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MPG decrease - Injectors, wiring harness? 700 1986

posted by 740_dan on Wed Nov 27 13:13 CST 2013
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last visit: Thu Aug 28 13:10 CST 2014

[RELATED]

Here's the basic problem: MPG is down 14 city, 20 highway, about the same of 6mpg when MPG was better around 16-17 and 23-24 highway. Car is 1986 740T Wagon at 245k miles.

I'm thinking now my wiring harness has finally degraded and/or fuel injectors are clogged. Although injectors were professionally cleaned by my mechanic's vendor a couple of years ago and fuel filter replaced at same time.

Background:
Car runs great, idles great, starts great, performs great.
It is tuned up with newer spark plugs, wires, distributor, air filter, fuel filter.
Also, has reman AMM, reman ECU working very well. Throttle body was cleaned and TPS readjusted.
Thermostat is 92C and Calorstat recently replaced. FPR is Bosch replaced a couple years ago. Nearly every vacuum hose has been replaced with Volvo OE hose.
O2 sensor is testing alright and mechanic said CO was hanging at .5%. ECT is new Bosch in last two months.

There seems to be some clue in that the MPG *difference* of 6 MPG between city and highway is the same, but the actual MPG is lower than it should be.

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MPG decrease - Injectors, wiring harness? [700][1986]
posted by 740_dan on Wed Nov 27 13:13 CST 2013 >

MPG decrease - Injectors, wiring harness? [700][1986]
posted by aleekat on Wed Nov 27 13:39 CST 2013 > V
- MPG decrease - Injectors, wiring harness? [700][1986]
  posted by 740_dan on Wed Nov 27 14:02 CST 2013 > V
  - MPG decrease - Injectors, wiring harness? [700][1986]
    posted by aleekat on Wed Nov 27 14:27 CST 2013 > V
    - MPG decrease - Injectors, wiring harness? [700][1986]
      posted by 740_dan on Wed Nov 27 19:02 CST 2013 > V
      - Check timing, valve clearance and vacuum nipples.. [700][1986]
        posted by Amarin on Sun Dec 22 04:50 CST 2013 > V
        
        Check timing, valve clearance and vacuum nipples.. [700][1986]
        posted by 740_dan on Mon Dec 23 12:50 CST 2013 > V
        
        Check knock sensor.. [700][1986]
        posted by Amarin on Tue Dec 24 01:34 CST 2013 > V
        
        Check knock sensor.. [700][1986]
        posted by 740_dan on Mon Dec 30 14:12 CST 2013 > V
        
        Check knock sensor.. [700][1986]
        posted by boxvolvo on Tue Dec 31 13:16 CST 2013 > V
        
        Check knock sensor.. [700][1986]
        posted by ktuuri on Tue Dec 31 23:20 CST 2013 > V
    - MPG decrease - Injectors, wiring harness? [700][1986]
      posted by jfs356 on Fri Dec 6 10:13 CST 2013 > V
      - MPG decrease - Injectors, wiring harness? [700][1986]
        posted by 740_dan on Fri Dec 6 14:18 CST 2013 > V
- MPG decrease - Injectors, wiring harness? [700][1986]
  posted by Blindboy subscriber on Wed Nov 27 20:52 CST 2013 > V
  - MPG decrease - Injectors, wiring harness? [700][1986]
    posted by 740_dan on Sun Dec 1 20:20 CST 2013 > V

