Help Diagnosing: 2.5 swapped '01 B2300 Low power/rev issues

Deets: 2001 Mazda B2300 purchased w/ a blown motor. Swapped in a 2.5 from a '13 fusion w/ ~67k on it. Reused most of the ranger parts (cams, manifolds, etc..). The goal has just been to get it running and pass emissions. It runs, but not well, and I'm on the clock now that I've registered and tagged it to get it through inspection.

Issue: Starts ok, but after it's warm, it has rough running issues w/ not wanting to rev, low on power, and stalling out of idle. It's generally down on power overall, but very specifically falls on its face between 2-3k rpm, picking up noticeably at the 3krpm point. Light throught inputs north of 3k and it does ok. Heavy throttle inputs don't do much, especially below 3k it just bogs. 

Relevant info:

- I deleted the IMRC (flaps in intake runner). Other people have done this without these issues. Between the displacement bump from 2.3 to 2.5 and significantly better flowing head, and issues other people have had with the IMRC setup failing and eating the motor, it seemed prudent. Now I'm worried it's part of the problem but can't figure out what it would be other than the stock tune needing it still?  The solenoid and rotator are still plugged into the harness, I've just capped the vac solenoid, and the rotator doesn't have a rod in it anymore to spin

- I up-sized the injectors slightly (~13%). Stock are 190cc @ 3bar. I put in a set of 215cc @ 3bar. With an 8.7% displacement bump, and better flowing head, that should put me pretty dang close, right (w/ stock tune)?

- Replaced fuel pump, both o2's and the fuel filter so far. No check engine light.

- Tested the TPS and it seems to check out. IAC also. Confirmed the plug wires are in the correct place.

- Other new parts include: battery, plugs, wires.

Thoughts on where to go next? I hate to parts-cannon it, but beyond needing to get it past emissions, Bluekid #1 is due to drop in a few weeks as well, so I'm very much out of time!

Sorry for the wall-o-text. Here's a pic of Betsy the 'lil red b2300 under the very watchful eye of our fur-baby Sunny to make up for it:

Well this answers my question about how the truck is doing.

Check fuel pressure?  If you don't have a way to measure it, maybe clamp the return line to see if it helps or hurts?

Also check ignition timing, both that it is set where it's supposed to be and that it advances itself to some degree.

Other dumb stuff- cam timing correct?  Firing order correct?  Does it do what you'd expect it to when you unplug an injector or an ignition lead?

If you didn't upsize the MAF sensor, it would still inject the fuel based on the old injectors.   Has really nothing to do with the displacement, since the MAF is doing the work.  If it were a speed-density system, you'd be more correct in what you did.

Any chance you can get a recording of the O2 sensor and the fuel trims?  

In reply to alfadriver :

Wouldn't you expect it to have a code for too rich/lean if it were off by that much?

In reply to ¯\_(ツ)_/¯ :

Not yet.  Given how crappy it runs, I doubt it's gotten around to run that monitor or fully adapt.  Which is why I'm hoping that the actual live fuel trims can be looked at.

Still, the match of MAF to injector and fuel flow is the important part on this era of vehicle- not to displacement.  

alfadriver said:

In reply to ¯\_(ツ)_/¯ :

Not yet.  Given how crappy it runs, I doubt it's gotten around to run that monitor or fully adapt.  Which is why I'm hoping that the actual live fuel trims can be looked at.

Still, the match of MAF to injector and fuel flow is the important part on this era of vehicle- not to displacement.  

Well that's interesting, but makes sense. Also explains why some people have done this swap, kept the old injectors, and didn't have issues. Would that make it rich enough to run this poorly, though?

I'd be able to put more miles on it for troubleshooting, but I'm also trying to find the leak in the AC. Can't commute in this heat w/out it...

It did have too rich codes previously, but they haven't come back since I did the o2's and replaced the battery. 

I have a bluetooth obdii tool and torque that I've been using. I know I can get o2 readings, but not sure about the fuel trim %. I haven't been able to figure out how to get a decent log of the info I want from the torque app yet, though.

Thanks, Alfa!  Figured you'd be one of the best resources for this 

Chris, yeah, I need to get it running decently,  then we can talk more. It's a priority for me, so I'm making time over the next few weeks to get this straightened out. I had some thoughts I was going to email you. Did you ever figure out a vehicle for the PLB this year at all?

In reply to bluej :

As far as I know, no PLB plans yet this year.

If you have the old injectors it should be relatively simple to plop them back in.

In reply to bluej :

I *think* the terms you want are LTFT and STFT.  

Not 100% if they would be the total cause or not, but a contributor, for sure.  I'd also double check the cams, which I know are a PITA, since there are no marks (at least some of the engines of the era didn't have marks, just used pressed on sprockets on the cams.)  13% is a lot, but not so much that it should be too rich...  

Can you put the old injectors back in?

Oh, and the new fuel pump- did you keep the old regulator?  IIRC, the truck has return-less fuel, so the main regulator is in the fuel pump housing.  And if it's returnless, it should be 65psi.

¯\_(ツ)_/¯ said:

In reply to bluej :

As far as I know, no PLB plans yet this year.

If you have the old injectors it should be relatively simple to plop them back in.

yep, definitely still have them. I just figured out how to set up the logging in torque, so i'll take a drive tonight to get some data. Also, ignition timing is controlled by the ecu, and I know the plug wires are on in the right order. I'll verify cam/crank timing, though.

alfadriver said:

In reply to bluej :

I *think* the terms you want are LTFT and STFT.  

