: how reliable is northstars limp mode



Talamant3z
06-20-09, 01:11 AM
well i have always wonder reliable is the northstars limp mode? i have seen some post where some members will say u ran it too hot the heads are no good. but then i see another post that says dont worry about running it hot the northstar was designed to dirve 50 miles with no coolant. so which is it? can it mess up with one overheat or overload or can the northstar be ran 50 miles wit no coolant and the heads still be fine ?

Ranger
06-20-09, 09:32 AM
I was designed and tested to run for at least 50 miles with no coolant and not do any permanent damage. That said, I would only do that if I where being shot at.

AJxtcman
06-20-09, 10:16 AM
well i have always wonder reliable is the northstars limp mode? i have seen some post where some members will say u ran it too hot the heads are no good. but then i see another post that says dont worry about running it hot the northstar was designed to drive 50 miles with no coolant. so which is it? can it mess up with one overheat or overload or can the northstar be ran 50 miles wit no coolant and the heads still be fine ?

Please don't take this the wrong way, but how old are you?

If you put a flame thrower against aluminum it will damage it. End of story!

The damage is the part the part that is judgemental.

The PCM just shuts off up to 4 cylinders. This will produce less heat. 4 flame are less than 8. The PCM does not cycle all 8 of the cylinders. Just the same 4 all the time.

If you think that the engine was designed to be air cooled you are incorrect. It must have coolant in the system. The same 4 cylinders will be the hot ones and they will not cool down.

The oil in the engine will break down with in minutes of an over heated engine. That is another thing to remember

If the PCM killed 1-7 and 4-6 for 30 seconds and the 3-5 and 2-8 for the next 30 seconds it would be better. The duration of time could be 5 minutes for all I care and the cylinders probably aren't paired up correctly for harmonics, but I hope you understand my point.

Oh BTW this is NOT a Northstar thing. Most of GM's cars and trucks have it in the calibration. I am not sure about 4 cylinder engines, but all the V6 and V8 that I look at have it.

Ranger
06-20-09, 10:28 AM
The PCM just shuts off up to 4 cylinders. This will produce less heat. 4 flame are less than 8. The PCM does not cycle all 8 of the cylinders. Just the same 4 all the time.
Are you sure? I have always been under the impression and I remember the old Guru saying that it alternately shuts down each bank of cylinders via the injectors and pumps air through them to cool it. It would make absolutely no sense at all to only do one bank. I'm gonna go look it up now.

EDIT: Well, for the life of me I cannot find it. I'm sure it is in the FSM somewhere.

N*Caddy
06-20-09, 05:41 PM
I remember reading somewhere that limp mode means shutting down up to 4 cylinders. Then in the same material it was stated that the banks are alternated. I didn’t pay much attention on this but how can you match the “up to 4 cylinders” with “banks are alternated”?
So in a way (as per what I read) you are both right.

My guess, the limp mode is not ON/OFF, I would assume (per what I read) that initial just some cylinders are shut off (in a certain sequence – that would be a partial limp mode) up to the full limp mode witch involve 4 cylinder run (and for some reason all 4 are part the same bank).

But I would not make any bet on this, I might be wrong.



EDIT:

Further more…in the same material it was explained that limp mode is a pretty unique feature tried in other engines with no success, but it was not stated that Northstar is the only engine with this feature (but some how implied). The explanation why limp mode works in a Northstar was aluminum design (aluminum dissipates fairly easy the heat) and powerful enough engine to carry the weight of the vehicle in just 4 of the cylinders (there we go! again talking about 4 cylinders – more confusing).
But regardless, as Ranger stated I would not use the feature unless I am pointed with a gun.


Jake, have you forgot about me (I can take 1-2 days off any time providing 1-week notice)?

Ranger
06-20-09, 06:03 PM
Perhaps I took a little literary license with the "alternating banks" comment. That is how I recall it, but I did not mean to say that with any authority as I am not 100% positive. I am pretty sure that is is not just the same 4 cylinders all the time though.

N*Caddy
06-20-09, 07:30 PM
I am pretty sure that is is not just the same 4 cylinders all the time though.
That's for sure! :D

Now reading what I said maybe I shuld use more words:
"... up to the full limp mode witch involve 4 cylinder run (and for some reason all 4 are part the same bank and the banks are alternated)."

97EldoCoupe
06-20-09, 10:53 PM
Do NOT overheat a Northstar. Just as AJ said- oil breaks down quickly and thins out. If your engine starts to heat up, shut it down. Why take the risk- a head gasket job is cheaper than replacing the whole engine.

Yes aluminum dissipates heat quickly, but the engine has cast iron cylinders and steel valves. Keep this in mind.

Ranger
06-20-09, 11:12 PM
I don't think anyone is advocating using it in anything but an emergency.

