84 LeSabre Custom Emissions

[Guest]

Hi, Just bought the car with 124K for a work vehicle. 307 Olds, 4 bbl Automatic . It's in great shape interior and body...and it runs ok but with a slight miss at idle. I think the CEL is dis-abled and most of the Vacuum lines and sensors are dis-connected and plugged. Can anyone point me to Emissions info (diagrams Etc.) on this car?

I've been surfing for 3 days and having trouble finding any info to help me put the emissions systems back in shape. The decal in the engine bay isn't readable and the Chiltons manual isn't very helpfull.

Thanks Alot

[NTX5467]

Any diagram you find in an aftermarket service book will probably be "representative" and not entirely accurate for your particular vehicle. GM stopped putting emissions vacuum diagrams in their service manuals in the later '70s so they could do updates without having to issue revisions for the service manuals. That leaves the underhood emissions decal as the best and most accurate source of information, unfortunately.

It might be possible to still get one from GM Parts, but I'm not sure about that. If it's discontinued AND you can find a GM Parts department that has a paper catalog from back then to find the original part number for the decal (which also might be on the decal somewhere too), they can probably (or used to be able to) call GM ParTech and have them pull a print of the decal and fax it to the dealership.

The fax will only be in black and white whereas the decal was in color. The decal will also detail what emission controls are on the vehicle too, with abbreviations up in one corner of the decal. Once you decode the abbreviations and identify the components of those various subsystems, it might make more sense. It seemed that those engines had more vacuum lines than any other GM engine back then--much less Ford V-8s.

Back then, most of the modulation of the systems was controlled by ThermoVacuumSwitches with about the only electrical signals to the ECM being for heat, oil pressure, exhaust oxygen content, and engine speed. Typically, the tvs switches had GM part numbers cast or stamped into them and were color coded (which helps greatly). There's also an AC-Delco Emissions Parts Book that details what particular items are on each year of GM vehicle/engine combination back then--plus pictures (another great place to look, but still no vacuum hose maps).

The computer systems for the engines were much less sophisticated than they are now also. You might also get a reputable shop to pull the codes and check them against the codes for that PARTICULAR YEAR of GM codes (back then, codes could change from year to year as to what they meant). That might be a good place to start!

Those were good, solid cars back then. Hope this helps.

NTX5467

[gungeey]

I remember the decal on my '85 LeSabre(w/307) didn't have quite the complete map you need. It shows the routing of the major vacuum lines. I can clearly remember this because there was a vacuum line at the rear of the carb, along with a few others, that was left undone by a "PRO" mechanic at some point to pass a state emissions test. the underhood diagram didn't illustrate every detail...in other words, wasn't exactly a snapshot of the engine compartment...besides, your local salvage yard must have a dozen of this car readily available to view the sticker and perhaps the vacuum routing.

My suggestion: undo the EGR valve and tap it with a plastic hammer to loosen up all the carbon in there...don't put it in a vice...while it's off ram a coat hanger down the passages on the intake and see if they're clogged.Steve

[NTX5467]

If in fact, the EGR has a bit of carbon where the plunger for the valve seats in the intake manifold, also make sure that the seating area hasn't degraded. Some of those Olds V-8s with aluminum manifolds were also known to have some problems in other areas too. It might also have a valve that's just starting to "burn" too, causing a slight miss that is only felt at idle too.

If the Check Enging Light is on, pull the codes and go from there.

If the vacuum line is part of the a/c vacuum harness or another non-engine-related vacuum harness, it will not be listed on the emissions decal's vacuum hose diagram.

These cars were also known to have problems with the Canister Control Valve, which controlled when the charcoal canister purged and how much. It's a several tiered round valve that will be suspended by the vacuum lines it attaches to near the front of the engine. If raw gas is in any of the vacuum lines, the valve is bad. When it completely fails, it will "fog mosquitoes" out the tailpipe when everything else is operating as designed. A small valve that can make a huge difference in what comes out the tail pipe.

Those cars with the Olds 307s were also known to have clogged dual bed catalytic converter problems back then. Now, an aftermarket converter would probably be a good emissions legal fix.

Enjoy!

NTX5467