: Northstar Experts Please Stand Up.....



1993 eldorado green1
03-17-06, 02:58 PM
hello again,

well i got another cadillac, this one is a 1995 eldorado etc that is super clean inside and out and the best part is i only paid 500.00 for this car!

paying 500.00 for a car like this means it probably has horrible troubles like it does. Ill give a quick run down on what it has and what its doing.

1995 etc with a 1997 motor that has 59,xxx miles on her

it was owned by a older gentelman who at 1 time was a bodyman at a cadillac dealership here in michigan. well the car had the typical oil leaks so he decided to pull the motor and replace all the gaskets. he knew nothing about the northstar and did all this work with a haynes manual.

well he finally got the car running but it wont run right so he gave up and thats how i got the thing. i pulled the codes to find that it had p015 p083 p137. i replaced the coolant temp sensor along with fresh wires, plugs and an oil change.

i since have also reeset all the codes and tried it again. the car runs AWSOME above 1300 rpms, smooth as glass and has plenty of power. no smoking no leaking nothing.

i rechecked the codes to find p083 as current still and the idle is HORRIBLE!! it idles as if there is no motor mounts left but there new. i cant seem to figure this one out. is it possible that he bent the valves when he put the motor back together? something simple with that code that could cause this problem? its not like a dead cylinder miss, its like a horrible shaking and it sounds funny through the exhaust aswell.

if the cams were off a tooth or something would it cause this? im stumped...

well, any help or replies about this would be sweet!! ill be outside working on her and checking this soon...

thank you jim

eldorado1
03-17-06, 03:40 PM
Need some more information. Is it running the original 1995 OBDI?

If the OBDI, you're going to have a problem, because it's expecting a throttle stop switch so it knows it's at idle. The 1997 throttle body doesn't have that. SO, I'm guessing that you swapped the 1995 throttle body on?

If that's the case, P083 is a 24x reference signal high. It sounds as though one of the crank sensors is suspect. The engine can run on 1, but it won't run very well. The problem is, to correctly diagnose it, you need to disconnect one crank sensor at a time while the engine is running. Obviously you don't want to get under the car to do this, so you have to have a special tool to disconnect it at the ignition module. The easy thing to do is to take it to a dealer. The "shotgun" thing to do would be to replace both crank sensors.

It also could be a bad ignition module (or wiring). Again, a diagnosis would pinpoint or eliminate that.

P137 is loss of ABS/TCS data, you don't need to be concerned with that right now.

1993 eldorado green1
03-17-06, 05:48 PM
Need some more information. Is it running the original 1995 OBDI?

If the OBDI, you're going to have a problem, because it's expecting a throttle stop switch so it knows it's at idle. The 1997 throttle body doesn't have that. SO, I'm guessing that you swapped the 1995 throttle body on?

If that's the case, P083 is a 24x reference signal high. It sounds as though one of the crank sensors is suspect. The engine can run on 1, but it won't run very well. The problem is, to correctly diagnose it, you need to disconnect one crank sensor at a time while the engine is running. Obviously you don't want to get under the car to do this, so you have to have a special tool to disconnect it at the ignition module. The easy thing to do is to take it to a dealer. The "shotgun" thing to do would be to replace both crank sensors.

It also could be a bad ignition module (or wiring). Again, a diagnosis would pinpoint or eliminate that.

P137 is loss of ABS/TCS data, you don't need to be concerned with that right now.



yes, the car is still running the obd1 and im not the original person who swapped the motor. the car was running perfect until the previous owner took the engine out to replace the gaskets, it has never ran the same since then..

question.. if the cam timing was off, (he told me he wasnt sure how to align it the right way) could it cause the p083 code? thats what im trying to figure out right now.. im on my way to get a compression tester right now to check compression and see if that narrows down any of this.

i figure if the cam/s are off the compression would vary from front head to rear head since he only replaced the front head gasket.. if the comp looks good then i will probably just put some new crank sensors in it and see what that does..

are the crank sensor plugs interchangable? like is it possible that he just has them plugged into the oppsites? like the plug for cs a plugged into cs b?

1993 eldorado green1
03-17-06, 05:49 PM
Need some more information. Is it running the original 1995 OBDI?

If the OBDI, you're going to have a problem, because it's expecting a throttle stop switch so it knows it's at idle. The 1997 throttle body doesn't have that. SO, I'm guessing that you swapped the 1995 throttle body on?

