Page updated on 12-15-2017

A french caprice owner need help !


Serge PETIT
11-09-2010, 05:56 PM
One of my friend owned a 1988 Chevrolet Caprice equiped with the V8 305ci ( 5,0 L) type LG4 . The car has been imported from Canada and is in the Police configuration .

Having troubles with the EGR , he has removed the valve and now when starting the engine and when engine is cool he has a small black smoke ; He thinks that without EGR the engine runs more rich .
1) Is it right that it's more rich ?
2) Concerning the spark plugs is it necessary to change the AC Delco R45TS (origine) for cooler or hoter ones .
3) If the change is necessary have you any recommandation for the spark plugs ( Brand and type ) ?

Thank in advance for your help

j cAT
11-09-2010, 06:42 PM
One of my friend owned a 1988 Chevrolet Caprice equiped with the V8 305ci ( 5,0 L) type LG4 . The car has been imported from Canada and is in the Police configuration .

Having troubles with the EGR , he has removed the valve and now when starting the engine and when engine is cool he has a small black smoke ; He thinks that without EGR the engine runs more rich .
1) Is it right that it's more rich ?
2) Concerning the spark plugs is it necessary to change the AC Delco R45TS (origine) for cooler or hoter ones .
3) If the change is necessary have you any recommandation for the spark plugs ( Brand and type ) ?

Thank in advance for your help


the egr above idle flows exhaust gases thru the intake manifold. this heats up the intake causing better fuel vaporization, especially when cool and damp .............

this exhaust gas is injected into the intake manifold directly between the two primary carb jets..

remove the carb and make sure this opening is cleaned out to the egr valve..if this port is plugged the engine will run poorly and you will get run on after engine is shutdown..

use the correct plugs.make sure the wires are the proper resistance...high resistance wires will also create engine problems.


since this vehicle is this old , replace the ignition module inside the distributor...


the egr also reduces the combustion chamber temperatures. this is to reduce detonation[pinging]

cold start with black exhaust check the choke pull off diaphrams for vacuum leaks...clean linkages with throttle body cleaner do not use carb cleaner as it will damage the pull off rubber diaphrams,,,,.

Blt2Lst
11-09-2010, 06:58 PM
Spark plugs should be changed every 30,000 miles.
You can use AC, Champion, Motorcraft, should make no difference just get the right heat range.
I use Bosch Platinum Plus in my 89 with no problems.

Check other tune-up components while you are at it.
cap
rotor
wires
fuel filter
pcv valve
air filter
breather

silicon212
11-09-2010, 09:24 PM
the egr above idle flows exhaust gases thru the intake manifold. this heats up the intake causing better fuel vaporization, especially when cool and damp ...

You're confusing EGR with EFE or Early Fuel Evaporation. There's not enough EGR gas recirculation to heat up the intake charge, also EGR is typically not active when the engine is cold (that's the job of the EGR solenoid).

To the OP:

The car is carbureted. The carburetor has a choke on it, which is closed when the engine is cold. This is what causes the black smoke; it should clear up within a matter of minutes. You can adjust the choke to lean it out a little so the "smoke time" is reduced.

The purpose of EGR is to limit/reduce creation of NOx (oxides of nitrogen) emission, which photochemically reacts with unburnt fuel to create ground level ozone. It works by injecting a small amout of exhaust gas into the intake charge, to reduce peak cylinder combustion temperatures (which are generally determined to be the cause of the NOx creation). A failure in the EGR system will not cause the engine to become rich, although it could lead to dilution of the intake charge which could reduce power, and cause detonation (pinging during acceleration) due to the leaning of the charge.

Living in the Phoenix, Arizona metro area (Mesa), I run R43TS plugs in my own car. These are a cooler heat range plug which work well in the hot summertime temps we encounter here. I believe the book specifies R44TS plugs. You can check plug condition to determine if your heat range is correct - if the plug insulator inside the business end of the plug is pure white, the plug might be too hot - if it's dark, it is likely too cold. If it's whitish tan, it's about right.

Add your comment to this topic!