D-body was longer. I had to add length to the exhaust in front of the mufflers. My Fleetwood also had a factory 9.5" 14-bolt, so I had to slightly rework the tailpipe section as well. The Fleetwood I had was ordered with the commercial chassis package but it was never stretched into a limo/hearse/flower car. It had the trunk mounted factory rear ac as well which was great for a black car in Texas heat.

 

D-body was longer. I had to add length to the exhaust in front of the mufflers. My Fleetwood also had a factory 9.5" 14-bolt, so I had to slightly rework the tailpipe section as well. The Fleetwood I had was ordered with the commercial chassis package but it was never stretched into a limo/hearse/flower car. It had the trunk mounted factory rear ac as well which was great for a black car in Texas heat. The one I had was also special ordered by one of my great uncles that worked at the Arlington, TX assembly plant. Never should have sold that car. He used it to tow a large pontoon boat. IIRC it had 3.73 gears in it. Being a 93 it had a TBI 350 that was pretty weak wristed and a 4L60(700r4). But being a service car it had an add on transmission cooler, an engine oil cooler, larger radiator and a clutch fan. It also had a LT1 F/Y-car style traction control setup. Car had a burned exhaust valve when I got it and I picked up a set of the ZZ4 heads new from GM. They were pretty inexpensive in the mid 2000s compared to refreshing the swirl ports. I left the stock peanut roller cam in it and added 1.6 rockers. It had great torque and ran very well with the head swap and dual exhaust.

Was always funny to me knowing that 93 Fleetwood had a big old 3/4 truck rear end under it with good gears and a G80 locker.


Mine had the same rear ac controls. Car would freeze you or cook you out of it.


Sorry to get so off topic but I love those old B/D body cars. Definitely brought back good memories.

I bet the emissions RPO codes are part of it. If you look at GM calibration database for a single model year of the same vehicle and engine size there are often 10-15 different factory calibrations. I sure some are California, some are Federal, some are Export, some were leaded fuel compatible, etc. That is not even including the vehicles GM built for the federal goverment that often had zero emissions system to them at all. There were a bunch of 350 TBI trucks that were built for the miliary that had the EGR openings in the intake manifold cast shut, no cats, no evap canister, and even lacked an 02 sensor at all, completely open loop and they could run on leaded fuel. A couple of years ago it was documented by someone with a keen eye that Ford was building F350/F450 6.7Ls that were completely factory deleted for the US Military.

Factory TBI manifold with the EGR opening cast shut.


Also as I mentioned before, you could order the factory GM EGR delete pieces for like $20 for a Vortec straight from a GM dealership parts department up until they discontinued them as well.

 

Back to the topic at hand. I stumbled across this in open source. I set it to Zero. Will see if it does anything helpful.

 

Back in the old days, I seem to recall that the factory limo chassis Fleetwoods were called a "75" (vs. a "60" for the normal Fleetwood). Was that still the case for your '93? But in those days, the 75 was actually longer to start with, even before being stretched by a coach company.

Very cool that your '93 came with that axle and the rear A/C. I wasn't even aware of that package. Mine was a 'normal' Fleetwood but was factory ordered by my Grandfather. It had K4C & KD1 oil coolers as well as V03 (which I think was a higher wattage electric fan, but not the 7-blade clutch fan that was part of the towing package). In this engine bay shot you can see the forward mount cooler:



I probably should've kept mine too, but I opted to let it go as part of a major move that I made about 7 years ago. I just had no where to keep it, and it had sat so long that it needed a ton of freshening up. To this day, I have still not seen a last gen Fleetwood that had a later VIN number. I suspect this one was part of the final batch of production (which had been delayed several months, hence the 11/96 build for a 1996 model). I've heard that some B-bodies were still coming off the Arlington line as late as 12/96, but I think the final D-bodies were all in November. This one was delivered very late, Thanksgiving weekend if I remember correctly.

 

More on that same line we were talking about the other day. 05/2003 production Avalanche. Factory block off plugs and no rear 02s.




I may try another method to get around the prolonged catalyst/rear 02 testing events as it seems it is enabled even in these trucks despite not even having rear 02s. I am thinking of piggybacking the front 02 sensor signal wiring to the rear 02 sensor pins at the PCM. I just do not know if it is going to freak out the PCM having 2 bias voltage sources pinned to the same 02.

For the record setting the Catalyst Test I posted above to 0 did not correct the issue and the issue persists until the 02 monitor test passes after 40-100 miles of driving.

I have another work around I have used for a while to prevent it from causing me issues tuning. I filter the data in HPT to only log the fuel trims when commanded AFR = 1.00 lambda. That atleast filters out the whackiness when you are trying to make back to back tuning adjustments without having to drive 40-100 miles on a Green tune for the testing to be finished.

Similarly when I am tuning I run the High Octane timing table in the Low Octane table as well so that the knock learn is not messing with the ignition timing. When I am done tuning I pull some timing out of the higher loads in the low octane table to re-enable the knock learn in the event I get a bad tank of fuel. i only do that though if the fuel level sender is wired through the PCM. I have learned that you really need the fuel level sending unit wired through the P01/P59 for the knock learn to work correctly otherwise some OS will often hang in the low octane table permenately as fuel level change from refueling is a reset trigger. I have learned a lot about the inner workings of these older PCMs tuning swaps in non OE applications. Another odd one I ran across a while back on my P59 24x DBW swapped 97 Express using a 2005 6.0L truck based tune. The van suddenly gained traction control. Turns out those 96+ ABS units communicated to the stock Black Box via serial data from day 1. The PCM has all the wheel speed data from the ABS. Spin the tires hard and suddenly out of nowhere traction control aggressively cut power. I found that a friend of mines DBC P59 1996 K1500 was doing the same via ignition timing retard. When he spun the tires the P59 was aggressively cutting ignition advance and shutting down injectors.