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2.9L Reality Check: Highway capable?

RonD

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Secondary fuel code means computer didn't see 12volts on the 12v wire to the fuel pump at some point in the past
Primary fuel code references the fuel pump relay
No, there is no "extra" fuel pressure at any time, and no fuel pressure sensor in any case
Lack of fuel pressure at higher speed would set Lean code, for sure, and engine would be pinging/knocking like crazy, can't miss that
Too much fuel also causes a lack of power, but that should set Rich Code

If its not a fuel issue, that leaves compression or spark
18" of vacuum at idle should indicate compression is OK
I would test base spark timing just to take that off the table
 


eightynine4x4

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Secondary fuel code means computer didn't see 12volts on the 12v wire to the fuel pump at some point in the past
Primary fuel code references the fuel pump relay
No, there is no "extra" fuel pressure at any time, and no fuel pressure sensor in any case
Lack of fuel pressure at higher speed would set Lean code, for sure, and engine would be pinging/knocking like crazy, can't miss that
Too much fuel also causes a lack of power, but that should set Rich Code

If its not a fuel issue, that leaves compression or spark
18" of vacuum at idle should indicate compression is OK
I would test base spark timing just to take that off the table
Thank you!
Still have 2nd half the code test to do because the skies opened up and needed to put a pause on it. So with the truck running, we’ll see what codes pop out.
 

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Ok, I think I might have a faulty computer in this truck.
Firstly, I checked the base timing minus the spout and it is dead on 10 BDC. That makes me happy because that must mean nothing has budged since I did timing in the fall.
But, with the spout back in, according to the OBD manual, the computer in self test mode is supposed to hold the truck at + 20 over base timing for like a few minutes, so that’s 30 BTD. There’s a clear notch on the gear/wheel between 27/33, obviously meant for this test. The instructions are a little vague in that they 100% state that AFTER the KOER codes are pulled that the engine is supposed to sit at the above timing for two full minutes for this purpose of checking it, but neglect to say how the timing should behave DURING those codes before this phase. Regardless, what happens during the codes is a couple ups and downs very briefly here and there. I know I’m supposed to be doing some throttle and brake stuff but for now that’s void until I check the +20. So, during this jumpy code phase I think I saw it reach momentarily to 30 BTD but it was a quick moment. But mostly it just sat at like 16-18 BTD (that’s +6 to +8). It moved around some.
So I waited that out and waited for the end of the codes, as indicated by the OBD reader no longer having a blinking square, and I was expecting computer to rev it up to 30 BTD but it never did at all. It just stayed at 16-18 BTD for another two minutes or and then suddenly (with kind of a muffled but scary pop sound) it went back down to about 10 BTD. So I shut off the truck.

Something’s gotta be wrong here becuse I’m following all the orders.

Could a faulty computer do this? Or could it be caused by something misleading the computer to thinking it’s at 30 BTD?
 

RonD

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If base timing was 10deg BTDC then with SPOUT connected it should go to about 18-20deg BDC
So what you saw was correct

I would try 12deg BTDC

Spark timing is based on the time it takes for the air/fuel mix to fully ignite(exploded)
That takes a few millisecond from spark to full explosion
So spark happens Before TDC, so full ignition happens After TDC so piston can push down on the crank adding power
The trick is you want the full explosive power to happen 8 to 10deg ATDC so the space between head and piston is still small(more explosive force) and connecting rod has some leverage to push down on crank shaft journal

As the RPMs increase the piston is moving faster from say 20deg BTDC to 10deg ATDC, but the air/fuel mix still takes the same amount of time to fully ignite
So as RPMs increase the spark needs to happen at 20, 25, 30, 35deg BTDC so the full explosion happens with piston in the correct position After TDC to get as much power as possible
Its a science, lol

And to add to it, air/fuel mixes change, and that changes the TIME it takes to fully ignite, richer fuel mix ignites FASTER
This is what the purpose of the SPOUT connection is for
Computer "knows" the fuel mix it is using so it "tells" the TFI module how to adjust spark timing for that mix

The TFI module has an RPM spark advance calculator, pretty simple really
The SPOUT does "load advance", it does what Vacuum advance did on the older distributor systems

If you slowly raise RPM you will see spark change to higher BTDC numbers
If you REV the engine, you might see it go up and then back down as the SPOUT adjusts it for the RICH mix you get when REVing the engine

If your spark timing is off then you may not get full ignition until 15-20deg ATDC which keeps the engine running but not much power added
The 12deg BTDC can help in that regard, but no more than that
 
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eightynine4x4

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If base timing was 10deg BTDC then with SPOUT connected it should go to about 18-20deg BDC
So what you saw was correct

I would try 12deg BTDC

Spark timing is based on the time it takes for the air/fuel mix to fully ignite(exploded)
That takes a few millisecond from spark to full explosion
So spark happens Before TDC, so full ignition happens After TDC so piston can push down on the crank adding power
The trick is you want the full explosive power to happen 8 to 10deg ATDC so the space between head and piston is still small(more explosive force) and connecting rod has some leverage to push down on crank shaft journal

As the RPMs increase the piston is moving faster from say 20deg BTDC to 10deg ATDC, but the air/fuel mix still takes the same amount of time to fully ignite
So as RPMs increase the spark needs to happen at 20, 25, 30, 35deg BTDC so the full explosion happens with piston in the correct position After TDC to get as much power as possible
Its a science, lol

And to add to it, air/fuel mixes change, and that changes the TIME it takes to fully ignite, richer fuel mix ignites FASTER
This is what the purpose of the SPOUT connection is for
Computer "knows" the fuel mix it is using so it "tells" the TFI module how to adjust spark timing for that mix

The TFI module has an RPM spark advance calculator, pretty simple really
The SPOUT does "load advance", it does what Vacuum advance did on the older distributor systems

If you slowly raise RPM you will see spark change to higher BTDC numbers
If you REV the engine, you might see it go up and then back down as the SPOUT adjusts it for the RICH mix you get when REVing the engine

If your spark timing is off then you may not get full ignition until 15-20deg ATDC which keeps the engine running but not much power added
The 12deg BTDC can help in that regard, but no more than that
Ok, this all makes perfect sense and clarifies the whole picture. I haven’t seen a better run down anywhere before! I’ll probably end up trying 12BTDC soon.

However I’m still up against a concerning obstacle with the computer/OBD. I didn’t fully explain in the previous post what I was doing…
Below is a page from the ODB manual, explaining that putting the computer in self test mode (KOER) you will enter a phase where the computer brings the timing up to +20 above your base timing and holds that for some time so that you can check (w light) the timing to confirm that is in fact at 30 BTDC. I only ever got to like 16-18. This is very much not within their range, and they’re saying in the last paragraph that “If timing light readings are not within the acceptable range, base timing may be out of adjustment or the computer may have problems with the timing advance circuit.”
So could something be vitally wrong with said Timing Advance Circuit in my truck?
I follow all of what you’re saying above. Is it possible my truck just isn’t doing it right? It would explain loss of power in high revs.

D3C0DCB0-B167-43B7-B104-94D044DCF0B5.jpeg
 
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RonD

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That's not for the TFI system

Should have this at the start of that tests description
IGNITION TIMING TESTS
NOTE: Timing is not adjustable on Electronic Ignition

So its for spark systems that use a crank sensor NOT a distributor, i.e. 2.3l and 4.0l, so wouldn't do it on the 2.9l and 3.0l(1994)

It is possible your computer has an issue, but not apparent from this test

If you plug in the SPOUT and the base timing at idle does go up 8 to 10deg then I would suspect it is working as it should
 
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eightynine4x4

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That's not for the TFI system

Should have this at the start of that tests description
IGNITION TIMING TESTS
NOTE: Timing is not adjustable on Electronic Ignition

