: Please Help!!! I am baffeled

05-21-10, 07:42 AM
Good morning everyone, My name is John and I am a newbie. :bigroll:

I am a proud new owner of a 1994 seville SLS with a 4.6L northstar with 143000 miles. I am currently experiencing a engine cut out problem. once the engine gets hot I say around 215 degrees I can be driving along and it just cuts out. I did have a P032 Map sensor code. the wiring checked out so I replaced the sensor. That helped with the performance but now it just runs along fine and then dies. I did have a history code for lost of sync. but it has nont returned. :(. Should I replace the cam and cranksensors????:suspense: If so, where are those things located???

Thanks for all of your info, Hopefully I can get this resolved without to much :alchi:

05-21-10, 10:30 AM
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05-21-10, 10:57 AM
Thank you so much submariner409.:worship:

I just want to let everyone know that I also replaced the plugs and wires. I used Bosch wires and Autolite double platiumn plugs. I also washed the engine down really good. :bouncy:

05-21-10, 11:38 AM
:eek: Don't wash a Northstar !!

Unfortunately these things have so many nooks, crannies, electrical connectors, sensors, you-name-it that the stories of "I washed it and now it misses/runs rough/stalls out" would fill a book. Most of us just pick away at it with Windex, Armor-All, good rags and a beer. Some judicious work with rags, tape, and a rattle can of semi-gloss black enamel doesn't hurt, either.

Remove the engine cover and use a good flashlight to see if there's any water down in the valley under the intake manifold - look in the openings under the ends - the starter motor is in there and it's easy to flood it out. You may need to get creative with a shop vac and some 5/8" vacuum tubing.

05-21-10, 12:30 PM
I am not disagreeing with Sub, but personally, I never had a problem washing down any of my N*s. Also, only use OEM wires and plugs - especially the plugs...for some reason, nothing else seems to work.

There are 2 crank sensors and 1 cam sensor - the engine only needs one to operate properly, so unless they are setting codes, I would not replace them.

Back in the day, when a car died when heated up, it seemed like it was usually the PCM or ICM, but neither is a common fault on these cars.

05-21-10, 12:33 PM
Check the coils for corrosion or water. Take them apart and clean them, don't just look at the outside.

There were some (my brother had one) with defective insulation on a wiring harness. This is the harness that goes to the top end of the engine and connects the sensors. Carefully open up the plastic cover and see if some of the insulation is missing from the wires. Over the years there have been a couple of others with this problem. It causes strange problems because the wires touch each other, not ground, and throw strange, erratic codes

05-21-10, 12:33 PM
While I doubt that the Bosch wires and Autolite plugs would cause it to "cut out", but Northstar don't seem to play well with anything but A/C Delco wires and especially plugs.

By "cut out" I assume you mean dies?

05-21-10, 12:55 PM
By cutting out I mean sitting at a red light going to take off, it stumbles a second, the check engine light comes on and then dies. I go to check codes and there are only history codes, nothing active except the air suspension and ABS which I dont think would effect the engine.

I will do that tonight, I will let you know what I find. :)

I did have a history code for engine sync signal lost. I will just go ahead and replace the cam and crank sensors. I have a friend at GM that will get me new pins and hardshell connectors as well. It is going to be a pain in the A** but I hope it corrects it. :bigroll:

05-21-10, 03:40 PM
Was the engine washed before or after these problems started?

05-21-10, 03:52 PM
By cutting out I mean sitting at a red light going to take off, it stumbles a second, the check engine light comes on and then dies. I go to check codes and there are only history codes, nothing active except the air suspension and ABS which I dont think would effect the engine.


The codes would be history by the time you check them.

05-21-10, 09:31 PM

I am not sure, I bought the car at a DEA auction in Detroit, It had bald tires, check engine light on and a frozen AC compressor. I replaced the compressor, plugs, wires, map sensor and took it for a test drive. Ran great for about 20 minutes. and it started happening.

05-21-10, 09:36 PM
Well, I replaced the Crank sensors:mad: Who in the hell made that engine mount design! :mad:
I also replaced the cam sensor. Why did GM put that sensor there? What is wrong with the front head?:bighead::mad:

I checked all the wiring, took apart the coils cleaned them , added some electrical grease to the coil module pins.

Road test tomorrow, I am too whipped by spending 3 hours changing those parts, It is time for a drink!!!:alchi:

05-21-10, 11:18 PM
Good question - I think the cam sensor is more protected there - from the elements or whatever - than on the other head. Does not seem like too bad a place to me. I mean, how often do you need to change it - probably NEVER?. Now, those cranks sensors...that's another story...they do sometimes crap out - mostly the OE 2000-2003 - kind of a bee-atch to get at, but there's a reason for that, too - can't remember for sure, but their central location had something to do with torsional twisting of the crankshaft, and trying to get the most accurate crank timing signal possible...something like that.

I know there are some things we don't like about the N*, but if you consider that it was designed, what - about 20 years ago?, it's actually pretty amazing.

05-23-10, 12:13 AM
Hello fellow caddy Friends, the road test went well for the first 40 miles. then it started cutting out again. :banghead:

The only code that sets is a PO## Extended travel brake SW input circuit

The problem occurs when taking off from a stop, light throttle :banghead:

Runs fine on expressway, actually runs really good. Coolant temps are steady between 190 to 215. :o

I am unsure to where to go from here, I am going to throw a throttle position sensor at it tomorrow, and hit the locale bone yard for a new ICM module.

Please if you know anything else please let me know, I hate to get rid of it. :bomb:

05-23-10, 05:08 PM
Sounds like a fuel delivery issue to me.
Have you checked pressures?

05-23-10, 08:02 PM

I checked the fuel pressure and it is 48 psi before and after the stall.

The good news is the I popped the top intake off and found a Map sensor in there. I thought it was next to the brake booster.:wtf: I went ahead and replaced it and took it for a long road test with no problems!!!!:2thumbs: