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Poor fuel ecomony question
Well, I've driven my new 924S after repairing a broken valve spring (do a search with keywords "Dallas 924S valve spring" if you don't know the story and are interested) long enough to burn through a tank of gas. My fuel economy is really disappointing.. something like 21MPG in about 50/50 city/freeway, and not terribly aggressively.
One of the repairs I tried before finding the root problem was to clean and reseal the injectors, replacing the o-rings, spacers and plastic "hats". When I pulled the rail a few days later to verify the fuel delivery, I noticed the new hats weren't completely seated - maybe a millimeter down and not compressing the o-ring at all, so I pushed them back down, reinstalled the rail and hoped for the best. When I pulled the rail again to pull the cam box, the same thing had happened. Will this mess up my spray pattern enough to screw up my mileage? Did I get a wrong or low-quality set of seals and hats? I used the Borg-Warner kit #274081 recommended in the tech article here. Anyone else have this problem?
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1987 Porsche 924S 1989 Volvo 760T wagon |
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08-31-2011, 08:08 PM
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Proprietoristicly Refined
Join Date: Jul 2001
Location: ~Carefree Highway~
Posts: 5,833
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Well I trust PorscheDoc in his use of the BW Borge-Warner kit 274081. PorscheDoc has years of experience with multiple high end cars, a web site and a blog.
Post 18 Re-sealing Injectors, wrong BOSCH kit - WTF! - Page 2 - Rennlist Discussion Forums If the "hats" are not seating properly or staying in place, the inner lip seal is probably broken and new hats are required. I just press them on---I do not warm the caps up. If removed, I replace. Yes, if the caps are low the spray will come out as a stream and not vaporize properly. Pull the rail and check the caps again. When you "cleaned" the injectors, do you mean wiping the outside or doing a DIY flush? BTW there are new Bosch injectors for the '87 924S that are cheap and not the expensive .......158s GL John
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1988 924S, 85,750K ..+ 1987 924S, 154K DD (+15K est. bad odo) |
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08-31-2011, 09:51 PM
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Join Date: Nov 2005
Location: Visalia, Ca
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158s ??
21mpg sounds right. I looked up the MPG recently on google and it was about 22-24 or something like that for my car with the same motor and that was 50/50 highway and street driving. You could check the little things like, Tire pressure, wheel bearings ( repack). Aux air vavle if it has one. Wilk chip?
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Jaime O. Thank god I crashed or i would never have owned a porsche 83 944 daily driver (clutch and tt time) 85 325e BMW T-boned R.I.P. |
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08-31-2011, 10:40 PM
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Proprietoristicly Refined
Join Date: Jul 2001
Location: ~Carefree Highway~
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......158s,
It was late and I could not think of the full part number. '87 & '88 Porsche 924S use the Bosch injector 0-280-150-158 The inexpensive replacement is the Bosch 0-280-150-360 Cost $39.99 each This is an alternative to sending injectors to be cleaned and returned with new seal for about $100 a set. This is especially good if you spend the money and rebuild an engine top and bottom. Why put in worn, used injectors in a fresh engine? John
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1988 924S, 85,750K ..+ 1987 924S, 154K DD (+15K est. bad odo) Last edited by John_AZ; 09-07-2011 at 11:32 AM.. |
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09-01-2011, 05:32 AM
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Location: Visalia, Ca
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Np John i thought you meant 158$.
I'm on a mobile right now but i thinknpelican sells injectors for 40$ each to, dont remember if they were rebuilt or new. Already replaced all seals and filters on my injectors and ultrasonic cleaned them but I'm sure a new set will flow better. Innregards to the hats poping off I used a 10 mm deep socket to push them down evenly. They are kinda a one shot deal they grab on the lil ribs on the tip-off the injector. Had tomdouble chek my work as some of the pintos caps were not seated fully. It should snap nicely once they are on |
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09-01-2011, 11:19 AM
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Join Date: Mar 2008
Location: Nashville, TN
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That mileage seems about right with 50/50 city/hwy driving. These things get under 20mpg around town even on light footed driving. Pump up your tires, change your filters and oil and lose some weight and it will increase
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09-01-2011, 03:58 PM
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Maybe I'm overreacting... I just remember my old 944 getting mid-20s with mostly city, and my friend driving it up here got 28 on the highway before the valve spring broke.
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1987 Porsche 924S 1989 Volvo 760T wagon |
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09-01-2011, 07:00 PM
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Join Date: Mar 2004
Location: Las Vegas, NV
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while our engines arent so different that it would make considerable difference on the mpg's, i just recently made a 1500 mile trip and averaged 34-37mpg on highway and 26-30 mpg 50/50 mix in the city daily driving to work. i would start with looking for vacuum leaks. i was getting what you had about 6 months ago, replaced all my hose's and the intake boot and it went back to normal
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1983 944 Guards Red (87' Implant Complete) |
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09-01-2011, 08:09 PM
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ASE Master
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So far, with my S2, I've seen a lowest MPG of 19.5, and a highest of 26. It is a three litre though...
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1989 944S2 (sold after 11 great years) 1980 911SC Weissach (bucket list car) 1975 914 1.8 (future restoration) 1993 968 Coupe 6 speed (new acquisition) |
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09-02-2011, 05:26 AM
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944 S2
