188k on mine without any major issues. Granted it's an 03 and I've added a shift kit and trans cooler. I've also been religious about fluid changes and have a nice tune on the car as well.

*shoot* situation for OP one way or another, but depending on the shape of the car and how much work it ...

I know this is an older post but I'm going to throw this out here...

91-92 L27 was 8.5 : 1 compression and 93-95 L27 was 9.0 : 1 compression..

You could use the 91-92 heads on the 93-95 block... 95 units used the series 2 crank and had a one year only balancer as well.

Has the Mass Air Flow Been checked? The fueling system on the older Bonnevilles is dependent on that MAF reading correctly.

I use Valvoline Max Life and Havoline( Dexron IV ) Both Licensed by GM

I have used Pennzoil and Pennzoil synthetic for a long time with no issues.. My old 91 Bonneville always had some valvetrain noise on a cold start but was quiet after a couple of minutes.. It always had great oil pressure as well.. It was like this till it met the car graveyard..

My 95 Thats been ...

97 had the 4T60E for the NA and 4T65E for the L67 Supercharged. But the NA tune will only control the 4T60E properly, and the L67 tune will only control the 4T65E properly.. If ZZP finds a way around this please let us know.

There is no crank learn or the like on these older ECM's... The ECM simply learns over time.. all of the basic info such as the tune are stored on the MEM-CAL Chip..

I agree with Randall, look at the crank sensor, ICM( Ignition Control Module )... Fuel pulse at the injectors and fuel pressure.. And ...

Some Bonnevilles had the F41 suspension( Firm Ride and Handling )

The 96 SSEi had keyless as standard equipment, The 96 SE is a tad different.. If the 96 had option group 1SB keyless was an option, if it was option group 1SC or 1SD it was standard.

The 97 PCM with the with a 97 SSEi tune will only properly control the 4T65E.. The 65E only uses a PWM solenoid for TCC lock.. Where the 96 4T60E uses a TCC on-off and PWM apply Solenoids So the 96 4T60E will never lock up with the 97 L67 Tune..

The codes you see are due to the PCM receiving no ...

Both the 92 and 95 Bonneville 4T60E use the PWM strategy... But they are wired differently internally... I really wouldn't go backwards from 94- 95 to 92, but I would go forward like 96 and or 97 as the 4T60E was improved for those years.. the 94-97 4T60E for the H body is wired the same.. 92-93 is ...

Congratulations !! Looks beautiful

I'm just glad you found that Darcy... Good to see another classic still running the road

I know I'm late to this ball game... But I would check and see if there are any Transmission Range Switch failure codes

did the balancer rub on the wires at all? That is fairly uncommon among the 3800's unless that wire/wires pop out of the holder.. But with the wire loom being destroyed the wire rub would be possible.

Look to see if you have a code P1361

All 3800's used a 195 T-Stat and had a high speed fan turn on of 227F, low speed was 210-212F..

The older Bonneville 88-99 had better cooling systems tho..

The 00-05 Bonneville had a skinny radiator and no option for HD cooling.. My 03 would spike to 225 on the highway climbing the mountains.. I ...

It could possibly be a drain or an alternator issue... I have seen strange things from time to time on the older H bodies.. And you never know you could have relay stuck on draining power some.. Could even be the RAC module.. Hard to point at any one item..

I was using Wal Mart batteries, had some ...

Essentially, it's to dial the combustion temps down a bit, hopefully out of the range that causes NOX emissions.

With no EGR, the early L27's were slightly more susceptible to burning valves.

This 100%... The 1991-1992 did not need an EGR valve to pass emissions, yes they were that clean even ...

This is not a great picture, But its what I used on my 95 Bonneville, My 03 Bonneville and I used the same kit to build the lines for my Van engine swap.
http://img.photobucket.com/albums/v294/Jr3800/Jrs3800/DSC_0257_zpsn7aflebm.jpg


This is the kit I used.. Again pics aren't good.. I used this ...