help here would be appreciated, it is getting cold her in Detroit & driving with cold feet while unable to see out of the windshield makes for a even more dangerous commute then usual.

Did you try replacing your fuel filter and checking your fuel pressure at the shredder valve for your acceleration issue?? Another possibility may be your EGR valve. Take it off and cleaned it out. When you reinstall it, I used an "Anti-Clog" type gasket to keep carbon from interfering with EGR valve operation. The only other thing i can think of would be a bad catalytic converter that has gone bad and will need to be replaced.

As for the heater issue, remove the switch on the dash and inspect the vacuum connections and see if it's cracked and not making a good seal. The switch it self is a valve to all the vacuum lines that control the flaps for the defrost, vent and heater fool settings.

Keep us posted and good luck.