Hi every one, I have a 2000 Astro van with 160,000 miles on it. In the past year I have gotten a problem that mostly happens at high way speeds. When I get on the high way and up to speed and set the cruse control and the van has to decelerate, I get what feels like a surging or stumble. It happes when I come down over an over pass or down a slight grade. when on flat road it is fine. And after maybe 30 or 40 miles it tends to get better. I have replaced the distrubitor cap and roter and it goes away for maybe a month and then returns. The plugs and wires are new. Now recently in the mornings it stumbles some until it warms up. Any one have any suggestions? I have been told that it may be the bushing on the distributor. Any help would make my day. Thanks, Steve
Surging At Highway Speed
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I did have a "come to my house" mechanic try and check it and he did not find any unusual codes. He did get one for a slipping trans. Transmision shop said that was not the problem of the surging. I have had the distributor off and changed a couple times. Did not see any moisture, but did see some whiteness inside the cap. What has me stumped is that when i change the cap and rotor it runs great for about a month. Steve
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Ok, here's the picture I was talking about:
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I know this is a HEI cap with the coil that mounts in the cap, but the principle works same way as the remote HEI caps. The hole in the center of the cap is where the button goes. The plastic directly around the hole is distorted. It is shorter than it should be and also there is material missing from the inside of the hole. What that does is it pulls the button upward away from the rotor. You can bend the tab on the rotor upwards and it will work but eventually the cap will crack and fail.
I know this is a HEI cap with the coil that mounts in the cap, but the principle works same way as the remote HEI caps. The hole in the center of the cap is where the button goes. The plastic directly around the hole is distorted. It is shorter than it should be and also there is material missing from the inside of the hole. What that does is it pulls the button upward away from the rotor. You can bend the tab on the rotor upwards and it will work but eventually the cap will crack and fail.
I am also having ignition problems like above. It manifests a little differently: no highway surging, but sometimes rough starting, definitely worse MPG, and less overall power. I have a 2001 Astro with about 52,000 miles.
In the last year I've changed out the cap & rotor twice. Both of the caps had brass electrodes. I replaced the cap/rotor at the end of November 2008. At that time I removed the screens in the bottom of the distributor, per the instructions that came with the new cap. About 1 month later, I opened it up again to find more of a greenish corrosion on the cap electrodes. The rotor tip was fairly clean, but I carefully sanded it by hand to remove any paint on it (not enough to remove metal). I also sanded the cylindrical electrodes to clean them off. I also vacuumed out the distributor, cap, and rotor to remove any dust, etc. I also at this time replaced the PVC valve, also suggested by the information that came with the new rotor.
The van ran well for a week or so, but it has steadily gotten worse in the three short weeks since. I've had the van since new. It used to turn in about 20mpg in town (I use a light foot), but now it's getting about 15mpg. All told, I'm on my 4th cap & rotor, including the original. The second replacement, done by a mechanic, was a cheapie with aluminum electrodes. I think the original had aluminum too. The original was in really poor shape. I have not opened it up since this last cleaning (it's too cold outside!). The check engine light is not on. Other than new cap/rotor, it has original plugs & wires (plugs looked good when I checked them last spring), and most everything else is original.
Could this constant failure of the cap/rotor be caused by a weak spark from the coil? Any other ideas?
I would really appreciate any help.
In the last year I've changed out the cap & rotor twice. Both of the caps had brass electrodes. I replaced the cap/rotor at the end of November 2008. At that time I removed the screens in the bottom of the distributor, per the instructions that came with the new cap. About 1 month later, I opened it up again to find more of a greenish corrosion on the cap electrodes. The rotor tip was fairly clean, but I carefully sanded it by hand to remove any paint on it (not enough to remove metal). I also sanded the cylindrical electrodes to clean them off. I also vacuumed out the distributor, cap, and rotor to remove any dust, etc. I also at this time replaced the PVC valve, also suggested by the information that came with the new rotor.
The van ran well for a week or so, but it has steadily gotten worse in the three short weeks since. I've had the van since new. It used to turn in about 20mpg in town (I use a light foot), but now it's getting about 15mpg. All told, I'm on my 4th cap & rotor, including the original. The second replacement, done by a mechanic, was a cheapie with aluminum electrodes. I think the original had aluminum too. The original was in really poor shape. I have not opened it up since this last cleaning (it's too cold outside!). The check engine light is not on. Other than new cap/rotor, it has original plugs & wires (plugs looked good when I checked them last spring), and most everything else is original.