So its for spark systems that use a crank sensor NOT a distributor, i.e. 2.3l and 4.0l, so wouldn't do it on the 2.9l and 3.0l(1994)

It is possible your computer has an issue, but not apparent from this test

If you plug in the SPOUT and the base timing at idle does go up 8 to 10deg then I would suspect it is working as it should
I trust your word on this, but also I find it really weird that this OBD manual and also the Haynes manual both give the same instructions to monitor timing of the self test KOER as it holds 30 BTDC. TFI is mentioned at the beginning of the Haynes chapter as being part of EEC-IV, and EEC-IV is the section I’m using in the OBD manual. The only other section in the OBD manual is an MCU section. The 89 ranger is very clearly listed in OBD manual as being EEC-IV. And there are no other OBD instructions in the Haynes. That short chapter is for all vehicles.
In any case, maybe it’s time to just throw a part at it. It seems that diagnosing faulty computer timing advance is a lost cause. Also, I’ve found stories of folks having rough times getting up hills and replacing the TFI module with successful results in power.

So what are all the parts involved in the timing advance system.. The TFI and the ECA (computer in cabin) and that’s it? Is anything else governing timing advance?

I may or may not bring timing to 12 BTDC before trying to blindly replace parts. I kinda like the idea of keeping it stock and fixing the source of the issue w timing advance rather than setting timing up a bit to compensate for something.

The more I think about it, the more I am convincing myself that there is a major timing/computer/control issue. During warmup, sometimes the engine swells up and down like a musical see saw. It gradually levels out if I let it idle for several minutes. It sounds like the computer trying to figure out what it’s doing.
 

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You could be right
EEC-IV is the computer used in all fuel injected Rangers 1994 and older, each was engine specific, i.e. software/firmware

EEC-V is the newer computer, 1995 and up, still used today, these are also engine specific

I have read about that ignition timing test but never in regards to TFI engines, distributor engines, because they are timed manually by user
 

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I think we may be on to something that explains why my truck is slogging on the highway under wind resistance and hills. I think RonD is right that timing is the key here and that my timing is just plain too late for higher RPM’s.
I found this quote below from another forum.
The first half seems to directly apply to me. Second half maybe not but it seems very interesting.
To summarize, maybe my cam position sensor is not working right, or my ICM (TFI unit) is not working right. If I had a second truck to compare, maybe I could determine that the truck is also not shifting at proper RPM in WOT, thus leading me to conclude that the cam position sensor is faulty and just not sending correct RPM information out to the whole system. But I don’t truly know how the system works.
In any case, I am discovering that there are various components to the timing/advance system that could be faulty and I need to try to diagnose.

One quick trial is to replace the whole distributor and its TFI and its cam position sensor (I think that’s part of the distributor) and see if that helps timing advance in KOER. It’s like a 100 project so not a terrible risk. When I replaced my distributor rotor and cap last year I did notice how crusty the distributor itself is.

“””I just finished resolving a similar problem on my 87 Ranger 2.9v6.
My truck's timing wouldn't advance under load or going up a grade,it severly lost power. I couldn't remove the screws that keep the ignition control modual (ICM) attached to the back of the distributor...one of the screws had a plug over it. I was going to remove the ICM and have it tested, but when I couldn't remove it from the distributor I just put in a new distributor and ICM. It solved a lot of problems.....From my understanding, the ECM recieves the engines RPM from the cam position sensor at the base of the distributor. The RPM signal is sent through the ICM to the ECM and sets the timing advance based on that signal. Another strange problem I was having was that the engine would lug down and hesitate when ever I increased the electrical load.....turning the fan on the climate control to 3rd or 4th (highest) position, using the cig lighter, using my bright lights......it didn't lug down if I engaged the a/c. I went through a lot of troubleshooting ( load tested the batt and alt, replaced the ignition switch, installed a new AIC, new fuel pressure regulator, new high pressure fuel pump, new fuel filter, complete tune-up), but nothing helped until I changed the dist/ICM. Hope this helps someone!!”””
 

