bnewman Posted April 20, 2009 Report Share Posted April 20, 2009 I’m wondering if its getting time to replace fuel injectors on my 97 Deville with 206k+ miles that I use as my 150mi/day commuter. What got me thinking about this was reading some of the posts on this board about something I figured was totally unrelated – strange DIC behaviors. A bit of background. I’m one of those people that reset all the counters every time I fill the tank and also keep pretty good records of fuel purchases and mileage. For most of the time since I’ve owned this car, my records, the DIC readings and fuel gauge have pretty well agreed. However, about 6-8 months ago, I started noticing that when the fuel gauge got between half and a quarter full, instead of going down, it would start going back up! So I started using the “fuel used” read out as a substitute. And that worked fine for quite a while. Now when I fill up, the amount of fuel that the DIC shows I’ve used is always 2-3 gal more that what it takes to fill the tank. Based on my records ‘actual’ mileage may have dropped a bit, and while the car still runs well, performance may also have falling off a bit. The only codes of any consequence have been a pesky set of PCM P0113 and P1111 codes caused by a loose connection on the Intake Air Temperature sensor. Could the all of this be caused by worn injectors? Link to comment Share on other sites More sharing options...
Texas Jim Posted April 20, 2009 Report Share Posted April 20, 2009 It is possible that injectors could be worn and throwing off the FUEL USED counter. It works by counting injector pulses..I think. Question for you...have you changed tires in the fairly recent past? If so, are the new tires the same OUTSIDE DIAMETER as the old ones? If not, that can affect fuel mileage and performance by effectively changing the final drive ratio. For the goofy gas gauge..try a can of TECHRON in the fuel tank. It can clean deposits that can cause the gauge to act crazy. Link to comment Share on other sites More sharing options...
bnewman Posted April 21, 2009 Author Report Share Posted April 21, 2009 It is possible that injectors could be worn and throwing off the FUEL USED counter. It works by counting injector pulses..I think. Question for you...have you changed tires in the fairly recent past? If so, are the new tires the same OUTSIDE DIAMETER as the old ones? If not, that can affect fuel mileage and performance by effectively changing the final drive ratio. For the goofy gas gauge..try a can of TECHRON in the fuel tank. It can clean deposits that can cause the gauge to act crazy. No new tires in the near past (actually due for a new set soon). Will try the techron ... can't hurt .. or can it? Link to comment Share on other sites More sharing options...
Texas Jim Posted April 21, 2009 Report Share Posted April 21, 2009 Will try the techron ... can't hurt .. or can it? I don't think so..several people here have used it with pretty good results. It is the same additive used in Shell and Texaco gas or maybe Chevron. Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 21, 2009 Report Share Posted April 21, 2009 Techron is fine, if you can find fuel that has it already formulated thats good too (Chevron). Many of us have struggled with inaccurate fuel gages, sulfer (I think) in the fuel plates the fuel gage sensor in the tank and poor gage accuracy results, try the techron. I must say however that yours is the first I have seen read higher, mine reads lower. Use of the techron every other thank has helped a lot, follow the directions carefully.... OFF THE SHELF FUEL INJECTOR CLEANER SHOULD BE AVOIDED Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Ranger Posted April 21, 2009 Report Share Posted April 21, 2009 Based on my records ‘actual’ mileage may have dropped a bit Have you checked for a leaky FPR? Link to comment Share on other sites More sharing options...
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