Could this constant failure of the cap/rotor be caused by a weak spark from the coil? Any other ideas?
I would really appreciate any help.
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Hello jal,
how did you check the plugs, besides just looking at them. Honestly, I would change the plugs and wires. I know that GM keeps raising the amount of mileage between recommended tune-ups but that figure is also based on 20,000 miles per year. That would have put the first 'full' tune-up around 2006.
Now what I am about to say is my own opinion. I have reached this opinion by working on a lot of cars and talking with a lot of mechanics and techs in this field. That being said:
I believe that bad and/or weak spark plugs and/or spark plug wires can cause excessive corrosion buildup in the distributor cap. Electricity always looks for the easiest path to ground. Corrosion is formed in distributor caps when electricity interacts with the air in the gap between the rotor and the electrodes. The more electricity there is to interact with the air, the more corrosion. When the plugs or wires go bad (start to lose their continuity), I believe that this allows for more spark to interact with the air between the gaps.
Much like a water hose that has a pinhole leak. With water running thru the hose, the leak will be minor if there is no restrictions at the end. Now restrict the open end by 50% and more water is forced out of the leak becausing of the building pressure.
Like I said, that is just an opinion that I have adapted from doing a ton of tune-ups and observing differences in the systems over the years.
how did you check the plugs, besides just looking at them. Honestly, I would change the plugs and wires. I know that GM keeps raising the amount of mileage between recommended tune-ups but that figure is also based on 20,000 miles per year. That would have put the first 'full' tune-up around 2006.
Now what I am about to say is my own opinion. I have reached this opinion by working on a lot of cars and talking with a lot of mechanics and techs in this field. That being said:
I believe that bad and/or weak spark plugs and/or spark plug wires can cause excessive corrosion buildup in the distributor cap. Electricity always looks for the easiest path to ground. Corrosion is formed in distributor caps when electricity interacts with the air in the gap between the rotor and the electrodes. The more electricity there is to interact with the air, the more corrosion. When the plugs or wires go bad (start to lose their continuity), I believe that this allows for more spark to interact with the air between the gaps.
Much like a water hose that has a pinhole leak. With water running thru the hose, the leak will be minor if there is no restrictions at the end. Now restrict the open end by 50% and more water is forced out of the leak becausing of the building pressure.
Like I said, that is just an opinion that I have adapted from doing a ton of tune-ups and observing differences in the systems over the years.
Thanks! How, exactly, could I check the plugs and wires to see whether or not they need to be replaced? Same thing for the coil. The color looked good for all of them, and it was consistent. I'm cheap and I don't want to replace unless they need to be.
Is there a write up around here that would describe how to remove each of the six plugs? When I pulled them I could get all but one out.
Is there a write up around here that would describe how to remove each of the six plugs? When I pulled them I could get all but one out.
Front ones I think are easiest through wheel wells. On the one I could not get out, I don't think my u-joint worked very well. I'll have to try again. I think it was the right rear plug.
To check the wires, is it sufficient to check the resistance to make sure it is consistent for the six plug wires? What about the coil wire? The coil is separate from the cap.
To check the wires, is it sufficient to check the resistance to make sure it is consistent for the six plug wires? What about the coil wire? The coil is separate from the cap.
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Checking the wires for resistance only tells you the ohm rating. That doesn't tell you if they are sealing good. You can visually inspect for cracks and such. Or you could take the doghouse off and run it at night. If its shorting, you will see a light show.
But really, with as many years as you have on the plugs and wires, they should be changed.
If you have problems getting the plugs out thru the doghouse or wheel wells, try from under the van. Hopefully, you can jack it up.
But really, with as many years as you have on the plugs and wires, they should be changed.
If you have problems getting the plugs out thru the doghouse or wheel wells, try from under the van. Hopefully, you can jack it up.
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2,641 Posts
Hi jal
I agree with what everyone says here to check or do, my comment here is on the U-Joint your using to remove the plugs. Might I suggest you go out and buy an "Impact Swivel" instead. It will give much more range/angle and won't put side pressure on the plug like the U-Joint types do.