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Well I decided to grab a TFI from the auto store down the street just to see if anything happened and after installing the truck literally doesn’t turn over. Starter cranks away with zero catch.
Probably a crap quality TFI.
Pretty serious learning curve with understanding the timing advance system/digitally. I’m still completely in the dark but it’s enlightening to know that the TFI could cause it to not turn over. What’s most interesting is that I already have occasional startup issues where sometimes it cranks for a long time, sometimes it catches immediately. So maybe, IF my TFI and/or computer are not working as a system I could attribute my weird startups to this too, in addition to my timing advance issue.
Am returning the faulty TFI and will receive a full distributor / rotor / cap / TFI from rock auto mid next week. That full set was the same price as just the same exact distributor so figured why not have it all.
Im a little intimidated by installing the distributor and understanding the alignment process so if anyone has some basic advice I’d love to hear it. I’m good with the top half, the actual cap timing at 10BTDC, just uncertain about the deeper segment.

Hopefully the next piece of gear isn’t faulty!
Also hoping I’m not overlooking some kind of computer related step I need to take to get any new TFI working. As far as I know it’s just play and play.
 

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I have read about that ignition timing test but never in regards to TFI engines, distributor engines, because they are timed manually by user
I just had a thought...
In a thread I had going last fall I discovered that the distributor had been loose for the whole time, some half finished project from previous owner and something i didn't know to inspect.
In that same thread i mentioned how difficult it was to turn the distributor for timing as far as it needed to be turned due to surrounding parts restricting it. I even had to very slightly bend a copper line i think since the TFI was butting up against it.
I don't really know how the whole distributor works mechanically and electronically.. is there something else that the previous owner could have done to throw off the timing in some way that i haven't discovered yet? I've been assuming that the clamp down bolt behind distributor is the only way to adjust the timing overall and that if the truck works then it's already in the right general helical gear spot, but is it possible that the truck could operate mechanically/electronically while the distributor sensor system is simultaneously giving the wrong information to the computer?
 

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I didn't read the whole thread, so just incase someone has not said it, and I know it helps you none. Put a V8 in it. Will pull hill at 70.
 

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does the distributor have a vacuum or centrifugal advance in it? maybe its stuck.
 

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TFI distributor has neither, it uses electronic advance based on RPM from the hall effect sensor

Internals seen here: https://www.supermotors.net/getfile/833749/fullsize/distributor8791.jpg
No mechanical movement of timing device inside distributor
I hadn't seen the octane rod before, not sure if Ranger distributors had that, looks like it would mechanically move the timing sensor to pre-set it for higher or lower octane fuel to prevent ping/knock issues

I guess you would call it 1st generation for pre-distributorless Spark systems, i.e. no mechanical spark advance
Duraspark used weights and springs(centrifugal advance) and vacuum advance
 

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TFI distributor has neither, it uses electronic advance based on RPM from the hall effect sensor

Internals seen here: https://www.supermotors.net/getfile/833749/fullsize/distributor8791.jpg
No mechanical movement of timing device inside distributor
I hadn't seen the octane rod before, not sure if Ranger distributors had that, looks like it would mechanically move the timing sensor to pre-set it for higher or lower octane fuel to prevent ping/knock issues

I guess you would call it 1st generation for pre-distributorless Spark systems, i.e. no mechanical spark advance
Duraspark used weights and springs(centrifugal advance) and vacuum advance
Maybe there could be an issue with the stator inside distributor and it’s sending fault/no information to the computer?

Im not quite sure how much it’s even possible to diagnose this advance system if it has issues since there are zero instructions for any next step if an advance issue is indeed found.

Basically, there’s the distributor/TFI, and there’s the computer in the cab. I think that’s it, although I’m not certain at all.
But if that’s it, and I replace both the distributor/TFI and the computer and it still doesn’t fix the timing advance to 30BTDC…

THEN WHAT?
 

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