cpayne

on my way to meet up with the crew doing the run on the Blue Ridge Parkway in Virginia, my car felt like it was running rough. To me it felt as tough it was running on less than 8 cylinders. We checked the spark on the drivers side plugs and started the other side when we broke a wire connection. Jadz928 had a spare rigged as the spark tester. We used it as a replacement so we couldn't check the rest. Pulled the drivers side rotor cap and it didn't look bad, but cleaned it a little. Car ran worse like a 4 or six cylinder. I turned back home about 120 miles. I noticed that my fuel consumption was close to that of a 12 cylinder. I filled up and drove about 90 miles and used almost 3/4 tank of fuel. Fuel smell was strong. When I arrived at home. Idle was at 1,000-2000. White smoke that had fuel smell rolled out from the exhaust and from under the passenger side and small amount under the hood behind the Airbox and under the car (This happened at the Parkway but not this bad. We felt it may be oil burning on the CATS.
I had something similar happen when the MAF went bad on me a while back. Very rich smell and smoke. Poor running and idling and backfire. No backfire. MAF was rebuilt and has about 400 miles on it.

Any guesses?

Thanks to all the guys on the BRP trip and special thanks to Jim (Jadz928 and Chris Landseer ) for the coil wires. Chris and I put them on tonight. I took it for a spin and despite a high idel issue its running well.

New photos of coil wear

Wear spot


Another spot a little worse


Removal of the end of the bad wire revealed this screw type connector.

James Bailey

It was running on 4 cylinders and you are very very lucky that the overheated cat did not ignite the undercoating and burn up the car....very lucky ! And when a car is talking to you....listen ! The urge to "make it home" can be a very expensive one. When you drive old cars and the 928 is an old car it makes sense to get Autoclub long distance towing at least the 100 mi if not the 300 mi and when in doubt use it....

fraggle

Yikes it sounds like near full blown cat fire!! You're lucky it didn't go up. Sounds like next weekend you'll have some real investigating to do.

cpayne

I'm thinking it's the MAF. I don't understand the fuel usage

928 at last

You had four doing the usual work of eight, while the four that weren't firing were dumping raw gas.

cpayne

That makes sense.

928 at last

Your MAF is probably fine, but the temperature sensors may not be. Lots of good info on here regarding the "Running on Four" issue. I'd also hazard a guess that it was definetely the Cats you were smelling, but it wasn't oil that was burning. (Unlikely you 'd have made it home without a roadside BBQ event).

928 at last

My issue with this was due to a bad injector. (Just one). and it's amazing how quickly the system reacts to the temperature differential. Just based on my experience, (YMMV). I'd run a noid light around and make sure everything's getting a proper signal. and then stethescope the injectors to ensure each one is cycling. (at least as one of the first checks). At least that can be done from above as opposed to below.

Kaz

I had this happen on my 89 and made it about another mile to a gas station whereupon I opened the door and glanced under the car to see the glowing red hot cats. Jim is right, you could've lost the car. I can't imagine trying to have made it 100+ miles with the car in that condition. Cars got 8 lives left.

cpayne

Sounds like I have some injectors to check.

Mrmerlin

Does the word Joey mean anything to you??

https://rennlist.com/forums/928-foru...he-ground.html

A sobering result.. if your cars is running on less than 8 look at the cats if they are glowing shut it off away from any buildings and step back

JWise

On my previous 90GT, I had symptoms similar to yours. It was one of the coils going bad, an easy fix.

928 at last

That causes a temp differential between the two banks will result in a shut down of four. The red or green lights on the brains will help guide you to the side that's the problem.

Then, it's the usual with the regular.......fuel, spark, (I think it's safe to assume you've got air.).

cpayne

From the posts and threads on this problem it seems as though more often than not a fire occurs. This begs a question. Why didn't it catch fire? after such a distance.

Tom. M

Don't forget that the ign monitoring relay shuts off the fuel to 4 injectors if it senses a temp imbalance.....so you can drive (but risk breaking the torque tube due to the rough firing)... This is on the 89 and up 928's.

Cpaynes has a 87 ..without the ign monitoring circuit..so if he loses spark..then he continues to pass fuel through the cylinders and into the cats...where it burns...up the car... He needs to look at his coils and ign parts to make sure any issues are resolved before he drives again.