If that's the case, P083 is a 24x reference signal high. It sounds as though one of the crank sensors is suspect. The engine can run on 1, but it won't run very well. The problem is, to correctly diagnose it, you need to disconnect one crank sensor at a time while the engine is running. Obviously you don't want to get under the car to do this, so you have to have a special tool to disconnect it at the ignition module. The easy thing to do is to take it to a dealer. The "shotgun" thing to do would be to replace both crank sensors.

It also could be a bad ignition module (or wiring). Again, a diagnosis would pinpoint or eliminate that.

P137 is loss of ABS/TCS data, you don't need to be concerned with that right now.



yes, the car is still running the obd1 and im not the original person who swapped the motor. the car was running perfect until the previous owner took the engine out to replace the gaskets, it has never ran the same since then..

question.. if the cam timing was off, (he told me he wasnt sure how to align it the right way) could it cause the p083 code? thats what im trying to figure out right now.. im on my way to get a compression tester right now to check compression and see if that narrows down any of this.

i figure if the cam/s are off the compression would vary from front head to rear head since he only replaced the front head gasket.. if the comp looks good then i will probably just put some new crank sensors in it and see what that does..

are the crank sensor plugs interchangable? like is it possible that he just has them plugged into the oppsites? like the plug for cs a plugged into cs b?

eldorado1
03-17-06, 05:59 PM
question.. if the cam timing was off, (he told me he wasnt sure how to align it the right way) could it cause the p083 code? thats what im trying to figure out right now.. im on my way to get a compression tester right now to check compression and see if that narrows down any of this.

i figure if the cam/s are off the compression would vary from front head to rear head since he only replaced the front head gasket.. if the comp looks good then i will probably just put some new crank sensors in it and see what that does..

are the crank sensor plugs interchangable? like is it possible that he just has them plugged into the oppsites? like the plug for cs a plugged into cs b?

I don't think bad timing would cause a p083. The book says a p083 would be set if NO 24x pulses were recieved since the last cam pulse. You would likely have a different code(s) set.

The crank sensor plugs are interchangeable - but I *think* they're color coded so xxx is on top, yyy is on bottom. I have mistakenly switched the crank sensor plugs before, and as I remember it, it either didn't run, or it ran so poorly that I immediately shut it off and checked it over. It's worth a try.

1993 eldorado green1
03-17-06, 06:27 PM
I don't think bad timing would cause a p083. The book says a p083 would be set if NO 24x pulses were recieved since the last cam pulse. You would likely have a different code(s) set.

The crank sensor plugs are interchangeable - but I *think* they're color coded so xxx is on top, yyy is on bottom. I have mistakenly switched the crank sensor plugs before, and as I remember it, it either didn't run, or it ran so poorly that I immediately shut it off and checked it over. It's worth a try.



cool, ill give it a try. it runs great except at idle. i can also smell raw fuel like its running way too rich.. hope it can all be related and its something simple.

it is possible that if he set the cams wrong that those valves are bent now and that would be awfull

eldorado1
03-17-06, 07:02 PM
I believe the northstar is an interference engine, so yes. It wouldn't run good under any conditions though, so I doubt that's your problem.

Ranger
03-17-06, 09:14 PM
cool, ill give it a try. it runs great except at idle. i can also smell raw fuel like its running way too rich.. hope it can all be related and its something simple.


Raw fuel? Have you checked the FPR?
Eldorado may be on to something. You are running an OBDI PCM with an OBDII motor.

Zorb750
03-17-06, 09:56 PM
Right. Interference.

Zorb750
03-17-06, 09:57 PM
1995-1999 are interchangeable with the exception of the intake manifold and throttle body. There are no other differences.

Zorb750
03-17-06, 09:59 PM
Cam timing actually could cause this, if it's off just by a bit. I think advanced but could be wrong. It may not be enough to at the valves hit the pistons.

auroradude
03-17-06, 10:38 PM
What the heck. I didnt even know you could run an OBD2 engine on OBD1. I know you could convert them for hundreds of dollars but still. Thats nuts.

Zorb750
03-18-06, 01:55 AM
The one in my Eldorado right now came from a 1995 Deville Concours. The intake manifold, TB, Cruise, and all related components are from my 1997 engine. Literally unbolt the 1995 manifold, take it and everything that comes off with it, put on the 1997, connect the 1997's cruise and you're done. This does NOT apply to 1993 and 1994 Northstar engines.

gorky
03-18-06, 08:16 AM
The one in my Eldorado right now came from a 1995 Deville Concours. The intake manifold, TB, Cruise, and all related components are from my 1997 engine. Literally unbolt the 1995 manifold, take it and everything that comes off with it, put on the 1997, connect the 1997's cruise and you're done. This does NOT apply to 1993 and 1994 Northstar engines.

