low power under 3000rpm

[Mark_88]

I'm sure you've done this in the past but have you physically calculated your fuel economy or do you just rely on the telemetry that your software computes from the PCM? If you haven't, try filling up your tank totally full, reset the trip odometer, drive a hundred+ miles, fill up your tank full again and divide miles driven by gallons of fuel added to tank. See how that compares to your droid app. Just trying to think outside the box a little bit.....

I was just wondering this myself...and going to suggest the same thing...

Oh, and make sure your tire pressure is correct because that can throw things off considerably...

Your compression is great...and you've thrown all kinds of money at this problem...since I'm a bit lazy right now and in the middle of the post, what size tires are you running? Just wondering if you're thrown off your measurements by increasing or decreasing tire size...

 

[fivestring]

Thanks guys for the ideas.

I do the physical math on each fill up. And, surprisingly, the Torque program is very close to what I actually get on mileage.

Tires are all new and at 38-40 psi, stock rims, 14" tires.

Things are looking better. After removing the cat and adjusting the fuel pressure regulator I didn't reset the computer and I think the engine is slowly readjusting to the free flowing exhaust and higher fuel pressure. My last 80 mile round trip to work is showing (OBD) over 30mpg average. And that is with the A/C on the entire time. My flat acceleration under 3000rpms seems to be gone.

I will not claim victory over this problem just yet. My next tankful of gas will tell the real story.

On the regulator adjustment, I found a discussion thread on a Subaru forum on adjusting stock regulators. On the top of the regulator is the vacuum nipple. Inside, a spring is seated around the outside edge. I removed the regulator and put it on the bench vise. Then I took a 13/16 spark plug socket and set it on top of the regulator and gave it a few taps with a hammer, just hard enough to dent the top in a little. This slighly compresses the spring inside the regulator and raises the pressure that it takes for the fuel to open the bypass valve. My pressure went from 35 to 43 psi.

 

[jlcs]

No Power under 3000 rpm

1995 Ranger 2.3l 5 speed 205,000 miles! Timing belt at 152,000. No power and I mean "NONE" under 3000 rpm. This baffled me for a month as I tested, vacuum / compression / fuel pressure and coil packs. Replaced plugs / fuel filter and air filter. Cleaned MAF / EGR / PDFE. Nothing helped ... Finally noticed my Harmonic balancer was wobbling (not good). Removed the bolt and found that the harmonic balancer would spin 3/4 " in both directions. Turns out the "Woodruff Key" snapped in half . The timing gear still had a piece of the key in it so the timing was on, but the crankshaft sensor was telling the computer the timing was off ! Replaced the key and reinstalled the belt. You would think I put a new engine in it ! Just a thought to check the key and your crankshaft sensor. Good Luck !

Jim

 

[fivestring]

jlcs, that is my next step, to remove the pulley and check the key and keyway, along with triple checking the alignment of cam/crank marks.

I did see another post somewhere showing a harmonic balancer pulley that had worn the keyway almost twice as wide as what it should have been. Some light weld bead and a little filing and it was good as new, he reinstalled with a new key and had the same results as you.

 

[fivestring]

Today I pulled the air filter housing and removed the baffle that sits inside the fender. I also replaced the intake muffler with a straight piece of pvc pipe.

I won't get to the timing belt for a few days. Other stuff to do besides work on my truck...

 

[killj0y]

fivestring, so did the regulator adjustment do anything noticeable for you? I'm curious because I still feel like i could get a little more out of my trucks low end.

 

[tomw]

Messing with the regulator will just increase fuel consumption. The flow through the injectors will be increased across the board, and the O2 sensors will be reporting 'rich', and the computer will try to compensate for the extra gas by cutting the injector time as far as it is able.
Whenever I've gone down to the other end of the state, I have found that most of the fuel is labeled "contains alcohol" or words to that effect. Ethanol will increase consumption by about 15% from what I have read elsewhere. Exact details are not in my brain right now.. It will withstand higher compression and more timing advance than straight gasoline, but most computers can't take advantage of that, so you use more.
Dumping the catalytic converter will just make the SES/CEL light up, as the O2 checking converter efficiency will report that the converter has failed... If you have OBD2, and a 'downstream' O2 sensor.
When I replace the belt on my truck, I set the timing incorrectly, and it made the engine gutless unless I revved it up past 3k. It didn't want to get out of its own way until I set the timing properly. I think a mis-timed cam belt can cause similar problems. I don't know specifically, but some engines have a sensor embedded where the distributor was located, and it must also be timed when the belt is replaced.
tom

 

[fivestring]

I know SOMETHING made a big difference in power. I can say I am now satisfied with the acceleration over the entire range. I can't say for sure it was the regulator or the removal of the cat. I did both at the same time.

