87 GN was running fine then lost power, smoke from front of cat

[DeltaT]

I was driving the car home from purchasing it, after a lengthy checkout and test drive. About 1 hour and 15minutes of no problems, it started running rough, like it was loaded up. I stopped at the first good spot and smoke was coming from the front of the cat, like burning oil. I had checked all the fluids and they were ok, and no obvious loose wires or missing vacuum hoses. Scanmaster showed no codes.

I babied it home - had to manually keep it in lower gears as it had so little power.
Pulled all 6 plugs, and they all looked fine. Tomorrow I'm going to pull the catoff to check it, and try starting it to see if it runs better.

Scanmaster seems to be working ok as when I pulled the MAF connector off it threw a code 34.

Also, how do you clear codes from the car or Scanmaster, please?

Pulled EGR hose off to see if it would run different - nada. Nosigns of vacuum at the EGR port either.

Any ideas appreciated. I don't know these turbo motors or their electronics at all but have a good EFI background.

Thanks,

Jim

 

[SHADOWII]

Oil getting on the d/p is probably a leak from the v/c. If on the crossover, the rear main seal or the back of the int. manifold gasket, from too much blow-by or a non-valley pan style int. gasket. The rough operation can be from unmetered air getting into the engine from one of the int. hoses being loose between the maf and the up pipe. Engaging the turbo can separate the hoses when under pressure if they are not on tight enough.
You can eliminate the codes by disconnecting the bat. butI believe that will require you to reprogram the s/m again.(own a s/m for years,but it's still sitting in the box.) Try disconnecting the org. wire from the bat. cable that goes to the ecm and that should eliminate the codes w/o the need to reprogram the s/m.

 

[hiboom]

I would call the previous owner since you just bought the car if he owned it a while it mite of happened to him and he knows the quick fix for it.

 

[Chuck Leeper]

That old cat, [if it's original], may have decided to have a melt down..............AIRC, they were the pellet type. If the engine is either too lean, or run too fat for an extended time, the pellets will melt into a blob.
To clear codes: Look at the battery. There should be a orange wire/connector there. That's the ECM power. Unplug it. That will dump the codes.

 

[aminga]

That old cat, [if it's original], may have decided to have a melt down..............AIRC, they were the pellet type. If the engine is either too lean, or run too fat for an extended time, the pellets will melt into a blob.
To clear codes: Look at the battery. There should be a orange wire/connector there. That's the ECM power. Unplug it. That will dump the codes.

86's and 87's were a honeycomb style.

 

[DeltaT]

Thanks, all. The cat may be original. The smoke was coming from inside the system, not outside. Called original owner and he knew nothing - said it never happened before (and it didn't during the 35 min. test drive or the next 1.25 hours driving home).

Could a turbo seal blow and allow oil into the exhaust stream?

Jim

 

[SCOOBY DOO]

My guess the cat is clogged up.

 

[Chuck Leeper]

86's and 87's were a honeycomb style.

They'll still melt. Have seen many of the hi flo cats do that, w/ ceramic and metallic substrate cores melt, even blow completely out of the system. [Or worse, plug up the muffs.
Usually on late model stuff w/ "performance tunes", causing lean conditions....

 

[DeltaT]

Thanks, gonna go grind the spot weld off and check it.

Jim

 

[Buick Mark]

Yep, I would say the cat is plugged, especially if its only smoking from the front. NOW, figure out WHY it plugged/melted down.

 

[Drewster]

Does it have a Max Effort thumb wheel chip? I had one once that would lose power and the program needs to be rebooted on wheel# 0. If I didn't, it would run just like you described.
Andrew

 

[Drewster]

Does the car have a MaxEffort thumbwheel chip?

 

[GullsGN]

Thanks, all. The cat may be original. The smoke was coming from inside the system, not outside. Called original owner and he knew nothing - said it never happened before (and it didn't during the 35 min. test drive or the next 1.25 hours driving home).

Could a turbo seal blow and allow oil into the exhaust stream?

Jim

A blown turbo seal could allow oil into the exhaust, but, you would not see the power drop that you are seeing. You would see a huge amount of smoke coming from the back of your care under boost.

Steve

 

[highboostgn]

just take your cat off and run it open dp down the road and see if that fixes it..

 

[TLIMITED]

If you have a known good MAF try and swap it.

 

[earlbrown]

Hammer and a drift will make a nice free flowing hole in the middle of the cat's honeycomb (yeah yeah yeah)