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Im not sure how much this website can help with this topic but I thought Id give it a try. Since my 96 Fleetwood has a Chevy LT1 in it I figured most of the knowledge here is about Cadillac specific engines. But Ive read topics on the impala SS forums about this same thing with this engine and I need more answers so here goes...

Like said its a 96 Fleetwood LT1 350 115k miles. With that mileage you automatically suspect maintenance things may or may not have been done at 100k. I have the towing package so the specs on gas mileage for this particular car are 17 city 25 hwy. Granted Ive always got about 2mpg below specs on all my cadillacs but this particular car its very low.

When I first got it a year ago I was getting 10.5 mpg in the city. I installed a cold air intake and an air foil for better breathing. That bumped it up 10% to about 11.5 mpg.

So next step was more tune-up stuff. I changed the plugs to the original platinum delcos. I checked every single vacuum line and replaced a couple of them. Changed the PCV valve. New fuel filter. Cleaned MAF. New wheel bearings and brakes just in case there was drag. Sea foam in the gas and through the intake. Throttle body cleaned. "Engine restorer" mystery oil to fix any compression issues. New fuel pump (old one broke). Plug wires are a hassle to do, I have some but still havent changed them. Well after all this I was up to about 12 mpg.

Also on the highway during these times I get horrible mileage. Not sure exact numbers but its between 15 and 20 I know. And there is no missing of any cylinders.

So after reading some forums I found that o2's can make it run rich if they are bad. Since the car has 115k miles Im not sure if they were changed at 100k so I changed them with the proper ones. I just did the upstream ones before the cat. Hoping this solved my problem I now am getting 13 mpg city and still below 20 highway.

So with some more reading on the forums its found that the manifold gaskets and connections leak on these cars. When removing them the bolts almost always break as well. Fun. But anyway if they are sucking in clean air then it throws off the o2's. This makes sense. And I did notice when I did the seafoam treatment I had smoke rolling out of the back of my manifold on the pass side down where it connects to the pipe for the cat I think. So I checked all the bolts on the manifold at the engine and at the other end of the pipe. The back bolts on the manifolds were not even finger tight. I tightened those up good but Im not sure if the gasket is still good in there? Where the manifold goes to the cat pipe those bolts were solid. AND there are no hissing or ticks coming from the exhaust that would sound like a leak.

All that said Im still not getting my potential gas mileage. Id be happy with 15 in the city. Im not sure if its worth changing manifold gaskets and replacing cats. Cats are expensive. All that stuff is super rusty though Im not sure how well it works on the inside. The o2's behind the cat supposedly just tell the computer if the cats are working or not, i dont think they control lean or rich settings.

Reading a troubleshooting guide on autozones website for this car it says the throttle position sensor can be bad and make it dump more gas in then it needs. I dont have throttle response problems though..

Also NO CODES and I dont have a scanner to read o2 readings

Does anyone else have any bright ideas? Im open to anything at this point.

Should I replace the downstream o2's? Thats the next cheapest route.

Thanks for your time


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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You have done a lot of mods to that car no?

Is that the stock rear end ratio?

What size wheels do you have?

How is timing controlled on that car? What octane do you use?

Stock air filter box?


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Sounds like the exhaust manifold bolts were loose - after you tightened them, did the exhaust leak stop? If not, you'll need to replace the exhaust manifold gasket on the side that is leaking.

The trailer package has a higher gear ratio which will affect fuel economy - probably not to the degree you are expierencing but I'll bet it is 2-3 mpg.

I would not throw a TPS at the engine - it is not likely to affect anything.

As far as the O2 sensors go, you need to find someone with a scan tool and monitor the O2 cross counts to see if the sensor is changing states and is not lazy (staying at 0.5 v or close to 0 volts for too long of time).


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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You have done a lot of mods to that car no?

Is that the stock rear end ratio?

What size wheels do you have?

How is timing controlled on that car? What octane do you use?

Stock air filter box?

No mods besides the cold air intake and air foil. Which bumped up mileage 10%

Stock rear end ratio is 3.42. Car is all stock

Stock wheel and tire size

Timing is computer controlled, cant adjust it.

I use 87 octane. It doesnt call for premium and 10% ethanol doesnt help anything.

Stock air filter box (homeplate and first base) was a horrible design idea. I did away with that thing. A straight shot of air seems better than 15 different passeges and dead ends of air flow to eventually get to the TB.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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Sounds like the exhaust manifold bolts were loose - after you tightened them, did the exhaust leak stop? If not, you'll need to replace the exhaust manifold gasket on the side that is leaking.

The trailer package has a higher gear ratio which will affect fuel economy - probably not to the degree you are expierencing but I'll bet it is 2-3 mpg.