Do you know what happens with a 1994 engine computer?

I have 1994 Seville, that I had engine swapped with a 97 block and manifold. I also had to use a 1995 throttle body. And the shop had to hack up original 1994 harness to accomodate the new manifold pressure sensor in the 1995 throttle body versus the 1994 implementation. At least that is what i was told.

It's been running for a year, but now it is stumbling badly. No real problems at idle or with no load but if it is going down the road, it will surge and slow down off and on, even when i am trying to hold steady speed.

Trying to pick your branins

Does this sound like anything obvious?

chevelle
03-18-06, 02:11 PM
Do you know what happens with a 1994 engine computer?

I have 1994 Seville, that I had engine swapped with a 97 block and manifold. I also had to use a 1995 throttle body. And the shop had to hack up original 1994 harness to accomodate the new manifold pressure sensor in the 1995 throttle body versus the 1994 implementation. At least that is what i was told.

It's been running for a year, but now it is stumbling badly. No real problems at idle or with no load but if it is going down the road, it will surge and slow down off and on, even when i am trying to hold steady speed.

Trying to pick your branins

Does this sound like anything obvious?



Did it run OK originally or has it been running this way since the swap. There are a number of ways this swap could be screwed up. It could/should work if it is done correctly, though. If the problem just started I would start by checking the fuel pressure under load (when the problem occurs). It sounds like the fuel pressure may be low causing it to be lean at load.


The "engine" itself doesn't know whether it is OBD or OBDII. That refers to the control system. The engine itself could care less. As long as the sensors are correct and swapped accordingly "engines" from either system can work fine with the other control system.

The actual difference that causes most of the problems with Northstar swaps from different model years is the change from 1995 to 1996 from speed density fuel injection to mass air flow control and the addition of the MAF sensor. The later MAF engines will work fine with the earlier speed density controls IF all the sensors are changed and installed correctly.

1993 eldorado green1
03-18-06, 08:20 PM
does anyone here know where i can possibly get ahold of some wiring diagrams off the internet for the crank sensor on this car? i have looked everywhere at local auto parts stores and i finds nothing.

i would like to be able to rule out a bad wire before i spend the 80 for the 2 crank sensors. im not sure where the wires run to or what color the wires are..

i drove it again today and it is exactly the same.. but i did find out that there was three different mechanics that looked at the timing before the motor was put back in the car and they all confirmed that the timing was correct... thats good but i still am stumped, it runs as if the timing was way retarted, sometimes when i stomp on the pedal it just downshifts and stumbles for about 15 seconds and then its like i hit the nos, its gone!!!

ill be checking for diagrams and tracing wires to figure this out and im gonna try to post a link with pics so you all can see what a deal (steal) i got on this baby..

eldorado1
03-18-06, 08:40 PM
i would like to be able to rule out a bad wire before i spend the 80 for the 2 crank sensors. im not sure where the wires run to or what color the wires are..


Probably a good idea... If you're looking at the ignition module, the large 6(?) pin connector nearest the 7/6 coil is what connects to the crank sensors. 2 wires each.

The top sensor Pin A is a purple wire, leads to pin B of the 6 pin ignition module connector. Top sensor Pin B is a yellow wire that leads to pin A of the 6 pin ignition module connector.

The bottom sensor Pin A is a light blue w/white stripe wire, leads to pin E. Sensor pin B is a black wire that leads to pin F.

Once all those check out, you can measure the resistance of the crank sensors. At the ignition module connector, go from E to F, and then again from A to B. Report back.

zonie77
03-18-06, 11:37 PM
It is pretty easy to check cam timing. The hardest part will be pulling the water pump drive pulley to get the cam cover off.

dad
03-20-06, 08:18 AM
I am not an expert but have had a post out there trying to solve a shutter, miss problem.

Problem on my 94 seville, is when in low rmp after it shifts to 4th at 42MPH it shudders til rpm changes with more speed. I have changed wires, plugs, cleaned ERG, changed TPS and have no engine code indications. (never had any)

The real mistery is that problem does not exist when engine temp below 180.

Its like an on off switch at 180.

