: Replaced water pump, now idle issues and airbag sensor issue,,,

126,000 Mile V
04-02-13, 07:35 PM
Like the title says, water pump failure on a short trip to the dealer, cold morning and I had just topped off the reservior, so the car never ran hot. Water pump spewed coolant all over the front of my engine. Had the water pump replaced and changed the oil and filter. Picked the car up and noticed the engine started fine, idled down to 833 rpms or so with an even idle. Once I start to accelerate, the car runs smoothly. Once I approach a stop sign, and take the car out of gear, the idle surges up to 1850 or so rpms and hold steady for the most part, some times dropping down to 1500, but ussually holding steady at 1850 rpms until I come to a complete stop. Then after stopping completely, the rpms drop to 833 for the most part, if it does drop into the normal range, The car runs normal for a while. Other times it goes to 1100 or so rpms and will surge up slowly to 1850 to 2000 rpms, and the whole process starts until it decides to stop acting up or I bring the car to a complete stop. I just replaced the MAF sensor/airbox lid a couple years ago. MAF was plugged back in. I checked the 3 wires in the MAF, and they are intact. THere are no air leaks up stream of the MAF. K&N drop in is in the right place and sealed up.
In addition to the idle issues, a warning light to service airbags comes on and goes off. I mention both issues to the service manager. He removed the code for the airbag warning, started a relearn on my ECM and reset the crank position sensor.
The ECM reflash, seemed to helpand even though I am awaiting court supervision for a recent ticket, I am driving it hard till I hit cruising speed and try to avoid the rmps my car seems to prefer recently, but the problem still persist for the most part. and once since (last 24 hours) my check airbag light has come on. The service manager assured me that it was SOP to disconect the battery before replacing the water pump, as I told him I had never had either problem. He said the next step is to replace the ecm. This guy did me a ton of favors during the 7 years my car was under warranty. So I have been respectfully holding my ground on whose reponsibility these problems are. What do you guys think? Replace CPS? It seems like the car did this a couple about 5 years ago, but I cant remember what they did and cant find the service ticket

04-02-13, 08:33 PM
There's almost definitely an intake/vacuum leak somewhere. Go to advance auto parts, hook up their actron scanner, and go to the diagnostics screen and pay attention to your absolute TPS.

Check the lines for PCV going from your valley cover to your elbow in your intake tubing, and then follow the line from your TB to your valve cover. Check for splits/cracks etc.

They had to remove your air tube to get to the water pump. As for the airbag light? Ask if they removed your radiator to replace the pump (I would assume they did), and then start poking around for loose/coolant filled connectors (as coolant is conductive, it could cause a short)

04-02-13, 08:40 PM
I agree with the things robojesus suggests. My guesses would include a vaccum leak; water/coolant intrusion in one of the main wiring harness connectors, including the ECM connector which is within reach of the water pump, or bad grounds in the same area under the hood.

126,000 Mile V
04-02-13, 09:39 PM
Thats what I fugured, thanks for the input. I will check things out. There was coolant all over the engine block by the time I got to the dealer, so not necessarily thier fault. Plastic/rubber peices on the intake are old and have heat soaked for years. It feals like an air leak to me. I took the air tube apart and checked it all out. I need to check the PVC tubing for cracks. Tubing was attached when I checked it. I find it very odd that idle issues always disappear when I come to a stop. I can creep in nuetral to the slightest almost impercievable creep and the problems continue until I come to a baraked complete stop. What do you fellows think???

04-02-13, 09:53 PM
Is your serpentine belt slipping, maybe?

04-02-13, 10:22 PM
hamstar, that would not cause the rpms to elevate.

126,000 Mile V
04-03-13, 07:43 AM
[QUOTE=robojesus;3273087]hamstar, that would not cause the rpms to elevate.[/QUOTE
belt squeaks like normal. no slippage. I cant see the belt causing a problem either,

126,000 Mile V
04-04-13, 12:22 AM
Dealer tried ot reflash the ECM, and reset the crank position sensor again without sucsess. He replaced the ECM for cost of parts. Problem solved. The coolant let loose by my failing water pump probably took out the ECM. Russ Braunecker Cadillac has been one of the top two dealerships I have dealt wtih, if not the best! I didnt mind paying a tad more for what I had done as they have treated me extremely well with my 7 year/ 100K warranty. The car is ready to sell and has a crap ton of replaced parts. It was under warranty until 11/11 so it has enough new stuff that I could call it a 2008+. Guy is coming to buy it Friday or Saturday. Thanks agian for all the help. You guys are great. Thanks for all your help in the past darkman. You sir are a wealth of V1 info. I am sure when I tire of the SRT8 slushbox (pushing slushboxes to thier limits good}, I will be back for a manual. The twin turbo CTS manual wagon with AWD would look good sitting nest to my GN...