Cause of my Ty's poor fuel economy found?

[DaveP]

I've been experiencing mileage in the 16-ish MPG range for awhile now. It used to get almost 20. I may have an answer. I took my Typhoon out for an 'insomnia drive' last night. Ran about 300 miles just for the fun of it.

I noticed that when I hit the mildest bump, the tach would jump up 300 RPM. If I pulled the brake pedal up with my foot, it would drop back down. I've also noticed that the ABS light comes on at 15 MPH after first-start. Same thing, I pull it up and it goes out. TCC and ABS use the same circuit in the brake switch.

I'm a dummy. I should have put 2+2 togeather. On my recent cross country round trip, I can't recall paying attention to TCC engagement. If I had, I might have saved a lot of gas money on a 6,000 mile trip.

Dave

 

[Z SKI]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

So is the brake pedal return spring worn out? Or is the TCC/ABS switch broken? Thats crazy....

 

[SY2455]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

Is it out of adjustment ? I would look into this 1st, because it is rare for these to go bad. I only had 1 that I could prove bad, the others were out of adjustment in 37 years of driving.

 

[DaveP]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

Well, I worked on it, and learned a few things. First, off I remembered I had trouble with the brake lights staying on in the past, and the switch kept coming out of adjustment. I would 'check' the adjustment occasionally by turning on the Hazard Flashers running down the reoad. If they flashed, the adjustment was OK. I thought I was also checking the ABS/TCC switch as well. I wasn't.

The ABS/TCC switch is part of the cruise control vacuum switch. Separate deal. In the pic below, notice the hose clamp around the upper switch, which is the brake lights, which I did years ago to keep it in adjustment, when I was having trouble with the stop lights staying on. The upper switch was still OK. The lower switch is the cruise switch, which had about 1/4" of 'plunger' showing, prior to adjustment, which has been done in the pic. Note that the body of both switches is flush against the actuator bracket. This is the way it should be for both switches. You can see that the purple and pnk/wht wires go to the lower switch. The purple wire is power to TCC and ABS. When the pedal is depressed, power is removed from this wire.

I haven't driven it yet to see if there is any improvement in TCC function, but it should be better. Whether this is the cause of the poor mileage, I'll have to wait for the next "insomnia drive".

Thanks for the interest,
Dave

 

[JSM]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

You may have just fixed the cruise in my tahoe also. hmm got me wondering

 

[i8av8]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

went out to check mine and sure enough it was out about a 1/4", also. i adjusted it to the "flush" position like you stated and i noticed a slight difference in drivability. maybe it was all in my head? one downside to it was that there was a intermittent rpm stumble where the truck almost turned off, twice. rpms dropped and the truck turned off but turned back on all on it's own. i did nothing but just keep my foot on the break as i was waiting at a stop sign. any thoughts? perhaps i may need to adjust it out some?

 

[warmpancakes]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

I need that switch douchecanoe before me broke it

 

[Luke]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

i thought greedy wall street was the cause of bad economy

 

[DaveP]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

i thought greedy wall street was the cause of bad economy

Ha, ha.

 

[Luke]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

Ha, ha. The double-meaning of the title didn't occur to me when I thought of it. I had more trouble figuring out which 'room' to put this thread in.

You made me laugh.:tup:

I fixed the main title. But it's still in the replies, so we can enjoy it.

ha at first I was thinking how in the hell does the economy belong in drivetrain tech? :rotf:

 

[BoostedSUV]

Re: Cause of my Ty's poor fuel economy found?

you're upset about 16mpg?? lol I'm lucky to get 13.5 when I baby mine around! Figured that's about normal for a modded Ty. 220-230max per tank! Glad you may have straightened yours out. keep us posted

 

[DaveP]

Re: Cause of my Ty's poor fuel economy found?

you're upset about 16mpg?? ............ 220-230max per tank!

This is open Interstate driving. I'm positive it got over 20 going to the Nats in 2000, and 2001. Now it gets 16-ish.

I would drive the Ty everywhere, but the extra cost over the Blazer (which does get 20.5 and uses regular) over a 5000 mile trip is significant. Plus the difference in time because the endurance in the Ty is 275 miles, and the Blazer is 375 miles. I had 26 gas stops on my 6,200 mile Florida trip in the Ty. That's a lot of time spent getting fuel.

I get 10 hot-footing around town. Which is about right, and I can live with. It's worth the 'happy foot' It gives me.

 

[BoostedSUV]

Re: Cause of my Ty's poor fuel economy found?

Even when my ty was 100 percent stock I don't think i ever got better than 16mpg. I never really took it out for extended periods of time the highway either though. Could just be me :dunno: I wish could get that mileage now now! Lol

 

[2kwik4u]

Re: Cause of poor economy found?

Re: Cause of poor economy found?

You may have just fixed the cruise in my tahoe also. hmm got me wondering

and the trailer brakes too?

 

[i8av8]

Re: Cause of my Ty's poor fuel economy found?

after adjusting mine to the "flush" position it gave me a bad intermittent stumble in idle. i had to readjust out about two quarters ($.50) thick. stumble went away.:2cents:

 

[SikVSix]

Re: Cause of my Ty's poor fuel economy found?

after adjusting mine to the "flush" position it gave me a bad intermittent stumble in idle. i had to readjust out about two quarters ($.50) thick. stumble went away.:2cents:

thats pretty strange. how would it do that? leaking vacuum?

 

[BoostedSUV]

Re: Cause of my Ty's poor fuel economy found?

after adjusting mine to the "flush" position it gave me a bad intermittent stumble in idle. i had to readjust out about two quarters ($.50) thick. stumble went away.:2cents:

Wouldn't that be giving your 2 quarters, not 2 cents? :rofl:

 

[BoostedSUV]

Re: Cause of my Ty's poor fuel economy found?

thats pretty strange. how would it do that? leaking vacuum?

I was thinking the same thing. What would that have to do with idle or stumble?? That's just a switch for the TC and ABS system? Pretty weird

 

[i8av8]

Re: Cause of my Ty's poor fuel economy found?

that :2cents: thing was extremely funny. no, seriously.

i have no vacuum leak, and no abs. your guess is as good as mine on this. i made no adjustment other than the one suggested at the beginning of this thread. i drove a couple of miles and then "stumble". readjusted out my 2 quarters and no more stumble.

in the beginning, mine was out about 1/4". just thought i'd try this adjustment hoping for better fuel eco., but nothing changed in that dept.

 

[BoostedSUV]

Re: Cause of my Ty's poor fuel economy found?

that :2cents: thing was extremely funny. no, seriously.

i have no vacuum leak, and no abs. your guess is as good as mine on this. i made no adjustment other than the one suggested at the beginning of this thread. i drove a couple of miles and then "stumble". readjusted out my 2 quarters and no more stumble.

in the beginning, mine was out about 1/4". just thought i'd try this adjustment hoping for better fuel eco., but nothing changed in that dept.

Definitely not doubting you, just trying to figure out what in that adjustment would cause what you're describing. Definitely strange but I've seen weirder things with these trucks.

The only way this adjustment would aid fuel economy would be if it was way out of adjustment and the TC wasn't locking when its supposed to.