New 5.0L built, low compression and horrible MPG

[boominXplorer]

My injectors are brand new, but I suppose that doesn't mean they're good. I've also checked for vacuum leaks and couldn't find any, but again that's not to say there isn't one.



Mine does sit how you described, but from what I've read the position doesn't matter. So long as it's mechanically lined up which mine is because I used the tool, it should be fine. Unless there is something I don't know about. Also when you're saying CPS I'm assuming you mean the cam sync aka distributor?



I had all 7 plugs in the engine during the test and the tester in one cylinder obviously. Remember I have GT40 heads which have bigger chambers, but then again my 99 has GT40P and still runs 130-140 psi. But that weird thing is my 99 runs amazing.

When mine had a bad injector it took me a little bit to figure it out. My symptoms were I would have a solid miss fire after running for about 5 seconds. I ohmed it out and it was right within range, checked signal with noid light and tapped it with a 9v battery with the key on and it would spray and sound just like the others and it didn't leak down. As a shot in the dark I spent $45 on a new one just to see and sure enough it was my issue.

At the time my cylinder was kinda washed with fuel so it had the lowest compression ratio at 125psi (others were 135-160). I though I had a bad rocker arm (mine are aftermarket) but after verifying everything looked good I needed to look somewhere else.

Since I swapped the v8 in my ranger it had always ran great but had just a slight shake at idle. I always thought It might be the tight mounts and exhaust hangers and I was wrong. After fixing the bad injector it runs 3x smoother at idle. It actually idles right at 600 rpm smoothly where it used to sit at 650-700. Now I did disconnect my battery during the process so it had to relearn idle during the restart but I still think the extra leaky injector was the issue of my fuel loss.

Your cam positioning sensor should be installed correctly if you used the tool. I have looked at a ton of used 5.0Ls before and none are in the same place. Hell I have one from a 99 and a 00 in my garage with less than 100k on them and one is straight out and the other is a few degrees to the drivers side. I know if you go towards the drivers side it will run richer or towards the passenger it will run leaner. It doesn't hurt to move it around a little and take it for a drive.

Also what helped in my fuel mileage was to get the speedo correct. Because of the 4406 swap in my truck it was reading 20% fast and shifting funny. I had to order the 23 tooth white gear to slow it down the VSS sensor to get within 2%. Now I can get into O/D at 35mph and the torque converter locks instantly. I have a new 7 tooth main drive with 20 tooth gear to swap in that will get me almost exact.

 

[1997XLTRollover]

You may want to verify that the compression gauge is reading accurately. There are plenty that don't. However, given the fuel consumption, it is clear that something is not right.

I've used 2 gauges. The only thing common between them was the rubber hose I used because it's the only one that would fit in a 302 because the plug holes are so small.

 

[1997XLTRollover]

When mine had a bad injector it took me a little bit to figure it out. My symptoms were I would have a solid miss fire after running for about 5 seconds. I ohmed it out and it was right within range, checked signal with noid light and tapped it with a 9v battery with the key on and it would spray and sound just like the others and it didn't leak down. As a shot in the dark I spent $45 on a new one just to see and sure enough it was my issue.

At the time my cylinder was kinda washed with fuel so it had the lowest compression ratio at 125psi (others were 135-160). I though I had a bad rocker arm (mine are aftermarket) but after verifying everything looked good I needed to look somewhere else.

Since I swapped the v8 in my ranger it had always ran great but had just a slight shake at idle. I always thought It might be the tight mounts and exhaust hangers and I was wrong. After fixing the bad injector it runs 3x smoother at idle. It actually idles right at 600 rpm smoothly where it used to sit at 650-700. Now I did disconnect my battery during the process so it had to relearn idle during the restart but I still think the extra leaky injector was the issue of my fuel loss.

Your cam positioning sensor should be installed correctly if you used the tool. I have looked at a ton of used 5.0Ls before and none are in the same place. Hell I have one from a 99 and a 00 in my garage with less than 100k on them and one is straight out and the other is a few degrees to the drivers side. I know if you go towards the drivers side it will run richer or towards the passenger it will run leaner. It doesn't hurt to move it around a little and take it for a drive.

