50 miles on 1/2 tank of gas

[Monkeybutt2000]

I used to drive a 68mi round trip in a stock 87 LX,went the whole week on one tank of gas and I wasn't nice to it. Fill it up,and a 5gal gas can and see what happens. Have a friend on speed dial.

 

[NooStang]

Anyone know which '87 Ford service manual has the troubleshooting procedure for the codes?

 

[KRUISR]

I am confused with your idle issue. In post #1 you said you can't get lower than 900 rpm. Then in response to my setting base idle question you said you had 750 and went with it. You also talked about setting idle with IAC unplugged, but are you unplugging BOTH IAC and SPOUT? That is what is required to get it right or else the computer will keep adjusting timing while you are trying to set idle. You will never get it right - ask me how I know.

 

[NooStang]

UGH! Thanks for pointing that out, makes perfect sense just didn't think about it.. Will set again tomorrow disconnecting distributor spout and IAC.

 

[KRUISR]

Then after you get the idle as low as you can (usually 500-650) you shut off the engine, plug everything back in and do the idle learn portion/steps of the base idle reset.

 

[TIGGER]

I know you probably have different issues but I wanted to comment on the fuel gauge and how inaccurate they are. The gauge on my 89 reads double what it really should. For example when it reads half tank full, it really is 3/4 full as it only takes 4 gallons to fill. My friend who sold me the car just though it got horrible fuel mileage right before he stopped driving it but he never ran the numbers. I get 20-24 mpg on commute to work. I am not sure what the issue is, if it is the gauge or the sender or if the loose baffle in the tank has something to do with it. The fuel gauge on my 86 seems to read ok

 

[NooStang]

Drove it about 20 miles. Shut off engine and unplugged timing spout and IAC. Started car- it died. Turned screw in one turn. Idling about 800. Turned screw (counter) to about 700. Idle started oscillating. which worsened every oscillation then died. Idled back up to 750ish and it seems to be as good as it will get for now.

Probably need to address these issues before I keep messing with this idle issue. Need to swap the O2s to see if I need both or just one. Might also need to do something about he CTS as it appears to be an intermittent connection issue or a faulty sensor.

Tigger, it sounds like my gauge works/reads exactly as yours, but I have some fuel economy issues.

 

[KRUISR]

Yes, first get any other issues sorted (like O2s or vacuum leaks). I didn't mention the warm up drive, but you did it, good move. Also don't forget to reset the computer by unhooking the battery for a few minutes after your warm up before you start the base idle reset (don't want a previous bad idle setup influencing your new settings).

While adjusting the idle with spout and IAC unplugged it will run like crap but it will run. The goal is to get it to idle as low as possible and still keep running, don't worry about idle quality or smoothness. The IAC when plugged in can only raise idle from this initial set point, it can't lower it.

 

[Cheapskate207]

11 mpg doesn’t sound right. My HCI vortech car with 3.73’s gets much better than that. It’s been a while, but I remember getting over 20mpg highway before.

 

[NooStang]

I will try disconnecting battery before setting idle next time...about how long? Hoping to do front suspension this weekend.

Something is going on with fuel economy. Drove it about an hour tonight in the city-we had a blast! Will fill up again soon and report back mpg. The 33 and 91 persist. Will swap o2s when I do suspension work and see if I can isolate that o2 that is throwing the 91.

Really enjoying this car...but I think they were faster 35 years ago. It hooks up better than I remember, oh well, I guess the limited slip diff is working fine.