Destroyer
06-20-09, 11:29 PM
It's all BS. The whole "N* system" is bogus. The "travels 50 miles without coolant" simply means it's LAST 50 miles. It is rather astonishing that GM saw fit to stress that the car can run 50 miles without coolant. Maybe they were trying to tell us something about the H/G problem ahead of time?:D

N*Caddy
06-21-09, 02:40 AM
I use to drive an air-cooled car. It had a 4-cylinder aluminum boxer engine. And the only mean of cooling was the fan in front of the engine and the 2 very small side mounted oil radiators (funny how no air from the fan was channeled over the radiators). Those engines were well known for pretty much every thing (starting with the lack of power) but never hear about one overheating ever. Well the belts driving the cams were breaking like crazy so the engine never had a chance to get enough mileage to overheat once…then the oil leaks. Aaa and the funniest issue ever had with an engine: after driving for say…3-4 miles at over 60 MPH the gap on the spark plugs was increasing for some reason. You suppose to take a break and re-gap the spark plugs. Then that engine had really hard time to start cold (wintertime or in rain forget-it take the other car). French peoples building cars…:histeric:

aac123
06-21-09, 05:21 AM
I beleieve that they are very resistant to heat from personal experiance, my 1999 deville got hot several times when the headgasket started to fail and i would "limp it" home or to the mechanic all the time. Hell i got so mad a couple times i tried to blow it up but just couldnt. Now fast-forward 2+ yrs, i did the headgasket job with norms inserts and felpro parts and did not take heads nowhere but the basement to clean up, no magna flux no nothing.

Just drove it 750 miles with WOT whenever i felt like it, mind u i live in NC and we have lots of hills.

The engine is high engineered quality, look at like this;u know how some people are smart as shit but do the dumbest shit in the world well thats what the engineers did. They made a high quality engine but didnt think about the 20 bolt holes being to small, if they would have used bolt holes like they are now headgasket problems would have never happened.

just my 2 cents though:stirpot:

tateos
06-22-09, 06:54 PM
I don't even know how anyone could go 50 miles in limp mode. I have had 2 N* engines fail due to HG and go into limp mode briefly - in both cases, there seemed to be very little power. I know they say it runs on 4 cylinders, but believe me guys - it feels more like 2 cylinders. My driveway is a hill, and it barely made it up that hill into the garage.

AJxtcman
06-22-09, 09:04 PM
Are you sure? I have always been under the impression and I remember the old Guru saying that it alternately shuts down each bank of cylinders via the injectors and pumps air through them to cool it. It would make absolutely no sense at all to only do one bank. I'm gonna go look it up now.

EDIT: Well, for the life of me I cannot find it. I'm sure it is in the FSM somewhere.

I am 100% sure I have the PCM calibration in front of me.

AJxtcman
06-22-09, 09:06 PM
It's all BS. The whole "N* system" is bogus. :D

Can anyone tell me what the Northstar System is? I am not talking about the thing on a boat!

The Northstar System is 100% a marketing illusion!
BS? :histeric: you called it.

97EldoCoupe
06-23-09, 11:35 PM
The Northstar System included a lot of interesting features, and yes, in my opinion, it is just a marketing tactic. The Limp Mode- (which, Destroyer, you hit the nail on the head about forseeing the HG failures :D), the Stabilitrak, Magnasteer, Magnaride, the fact that you cannot engage the starter if the engine is already running, all part of that "Northstar System".

Wonderful cars. A few things to improve but I love the Devilles, Eldorados and Sevilles of the late 90's/early '00's. They needed to be RWD!!!

N*Caddy
06-25-09, 06:36 AM
:yeah:
And the magnasteer, and the Stability System (accelerometers, yaw rate sensor) ...


Wonderful cars. A few things to improve but I love the Devilles, Eldorados and Sevilles of the late 90's/early '00's. They needed to be RWD!!!

I'll drink for that...

But then you wouldn’t be driving the 2-nd most powerful FWD car ever made, … still RWD will definitely be better.

DevilleRyDeR
06-30-09, 02:33 PM
I took my car to just brakes to get pads on all four wheels. They said I need all four rotors/calipers/pads. I found that hard to believe because i knew the pads were just low. I told him i would come pick the car up...........I get the car back and all my lights are on, tractions control, abs and check enginel light. I didnt notice any difference right away besides the lights being on.

Then a day or so i noticed i had alot less power. And just triggered me that i didnt have first gear! I drove for about a year with no first gear and my car runnin like ish. Thought I needed a new tranny. But come to find out the dumbass at just brakes didnt plug in one abs sensor. Plugged it in and wala first gear back in action. Car ran perfect from there.

SO point of story, is there two kinds of LIMP MODE? or was that just ABS MODE? LOL

STSS
06-30-09, 03:26 PM
Read through the rest of this thread, the limp mode they are talking about here is the "no coolant limp mode". Advertised as "50 miles at 50 MPH with no coolant"... good luck with that.

Your car locked out first because TC was turned off and it didnt want you to break something. Do some searching, its been covered.

Destroyer
06-30-09, 11:40 PM
Your car locked out first because TC was turned off and it didnt want you to break something.
Yeah, Northstars need no help breaking. They do just fine on their own!:thumbsup:

STSS
07-01-09, 02:43 PM
Yea, something about pushing 300 horse to the front wheels.

Does the Suzuki even have traction control?

N*Caddy
07-01-09, 03:53 PM
Does the Suzuki even have traction control?

:histeric:

Well said!

Destroyer
07-02-09, 12:01 AM
Yea, something about pushing 300 horse to the front wheels.

Does the Suzuki even have traction control?Head is still intact with the block.:lildevil:

Destroyer
07-02-09, 12:02 AM
Does the Suzuki even have traction control?Does it need it?:tisk:

STSS
07-02-09, 11:24 AM
Does it need it?:tisk:

You dont need TC if you cant spin the wheels.:spin: