: Northstar and carbon cleaning

03-13-14, 11:57 AM
Hello Tailfin, does this also apply to a 2003 Cadillac Seville STS as well?

03-13-14, 12:32 PM
Considering that the thread has been dead for 8 years and tailfin has not logged in for a long time (2 months), I doubt you'll get an answer.

Later wisdom basically says "Don't pour liquids and snake oils into the Northstar intake manifold". What makes you think that you need to pour magic potions into the engine ?

Have you studied the often-recommended Google searches for top tier gasoline ?

EDIT: I believe the old GM TEC has been replaced by a newer liquid/method that involves removing spark plugs, soaking the pistons for 2 hours, vacuuming out the liquid, running the engine, and then changing the oil and filter.

03-14-14, 02:57 PM
Hello Sub,

My 03 Seville has been getting bad MPG's, local Caddy dealer checked it out and wants to do this TEC procedure for $150.
Just last summer I had the plugs, air filter, cabin filter, and fuel filter all replaced with no major improvement.
Car now has 77k on it and i don't abuse it only WOT once a while as you mentioned to me a while back.
Any thoughts on this Sub?

03-14-14, 04:11 PM
Moved from Tech Tips to Northstar questions.

Please define "bad mileage" - what do you get - long term average - in the city, suburban, and open highway (over 200 miles) ?

I doubt that you have carbon problems. With today's gasolines and clean engine oils, if you run a Top Tier fuel, exercise the engine regularly and don't dump snake oils into the gas or engine you probably do not have a "carbon problem".

03-14-14, 04:24 PM

I fill up only using Top Tier fuel (Shell or BP) nothing else. Oil is always replaced at the Caddy dealer or by me when ever it gets down to 40% on the oil life monitor.
A full tank of gas gets me less then -200 miles, roughly 11 MPG. I do about half city, half highway driving and once in a blue-moon stick in Chevron Techron for good measure.

03-14-14, 09:55 PM
Have you checked the FPR? If it's leaking it will play hell with your fuel mileage.

03-14-14, 10:09 PM
I still have something against BP for the spills in the ocean. Carelessness in my opinion.

I won't fill up at BP if I can help it. I'd rather go to Marathon or Shell.

03-15-14, 11:10 AM
I checked under the hood on anything i could get my hand on, and had my mechanic put it on the lift and no signs of leakage.
I also checked and cleaned every connection I could get my hands on, and thoroughly cleaned the TB and plate.

Have you checked the FPR? If it's leaking it will play hell with your fuel mileage.

03-15-14, 11:54 AM
The FPR - remove the engine cover, start the engine. Carefully remove the vacuum line from the FPR metal nipple. ANY raw fuel there means replacement.

The FPR bypasses a LOT of fuel in a loop back to the tank - and any leak at the O-rings or in the vacuum diaphragm plays hell with fuel mileage.

Quickie - NAPA. otherwise talk to Chris in parts at Rippy Cadillac over there >>>>>>>>>>

You slide the hairpin clip off and pull the regulator out of the fuel rail receptacle. make sire the small lower O-ring comes out. Smear some engine oil on the new FPR O-rings and press it back into place in exactly the same orientation as the old one. Slide the hairpin clip back into place. IF (when) you break a plastic vacuum line it can be replaced by a length of proper sized rubber vacuum hose from the Help! racks at any parts store. Take the old vacuum line with you to get the correct ID - one piece of rubber hose, no connector rubbers.

Here's your FPR - the diagram is generic and explains the function - hose barbs vary. Click to enlarge, use your browser < to back out

03-15-14, 12:14 PM
Ty Sub, I will make sure to try this once I get her back from the Cadillac dealer, they are replacing the steering column for a different issue.
They are recommending the top engine cleaning for the bad~MPG's, they now have had my car for a week (Friday).

03-15-14, 04:24 PM
They are recommending the top engine cleaning for the bad~MPG's.
THEY will benefit more from this procedure than you will.

03-16-14, 06:39 AM
Your right foot can be used to clean the piston tops.

03-17-14, 01:18 PM
That cleaning with the right foot is effective. I didn't have any long downhill roads to use but long interstate exit
ramps seem to be better than nothing. I wouldn't suggest any 5500 rpm starters but some 4k to4500 and a
midway pull to lower gear to keep the dwindling R's up worked pretty well for my N*