intake 4.6l northstar

[leenorthstar]

i just replaced the intake on my northstar 4.6l . its the one with 2 plug wiring harness. it wont start or even try to start. does the computer need resetting. it turns over sounds like its not getting no gass, or fire. ?

[MrEldo97]

Check all of your electrical connections and grounds, and vacuum lines; really spend time and go over your car in great detail. Sounds to me like you missed a connector or ground connection or vacuum (MAP sensor?). The car ran fine before you changed intakes right?

[MAC]

i just replaced the intake on my northstar 4.6l . its the one with 2 plug wiring harness. it wont start or even try to start. does the computer need resetting. it turns over sounds like its not getting no gass, or fire. ?

What trouble codes do you see?

Simultaneously press the 'OFF' and 'WARMER' buttons on the Climate Control Panel and hold for about 4 seconds. Write the codes down and check the GM Diagnostic Trouble Code List.

[leenorthstar]

yes it ran fine before

[BodybyFisher]

Lets get a clarification here

You said you just replaced the INTAKE, do you mean, you replaced the ENTIRE INTAKE MANIFOLD?

Why did you replace the INTAKE, if it was running fine

[leenorthstar]

Lets get a clarification here

You said you just replaced the INTAKE, do you mean, you replaced the ENTIRE INTAKE MANIFOLD?

Why did you replace the INTAKE, if it was running fine

i replaced the ENTIRE INTAKE MANIFOLD because the passenger side expolded big hole in side of intake

[Ed Hall]

i replaced the ENTIRE INTAKE MANIFOLD because the passenger side expolded big hole in side of intake

This is a classic symptom of a bad FPR (Fuel Pressure Regulator). Make sure the new intake manifold has the rubber grommets and make sure you replace that FPR.

[leenorthstar]

i replaced the ENTIRE INTAKE MANIFOLD because the passenger side expolded big hole in side of intake

This is a classic symptom of a bad FPR (Fuel Pressure Regulator). Make sure the new intake manifold has the rubber grommets and make sure you replace that FPR.

ok thank you could you tell me were the FPR is located. do you have pic of it ?

[BodybyFisher]

Lets get a clarification here

You said you just replaced the INTAKE, do you mean, you replaced the ENTIRE INTAKE MANIFOLD?

Why did you replace the INTAKE, if it was running fine

i replaced the ENTIRE INTAKE MANIFOLD because the passenger side expolded big hole in side of intake

That is exactly correct, as noted above, there is a blow out plug, that blows so that the intake does not explode into pieces due to a serious backfire...

As noted, its probably a leaky FPR, its in the intake,

[Ranger]

i replaced the ENTIRE INTAKE MANIFOLD because the passenger side expolded big hole in side of intake

This is a classic symptom of a bad FPR (Fuel Pressure Regulator). Make sure the new intake manifold has the rubber grommets and make sure you replace that FPR.

ok thank you could you tell me were the FPR is located. do you have pic of it ?

The FPR is mounted on the fuel rail. On the '93/'94 it is inside the manifold.

[Cadillac Jim]

Do we have a scanned figure showing the intake manifold, FPR, fuel rails, MAP sensor, and such? I think that's what this guy needs.

[joeb]

a 96 intake is nylon. has plastic beauty cover. is a 93-94 also nylon with a metal cover? i replaced my intake with a used one. found out a 95 has different vacuum line fittings. pre OBD2 i guess. i ended up using a 98 aurora intake. identical. i think? maybe the ports are smaller?

[Cadillac Jim]

The 1993-1994 model years have an entirely different intake. The bolts that hold on the beauty cover also hold down the intake manifold, and I believe that the intake manifold is metal. Also, the EGR passages are in the heads in grooves under the intake manifold in those years. In 1995 and later, the EGR passages are external.

Is it possible that only the blowout cover was kicked out on your old manifold? If so, it's repairable.

I don't know what's interchangeable from the Aurora. It's similar to a VIN Y engine except the bore, I believe, it's 4.0 l, and it's rated at 250 hp.

I looked in my 1997 FSM at the intake manifold installation and the main things it talked about were the fuel injection wiring harness, connections, and ground connection. Other things on the intake manifold are the MAF sensor, the two-connector sensor, a small black square on the driver's side near the center, and the FPR, which looks a little like a vacuum diaphragm. The FPR is on the driver's side at the end of the metal fuel line near the firewall.

At this point I would look at all the connections for the fuel injection wiring harness, in particular the conections onto each fuel injector, plugging into the main harness, and the ground. Also, check the MAF wiring. Of course, look at anything else you have been working on to make sure that everything is hooked up. Then, try to start it, and with the key still on, run the OBD codes, write them down, and post them here. They will be like this example:

PCM P0192 CURRENT

The first three letters are an abbreviation of which module threw the code, and here we are looking for Powertrain Control Module (PCM) codes. The letter with four digits is the code itself. It will be followed by CURRENT if the code was thrown since the key was turned on, and HISTORY if the code existed when the key was last turned on.

