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Egr

2K views 8 replies 5 participants last post by  Volvord 784VC 
#1 ·
My 85 grand marquis has been getting very poor mileage, anyways I found that the egr valve was not connected to the vacuum line would this have caused the poor mileage? 302 with autolite 2bbl carb
 
#2 ·
Not realy. It may affect timing on distributor. But good spark leads, plugs,cap etc can do wanders..Good tune too...
 
#3 ·
Welcome to the forums.

Did it make a difference when you plugged it back in? I would try a new set of leads, plugs and a tune, that always helps.

Have you got a few pics of your car? I don't think i've seen an 85 Grand Marquis before.....
 
#6 ·
A disconnected EGR will not cause poor fuel economy, the EGR valve meters a quantity of exhaust gases back into the combustion chambers, since the exhaust gas is inert and will not burn it reduces the efficiency of the engine, this reduced efficiency lowers the combustion temperatures and reduces the amount of NOx emmisions. I am very familiar with the Grand Marquis, they are a great car, but very big and heavy, especially the mid '80's are not known for great fuel economy from new, the problem is more in the cam, compression, and heads.

Then you say poor milage what are you getting?
 
#9 ·
That is not surprising, but take a close look at your catalitic converter, they will plug and cause very bad gas milage, a good tune-up, make sure the timing is advanced to the factory spec's or even a bit more (to set, disconnect the vacuum advance, using a good timing light increase the rpm until full mechanical advance is obtained, then at that rpm adjust the timing to 34 -36 deg, finally reconnect the vacuum advance). This will usually provide the best milage and power, but watch for detonation and adjust the timing down if any is suspected.
 
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