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NEW SMALL PROBLEMS WITH OUR DEVILLES


caddyon20s

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Hi my friends deville has a P0300 Random/Multiple Cylinder Misfire Detected, the car hesitates a lot he told me to take a look at the engine, i looked at it at night and there wasnt any spark light, nor tik tik noise from a bad wire, but car engine would vibrate a lot. what could be the cause of this??? he said he replaced the spark last week ac delco ones and that he had to remove the spark plug coil to get to the back plugs, could this be a bad spark plug coil or maybe the spark plugs them selves?? he didnt gap the spark plugs.

in my case my deville keeps on having the p0440 code Evaporative Emission Control System Malfunction, i lost my factory gas cap i bought another one from orrelly auto parts and im still getting this code, what could be wrong to make my car have this code? thanks everyone

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Are you sure that the spark plugs are the exact AC/Delco plugs recommended for your car? If so, then first, make sure that the wires from the coils are to the correct plugs. This simple error is easy to make. Then, make sure that the plug wires are properly attached to the coils, and the plugs, and that they are routed properly (i.e., they way they came on the engine from the factory, or check your FSM). The plug wires have been known to couple spark from one plug to another when routed improperly. Also, you should check the plug gap because you never know if somebody dropped a box of plugs or whatever.

A vented gas cap can cause your EVAP code. Get an OEM one that is recommended for your car and the EVAP code should go away.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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hi, today my friend told me that his 98 deville seems to be consuming coolat, he said he top off the reserve tank and that this morning it was almost empty, i checked the oil and it seems to be at level and opened the oil cap and i dint see any chocolate looking oil, the car doenst seem to leak any coolant but it did started to hesitate a lot throwing code p0300, what percentage northstar engines from 96-99 could fall into the head gasket problem??? i bought my 99 deville 123kmiles and i had the head gasket problem, i know if another guy that got a 94 concourse head gasket, i know of another guy with a seville and yes same head gasket, i went to a mechanic shop today they had a 97 seville i asked them what was wrong with it they said head gasket wtf??? i love my car but since i have an used engine with about 100kmiles now im pretty worry again of a head gasket problem what yall think??.

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Our poll showed that about 15% of Northstars will eventually have blown head gasket. Timely change of coolant accompanied with a doze of fresh coolant supplement (Bar's Leaks or similar GM tablets) should noticeably decrease the possibility of such a failure.

The saddest thing in life is wasted talent

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Wait a minute. Coolant supplement tabs have absolutely nothing to do with head gaskets. Neither repairing nor preventing.

Have a cylinder pressure test done. Sounds like another head gasket.

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yep it does, it suck for my friend cuase he just bought it spend all his money on it and it seems to have a blown head gasket, exact same thing happen to me i spend all of my money on my deville and a month later the head gasket problem cost me around 2700 parts and labor to repair so i was broke for a long time. now everytime i see a nothstar engine i have this back feeling of blwo head gasket.

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An awful lot of GM 3.4 Liter V6's have intake manifold gasket coolant leaks, too, and for the same reason: not changing the coolant before it goes out of date and becomes corrosive to aluminum. Since most modern engines have major aluminum components, and the new red coolant has removed consumer consciousness of the necessity of changing antifreeze every year or so, corrosion problems in cars 6 years old or so are becoming common.

Check out the Timesert web site. You will see that they sell stuff for everything, and that GM, Ford, Honda and Volkswagen all apparently use them for OEM dealer repairs.

It seems that keeping the coolant changed is more important in modern engines than keeping the oil changed.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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It's kind of like the chicken and the egg theory. Did the threads pull and cause the gasket to leak or did the gasket deteriorate (from lack of cooling system maintenance) and allow coolant into the threads which then caused corrosion due to galvanic action (thus the threads pull).

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