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'92 v. '90

Started by gross707, December 30, 2014, 07:25:58 AM

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gross707

Gentlemen,
I have recently acquired the third Brougham in my life for use as a daily driver.  My first two were 1990's models, while the current one is a '92.  They all had the 5.7 but there seems to be a lack of motivation in the latest and last iteration of this land yacht.  Everything from under the hood back to the tip of the exhaust pipe is as it should be.  My question then is: is there a fundamental difference in the engine mapping or exhaust systems (or in some other realm made perhaps in the name of emissions standards) or some other reason that the characteristics of the engines between these two model years should be so dramatically different?
Puzzled,
Gerald
Gerald Ross

936CD69

Is the rear axle ration the same on the 92? IIRC, in 90 the only way to get a 5.7 was with the trailer tow package, which had a lower rear end ratio?
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top-SOLD!
1993 Sedan deVille Spring Edition Triple Black
CLCMRC Benefactor #302

Eric DeVirgilis CLC# 8621

I could be mistaken but I believe the 5.7 was available only in conjunction with the heavy duty towing package which included the following heavy duty items: Alternator, cooling system & suspension. Heavy duty rear end with special axle ratio, possibly more.

Cannot account for power loss in 1992 model w/ 350 - all three years should perform similarly.

Of course, I defer to Craig's expertise!

*When was the last time it was tuned up?

A Cadillac Motorcar is a Possession for which there is no Acceptable Substitute

TJ Hopland

Axle ratio is a good thought,  I think 92 the 350 was still an option, maybe 93 it became standard?   I don't know what the ratios are/were.   In 90 the base engine was still the carburated 307 which was quite difference performance wise than the EFI chev so I could imagine there was a bigger difference in axle ratios that year.   

I think the Chev engines got roller cams in 91 or 92 but that should not really have made a performance difference. 

May be worth having someone that knows what they are doing check the base timing.   I used to see a lot of those era engines where the base timing was not set properly so the computer gets confused and does not run the timing correctly.   You could also have a shop check the back pressure in the exhaust to make sure things are flowing properly there.  They put a gauge in the O2 sensor port.
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

Eric DeVirgilis CLC# 8621

307 Olds got roller lifters beginning 1988; 350 optional 90-92.

1990 was last year for 307 Olds as standard plant; replaced by 305 Chevy FI for 91-92 for base engine.

350 standard in RWD Fleetwood 93-96; LT1 350 began 1994 as standard.
A Cadillac Motorcar is a Possession for which there is no Acceptable Substitute

936CD69

When I get home this evening, I'll check the 90 and 92 dealer order guides for axle ratios. If you can find the service parts ID label, usually on the trunk lid, get the codes that start with G like gu6, etc. That is the axle ratio code.
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top-SOLD!
1993 Sedan deVille Spring Edition Triple Black
CLCMRC Benefactor #302

gross707

I've had the tune checked and replaced the original muffler with a new one.  The cat is a newer replacement unit and everything checks out as functioning properly.
It was my understanding that all 5.7s came with the trailer tow pkg, so I thought that the ratios were the same.  Anyways here's a picture of the service parts i.d.

Thanks,
Gerald
Gerald Ross

TJ Hopland

GU4 is 3.08.   For the period that seems like a fairly high ratio that would fit a towing app.  I would expect the typical car of the era to be in the 2.50's so that should not be the problem.   Also the 4L60 / 700r4 trans has a 3.06 first gear compared to a 2.50 ish for the typical 3-4 speed autos so that also should give out a 'off the line' advantage.   The 90 w/350 should have also had the 700 so that should have been the same. 
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

936CD69

Gerald,

In 1990, the 5.7 was ONLY available with the Trailer towing package. In 1991 and 92 the 5.7L was a stand alone option, but was included if you ordered the trailer tow pkg. According to the 90, 91 and 92 new vehicle portfolios, the gear ration on all 90 and 91s was 3.08. A 92 like your car WITH the 5.7 but WITHOUT the trailer package was also 3.08, 92s with trailering had a 3.73 ratio. So, that disproves my theory! Interestingly, the 91-92 5.7 was rated 10HP higher than the 90.

Sorry I cannot shed any light on your issue... everything else that crossed my mind was asked..and answered by you.....

Craig
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top-SOLD!
1993 Sedan deVille Spring Edition Triple Black
CLCMRC Benefactor #302

Bill Young

I owned 3, 5.7 litre Cadillac Brougham's the first had 23,000 mi when bought and I drove to 200,000 and the second had 18,000 mi. whan bought and was driven over 200,000 mi the third I did not own long. However I found them to be the most trouble free cars I ever owned and got 19mpg around town and 21mpg on the road reliably.