Question of the day.. what program or module tells the engine to do what at 180... I assume there is sensor somewere that tells the PCM to change something.

another item.. my mechanic put a meter on this issue while running down the street and gets a -20 degree on the timing... does that mean anything...

dad

1993 eldorado green1
03-20-06, 02:39 PM
ok here are some updates, sorry it took a few days but i own my own business and i have been busy working...

well after digging out my volt meter i dont think it has the proper scale for this testing, but it does have the "x1k" scale, or the "x10" scales on the x10 i get nothing at all form either crank sensor, on the x1k scale i get like almost full resistance, it goes all the way over to #1, that is for crank sensor a (or the top one) on that same scale for crank sensor b i get absoultly nothing!! i double checked and they are both plugged in and the wire diagrams appear to match.
the yellow/purple is the top sensor? thats what mitchell on demmand 5 shows.. i guess for now im gonna run out and pick up 2 fresh sensors and change the oil again and see what happens..

does this give anyone else any ideas??

eldorado1
03-20-06, 04:13 PM
sounds like you found your problem. You should see about 1k resistance on both. I'd replace just the bottom one. save the extra money for when something else breaks. :rolleyes:

btw, it wouldn't hurt to check the resistance of the wires to the bottom sensor, just to make sure one of the wires isn't cut or something.

1993 eldorado green1
03-20-06, 05:06 PM
sounds like you found your problem. You should see about 1k resistance on both. I'd replace just the bottom one. save the extra money for when something else breaks. :rolleyes:

btw, it wouldn't hurt to check the resistance of the wires to the bottom sensor, just to make sure one of the wires isn't cut or something.


just got home from the caddy dealership and bought 2 new crank sensors, and installed them and still,,, p083 W.T.F. I just checked the resistance again and i get 1.5 on the upper one and nothing on the bottom again. i guess im gonna go cut the plug at the sensor and at the icm and manually run 2 wires direct, that way i can rule out for sure that sensor.

i also cleared codes again and reved it up a few times and now i get p019 in the history and also p030 in the history. everytime i clear the codes those always come back as history codes. maybe something intermitten?

this car is turning into a real headache. ill post up a link to some photos of it. if the car wasnt sooo nice i would have sold it off just like it sits.

i also keep smelling raw gasoline real bad, the wxhaust is smelling horribly like raw fuel. i hope its related to this p083 thing...

any thoughts? im going right now to clip those wires and make my own little harness to see what happens, ill let you all know how it goes as soon as i get done and clear/ check codes again..

1993 eldorado green1
03-20-06, 05:55 PM
heh ok... now im really stummped, i made up my own harness and hooked it up. upon removal i found that the sensor b or lower sensor was actually cut and taped into the harness.

i hooked up my harness and checked resistance, i got the same reading on both sensors, about 1.5-1.0 i tried to fire it up and guess what??? no spark!!!! i just replaced the icm a few days ago, i even treid the old one just for shits and giggles and nothing!! as soon as i remove 1 of the crank sensor wires it fires right up and runs like crap..

im really starting to think that this is a timing issue and there is conflict between the cam sensor and the crank sensor.

i cleared the codes and suprise i get " no pcm codes" i cant understand all this. it has to be a timing issue, if the cam and crank were giving different signals i cant see how the computer would fire the engine.. i guess my next step will be trying to check the timing marks. is this easy with the motor in the car?

i was looking at it and i cant see anyway how it can be done but i didnt really pay too much attention to it. its now dark and getting colder so ill have to do it tomorrow i guess..

any thoughts? im out of ideas here now..

eldorado1
03-20-06, 06:07 PM
switch the top and bottom connectors just for grins.

1993 eldorado green1
03-20-06, 06:50 PM
i tried that too but it didnt seem to make a difference.. thats the wierdest thing ive ever seen...

eldorado1
03-20-06, 07:35 PM
heh ok... now im really stummped, i made up my own harness and hooked it up. upon removal i found that the sensor b or lower sensor was actually cut and taped into the harness.

i hooked up my harness and checked resistance, i got the same reading on both sensors, about 1.5-1.0 i tried to fire it up and guess what??? no spark!!!! i just replaced the icm a few days ago, i even treid the old one just for shits and giggles and nothing!! as soon as i remove 1 of the crank sensor wires it fires right up and runs like crap..

im really starting to think that this is a timing issue and there is conflict between the cam sensor and the crank sensor.

i cleared the codes and suprise i get " no pcm codes" i cant understand all this. it has to be a timing issue, if the cam and crank were giving different signals i cant see how the computer would fire the engine.. i guess my next step will be trying to check the timing marks. is this easy with the motor in the car?

i was looking at it and i cant see anyway how it can be done but i didnt really pay too much attention to it. its now dark and getting colder so ill have to do it tomorrow i guess..

any thoughts? im out of ideas here now..