I would not throw a TPS at the engine - it is not likely to affect anything.

As far as the O2 sensors go, you need to find someone with a scan tool and monitor the O2 cross counts to see if the sensor is changing states and is not lazy (staying at 0.5 v or close to 0 volts for too long of time).

It has the higher 3.42 gear ratio but the base models of these cars got 17 city 27 or 28 highway and the towing package car got 17 city 25 hwy. The computer is tuned for different shift points to work with the higher ratio, giving you good mileage in the city still and a little lower on the highway. To show how bad it is on the highway I drove a 180 mile trip and used about a half tank of gas (23.5 gallon tank). And my buddy has the same car non towing package he drove right next to me and he used a little over a 1/4 tank.

I havent checked if the exhaust still leaks. Like I said I cant hear it if it is. I would have to suck down some more seafoam to see if it still smokes up.

What kind of scanner do I look for? Its a 96 car and considered OBD II even though it throws the old style trouble codes through the old climate controls. From what Ive seen OBD II scanners are $100? Kinda steep but I should get one someday because my wifes 05 Ranier doesnt have onboard diagnostics by the gauges. Does autozone let you use that tool? I thought about asking on craigslist maybe. Im not paying a shop $60 to hook one up thats for sure.

Thanks for the replies

Edited by CoupeDTS

* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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I purchased my 94 Fleetwood back in 96 from a Toyota dealer that had the vehicle returned twice for poor fuel economy. They practically gave it to me with the stipulation that it was AS IS NO RETURNS and had a fuel economy problem. $9 bucks later I replaced the temp sending unit. The poor car thought it was -40 out all the time so no codes, just lots of fuel. My kids are still driving the car 13 years later and it get 25 mpg easy on the highway, even with 145K miles on it. Best Caddy I ever owned and I've owned many. BTW, replace those plug wires. They run very hot and are worth replacing with high end wires. Good Luck.

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It has the higher 3.42 gear ratio but the base models of these cars got 17 city 27 or 28 highway and the towing package car got 17 city 25 hwy. The computer is tuned for different shift points to work with the higher ratio, giving you good mileage in the city still and a little lower on the highway. To show how bad it is on the highway I drove a 180 mile trip and used about a half tank of gas (23.5 gallon tank). And my buddy has the same car non towing package he drove right next to me and he used a little over a 1/4 tank.

I havent checked if the exhaust still leaks. Like I said I cant hear it if it is. I would have to suck down some more seafoam to see if it still smokes up.

What kind of scanner do I look for? Its a 96 car and considered OBD II even though it throws the old style trouble codes through the old climate controls. From what Ive seen OBD II scanners are $100? Kinda steep but I should get one someday because my wifes 05 Ranier doesnt have onboard diagnostics by the gauges. Does autozone let you use that tool? I thought about asking on craigslist maybe. Im not paying a shop $60 to hook one up thats for sure.

Thanks for the replies

The non-trailer towing models of the Fleetwood/Fleetwood Brougham were rated 17 city/25 Highway. The trailer towing option will reduce the fuel economy 2-3 mpg.

I was not aware the '96 Fleetwoods still had the onboard diagnostics from the climate control panel. I know they had them through the 1995 model year.

AutoZone can read the codes but you need to drive with the scan tool connected to observe the O2 cross counts.

The dead-end chambers in the intake path are there to reduce induction noise. Hopefully, your intake is shielded as to not allow an ingestion of water which could hydrolock the engine.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I purchased my 94 Fleetwood back in 96 from a Toyota dealer that had the vehicle returned twice for poor fuel economy. They practically gave it to me with the stipulation that it was AS IS NO RETURNS and had a fuel economy problem. $9 bucks later I replaced the temp sending unit. The poor car thought it was -40 out all the time so no codes, just lots of fuel. My kids are still driving the car 13 years later and it get 25 mpg easy on the highway, even with 145K miles on it. Best Caddy I ever owned and I've owned many. BTW, replace those plug wires. They run very hot and are worth replacing with high end wires. Good Luck.

Good stuff. Are you talking about the engine coolant sensor or the outside temperature sensor?

My climate controls list the correct outside temperature.

The coolant sensor, yes those sensors go bad alot. But usually you can tell because the fans wont turn on. If it thought the engine was always cold it just wont turn the fans on. I have a clutch fan but an electric secondary fan which will turn on when sitting too long in the heat.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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It has the higher 3.42 gear ratio but the base models of these cars got 17 city 27 or 28 highway and the towing package car got 17 city 25 hwy. The computer is tuned for different shift points to work with the higher ratio, giving you good mileage in the city still and a little lower on the highway. To show how bad it is on the highway I drove a 180 mile trip and used about a half tank of gas (23.5 gallon tank). And my buddy has the same car non towing package he drove right next to me and he used a little over a 1/4 tank.