Possible fix, evap vapor canister hose split - MPG decrease - Injectors, wiring harness? [700][1986]
posted by 740_dan on Sun Dec 1 20:09 CST 2013 > V
- Possible fix, evap vapor canister hose split - MPG decrease - Injectors, wiring harness? [700][1986]
  posted by pageda on Mon Dec 2 04:11 CST 2013 > V
  - Possible fix, evap vapor canister hose split - MPG decrease - Injectors, wiring harness? [700][1986]
    posted by 740_dan on Mon Dec 2 12:31 CST 2013 > V
    - Possible fix, evap vapor canister hose split - MPG decrease - Injectors, wiring harness? [700][1986]
      posted by aleekat on Mon Dec 2 12:37 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by Peetz on Mon Dec 2 18:19 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by VTV745T on Mon Dec 2 23:19 CST 2013 > V
- MPG decrease - Injectors, wiring harness? [700][1986]
  posted by 740_dan on Tue Dec 3 10:06 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by VTV745T on Tue Dec 3 10:27 CST 2013 > V
- MPG decrease - Injectors, wiring harness? [700][1986]
  posted by 740_dan on Wed Dec 4 09:23 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by Will740turbo subscriber on Sat Dec 7 02:57 CST 2013 > V

Update - Leaky injector found and replaced - Interchange Part Numbers [700][1986]
posted by 740_dan on Mon Dec 9 13:48 CST 2013 > V
- Keep Us Updated. nmi [700][1986]
  posted by aleekat on Mon Dec 9 22:20 CST 2013 > V
  - MPG remains horrible after injector replacement [700][1986]
    posted by 740_dan on Mon Dec 16 09:27 CST 2013 > V
    - MPG remains horrible after injector replacement [700][1986]
      posted by Peetz on Mon Dec 16 11:07 CST 2013 > V
      - MPG remains horrible after injector replacement [700][1986]
        posted by 740_dan on Mon Dec 16 14:56 CST 2013 > V
        
        Just a Swag [700][1986]
        posted by aleekat on Mon Dec 16 15:53 CST 2013 > V
        
        Just a Swag [700][1986]
        posted by 740_dan on Tue Dec 17 12:36 CST 2013 > V
        
        Just a Swag [700][1986]
        posted by aleekat on Tue Dec 17 12:42 CST 2013 > V
        
        Another Thought [700][1986]
        posted by aleekat on Tue Dec 17 22:07 CST 2013 > V
        
        Another Thought [700][1986]
        posted by 740_dan on Wed Dec 18 18:50 CST 2013 > V
        
        Another Thought [700][1986]
        posted by 740_dan on Tue Dec 31 11:56 CST 2013 > V
- Update - Leaky injector found and replaced - Interchange Part Numbers [700][1986]
  posted by Nahtanha on Wed Dec 18 21:37 CST 2013 > V
  - O2 New this year and recently tested, got NGK direct-fit at Amazon for $30 (!) (end) [700][1986]
    posted by 740_dan on Thu Dec 19 14:38 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by Will740turbo subscriber on Wed Dec 18 20:04 CST 2013 > V
- Doubt it's AMM [700][1986]
  posted by 740_dan on Thu Dec 19 09:14 CST 2013 > V
  - Doubt it's AMM [700][1986]
    posted by Will740turbo subscriber on Sun Dec 22 03:19 CST 2013 > V

Got new pump - Plan to install Saturday [700][1986]
posted by 740_dan on Fri Dec 20 14:51 CST 2013 > V
- Got new pump - Plan to install Saturday [700][1986]
  posted by Will740turbo subscriber on Sun Dec 22 03:12 CST 2013 > V
- Update, pump in and leak free! - Got new pump - Plan to install Saturday [700][1986]
  posted by 740_dan on Mon Dec 23 12:40 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by riverbend subscriber on Fri Dec 20 15:16 CST 2013 > V
- MPG decrease - Injectors, wiring harness? [700][1986]
  posted by 740_dan on Fri Dec 20 20:17 CST 2013 > V
  - MPG decrease - Injectors, wiring harness? [700][1986]
    posted by riverbend subscriber on Fri Dec 20 20:38 CST 2013 > V

MPG decrease - Injectors, wiring harness? [700][1986]
posted by kittysgreyvolvo subscriber on Tue Dec 31 19:16 CST 2013 > V

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MPG decrease - Injectors, wiring harness? 700 1986