I do have a downstream o2 and have not gotten any error codes yet. The OBD waveform of the second sensor didn't change much.

I decided to try a little higher fuel pressure than the 30-35 I was getting. So I went to the boneyard and got a regulator to experiment a little. I am now at 43 lbs so I am not very far outside the stock range, just on the high end.

I am at half a tank of gas right now. I will run another couple trips to work before fueling again and checking mpg.

I am still going to recheck the timing belt as soon as I get the time to do it. IF it is still a tooth off, I can't imagine how it will run when corrected.

 

[killj0y]

keep me in the loop cause i still want a little more power too. Nothing crazy but I feel like this truck probably has it in her.

 

[Musick17]

I dont know the difference between your 2.3 and mine in my 2002. But last night I filled up, drove 32 miles highway 37 in town miles, and 32 highway miles back home. So 101 miles total. When I filled up again it only took 3.332 gallons. You could do the math, but 101/3.332=30.3 MPG... Seems a bit far fetched to me. I know its got 3.73 gears and I presume stock tire size, I have never put new tires on it and the previous owner was an old man.

But my pull still sucks under about 3k rpms too. It gets jerky and bogs down if you give it to much gas.

Edit: checked on my lunch break and it does have stock size tires and wheels. Also cruising at 55 my RPM's set just a hair above 2k

 

[fivestring]

Musick, I really wish I could get somewhere near that kind of mileage. I am driving like a pappy and I still only got 19.6 mpg on my fill up today.

I swapped in another tps yesterday. Torque was reading 16.9% throttle at idle. After changing it out I am getting a reading of 16.1%.

I came home and opened up the timing cover again. The marks were where they should be. The keyway and key were all in good shape on the crank pulley.

I had read somewhere that a guy had used a different mark on the cam gear when lining up everything. There is a 'dent' or divot pressed into the edge of the cam gear, about three teeth counter-clockwise from the triangle. I realigned the cam gear using that mark and started the engine. It started fine but sounded like a V8 with a big cam in it. It revved up quickly but I could tell it wasn't right. So I went back to using the triangle mark and set everything up but advanced the cam one tooth. After turning the engine over twice by hand to take the slack out, the marks were very close to where they were before I started. It may be one tooth advanced from where I started, not really sure it is so close. I will be able to tell more if I made a difference on the way to work tomorrow when I can monitor the OBD and get a feel for longer range driving and mpg estimates from Torque.

Still no error codes.

I'm considering trying a different ecm from the boneyard.

I'm running out of ideas of what to look for next. Suggestions welcome.

 

[fivestring]

So today I went to the junkyard and pulled an ECM from a 97 Ranger with same engine/tran setup. I put it into service before driving home from work tonight.

First impressions are that it seems to have a little more acceleration on the low end but it could have had more to do with the cooler night air. A few more miles during the heat of the day and more time for the ecm to learn setting is required.

I had a guy suggest to me today to replace the cam sensor. I never considered it but now I am wondering....??

Here's a couple screen shots of the Torque program. The first one is at 70mph....

...and this one is at idle...

This one is showing the upstream O2 sensor voltage on the vertical and time in seconds across the bottom,as well as fuel trim for that O2 sensor. This was at 70mph. Does this look like a properly functioning sensor?...

And here's what it looks like at 60mph in 4th gear. All these were snapshot while on level road....

 

[rrbrian222]

Dang....no pics.... Just in case you weren't aware, you need to serve your pics from an external host like photobucket, flickr, google picassa, etc.

My OBD-II scanner is on the way (scantool.net) from Amazon. I will compare values to what you have posted and see if anything stands out. Hopefully the included Obdwiz program is similar in function to torque.

Also, the other poster, MusicK17 has a Mazda designed Duratec 2.3L, not the older Lima engine so comparing fuel economy isn't really apples to apples.

 

[fivestring]

Oh,sorry. I didnt know that. I'll fix them tomorrow when I am on a computer instead of this droid.

rrbrian, isn't your 95' OBD1 instead of 2? I thought OBD2 started in'96.

 

[rrbrian222]

isn't your 95' OBD1 instead of 2? I thought OBD2 started in'96.

I don't when in 1995 Ford started implementing OBD-II, but my truck was built in August of that year and has it. I think around late summer, auto manufacturers start getting ready to switch over to next-model-year production, so being that it was federally mandated for 96, they must have gotten the ball rolling a little early.