Non-F body: Caddy from hell; any thoughts?

[unstable bob gable]

I know we have some GR8 mechanical minds here, so please mull this over and tell me waht you think:

Car in question is a 90 Caddy Fleetwood. 4.5 V8, MPI injection, HEI distributor ignition.
History of problems:

Car seemed to REALLY be down on power. Cat converter must have gotten plugged up. Cat blew apart on way home from work, drove car to shop for repairs.
Had following work done: complete new exhaust system, new 02 sensor, tranny filter and fluid change, oil change, new plugs, cap, rotor, and wires.
Got car back, drove to work. Car stilled seemed to be down on power. Got within a few blocks of work, and exhaust system fell down due to what seemed to be broken rear hanger. Had car towed back to shop.
Had muffler/tailpipe/rear hanger replaced. Picked up car, drove it a few miles back home. Car STILL seemed to be way down on power. Called shop, was told to bring car back.
Took car out on highway to see how bad performace was; could barely get above 60 MPH. Drove car back into town to get to shop, rear rubber exhaust hanger CAUGHT ON FIRE and dropped exhaust. Put out fire, limped car to shop, and dropped it off.

Now, I'm trying to figure out this mess, and I'm focusing on a couple of things: lack of power, and the exhaust getting so hot by the muffler that it caught the hanger on fire. I'm thinking timing must be waaaay off: that could cause car to run crappy and build excessive heat in the exhaust. The distributor must be computer controlled, I don't know if you can adjust the timing by unplugging the distributor like on a 3rd gen F body.
Don't know, don't know, don't know...want do YOU think???

[Pampered-Z]

Sure sounds like too much timing, either the distrib or maybe it jumped time? How many miles on it? Thinking maybe the timing chain streatch and it jumped a gear?

On me TBI engine you unplug a connection on the fire wall, not a plug in the dist. Yuo might look in a Chilton's or Hayne's for where the connect is.

[V]

i know its a logn shot, but any chance pieces of the cat made it back to the muffler where it clogged that? or was the muffler also new when the cat was fixed?

[Jared1970Chevelle]

if the exhaust is getting that hot the new cat converter could be working that hard and fouled but i would check the spark plugs, they might be wrong for the car especially if your mechanic got them from autozone or sumthing lol..... the distributor could be the main problem.... check the plugs and new cat then if thats fine then its the dist. and control computer...

[unstable bob gable]

Originally Posted by Pampered-Z

Sure sounds like too much timing, either the distrib or maybe it jumped time? How many miles on it? Thinking maybe the timing chain streatch and it jumped a gear?

On me TBI engine you unplug a connection on the fire wall, not a plug in the dist. Yuo might look in a Chilton's or Hayne's for where the connect is.

Zeke,
It has around 100K miles on it. Def does sound like a timing issue, but gotta figure out where the issue is.

[unstable bob gable]

Originally Posted by SmokingSS

i know its a logn shot, but any chance pieces of the cat made it back to the muffler where it clogged that? or was the muffler also new when the cat was fixed?

The whole exhaust was replaced when the cat was replaced.

[GP99GT]

crossed plug wires?

[BonzoHansen]

Really hot exhaust - waaaay lean? Is it hard starting?

[unstable bob gable]

Originally Posted by BonzoHansen

Really hot exhaust - waaaay lean? Is it hard starting?

It fires right up real easy. And tops out @ like 60 MPH!

[WildBillyT]

It certainly sounds like it could be timing related.

Obligatory stupid tune-up questions:

1.) Air filter is in good shape?
2.) Fuel filter recent, fuel system working properly?
3.) Plugs and wires in good shape?

[unstable bob gable]

Originally Posted by WildBillyT

It certainly sounds like it could be timing related.

Obligatory stupid tune-up questions:

1.) Air filter is in good shape?
2.) Fuel filter recent, fuel system working properly?
3.) Plugs and wires in good shape?

1. Air filter is new
2. Fuel filter recently done, fuel system OK afaik
3. Plugs/wires are brand new, were just done during this fiasco.

[Jared1970Chevelle]

damn... get full coverage.... take the new stuff off and sell it... leave a copy set of the keys in the ignition in downtown newark...

CASE SOLVED! hahahah

[NJSPEEDER]

one fo the things that the older GM computers all had in common was to dump fuel as a solution. look at your plugs and see if they are all junked up. if they are start checking some of the simple/obvious sensors. the water temp for the computer is a good one for silently going bad and causing headaches.
i woudl also check to see if the wiring for the O2 is good. those connectors can get humidity into them and corrode fairly easily after 15+ years of use.

good luck with it.

[BonzoHansen]

No codes?

[NJSPEEDER]

another great trick of the 80's and early 90's OBD1 computers, they may or may not decidde to throw a code. GM only made the "important" sensors feedback related to throw a code, but they made al of them to dump fuel when there is a failure. brilliant planning on their part. lol

[Pampered-Z]

Maybe we're starting off looking to deep into the problem?

Did this problem start after a recent fill up of gas? Did you switch to a lower octane? My 93 PU wouldn't run on reg, only premium. With reg it had no power to go 50 MPH and if I tried too, the water temp would jump up quickly. No check engine codes and the car scanned perfectly too! I played with timing and tune-ups and replacing injectors until I figured it out!

[unstable bob gable]

The plot thinckens...just got off the phone with the shop, and they are saying it is an injector issue. Looking at the facts, I guess it makes sense. But at this stage of the game you could tell me the problems were being caused by mutant spiders living in the intake ports n' I'd believe it!

[NJSPEEDER]

if an injector was leaking or dumping fuel, they shoudl have noticed it long ago. that is an easy issue to spot/smell/notice unless they are just complete JO's and don't know what they are doing

[unstable bob gable]

Originally Posted by NJSPEEDER

if an injector was leaking or dumping fuel, they shoudl have noticed it long ago. that is an easy issue to spot/smell/notice unless they are just complete JO's and don't know what they are doing

Let's just say this will be my last dealings with this shop. I've used 'em for a while because they are close to home and a friend of mine used to work there, and I never really had a problem w/ 'em. But this is strike 1-5 all rolled into one.

[V]

if the injector setup is the same as the TBI off a 91 305 RS camaro... i have a complete setup ill give ya free

[unstable bob gable]

Originally Posted by SmokingSS

if the injector setup is the same as the TBI off a 91 305 RS camaro... i have a complete setup ill give ya free

Thanks, man. But the Caddy set up is a multi port. Nothing ever comes easy...