Monday, March 21, 2011

2004 Saturn Vue 3.5L

I was called to one of my favorite shops recently. The shop owner I will call Mr. D is a larger than life type of guy. It is the type of shop you stop in for morning coffee and you don't leave until the afternoon or later after he has bought you lunch. I am also eternally grateful to this shop owner for employing me "piecemeal" when I was in between jobs. His shop has some really good people that come there for service as well.
Anyway back to the task at hand. The complaint is that the car would run then stall and have issues restarting. After talking to Mr. D he tells me that he had it running in the shop and it ran rough for a second and then stalled after a period of time. Trying to restart the vehicle it would start and stall immediately. "Like a theft issue Johnny". After letting it sit it would restart and then the whole cycle would repeat itself.
Doing a quick visual it is apparent that this vehicle took a hit in the left front and was "repaired". I will leave repaired in quotations. I hope the body shop saved this guy his deductible at least.
I start the vehicle and it runs well with a MIL lamp on. So lets pull some codes. I pull a P0300 (Random Misfire), P0301(Cyl. 1 misfire), P0302 (Cyl. 2 misfire), P0303 (Cyl. 3 misfire), P0304 (Cyl. 4 misfire), P0305 (Cyl. 5 misfire), and a you guessed it P0306 (Cyl. 6 misfire). Geez, what is going on here. All sorts of thoughts run through my head with these codes and the complaint. Do I have a fuel pump pressure problem, possibly a power issue to the COP (Coil on plug) units, or something else affecting all the cylinders with 122k anything is possible. So, I hook up the scanner and set it up to read map kpa, rpm, and short term fuel trims on both banks. Now I wait and observe the scan data and how the engine is running. Map kpa is smooth amd fuel trims are well within reason. As myself and Mr. D are leaning over the car commenting on the "fantastic" body work, I say to Mr. D that I bet this thing stalls when the cooling fans come on. No sooner than I say that the cooling fans come on and the car runs rough and stalls. Trying to restart nets me the start and stall issue. So, I disconnect the cooling fans because I already know where I am going and the car starts and stays running. Lets examine the wire schematic for the cooling fans below. By the way double click on the image to get it to be full size.
G101 is the ground for the cooling fans. More importantly it is part of splice pack SP101. Splice packs are where a manufacturer will share wiring paths from one area. In this case Saturn will use this splice pack to give many other components ground from this one ground connection. Now want to take a guess where this SP101 is located? You guessed it right behind the left front headlamp assembly. Right where the vehicle got hit and right where the "body work" was done. At this point we remove the left front headlamp assembly which wasn't too hard considering how it was "installed".
Above is the picture of SP101 installed on the left front frame rail. I removed the harness going to SP101. It is in the next picture. Sorry for the blurry pictures, but you get the idea. As my good buddy Joey Bag of Donuts would say "What part of a bad ground don't you understand?"
Lots of green mold, one bent terminal, and signs of water damage here. But we still need to get the part that is attached to the frame out and clean. Between Mr. D and myself we get it out.

There is enough filler, undercoating, and goop on this framerail that I do not want to use this as a ground. I would need to spend some serious time grinding to get it clean enough to where I would feel comfortable about using this as the ground for SP101.

A little time with a terminal brush, straighten out the bent pin, and some wd-40 with some shop air I feel confident that we can save SP101. While we are at it, look at the schematic for SP101/G101 below and you can see how many items are grounded here.

You can see why this caused the stalling issues. This ground is used for the fuel pump relay. When the fans came on they "sucked" the ground from the fuel pump relay. The vehicle basically ran out of gas. This was evident looking back at my scanner readings the short tem fuel trims elevated drastically right before the stall. So now we are left with where are we going to ground SP101 and get this vehicle back on the road. So we decide to go right from battery negative to the splice pack itself with a nice 10 gauge wire. Considering the rest of the vehicle is suspect for ground potential after the "body work" we feel this is best.

Now, by no means is this a "correct" repair. But, all things considered this was the best path. I cleared the codes and ran the vehicle through a couple of cooling fan cycles. No problems.