Your display may differ slightly; for example the CURRENT/HISTORY may be a C or H instead of the whole word.

[joeb]

seems odd that the development team that designed the northstar would change the intake construction so much from 93 to 96. to go from all metal construction to nylon seems like a big jump. the block/heads did not change much but the whole induction system was redesigned. was it due to the obd2 stuff coming online around 96? i have found out that my blowoff flap has a bad gasket seal and whistles now. seems you cannot fix that other than to change out the intake.

[BodybyFisher]

seems odd that the development team that designed the northstar would change the intake construction so much from 93 to 96. to go from all metal construction to nylon seems like a big jump. the block/heads did not change much but the whole induction system was redesigned. was it due to the obd2 stuff coming online around 96? i have found out that my blowoff flap has a bad gasket seal and whistles now. seems you cannot fix that other than to change out the intake.

I found this, I guess this is why they also used the beauty cover. It is my understanding that the intake breaths better also:

The intake manifold is Nylon 66 thermoplastic, which helps cool intake air by conducting less heat from the engine.

Intake manifolds is another heavy component, especially today's variable length manifolds. Using aluminium alloy instead of cast-iron was just the first step. Many car makers now switched to thermoplastic manifolds made of Nylon 66 or other heat-resisting reinforced plastics. It's cheap, light and free-flowing, nearly a dream for car makers.

However, plastic manifold's biggest flaw is noise, which is considered to be too much for luxurious cars. Therefore Mercedes-Benz chose to use Magnesium manifolds. This material is even lighter than aluminium, although a bit dearer and less resistant to heat. No problem, intake manifold is not too hot. Like any metal, air flow in Magnesium pipes generates less noise than plastic one.

TVR's and Ferrari's V8 even employ Kevlar for intake manifolds

[KHE]

seems odd that the development team that designed the northstar would change the intake construction so much from 93 to 96. to go from all metal construction to nylon seems like a big jump. the block/heads did not change much but the whole induction system was redesigned. was it due to the obd2 stuff coming online around 96? i have found out that my blowoff flap has a bad gasket seal and whistles now. seems you cannot fix that other than to change out the intake.

They picked up an additional 5 HP with the plastic intake. There could be several reasons that the use of the plastic manifold. It is possible the proper plastic resin wasn't available when the gen 1 Northstar was designed. Plastic resins are continuously under development and new resins are available each year. It could also have been a cost savings - look at the components that the one piece plastic design eliminated. It could also have been market driven as in 5 extra HP.

[jackc]

The 1993-1994 model years have an entirely different intake. The bolts that hold on the beauty cover also hold down the intake manifold, and I believe that the intake manifold is metal. Also, the EGR passages are in the heads in grooves under the intake manifold in those years. In 1995 and later, the EGR passages are external.

Is it possible that only the blowout cover was kicked out on your old manifold? If so, it's repairable.

93 intake manifolds are a magnesium alloy box with a removable lid. There is no blow-out valve. Early 93 manifolds had no blowout protection. Rubber grommets for the cover bolts were added later as a kit, so that the cover could lift and vent in case of backfire. Be sure you're using those bolts and grommets on the replacement.

There are about 11 cover bolts, and 4 separate long bolts in the middle that mount the intake to the block. The intake can be removed without opening the cover.

Taking the cover off, the fuel rail is mounted to the underside of the plastic plate that also serves as the cover gasket. The fuel inlet and return lines are on the drivers side inside the manifold. The FPR is on the firewall side and goes between the fuel rail and the return line. Tug gently but firmly on the gasket/fuel rail assy and it will come up and out.

Personally, I'd go back with the guts from the old manifold and a new FPR. If it was running fine, that tells you the injectors and wiring were ok. A fuel pressure guage will tell you if it is holding pressure ok. Visual inspection for fuel leaks is darn near impossible inside the box.

Note - If you haven't seen it yet, there's an excellent diagram of the intake parts in this thread:

http://caddyinfo.ipbhost.com/index.php?sho...22430&st=30

[leenorthstar]

Do we have a scanned figure showing the intake manifold, FPR, fuel rails, MAP sensor, and such? I think that's what this guy needs.

i tryed to add a pic of my old intake, but it wont let me the hole is not fixable looks like its been shot with a shotgun lol . any of u can add me to yim leexx_xx and all show u my old intake, if i had a pic of what to fix i could probly fix it myself, everytime i take my car some were to get worked on. its so expensive . thank you all very much for helping me.

