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Discussion Starter #1
Hi all, working on my 94 eldo base.
94 Northstar 4.6, it's idling rough, and has a random misfire, I have:

Replaced the fuel pump
Replaced the FPR
Cleaned the TB
Checked my wires
Confirmed all coils are working
Replaced PCV valve
Done a vacuum leak check with an unlit torch (non conclusive)
And alot of general engine bay cleaning.
I'm gonna replace the injectors here soon, and do intake gaskets

Does anybody have a link to a guide for replacing the intake gaskets on the 93-94 4.6?

And what else do you guys think I should check out?

Thanks in advance!
 

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Currently working on an '01 Eldorado with similar code problems of random misfiring. However, the engine runs strong & has no performance problems.
In trying to get the misfiring code to clear, like your list of 'did that & that,' I changed out & did everything you did, & (cuz my Dad didn't raise any stupid sons,) I changed out the less expensive items first, the EGR, the crankshaft & camshaft sensors. To no avail.
Just bought the fuel injectors (a steal on ebay for Bosch made in USA or Germany for $170.! complete set) & hoping to rid the code problem with those, as there ain't much more to check out or change out.
Please post your progress.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Kingston, Your best bet for quick, useful info is a subscription to the online version of the GM/Cadillac 1994 service manuals. www.alldatadiy.com - or try to find a used paper set on eBay.

Kavash, your 2001 Northstar engine is VERY, VERY different mechanically from his 1994. Almost apples and oranges.

For the 2001 you need to pull trouble codes from the car's built-in scanner.
 

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White Diamond '03 DHS (with DTS floor shift)
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Does anybody have a link to a guide for replacing the intake gaskets on the 93-94 4.6?
The '93/'94 intake cover is functional, not a beauty cover like later years. Be sure to use the proper torque setting when installing it so as not to squash the rubber grommets. The cover is designed to lift and vent the intake manifold in the event of a manifold over pressurization aka backfire.

I believe the torque specs are 89 in/lb (7.4 ft/lb.).
 

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Discussion Starter #5
So I replaced my intake gaskets, the subscription site was a great help.

I have never seen such a buildup of carbon inside any intake I've seen in my life. The gaskets had visible leak spots on them, there was a mouse nest behind my starter (also 2 pairs of monarch wings??????) And from taking a boroscope down in the valves, it is IMMEDIATELY obvious someone ran ethanol in this poor old beast. Its still missing now and then at idle, but my injectors were also super cruddy, so new ones on the way.

I feel bad for driving the car like it was. And it still has the problem I started with, but again, Injectors.

It drives and cruises like a new car though, and it sounds correct now. Which is awesome.

Worth mentioning I also did an EGR delete.
584647
584648

Look at this! This one was MOLDY!!!
MOLD, WHERE THERE IS REGULARLY GASOLINE, absolute madness.
 

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White Diamond '03 DHS (with DTS floor shift)
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I have never seen such a buildup of carbon inside any intake I've seen in my life.
That is normal. It's a combination of exhaust gasses from the EGR and crankcase gasses from the PCV. When running, they get sucked through the engine, but when it get shut down, those gasses cool and condense out. Nasty but harmless.



it is IMMEDIATELY obvious someone ran ethanol in this poor old beast.
Probably the majority of these cars run 10% ethanol, not by choice, but because it is all that is available. I've been running it for 14 years and 100,000 miles, with no ill effects. It's just something we have to live with.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Absolutely nothing wrong with running an E-10 fuel. Ethanol is a powerful fuel system cleaner. Matter of fact, ethanol burns much cleaner than gasoline.

EGR and PCV will deposit some amount of condensed moisture, oil valor, blowby gases, and soot. Normal.
 

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Discussion Starter #8 (Edited)
Its good and fine that stuff deposits into the intake, but regardless the seals needed to be done.

I know how EGR systems work, and I'm familiar with what they do. This is my first OVERHEAD CAM engine with an EGR system. So a 1/4 inch thick layer of raw grossness anywhere in the intake looks awful to me.

I've also just replaced all 4 coils.

Now it's time for Injectors, which is what I believe to be my super low idle misfire. I've got one question, my current ones have a green blue seal that's abt a 1/2 inch tall on the bottom of them, and my replacements just have a regular o-ring. Should I worry about this/find a replacement set of these thick Injector boot things?

(The seals on the injectors in the car right now are super nackered, I know one is missing a chunk, I pulled it out of the intake.)
 
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