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'92 5.7

Started by gross707, November 05, 2014, 07:18:49 AM

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gross707

I recently acquired a '92 5.7L Brougham in excellent condition.  Compared to the '90 I've had before the car seems sluggish and loud (as if holding first gear too long) when starting off.  She shifts smoothly but the engine noise seems too loud for a Cadillac.  My question is: was there a remapping of shift points between the two models, is this normal?
Thanks,
Gerald Ross
Gerald Ross

TJ Hopland

I didn't have Cads from that era but I did have several Roadmasters and Custom Cruisers and I don't recall thinking there was a huge difference between the 5.0 and 5.7.   I remember being kinda disappointed when I went from my 92 5.0 to the 93 5.7. 

I don't think the Cadillac had the electronic control transmission yet in 93 so its got a 'TV" cable.   That cable is pretty much the only input the transmission gets to know what you are expecting it to do.   The adjustment is pretty critical.  In a more demanding application like a truck towing a miss adjusted cable can kill the trans in just a couple trips.  I don't remember the exact process but the cable has a sort of ratcheting mechanism at the throttle body end.   There is a procedure for setting it.  I don't remember it, it may have been to hold the throttle wide open then extend the cable then back off one click.     

One issue I saw a lot with that era TBI systems is the base throttle stop and base timing are often not correct.   I don't remember the exact procedure but if you follow it in the proper sequence and use the factory specs they actually ran pretty good.   If either was off or they were set in the wrong sequence things just didn't run right.  Idle and timing would often 'hunt'.  I think that was the computer looking for its happy spot and never finding it because the base settings were wrong. 

I also can't remember where the MAP sensor was on those, if its right on the intake manifold it should be fine but if its on the firewall check the vacuum hose going to it.  I remember it was common to find a crack in the hose so the computer was not seeing an accurate reading of manifold pressure.    I can't remember if it was the trucks or cars that had them remote mounted. 

StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

John Washburn CLC 1067 Sadly deceased.

Folks,

I have two 92's one a Sedan Deville and one a Eldorado both with 4.9 engines (both have different rear end ratios).

If you look at the specs for the 1992 engine in the Brougham with the 5.7 liter V-8 you will find that it is rated at 185 HP. The 4.9 Liter V-8 was rated at 200 HP.

The 5.7 was taxed for extra HP at around $1200.00 by the feds in 92.

Interesting.

The Johnny

John Washburn
CLC #1067
1937 LaSalle Coupe
1938 6519F Series Imperial Sedan
1949 62 Series 4 Door
1949 60 Special Fleetwood
1953 Coupe DeVille
1956 Coupe DeVille
1992 Eldorado Touring Coupe America Cup Series

CEC #20099

Gerald: First thing you want to do is check for a plugged/melted Cat Converter. After you find it & replace it, the car will run much better. The `Roaring` sound is the key. Exhaust is plugged. Second thing is check for an inoperative air diverter valve, that sends air to converter. Will fail & not set a code.

Be sure your engine is not running rich, as that will melt a converter.
Common GM problems.
c chleboun #20099

TJ Hopland

Good call on the cat, I should have thought of that.     The roar could be the cooling fan clutch engaged more than usual due to the elevated temps from the exhaust restriction.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

gross707

Thanks for all the input.  The cat is a replacement unit and looks (from outward appearance) to be  in as new condition.  I've been thinking about ditching it.  Would that be a bad idea?
Gerald
Gerald Ross

CEC #20099

Gerald: If the Cat is good, it wouldn`t hurt to pull the muffler, to see where the melted catalyst went. I`m still thinking excessive exhaust back pressure.
c chleboun #20099

Scot Minesinger

Generally if your Cadillac 5.7 seems like it is not running right, it probably is not.  My friend (back in like 1995) bragged about his 92 Cadillac RWD with 5.7 liter, saying it hopped when you stepped into the throttle.  Something is wrong as you suspect.  The exhaust system is a great place to start on an older car.   
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

cadillacmike68

Quote from: John Washburn CLC 1067 on November 05, 2014, 10:03:50 PM
Folks,

I have two 92's one a Sedan Deville and one a Eldorado both with 4.9 engines (both have different rear end ratios).

If you look at the specs for the 1992 engine in the Brougham with the 5.7 liter V-8 you will find that it is rated at 185 HP. The 4.9 Liter V-8 was rated at 200 HP.

The 5.7 was taxed for extra HP at around $1200.00 by the feds in 92.

Interesting.

The Johnny

Johnny,

that was a Gas Guzzler tax and in 1992 the Brougham with the 5.7L managed to not have that penalty.

Those 4.9s were on the FWD DeVilles, Sevilles and Eldorados; the RWD Brougham had a completely different engine layout.

Gerald, If it's blue, black, silver or grey, just sell it to me and your troubles will be over.  :P If you are somehow inclined to keep it, check the entire exhaust. I don't think they used stainless and there could be holes, and leaks, even up front on the manifold.
Regards,
"Cadillac" Mike

gross707

It IS Firemist Sapphire.
I've already replaced the (original) muffler and the cat is new.  I'll dig into the rest when I get a chance.
G
Gerald Ross

cadman56

A suggestion would be to have a shop check the exhaust back pressure, done by using a special gauge inserted into the O2 sensor location.
I would also suspect a bad fan clutch.  good luck.  Larry
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820