I havent checked if the exhaust still leaks. Like I said I cant hear it if it is. I would have to suck down some more seafoam to see if it still smokes up.

What kind of scanner do I look for? Its a 96 car and considered OBD II even though it throws the old style trouble codes through the old climate controls. From what Ive seen OBD II scanners are $100? Kinda steep but I should get one someday because my wifes 05 Ranier doesnt have onboard diagnostics by the gauges. Does autozone let you use that tool? I thought about asking on craigslist maybe. Im not paying a shop $60 to hook one up thats for sure.

Thanks for the replies

The non-trailer towing models of the Fleetwood/Fleetwood Brougham were rated 17 city/25 Highway. The trailer towing option will reduce the fuel economy 2-3 mpg.

I was not aware the '96 Fleetwoods still had the onboard diagnostics from the climate control panel. I know they had them through the 1995 model year.

AutoZone can read the codes but you need to drive with the scan tool connected to observe the O2 cross counts.

The dead-end chambers in the intake path are there to reduce induction noise. Hopefully, your intake is shielded as to not allow an ingestion of water which could hydrolock the engine.

woops got the mpg mixed up with another car. Yes 17/25 for non towing fleetwoods and 17/23 for towing package. Still Im not near that.

My intake is fine it wont get any water in it. Cant say the same for that stupid air pump. I would delete it like youre supposed to but on the 96 models you have to have your ecm reprogrammed for it to be gone.

96 has the codes in the climate control but like I said they are the obd1 style even though its a obd2. And I have the roadmaster controls in so I can control where heat comes out but its all the same electronically.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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I purchased my 94 Fleetwood back in 96 from a Toyota dealer that had the vehicle returned twice for poor fuel economy. They practically gave it to me with the stipulation that it was AS IS NO RETURNS and had a fuel economy problem. $9 bucks later I replaced the temp sending unit. The poor car thought it was -40 out all the time so no codes, just lots of fuel. My kids are still driving the car 13 years later and it get 25 mpg easy on the highway, even with 145K miles on it. Best Caddy I ever owned and I've owned many. BTW, replace those plug wires. They run very hot and are worth replacing with high end wires. Good Luck.

waaaaait a minute, you might mean the air intake sensor that detects the temperature of the air coming into the engine? Thats a good idea! If it thought the air coming in was -40 it would run rich, and probably not throw a code.

I see they are only 15 bucks, I think Im gonna throw one of those at it and see how it goes!


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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There should be a test in the service manual that will list the resistance of the sensor at a given ambient air temperature. You could test the existing sensor to see if it was bad.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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There should be a test in the service manual that will list the resistance of the sensor at a given ambient air temperature. You could test the existing sensor to see if it was bad.

thats the first thing that ran through my mind. But I dont have a manual for this car so.... Second thing was look at it see if its dirty. It was a little dirty so i sprayed it down with carb cleaner. I either cleaned it or ruined it I dont know. I think Im just going to pick one up today I found them for 11.99 thats cheap enough for me to just replace it anyway. Plus Im bout to put a new tank of gas in so I gotta change something this go-round!

Next since Im too lazy or cheap to get a OBD2 reader I may just replace the downstream o2's. Its only $60 any they probably need it anyway. I mentioned to my dad that it would be nice to have a OBD2 scanner so maybe that clicked with him to get me one for christmas :D


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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Let us know the results ! good luck..

I replaced that AIT sensor and through 3/4 tank of gas it looks like the same mileage. So no help there. But it was a great suggestion as it couldve been the problem!

Any other ideas Id surely listen.

Next I'm going to do the rear 2 o2 sensors. This is unlikely the problem but you never know.

Another thing I was thinking about was about the MAF. Ive heard of some completely failing and allowing the car to barely run. But I wonder if they can screw up just a little? Theyre $100 new so Im not going to throw one of those at it but I wonder in what ways it can fail or fail to read correctly. Obviously if Im getting horrible mileage you would think its running rich so you have to think of what causes it to run rich. Its not a ton of things so Im trying to narrow it down.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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I would put a real time analyzer on your car and watch the O2, temp, etc readings to see what you are getting, parts replacing is just guessing and a waste of money.

How is timing set on that car?, could there be an issue with timing?, or timing advance?