Also what helped in my fuel mileage was to get the speedo correct. Because of the 4406 swap in my truck it was reading 20% fast and shifting funny. I had to order the 23 tooth white gear to slow it down the VSS sensor to get within 2%. Now I can get into O/D at 35mph and the torque converter locks instantly. I have a new 7 tooth main drive with 20 tooth gear to swap in that will get me almost exact.

I don't feel any miss. The engine is fairly smooth. Sometimes I do feel like it could be better, but I might be spoiled by newer OHC engines. I can rev it in neutral to 4k and it's very smooth, no shakes or misses. My last engine was destroyed by a bad injector so I bought all new ones hoping I wouldn't have any issues :/

Also my 96 for arguments sake is all stock apart from the exhaust. Tires are factory size and trans shifts and locks up great.

 

[1997XLTRollover]

So I had another thought. Since my mileage is so bad I'm thinking there are a combination of things doing this. Step one is I'm going to get an alignment and then swap my rear tires up front. The truck pulls right a bit and I'm thinking maybe a messed up alignment and me loading the PS pump constantly to keep it straight is part of my problem.

Also and tell me if you guys think this will make a difference, but every so often I smell burnt rubber. I feel the tires and they aren't overly hot, just normal on all edges. The only thing I can think of is maybe it has something to do with my t-case (indirectly). I measured my tread depth and my two front tires are about 2/32'nds lower than my rears. Do you guys think this will effect fuel mileage? I know that's within allowable spec, but still obviously isn't ideal.

 

[1997XLTRollover]

Well at the risk of just talking to myself, I'll post this up for anyone in the future. My last tank I got 12 MPG. I noticed this change after replacing my old horrible looking o2's (looked like someone ran some type of engine cleaner through my old worn out engine) and the truck seems to be running better.

One tank isn't a great test but I'm pretty sure this isn't in my head. So next step will be a front end alignment. After that I think I may ditch my almost brand new tires for another set of new tires that are exactly the same tread height. I'm constantly smelling a mild burning rubber smell when I park and I'm starting to think the t-case is working too hard due to the 2/32nd's of tread difference between my front and rear tires. Not only is this burning up my tires and t-case, it may also be hurting my MPG.

I'll probably start by swapping the tires off my 99 onto my 96 to see if this makes a difference before I shell out 1000 bucks for new tires.

 

[Dono]

Were just all out of ideas' that's all.
Don't think we are not all watching. I still just can't believe that mileage is that bad.....Its terrible.

 

[1997XLTRollover]

Were just all out of ideas' that's all.
Don't think we are not all watching. I still just can't believe that mileage is that bad.....Its terrible.

Was just wondering what you guys thought about the burning rubber smell. Is that just an AWD thing? None of the tires are hot, but I feel like maybe it's because of the tread difference?

 

[boominXplorer]

Are you sure you don't have a caliper locking up? Have you checked the wheels for one hotter than another? The common burnt smell is brakes or oil dripping on exhaust

 

[1997XLTRollover]

Are you sure you don't have a caliper locking up? Have you checked the wheels for one hotter than another? The common burnt smell is brakes or oil dripping on exhaust

Yes I already checked all of that. Brakes are perfect. The smell is definitely burnt rubber.

 

[Dono]

Its funny you mention the burnt rubber smell. Mine always had that, even after changing the xfer case to a 4406.

In my case, I always had a slow drip on the catalytic converter. After overheating the leak is more of a river flowing on the cat. I can't comment on the rubber smell anymore as I have other issues making it that I'll need to address (New 347 is the plan).

 

[boominXplorer]

Are you having the smell under medium to hard acceleration or every time you drive the truck? In my case when running the truck hard I get the smell of burnt blow-by. I have had this on every v8 explorer I owned even with low miles. I'm pretty sure it has to do with the baffling to the pcv under the lower intake.

 

[1997XLTRollover]

Are you having the smell under medium to hard acceleration or every time you drive the truck? In my case when running the truck hard I get the smell of burnt blow-by. I have had this on every v8 explorer I owned even with low miles. I'm pretty sure it has to do with the baffling to the pcv under the lower intake.

