Chevy & GMC Vans

Minor update.

Last week.
Added 4 cans of Seafoam into the tank and have run most of it out.

Today....
Changed timing to 0* TDC or maybe 1*BTDC (was hard to tell).
Replaced PCV.
Cleaned out the PCV tubing. It was maybe 50% or less airflow.
Replaced the air filter.
Checked voltage in the fuel pump harness (near the fuel tank) and it reads 13-14 volts with the motor running.

Tomorrow....
Test the fuel pressure.
Run a can of Seafoam thru the PVC port.
The last can I ran in it was thru a vac line that is ported near # 4 so may not have helped # 3 + 5.

Any other thoughts ? ? ?

Have you replaced those plugs yet? They look like they could use it! That should help with unburnt HCs.

Great plug pictures.... that really helps us smog and technical guys to help with your problem. ( an FYI to everyone else, take quality close up labled plug pictures like this )

You are burning oil in those two cylinders, from bad valve stem seals and or worn valve guides, the oil is leaking down the valve shaft and burning in the cylinder upon start up. You will see a puff of blue-ish smoke when you start your motor in the morning.

If it was a result of using a different gas or additives, ALL the plugs would have that funky growth on them.

Fit brand new plugs and warm up the cat by driving your van for 20 minutes before the test, don`t shut it off while you are waiting for your test. You can even do a 2000rpm cat warm up for 2 mins in the parking lot of the smog station.

SoCalli V8 wrote:Great plug pictures.... that really helps us smog and technical guys to help with your problem. ( an FYI to everyone else, take quality close up labled plug pictures like this )

You are burning oil in those two cylinders, from bad valve stem seals and or worn valve guides, the oil is leaking down the valve shaft and burning in the cylinder upon start up. You will see a puff of blue-ish smoke when you start your motor in the morning.

If it was a result of using a different gas or additives, ALL the plugs would have that funky growth on them.

Fit brand new plugs and warm up the cat by driving your van for 20 minutes before the test, don`t shut it off while you are waiting for your test. You can even do a 2000rpm cat warm up for 2 mins in the parking lot of the smog station.

Thanks for the pics comment.

I "burn" a quart (946.352946 Canadian) every 200 miles (321.8688 Canadian).
I've had morning AND afternoon AND evening puff for a while.
New plugs were installed prior to the test.
I do try and keep the rpms up while I'm waiting in line for the test.

Anyway, today was a bad bad for my van.

Couldn't get over 50mph (80.467199999 Canadian) while on the gas.
It would backfire badly into the intake.
Didn't notice any unusual smoke from the tailpipe.
Idles OK.
I can ease into the gas to gain MPH (KPH Canadian) if the road was level.

Hummmmm

It may be time for the "We Buy Junk Cars" phone call.

It has been in the "family" since it was new.

I had the same problem and it turned out to be bad plug leads shorting out on the foil on the inside of the dog house and caused massive backfires. Like you I was about to have the van crushed if the plug leads didn't fix the problem but it has been running great since the new plugs.

I also put a rebuild kit into the TBI that helped it out alot. the kit is only about $50.

Hope this helps.
Kevin

SoCalli V8 wrote:Great plug pictures.... that really helps us smog and technical guys to help with your problem. ( an FYI to everyone else, take quality close up labled plug pictures like this )

I agree,they help to understand the problem better,nice work WB

a related thought to Kidhauler's post: pop the hose off the pcv valve with the engine idling and put your thumb over the end of the hose to see if you are getting good vacuum. With the kind of mileage you have, I'm sure you are getting a ton of blow by gas in the crankcase. My engine ran progressively worse each time I drove it as the crankcase pressure built up.
I had the same result as Kidhauler when I rebuilt the throttle body and cleaned out the pcv port (which was completely blocked on mine). An ounce or so of synthetic oil in the gas tank will lube the cylinders from the top side and help to seal the rings as well. But...I think your faithful engine may be on life support. I'd say you got your money's worth out of it.