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I just read that you said you were too lazy or cheap to get a OBD2 reader and you may just replace the downstream o2's because it may need it anyway

I believe your car is OBD1, and a reader is cheap for that, why parts replace, we are talking about $20 here

http://www.amazon.com/Equus-3123-GM-Code-Reader/dp/B000EVU8C0/ref=sr_1_4?s=automotive&ie=UTF8&qid=1293038025&sr=1-4


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I just read that you said you were too lazy or cheap to get a OBD2 reader and you may just replace the downstream o2's because it may need it anyway

I believe your car is OBD1, and a reader is cheap for that, why parts replace, we are talking about $20 here

http://www.amazon.com/Equus-3123-GM-Code-Reader/dp/B000EVU8C0/ref=sr_1_4?s=automotive&ie=UTF8&qid=1293038025&sr=1-4

96 is obd2, previous fleetwoods are obd1

For instance GM sent out a bulletin on how to remove the air pump on these cars because they werent necessary and just filled with water. On 94 and 95s you can just unplug and remove the airpump and plug the manifolds. On a 96 you have to have the computer reprogrammed to accept the missing air pump because of the obd2.

The display displays obd1 codes but its an obd2 system.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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I had a 96, so I know its OBD2, and my 96 didnt need a reader

I thought you were talking about the 83

Then I am confused, if you have a 96, why do you need a reader?

Does a 96 Fleetwood 5.7 display codes like my 96 Deville?


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I had a 96, so I know its OBD2, and my 96 didnt need a reader

I thought you were talking about the 83

Then I am confused, if you have a 96, why do you need a reader?

Does a 96 Fleetwood 5.7 display codes like my 96 Deville?

yes it will display codes but a detailed reader you will be able to see reading of what the sensors are sensing and how they are performing. So ive been told. People say you can see how the o2's are working and so you can tell if they are reading out of the range they should be.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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I know that I have been slammed for recommending Autotap in the past by someone who liked something else, but I like it. I can read real time data on my laptop, I cant change anything but I can read it and its relatively inexpensive, check it out

http://www.autotap.com/


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I know that I have been slammed for recommending Autotap in the past by someone who liked something else, but I like it. I can read real time data on my laptop, I cant change anything but I can read it and its relatively inexpensive, check it out

http://www.autotap.com/

Cool. Didnt know things like that were out there. $150 wouldnt be too bad if I make $10-$20 for diagnosing other peoples cars :)

So have you used this to find actual problems? Ive never used a scan tool either so I cant compare which is better but I would imagine seeing everything on a laptop would be alot easier to work with.


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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Well, when you said you were going to replace the O2 sensor, the neat thing about that program is that you can get real time data on them and I have seen when an O2 sensor is bad

See this link to a tech report at autotap, see the Sensor Diagnosis

http://www.autotap.c...gen_sensors.asp

See this fuel economy is down paper

http://www.autotap.c...conomy_down.asp

There is a DIY guide, download it, its pretty interesting


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Well, when you said you were going to replace the O2 sensor, the neat thing about that program is that you can get real time data on them and I have seen when an O2 sensor is bad

See this link to a tech report at autotap, see the Sensor Diagnosis

http://www.autotap.c...gen_sensors.asp

See this fuel economy is down paper

http://www.autotap.c...conomy_down.asp

There is a DIY guide, download it, its pretty interesting

Got it thanks!

It would be real nice to get into this sort of thing instead of guessing and throwing parts at cars like Im used to. I love doing things right but for some reason with cars alot of the info is hard to find or cost money like alldata. It seems like all some kind of conspiracy for mechanic shops to make money and keep the DIY'er from easily finding info. Great find thanks again!


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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No problem, Let me know what you need, I am a data packrat


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Some more updates of parts thrown at the car.

Rockauto was having a clearance sale so I bought some more parts.

I bought and replaced the 2 downstream o2 sensors. And I replaced the purge valve. I havent gone through enough gas yet to see any improvement.

Also I thought about the MAP sensor. They are $40 so Im not about to throw one of those at the car but I took mine off and cleaned it out a couple weeks ago. It was pretty oily inside. That alone didnt help mileage though.

With the fuel blend gas and cold weather I am back down below 12mpg just like last winter. I dont let my car sit and warm up either.

I also have found OBD2 scanners on ebay for like $20. Sure they are cheap, but they hook up to a laptop and people have given good feedback about them. Some say they even give graphs with certain software. Im wondering if these would be any good compared to a $100 reader or program. My experience with cheap electronics from china are that they work and do what they say but they either dont last very long or dont do as good as you would expect. But $20 is tempting.

YES I know Im cheap and I shouldve just bought a good scanner before doing all this tuneup stuff. But I dont feel guilty at all for what Ive done. The car 15 years old so replacing all these parts may not be 100% necessary but will be someday. Plus I havent spent all that much money.

If replacing all 4 of the o2 sensors and every other sensor I can think of doesnt fix the mileage I will either give up and accept the low mileage or then break down and get a good scanner. Im starting to run out of options.

A buddy of mines fleetwood is being stored for the winter and Im thinking about swapping MAF sensors with him to see what happens :D


* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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