[Cadillac Jim]

The first Northstar was the 295 hp with metal intake manifold and internal EGR for the 1992 Allante, followed by an almost identical (the intake cams changed but nothing else to my knowledge) 270 hp companion in the 1993-1994 Seville and Eldorado. The Touring packages got the 295 hp, the Luxury packages got the 270 hp.

The first change came with the 1995 model year, which still had OBD I, I believe. The intake manifold became nylon, and the heads were changed for external EGR. The intake manifold change brought 5 more horsepower for both versions. The 1995-1999 Northstars were virtually identical, any differences being mounting of accessories. I'm not sure what these were or when they occurred, but I believe that there are only two versions in the 1995-1999 model years. The Northstar replaced the last 4.9 liter OHV engines in the rest of the line by 1995.

There was another design in 2000 for roller tappets, and in 2002 for VVT and 320 hp. Supercharged versions were introduced for the STS-V and XLR-V. I do believe that these are likely the last Northstar V8's. They will be around for a while for the larger cars and the halo cars -- we will always need a DeVille and a commercial chassis for limos and hearses -- but the V6 has already become the de facto engine for the majority of the daily drivers.

[Cadillac Jim]

The first Northstar was the 295 hp with metal intake manifold and internal EGR for the 1992 Allante, followed by an almost identical (the intake cams changed but nothing else to my knowledge) 270 hp companion in the 1993-1994 Seville and Eldorado. The Touring packages got the 295 hp, the Luxury packages got the 270 hp.

The first change came with the 1995 model year, which still had OBD I, I believe. The intake manifold became nylon, and the heads were changed for external EGR. The intake manifold change brought 5 more horsepower for both versions. The 1995-1999 Northstars were virtually identical, any differences being mounting of accessories. I'm not sure what these were or when they occurred, but I believe that there are only two versions in the 1995-1999 model years. The Northstar replaced the last 4.9 liter OHV engines in the rest of the line by 1995.

There was another design in 2000 for roller tappets, and in 2002 for VVT and 320 hp. Supercharged versions were introduced for the STS-V and XLR-V. I do believe that these are likely the last Northstar V8's. They will be around for a while for the larger cars and the halo cars -- we will always need a DeVille and a commercial chassis for limos and hearses -- but the V6 has already become the de facto engine for the majority of the daily drivers.

[leenorthstar]

The 1993-1994 model years have an entirely different intake. The bolts that hold on the beauty cover also hold down the intake manifold, and I believe that the intake manifold is metal. Also, the EGR passages are in the heads in grooves under the intake manifold in those years. In 1995 and later, the EGR passages are external.

Is it possible that only the blowout cover was kicked out on your old manifold? If so, it's repairable.

I don't know what's interchangeable from the Aurora. It's similar to a VIN Y engine except the bore, I believe, it's 4.0 l, and it's rated at 250 hp.

I looked in my 1997 FSM at the intake manifold installation and the main things it talked about were the fuel injection wiring harness, connections, and ground connection. Other things on the intake manifold are the MAF sensor, the two-connector sensor, a small black square on the driver's side near the center, and the FPR, which looks a little like a vacuum diaphragm. The FPR is on the driver's side at the end of the metal fuel line near the firewall.

At this point I would look at all the connections for the fuel injection wiring harness, in particular the conections onto each fuel injector, plugging into the main harness, and the ground. Also, check the MAF wiring. Of course, look at anything else you have been working on to make sure that everything is hooked up. Then, try to start it, and with the key still on, run the OBD codes, write them down, and post them here. They will be like this example:

PCM P0192 CURRENT

The first three letters are an abbreviation of which module threw the code, and here we are looking for Powertrain Control Module (PCM) codes. The letter with four digits is the code itself. It will be followed by CURRENT if the code was thrown since the key was turned on, and HISTORY if the code existed when the key was last turned on.

Your display may differ slightly; for example the CURRENT/HISTORY may be a C or H instead of the whole word.

heres the codes it gave me pcm? s011 p109 s030 so49 so44. anybody know of a caddy mechanic in louisville kentucky, im kinda lost on this engine. tyvm for all your responds .ss . lee

[Cadillac Jim]

These are OBD I (1995 and earler) codes:

S011 Left Front Damper Solenoid Valve Short to Ground/Open

P109 (E109) Keep Alive Memory (KAM) Reset/PCM has lost primary battery power

S030 Speed Sensitive Steering Fault

S049???

S044 Lift or Dive Signal Fault

There is no S049 OBD I code that I could find. Possible typos:

A049 HVAC - Coolant Temperature Too High

P049 (E049) Air Injection Reaction (AIR) System Fault

None of these account for a no-start condition. None of them relate to the intake manifold. You have a connector off of the left front shock, if there is such a thing.

Back to basics: Buy or borrow an FSM and use its instructions to take the intake off, then put it back on.