Gas Mileage

[krsowles]

I have a 1991 AWD with a v6, auto and 3.42 gears. I've put about 2000 miles on it since December when I got it. It had been sitting for 3-4 years before I got it. I am getting about 11.5 mpgs. Way better than my dump truck but not up to what I would think. The fuel system is new from the tank to the motor. I changed the oil, put in injector cleaner twice, changed air filter, aftermarket cap and rotor. I was told plugs and wires done right before he parked it. I have checked for the "light show" after dark and see no arcing(sp?). The EGR valve was pulled and cleaned. The only codes I pull are 15 and 44. 15 not for a while but 44 is persistant. I'm sure many things need attention but I'm curious what the collective brain trust has to offer about my assumption of poor mileage, any order of things that should be corrected first or anything I've missed. The motor seems to run fine! The choke system doesn't work but after 5 mins it runs fine. Other quirk is that when it is warmed up I have to hold gas pedal to floor to start but starts right up. I don't have much time to work on it from now til summer but would appreciate any input. Thanks, Kelly

[MountainManJoe]

According to my Hanes manual (great investment, by the way):

Code 15: Coolant sensor/low temp
Check wiring an connectors and the sensor and PCM, or replace sensor.

Code 44: Lean exhaust.
Check PCM connections. Check for vacuum leakage at the TBI base gasket, vacuum hoses, or the intake manifold gasket. Or replace the oxygen sensor.

In my opinion, either a malfunctioning coolant sensor, or a vacuum leak can cause poor mileage.
The coolant sensor can be easily checked using a cheap-o $10 multimeter, and this chart:

177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C.

Hope that helps.

[krsowles]

Thanks TB, I believe the code 15 to be licked. I had replaced sensor and rewired it. The 44 I have not found. I half - heartedly checked for obvious vacuum leaks looking and playing with hoses and found nothing so I was assuming it was the intake gasket. I thought a bad gasket would have been more obvious, perhaps I'm wrong on that? I had not included the O2 sensor in my scope to check on though. I have a spare I will swap in when I can.
I own a landscaping business and spring is here early this year. My long term right hand man just got another job and we are scrambling to get everything ready so van time will have to take a backseat. Good news is the Jeep came out of storage and being my first love, takes some of the hurt out of van being down!
Thanks again, Kelly

[1Gary]

Kelly-you'll find that these vans like Delco plugs,wires,cap,and rotor only.Even if your aftermarket wires are not showing you a light show,they could not be conducting the correct voltage.I would also clear the codes you have.Then look hard at the very first code that shows up.The other ones you see after is a effect of the first one that is the cause of your problem.It is interesting your saying you have to floor board the gas to get it to start.All EFI systems the only way to clear a flooded situation is haft throttle.I would look hard at the TBI and they are a simple to work on and rebuild and the kits are very cheap.Before the o2 sensor is a TPS that can carbon up and would give you the o2 code and effect your seeing.As TB told you vac leaks and spraying it down with carb cleaner to see a raise in rpm can help you locate where the leak is.One common area is the vac line running to the a/c.

[krsowles]

Thanks Gary, I have read repeatedly throughout the forum about AC Delco only parts which is why I specified they were not. That potential problem will be fixed! It had better gas mileage (about 15mpgs) and seems to have dropped suddenly. The other one annoying me is the non AC Delco fuel pump I put in. Got a feeling I'll need to address that too. The first code is the 15 if it shows. Hasn't been showing up lately but the 44 is persistant. Will try the carb cleaner trick, sounds like fun! I'm not pulling an O2 code and hadn't thought to check it. I can swap out the TPS too. One at a time tho. Don't understand the throttle thing for starting but if its not to the floor it just cranks. Can't be just off floor, right to it. When I do it it starts everytime! I'm going to try to sneak a couple hours to play with it some in the next couple days and will keep you posted. Thanks again! Kelly

[1Gary]

Kelly-what is important is to clean out the carbon build-up in TPS.

[krsowles]

Will do! Would a diesel/kerosene mix work well? I thought I'd pour it ALL over the inside and light. Guess I'll check my insurance first! Thanks, Kelly

[1Gary]

Kelly-this will help:

http://www.autozone.com/autozone/repair ... 52800a7fc5

[krsowles]

Thanks Gary, I appreciate your help. I stood in the back 40 last night with fuel and weenies but couldn't bring myself to do it. Guess I'll fix it...

[krsowles]

Well Gary, you pointed me in the right direction... I checked the TPS wiring and it's not even getting power. The first wire I checked (grey) had the 5 volts it should. The blue wire had 0 volts and when accelerator pressed it stayed at 0 and did not climb to the 5 volts. I checked the temp sensor for grins and it had no power either. Think I have a problem in the main engine wiring harness maybe related to fire that took out main harness across top of firewall. Probably pull the main harness off parts vans and make sure it's good. If so, swap it in. Sounds easy, doesn't it? Thanks again,. Kelly