I ONLY smell it when I park and get out of the truck and it's very mild. I never smell it when I'm driving normal or even under WOT at redline.

 

[Dono]

I know the smell you are talking about as mine was the same. When I'd pull in to the garage I'd smell it. Not really the smell of oil on the cat. I have no idea where that smell comes from.

 

[1997XLTRollover]

I know the smell you are talking about as mine was the same. When I'd pull in to the garage I'd smell it. Not really the smell of oil on the cat. I have no idea where that smell comes from.

Mine seems to be passenger side always. Yesterday I stuck my head in each wheel well and it seems to be the drivers rear wheel.

I also after replacing my wheel bearing and not being able to get an alignment the first time... went back, got the truck half aligned and the alignment machine broke . So now I have to go back for a third time. I then got into an argument with the guy because he didn't want to align the truck at a 2" TT. So I lowered it down to 1.5, and managed to get him to just align it next time they can "squeeze me in" which happens to be the 28th. He says he's not going to have enough adjustment at 2" and I HAVE to lower it down to 33.5" from the fender which is only a .5" TT. I have the 3.25 degree CC bolts in the truck. If this guy can't align it he shouldn't be working on trucks (BTW this is a pretty well known 4x4 place near me). Ok enough with the rant.

I noticed something else interesting today. Well actually I noticed it last week and then it happened again today. My odometer stopped rolling!!!! I had to just tap the reset button or reset it all the way for it to start moving again. Now I really think this is a new issue and has not been my issue this entire time because my ultra gauge instantly started reading better MPG when I put in the new o2's, and I do watch my odometer quite often. But it seems to have started after I changed my o2's and I'm wondering if I maybe bumped some connector down there while I was messing with my exhaust. But that would be odd because when I reset the thing on the dash it starts to spin again. It's almost as if the motor behind the cluster is going bad. Anyone ever had this issue before?

 

[rb142]

Are you talking about the actual odometer or the trip counter (I assume the trip counter). I have found it pretty common to get the trip counter stuck when you press the reset. The right wheel gets stuck half way between numbers if you don't press the reset all the way, and then it doesn't get turned. You just have to press the reset all the way again to get it moving. That's pretty common.

 

[1997XLTRollover]

Are you talking about the actual odometer or the trip counter (I assume the trip counter). I have found it pretty common to get the trip counter stuck when you press the reset. The right wheel gets stuck half way between numbers if you don't press the reset all the way, and then it doesn't get turned. You just have to press the reset all the way again to get it moving. That's pretty common.

Yes I'm talking about the trip odometer, I'll have to check the regular one to see if that's still moving next time the trip one jams. Are they two separate entities? I always assumed the trip one was what drove the main one as well.

My trip always moves from zero but seems to just hang sometimes once it moves a bit. For example today it stopped while showing 50.7 miles. Last week it was at 1xx.x when it stopped.

 

[1997XLTRollover]

Ok trip odometer stopped at 50 miles again, as did my main odometer when my trip odometer stopped. I didn't touch it and after about 20 miles or so it started moving again. Anyone have any idea what might cause this?

 

[Dono]

If the speedometer in the cluster is working when the odometer stops, we really need to look at the instrument cluster. Probably easiest just to replace it with a different one.

 

[1997XLTRollover]

If the speedometer in the cluster is working when the odometer stops, we really need to look at the instrument cluster. Probably easiest just to replace it with a different one.

The speedo works fine. My temp gauge does jump a bit but I never cared because my ultra gauge reads right from the ECU. Guess I'll have to find another one with the same miles in the yard. Figures. I was just there Saturday.

 

[Joe in NY]

Ok, 90s Ford odometers strip gears often. Known and common problem for Ford. As for your cam...

To improve emissions and get past smog car companies usually retard their cams and cam drive together. You put a new non emissions chain and sprockets right? Wellllll maybe the cam alignment is off set for a factory build and with the new equipment its way off base... I have read a lot about being careful with stock components due to having to meet emissions in older V8's when building them up...

Just a thought from a learning amateur