Tripminder - 13gal, fillup - 15gal = ? December 07, 2010, 09:17:09 AM For a short while now, I seem to be losing more fuel than the tripminder claims. It used to be dead on with the current setup but now it almost always reads 15-20% lower than what I get at the pump. I've tried the same station/pump for weeks at a time, different stations, etc and I always put in more than the tripminder says I've burned.Car doesn't smell like fuel anywhere and nothing looks out of the ordinary when datalogging through the QuarterHorse, including both banks with the nb o2's. I don't know how the tripminder works but I thin kit's still find as it still reads the same fuel usage as is used to, for different trips (~4.5 gallons of gas to dad's house, ~1.1 gallons to work, 0.9 gallons from work) but it consistently takes more fuel to fill it up.Where do you guys think it is going? No rust and all fuel lines look good. My charcoal canister is ancient and fuel injectors should only have less than 10k miles on them since being rebuilt a couple years ago. Tank was in good condition when a larger fuel pump was installed a couple years ago. Ideas? Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #1 – December 07, 2010, 12:49:14 PM How big are the injectors? Mine trip minder is off due to me running 24s and a calibrated MAF. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #2 – December 07, 2010, 01:16:26 PM Increased fuel pressure maybe? Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #3 – December 07, 2010, 06:13:29 PM I was wondering if mod-ing the engine would throw off the factory dash computer mileage/Distance til empty thingey. Any other experience?? Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #4 – December 07, 2010, 07:22:53 PM Mine was always optimistic ... Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #5 – December 07, 2010, 08:37:59 PM Quote from: Loaded87IROC;344852Increased fuel pressure maybe? Good call - I didn't think of pressure. I'll have to check it.19lb injectors on A9P eec. The thing was dead on in the past so I was glad to see the move from 14lb to 19lb didn't affect it. The most I've got it to read "used" between fill-ups is about 16 gallons which is also about the max I can fill in from the low fuel light being on, to topped off. The tripminder has been very off for awhile though and I should check/replace my FPR as it's ancient.Can anyone explain how the thing actually works? I would think that if the 14 to 19lb injector move didn't impact it, going to 24lb injectors with a properly tuned chip would work fine (unlike a lying MAF where the EEC still calculates thinking it still has 19lbers). Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #6 – March 25, 2011, 09:27:41 PM Okay, a bit late but I had a few issues recently that I had to sort.Between then and now, I installed a larger maf sensor, 24lb injectors, and larger tb. Having just gotten my BE/EA licensing sorted, I got the thing in tune today. For the last month I've been reading some 40% off on fuel consumption. Now it's back in check but the 13/15 gallon thing is still happening. I picked up a new FPR and fuel pressure is perfect now. BE matches up with the tripminder's economy values so both, which meter differently, are observing the same fuel consumption.So the EEC knows its burning 13 gallons and no change with new FPR and injectors. Any simple ways to look for some type of fuel leak when the fuel lines are pressurized? I'm not sure how to spot fuel leaks with how dirty undercarriages typically get. The car sitting for periods or time does not show any additional fuel loss. Fillup, long drive, and refillup the same day shows the same missing fuel.Note: I was always getting up in the 15-16 gallon range on the tripminder after the engine swap some years ago. This is a recent problem. Ideas? This is starting to get expensive with gas in hitting $4/gallon. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #7 – March 25, 2011, 09:33:30 PM Quote from: Seek;356368 Any simple ways to look for some type of fuel leak when the fuel lines are pressurized? I'm not sure how to spot fuel leaks with how dirty undercarriages typically get. If you think it may be leaking and dripping on something underneath look for spots that seem unusually clean for underneath a car. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #8 – March 25, 2011, 09:41:12 PM Are you sure the pump at the gas station is accurate, some times they fudge to make even more profit. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #9 – March 25, 2011, 09:42:20 PM It has got to be as there really is no other explanation I can come up with as to why the EEC has been off with its fuel estimates for awhile. I figured it could also be some issue with injectors but new ones proved that theory invalid. Nothing in the datalogs stands out as any odd fuel consumption behavior, including standard HEGO switching (including on long drives where it stays in closed loop the entire drive but shows fuel loss at the end of the trip).I really wish I had a lift. Anyway, I'm going to look at my next suspicion area - fuel filter. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #10 – March 25, 2011, 09:46:24 PM For months, at all stations, I doubt it. I have many receipts, all adding up to some 15% number differences for the last few dozen fillups. I wish it was that easy. The change happened pretty quickly as I noticed it once I thought nothing of it - as just a pump shutting off early. Then again, and again, I started questioning it. I started going to different stations being Shell, Chevron, and 76. At this time, both the tripminder and BE were showing the same consumption numbers as previously but the pump was saying different.This has been driving me crazy, especially with the thought of losing 2 gallons every week. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #11 – March 26, 2011, 12:08:15 AM Chapter 14 Data Output Link.If you can understand it, you are a better man than me.Basically I think it is a count of injector pulses and taking into account the pulse widths.http://eecbuttstuffyzer.net/tech/docs/GUFB.pdf Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #12 – March 26, 2011, 11:05:06 AM Have you checked to see if the charcoal canister is ok? Sometimes they go bad and can leak. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #13 – March 26, 2011, 12:27:29 PM Quote from: thunderjet302;356404Have you checked to see if the charcoal canister is ok? Sometimes they go bad and can leak. You know, I thought about this before but couldn't figure out how 2 gallons would go out/through that. I swear I had some wet spot on the pavement below that area of the car before but it seemed like it could have been the drain pen 15 on the radiator also (or overflow bottle). I had a shop look at the area when I had new tires being put on but they didn't see anything that resembled a leak. I'd still like to replace it as the canister is stock.I'll check it out better myself and see if I can pinpoint anything. I forgot about the wet spot on the pavement until you just reminded me. I haven't seen it lately though. Quote Selected
Tripminder - 13gal, fillup - 15gal = ? Reply #14 – March 26, 2011, 01:50:11 PM Usually it's vapors (ie the gas) that leak. Gas evaporates like water. Quote Selected
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