I cracked the #6 ceramic insulator on a new plug using a U-Joint type swivel (for lack of a better word). I have never had anymore problems since I switched to the impact swivel. Highly recommended to everyone changing their own plugs. Please keep us updated, Thanks.
I agree with what everyone says here to check or do, my comment here is on the U-Joint your using to remove the plugs. Might I suggest you go out and buy an "Impact Swivel" instead. It will give much more range/angle and won't put side pressure on the plug like the U-Joint types do.
I cracked the #6 ceramic insulator on a new plug using a U-Joint type swivel (for lack of a better word). I have never had anymore problems since I switched to the impact swivel. Highly recommended to everyone changing their own plugs. Please keep us updated, Thanks.
Seahunt56 here again, Thanks for the picture of the distributor. What would cause the problem of the chiping around the top center? I am going to pull the dog house off tomorrw morning to check this out. I dont quite understand when I put on a new cap and roter the problem goes away but slowly returns. Thanks for your help. Steve
Seahunt56 Here once again,
I have replaced the plugs and wires, and it seemed to idle a bit better. A machanic at my local NAPA gave me his code reader to use. I found 3 codes PO300, PO420, and P1870. I erased the codes and took it out for a run. Had it in 3rd gear up to highway speed and the surging is still there. Mechanic at NAPA thought that maybe the converter might not be locking up in OD for the code P1870. Check engine light came on, read the code and got PO300 again. Also, inside the dist. cap on the little studs it seems not to be firing at the center but just before like at maybe 5 o clock or 4:30 o clock. (according to the burn marks) No moisture found no chips or cracks. Anyone have some ideas on what throws a code PO300. Thanks, Steve
OH YEAH, read on here about replacing the plugs and how hard they are to get to. Yep! I went through the wheel wells on both sides for all with auniversal and up to a 16 inch extension.
I have replaced the plugs and wires, and it seemed to idle a bit better. A machanic at my local NAPA gave me his code reader to use. I found 3 codes PO300, PO420, and P1870. I erased the codes and took it out for a run. Had it in 3rd gear up to highway speed and the surging is still there. Mechanic at NAPA thought that maybe the converter might not be locking up in OD for the code P1870. Check engine light came on, read the code and got PO300 again. Also, inside the dist. cap on the little studs it seems not to be firing at the center but just before like at maybe 5 o clock or 4:30 o clock. (according to the burn marks) No moisture found no chips or cracks. Anyone have some ideas on what throws a code PO300. Thanks, Steve
OH YEAH, read on here about replacing the plugs and how hard they are to get to. Yep! I went through the wheel wells on both sides for all with auniversal and up to a 16 inch extension.
I had a 1991 Safari that acted like it had a transmission problem. Acceleration was strained and it seemed to surge under any steady load. It would start and idle fine. The second transmission shop that I visited had an honest (very unusual) guy working the counter. After I described the symptoms he looked around to see if the boss was near and told me to change the fuel filter. I did and the problems went away. When was the last time you changed your fuel filter?
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Hi seahunt56
If the problem still continues after replacing the fuel filter, then maybe try something out here, put the transmission in 3rd and put it under the same conditions you get the miss from when the transmission is in Drive. Please let us know what the out come is, Thanks.
PS: The fuel filter should be replaced every 6 months with these vans seahunt56, this really helps in adding life to the fuel pump.
If the problem still continues after replacing the fuel filter, then maybe try something out here, put the transmission in 3rd and put it under the same conditions you get the miss from when the transmission is in Drive. Please let us know what the out come is, Thanks.
PS: The fuel filter should be replaced every 6 months with these vans seahunt56, this really helps in adding life to the fuel pump.
Matrexx,
On Tuesday night I got the van up on the highway in 3rd gear. When I got up to speed (75) and backed off the throttle I got the same surging or bucking. Put it in OD and it continued. Cruisiing along it will surge a little, almost like you were driving into ha head wind. I will try and replace the fuil filter today and let you all know whats happening. I apperciate all the help. Steve
On Tuesday night I got the van up on the highway in 3rd gear. When I got up to speed (75) and backed off the throttle I got the same surging or bucking. Put it in OD and it continued. Cruisiing along it will surge a little, almost like you were driving into ha head wind. I will try and replace the fuil filter today and let you all know whats happening. I apperciate all the help. Steve
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