[astro_niki]

Hi, all we have a 2003 Chevy Astro Van (AWD) that stopped accelerating over 20 mph after a 10 hr drive from Portland to San Francisco. We limped home and upon inspection found coolant levels were low. We drained, flushed, and refilled the coolant, but still could not get over 2500 RPM. When we tried the engine would bog and fuel trim would go to about -25%.

We took the car in and the shop said the cat was bad/clogged just as someone on FB had suspected. I asked the shop to do a pressure test to make sure we weren't leaking coolant into the cat and it passed. Now we have a new cat and the shop says everything is working, but I can't help but be paranoid. I asked what caused the cat to go bad and they said "This happens on some cars this age. There's a reason they discontinued them (dunno if she means the cat or Astros)."

I am still skeptical, is there something else we should look at or inspect? I don't know the last time the plugs were replaced. Hard to know what maintenance the previous owner did if any. The Van made it up to Oregon fine, so we were really surprised it died on us on the way back. Thanks in advance!

 

[Mmusicman]

If it's running RICH.. it will destroy a CAT.
You'll have to check your OBD readings (fuel trims, O2, codes, etc) to see if something is wrong.
A bad fuel-injection regulator can dump raw fuel into engine as well.
Check fuel pump pressure... and see if it is holding.
Of course you need good plugs, wires, cap rotor and other electrical components as part of your regular maintenance.

Running bad usually has nothing to do with coolant levels, unless you are overheating.

Welcome to the site

 

[astro_niki]

Thanks, @Mmusicman. We've got a scanner so I can drive around and check levels. If I've done my research correctly here's what I should see:

• Short term & long-term fuel trims close to 0 (anything below +-5 is probably OK?)
• O2 sensors between approximately 0.1 and 1.0 volts (shop just replaced these so I'm assuming they're good)
• No codes

A bad fuel-injection regulator can dump raw fuel into engine as well.
Check fuel pump pressure... and see if it is holding.

1. How do we check the fuel-injection regulator?

Thanks again!

 

[Mmusicman]

Put a fuel pressure gauge on the fuel tap (located directly behind the fuel injector.
You can usually rent/borrow one from local auto parts store.
Run engine.. check pressure.
Stop engine.. check to see if pressure holds.

I don't know exact numbers, but somewhere between 50-60psi.

O2 sensors sweep dramatically from 0 to 1 when they are working correctly.
Reading trims is a little more involved

 

[Sailing_Faith]

Hey guys…. I was the one you talked to on Facebook who troubshoot the cat.

Coolant can and will also destroy a cat…. Just as running ritch will. See the post there for my recommendation about checking fuel trim and fuel pressure leak down.

glad you are here, Facebook is a zoo.

 

[AstroWill]

• Short term & long-term fuel trims close to 0 (anything below +-5 is probably OK?)
• O2 sensors between approximately 0.1 and 1.0 volts (shop just replaced these so I'm assuming they're good)
• No codes

Your fuel trims are just fine so I wouldn't be worried about the regulator nor the fuel pressure.

How many miles are on your van? If you have any question about the plugs, pull them and check as well as testing/inspecting the wires as well. Also, do you have any symptoms of Pancake Distributor Disease? See link in sig for manuals and such.

I know you put it in your post, but it also helps if you put your year/make/model/engine/AWD/conversion/etc in your profile or signature line so we know what we are working with in the future. https://www.astrosafari.com/account/signature

 

[astro_niki]

Your fuel trims are just fine so I wouldn't be worried about the regulator nor the fuel pressure.

How many miles are on your van? If you have any question about the plugs, pull them and check as well as testing/inspecting the wires as well. Also, do you have any symptoms of Pancake Distributor Disease? See link in sig for manuals and such.

I know you put it in your post, but it also helps if you put your year/make/model/engine/AWD/conversion/etc in your profile or signature line so we know what we are working with in the future. https://www.astrosafari.com/account/signature

Thanks, profile updated

We haven't done the scanner diagnostics yet, but will probably get to it today.

I have not heard of PDD, thanks for the link. Will check the gear play.

 

[Mmusicman]

Your fuel trims are just fine so I wouldn't be worried about the regulator nor the fuel pressure.

According to the numbers the OP posted.. I would agree.
If it had vacuum or leaking regulator, the trim levels would show it.

Ironically, when my distributor failed.. it didn't show any codes (at least in my case).
There was however no mistaking the erratic misfires.
But I'm not aware this could lead to CAT failure either.

One thing for certain.. it's best to look at everything to hopefully find the likely culprit.. or you may find yourself replacing another CAT.

 

[AstroWill]

Ironically, when my distributor failed.. it didn't show any codes (at least in my case).
There was however no mistaking the erratic misfires.
But I'm not aware this could lead to CAT failure either.

It's what took out the cat in my first Astro.

 

[Mmusicman]

Good to know... especially when everything else comes up clean.
I've replaced 2 distros so far.. but their failures each time led to obvious erratic acceleration

 

[astro_niki]

Hey, ya'll, I know everyone recommends AC Delco parts for plugs/wires. Can someone tell me the difference between all the options here?

https://www.carparts.com/spark-plug?&itemsperpage=15&refinements[part]=Spark_Plug&refinements[brand]=AC_Delco&vehicle[cylinders]=6&vehicle[liter]=4%2E3&vehicle[submodel]=Base&vehicle[model]=Astro&vehicle[make]=Chevrolet&vehicle[year]=2003

The local shop only carries Iridium. When I started browsing for better prices online there were a lot more options.

 

[Sailing_Faith]

Catalytic Converter Failure: 3 Common Causes

Your catalytic converter is a critical part of your car's exhaust system. Here's 3 common causes of catalytic converter failure.

knowhow.napaonline.com

 

[AstroWill]

Can someone tell me the difference between all the options here?

Basically you have a copper core with a coating and depending on that coating and how hard it is will determine how fast it wears down. The only real differences are longevity and price, as long as you buy the correct plug in the correct heat range they will work the same. For many they aren't the easiest thing to replace so longevity is important. For me I wouldn't bother with anything other than Iridium at this point.
Watch for sales/rebates like: Almost free ACDelco spark plugs! Rebate's back...

 

[Sailing_Faith]

I agree with Will. There is really no advantage to running anything other then AC Delco iridium (or possibly NGK iridium).

Ac Delco Irdium after 103,293 miles

I just pulled my AC Delco Irdium plugs after 103,293 miles. They ran great, no noticeable decrease in gap…. Electrodes are in good shape. I have pulled one or two out for checks at different mileages, but always put them back in. Just a post to show they live up to the billing and...

www.astrosafari.com

 

[astro_niki]

I agree with Will. There is really no advantage to running anything other then AC Delco iridium (or possibly NGK iridium).

Ac Delco Irdium after 103,293 miles

I just pulled my AC Delco Irdium plugs after 103,293 miles. They ran great, no noticeable decrease in gap…. Electrodes are in good shape. I have pulled one or two out for checks at different mileages, but always put them back in. Just a post to show they live up to the billing and...

www.astrosafari.com

@AstroWill & @Sailing_Faith thanks you two. Going to use the rebate!

 

[sixsix]

Seems so ABSOLUTE...

And hoping it applies to all years and variations of engines...