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Okay, I got new plugs 41-950's. I plan to do the wires next weekend, but wanted to get new plugs going first. Now, I cannot find the gap for these. Not on the underhood sticker(s) and not in the manual. However, the manual lists the correct plugs as the AC 41-900's. :confused: I'm assuming the 41-950's are the replacements? So what is the correct gap? .050? Also, so you all use dielectric grease on your wire boots too? I have on all my vehicles, but haven't seen anything on this board regarding it. BTW, I have done searches on here but found nothing regarding my year vehicle. Thanks all! V.


I forgot: Is it easier to remove the plgs when warm/hot or cold? Thanks.
 

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A/C 41-950's superceedes the 41-900's

Gap is .050

No grease. You'll notice the OEM wires are prelubed and there is a note on the box to indicate so.

Remove them cold and save your skin.
 

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Thanks! I changed the plugs. Not bad at all. Anyone else cringe when remove plugs for the first time? I did. Luckily all was good. Normal wear, could of lasted the other 30000 miles. Decided to clean the throttle body; good Lord was it dirty!! The whole intake was filthy with oil sludge crud. Wondering why. Previous owner babied it too much? I sprayed quite a bit of throttle clear thru it, quickly assembled the air flow sensor and revved it pretty good. Hopefully cleaning a little bit of that crap out. Idles better now. Will replace wires tomorrow.



"Why the hell did I go through 15 vehicles before buying a Cadillac?? - idiot!!:helpless:
Thanks all for the great advice and help on this forum!! V.
 

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The oily deposits you saw in the intake are normal. I gasped when I saw it for the first time as well. It is residue from the PCV gasses that settle when the engine is shut down. Cleaning it is a waste of time. What needs to be cleaned is the throttle plate and the TB bore. In particular, the mating surface where the plate meets the bore when in the closed (idle) position.
 

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After the tune up and TB cleaning, you might want to disconnect the battery for about 60 seconds to clear out the learned values for idle, etc. Technically, it should pick up on the changes fairly quickly, but I feel reasonably confident that my car idled better after I did the disconnect. All it can hurt is clearing out your radio presets and resetting the clock. Might be worth a try.

I agree 100% with Ranger. Don't worry about the stuff inside the intake. It's normal and won't hurt anything. If it smells like gas, it could be a leaking FPR, but if you aren't having any hot restart problems, don't worry about it. Just drive it and enjoy.
 

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Ranger,

I have a 1998 Deville, Northstar with 77K miles - babied.

The car 'immediately' starts when cold, but after it warms up it takes several turns to get the car to start . . .

I had new plugs put in at 50K miles.

Also, how does one clean the throttle body plate & TB bore?

The car idles around 625, but feels a little rough.

I've cleaned the throttle body, put in a new ERG, air filter, fuel filter and added Seafoam to clean the fuel system, disconnected the battery for 2 hours, but still the above problems persist?

Comments please!

In advance, thanks . . .
 

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Hard hot starts are usually indicative of a leaky FPR. Check the Tech Tips section for a tutorial on checking it. It's very easy.

Cleaning the TB is basic. Block the throttle plate open, spray with TB cleaner and then scrub with a toothbrush and wipe with a rag til clean.
 

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Ranger,

i found the url:


Checked on the FPR parts, does my 1998 Deville Northstar take a nylon or stainless steel FPR ?

THX!
 

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The FPR itself is steel. The fuel rail is another story. You'll have to take a look, but I believe the '98 is nylon.
 

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Ranger,

My 98 Deville with the Northstar has 77K miles, with the original FPR.

If the FPR does not leak, is there still a chance the FPR is bad?

How often should these FPR be replaced?

Again, the car starts immediately when cold, but after it's warmed up, much harder to start, and while it idles around 625, it may go to 700, then back to 650 then 600, then 625.

Does this still sound like a FPR problem?

In advance, thanks . . .
 

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Ranger,

Could my problems be an engine temperature sensor, since, it immediately starts when it's cold, but difficult to start when it's warmed up?

Where is the engine temp sensor located?

In advance, thanks . . .
 

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FPR only gets changed when it leaks. If it doesn't leak, it's good. Hard hot starts are usually indicative of a leaky FPR or injector(s). I would doubt if the ECT sensor is the culprit. Have you pulled the DTC's? Have you checked the fuel pressure when the problem is present?
 

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Ranger,

I have not performed any of the tests trying to identify and isolate the problem.

With your last comments, I will begin the testing . . .

Again, thank you for your ongoing suggestions . . .
 

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Ranger,

I checked the FPR, and 'indeed' it was leaking through the vacuum side. I just replaced it with a new one, the car started. Now I have disconnected the battery for 1-2 hours, will then reconnect, and drive it around to see if it resolves the problem of hard starting when warm/hot, again the car always started immeditiately when it was cold.

Since there 'was' gas leaking into the vacuum side of the FPR, where did that gas go to, did it go back into the air intake or where did the gas go, and what problems would occur?

Again, in advance thanks . ..
:thumbsup::thumbsup::thumbsup::thumbsup:
 

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The gas was drawn into the intake manifold via the vacuum line then burned, so you where running rich. That raw gas in the intake acts like a choke on a carbureted engine. It assists in cold starting, but hinders a hot start. You should see a marked difference in hot starts as well as an improvement in your fuel mileage.
 

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Ranger,

Great explanation, thanks for your prompt and courtious replies . . .

I will post the results after I run the car for a week or so.

Again, THX!
:):):):)
 
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