I wonder why someone would cut the crank sensor connector off? Were the color codes correct? Did you check the wiring from the crank sensors to the ignition module to check for shorts between the two circuits? Right now, all I can think of is the person who cut the connector off accidentally tied into the wrong wires, so it runs with either one just fine, but try to plug in two, and it doesn't work because both signals are mixing with each other.....

1993 eldorado green1
03-20-06, 08:37 PM
I wonder why someone would cut the crank sensor connector off? Were the color codes correct? Did you check the wiring from the crank sensors to the ignition module to check for shorts between the two circuits? Right now, all I can think of is the person who cut the connector off accidentally tied into the wrong wires, so it runs with either one just fine, but try to plug in two, and it doesn't work because both signals are mixing with each other.....

yes, the sensors are on different circuits now and are not shorted. it was probably like that because there was something else wrong and they were trying to mask the problem. if one of the sensors were bad, or something.

and probably because the car wont run unless theres only 1 sensor hooked up. it doesnt matter if its sensor A or sensor B the car will run with either or and on either circuit but not together.

and remember the car runs like complete crap unless its over like 1300rpms, it shakes and idles like theres no harmonic balancer on the engine but its new.

well, ill post back if i get the motor tore down enough to check timing tomorrow. ill let you all know what i find..

parts68
03-20-06, 09:15 PM
I dont know if this applies but when I changed out a CPS on our GTP I had to do a crank pos sensor relearn. I did that with my SnapOn scanner and all was well.

1993 eldorado green1
03-21-06, 07:12 PM
here are some pics of the ride, its a link to another post here that i made


http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/69127-pics-pics-pics-pics.html

fubar569
03-22-06, 01:57 AM
cliff notes:

runs like ass till 1300rpm - codes related to crank sensor - also smells like raw fuel...

changed both sensors, checked wiring, ran dedicated wiring, will not run with both plugged in. will run on one and either circuit but will not with both at the same time.

if run on one, above symptoms persist.

both sensors check out ok, wiring checks out ok. replaced ICM and related ignition components test out ok

everything else appears ok, but codes return either as current or history depending on car's mood and phase of the moon and pluto's orbit around the sun.

car still runs like ass below 1300rpm.
-------------------------------

in summary...i really have no clue what's wrong, but it's possible that it could be off a tooth...either intake or exhaust...

and the raw fuel could be a result of that, OR the FPR

davesdeville
03-22-06, 04:19 AM
If I were in your position I'd first check the fuel pressure. Then investigate cam timing...

eldorado1
03-22-06, 07:20 AM
I believe he said cam timing was checked multiple times by multiple people.

Right now, I still gotta believe it's the wiring. I *very much believe* that both crank sensors ARE polarity sensitive. You *need* to check to make sure each pin goes to where it is supposed to go. Each connector pin is labeled with a letter. Check for continuity between the connectors, using my previous post as a reference. If one of the crank sensors is connected backwards, the crank position is going to make no sense to the ICM. I wouldn't be surprised if it didn't run.

1993 eldorado green1
03-27-06, 08:47 PM
well today is monday 3/27/06 and still no update from the shop yet, they said they should know something by tomorrow i hope.. keep your fingers crossed for me....

Raze
03-29-06, 03:21 PM
Usually when they smell like gas with a bad idle, you've got a problem with the FPR, I know many have mentioned it but did you test the fuel system?

1993 eldorado green1
03-29-06, 03:51 PM
Usually when they smell like gas with a bad idle, you've got a problem with the FPR, I know many have mentioned it but did you test the fuel system?



yesm it has a new fpr from cadillac and we double checked it aswell. it is also showing the correct fuel pressures as it should. i believe if the timing was off a bit it would run rich aswell. i cant quote myself as this is from past expierences, i had a ford mustang with bent valves and it ran great at wot but it idled soo rich that it would burn my eyes out. it aslo smelled like raw fuel out back.

as soon as i got the new valves and valve-job it ran perfect. i hope if it is the timing that it didnt bend a valve or something. if so than its gonna be on the rear head and the motor will have to come out.

but i guess that would be a good time for a timesert kit:) im hoping for the best though.

please excuse my typing im on a SMALL sony vaio and i cant type worth a crap on this thing. lololol...