Not 100% if they would be the total cause or not, but a contributor, for sure.  I'd also double check the cams, which I know are a PITA, since there are no marks (at least some of the engines of the era didn't have marks, just used pressed on sprockets on the cams.)  13% is a lot, but not so much that it should be too rich...  

Can you put the old injectors back in?

Oh, and the new fuel pump- did you keep the old regulator?  IIRC, the truck has return-less fuel, so the main regulator is in the fuel pump housing.  And if it's returnless, it should be 65psi.

yeah, checking the cam/crank timing is a pain, so I'd like to do what I can before going there. Yes, it's a returnless setup w/ a pressure regulator on the main rail that appears to be just a vacumn reference.

This is the rail (ebay pic):

Yes, I think those injectors are off by enough to really screw with how it runs.

Robbie said:

Yes, I think those injectors are off by enough to really screw with how it runs.

well, swapping them is a minor pain, but if that turns out to be the fix, that'd be great!

Relevent thread (short). He had fueling issues/CEL while trying to use the 2.5 injectors with 2.3 PCM and MAF. Didn't like how it ran after switching back to the 2.3 injectors, so he did a band-aid "calibratable" MAF/aftermarket filter. Not sure if that would fly for your emissions testing or not.

Sidebar: Did you do a VVT delete? Balance shaft delete?

Thanks for the link! I did spend time trying to search the various mark specific forums, but without a ton of luck.

Yep, both VVT and the balance shafts deleted. I had to stick with the ranger cams because the timing lobes/teeth were very different from the VVT cams the 2.5 came with and the stock ecu wouldn't have worked with them for sensing cam timing.

Ultimately, I've got a microsquirt and turbos sitting on the shelf waiting to go, but I need to get it usable as a truck and do some other work before I go that route.

WRT the cams, see if you can find some 2.3l Focus or Fusion (or Milan) cams (the early versions are the same base non VCT cams).  They are a lot better than the Ranger cams- more lift and duration.  And that does work with a turbo, too- at least it worked 15 years ago when we made a 2.0 turbo out of a Mondeo...  

edit- for that matter, the 2.0l and the 2.3l had the same cams in the cars...  IIRC.  Those engines are pretty common out there, including the 3 and the 6.

alfadriver said:

WRT the cams, see if you can find some 2.3l Focus or Fusion (or Milan) cams (the early versions are the same base non VCT cams).  They are a lot better than the Ranger cams- more lift and duration.  And that does work with a turbo, too- at least it worked 15 years ago when we made a 2.0 turbo out of a Mondeo...  

edit- for that matter, the 2.0l and the 2.3l had the same cams in the cars...  IIRC.  Those engines are pretty common out there, including the 3 and the 6.

Looking longer term, do you think those would be better than the VCT cams for a turbo if I were to take control over the VCT via the standalone?

again, thanks so much for your insight!

In reply to bluej :

Yes and no.  Yes if you have a lot of dyno time and can tune the crap out of them.  No, if you do not.  Personally, I think you can get it to run great w/o VCT.  

The cam schedules were really set up to get better fuel economy, and also tuned slightly to get better catalyst light off performance.  So if you set them to best power and leave them there, you, theoretically, will be giving away a little fuel.  But, again, to really find that fuel, you need dyno time and in cylinder pressure measurements to get the spark exactly right.

So I'd lean to a fixed cam and turbo.

Works for me. Thanks for saving me the trouble!

K. Did some driving, logging, and testing yesterday evening. Re-checked for vacuum leaks, verified the injector connectors and plug wire connections were good.  I did order a new ignition coil since they're fairly cheap and it seemed to be a common enough failure point w/ odd symptoms (comes tomorrow).

Nothing changed unexpectedly. Driving the truck it just doesn't want to rev overall. Does that point more towards a cam/crank timing mis-match as opposed to a rich condition? 

Anyway, here are some excerpts graphed from the logging. Happy to send the full thing to anyone willing to take a look! Some values are scaled to get them to be visible on realistic graph scale.

Warmup:

Early Light Throttle:

Full Throttle:

Hot Idle:

I tried to assemble everything so that it scaled at readable values, but let me know if it's not clear or want some other info from the logs. happy to share!

thanks!

hmm, that's hard to read still. I threw the PDFs of those graphs, and the raw and cleaned up excel files in a google drive folder:  Logs

hmm... looks like the timing advance pulls negative in the 2-3k range on the full-throttle set, then jumps up to 22ish @ about 3k, before tapering back down, even as revs increase. That seems odd, and explains some of the driveability.  

If the fuel trims are all getting pulled negative enough, would that also pull the timing advance?

edit: looking at the light throttle graph, the timing advance punches up to 38-43* when using very light throttle (sub 25% and 16% is closed). that makes sense, right? 

Not looking at the data (I'll download it and look at it when I get home from work....), but the spark reaction is 1005 because of the IRMC being gone.  The computer totally expects them to be there, and the retarded spark is because they make the engine much more knock sensitive when they are closed.  And they open at about 3000rpm.

But I'll find some time to look at the data some tonight.  (I may have to send a clean version of it to work, as I have better potting programs.)

As for the light throttle spark- yes, that's what it's supposed to do.  Except at idle, where it will be in the 10ish range.  And on the cold start (and by that, I mean ~70F after 8 hours of being off).

Is "1005" a typo, or do I just not understand the reference?

So it's stock that at WOT in the zone that the flaps would be closed, it pulls timing all the way to -16 and -5?

100%.  % is just above 5.  

And yes, the IMRCs are closed, even at wot, up to about 3000rpm.  Being knock limited is a bitch, but getting crappy combustion due to poor turbulence is worse.  Remember that when you put a spark calibration in for your MS system... 

Ah!(100%) Ok, thanks!