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Cold engine sputter/miss


Shran

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OK I had a couple spare hours to mess with this some more today.

Found the ACT sensor, replaced it with a spare, no change.

If I push the EGR valve open manually, the engine sputters pretty hard, so other than the fact that it was stuck, I can sorta rule that out but will still replace it.

Vacuum - holds steady around 20 or so at idle, drops to zero as it should if throttle is opened quickly and returns to where it should be... the only exception is if the engine is allowed to run at high rpm and then the throttle is abruptly closed, it will sputter for a few seconds and the vacuum gauge will jump rapidly around between 15-20 or so until it clears up, then back to normal.

Fuel pressure - might have found an issue here. If I prime the system without starting the engine, I get roughly 30psi for a second or two and it bleeds off very quickly to zero. Running, it is within specs, holds steady at a little over 30 and will hit 40 if the throttle is opened.

^ All this was with a warm engine. I'm concerned about losing fuel pressure, it should not bleed off like it does. Seems the only possibilities here are one or more injectors stuck open, regulator is allowing fuel to bleed back through the return, or bleeding back through the pump... regulator seems the most likely, but I don't have the typical warm hard starts and erratic pressure. Through the injectors seems like a good possibility too but I'm not seeing fouled plugs or gas in the oil like I'd expect.

Thoughts? Thanks for the help so far.
 


tomw

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I believe you are right on track with the fuel pressure diagnosis. You might want to pull the vacuum line from the regulator and give it the smell test. If you smell raw fuel, you may have a punctured fuel pressure diaphragm. I think if you had a leaky injector, you'd have hard start - restart - of a warm engine as the fuel would leak into the intake leading to a too-rich mix, leading to stumble and rough idle when restarted.
The suspects in my mind are injectors, regulator check valve, and fuel pump check valve.
I think your fuel pressure is low. From memory, 40psi was the regulated number, and it would 'bump' a bit higher when the vacuum line was disconnected, or the throttle opened(low manifold vacuum @WOT). A quick search, with zero validation, indicated 40-47psi. I did not download & open the pdf. search: '1988 ford ranger 2.3 fuel pressure' Replacements showed on the page in the $66-69 range for complete sender. If you replace the sender, your fuel gauge will read different(likely) from what your old one did, FWIW. The resistors are just not the same, so a 1/2 tank reading would likely be earlier/later than your norm.
The high rev thing(misfire and stumble after crazy revs) is likely pumped up lifters that are not contracting quickly, so they hold the valves open a bit. Possibly a bit sticky?
tom
 

Shran

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Regulator passes the smell test, forgot to mention that. The vacuum line is dry.

I am under the impression that first gen trucks are supposed to show right around 30psi at idle and 40psi under low vacuum and that is what my other trucks from that era have always shown.

After thinking about this overnight I am really leaning towards leaking injector(s). I guess the test would be to prime the system repeatedly and see if it floods the engine. A leaking or stuck open injector would make sense here with the poor mileage symptom, and could explain why it runs better at a certain point too when the computer starts to compensate for the extra fuel. Could also explain why it's so hard to get it restarted when it dies as well, if it's running extremely rich and floods then it would take a lot of cranking to clear the excess fuel.

Fuel pressure bleeding off through the pump check valve makes sense too but since I have two pumps, do they both have check valves? If that's the case I would think that both stuck open is unlikely. The sending unit and lift pump were both replaced in the last couple years but I don't remember if I was having this issue at that point or not.

Maybe I will run a can of Seafoam in the oil and see what that does, the lifters thing makes sense. I had not specifically seen the stumble after high RPM before just recently, maybe it's always been there and I didn't notice it.
 

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Fuel injection computers all have a "Clear Flooded Engine" mode.

Turn on the key
Press gas pedal to the floor and hold it down all the way
(the TPS(throttle position sensor) should now be sending computer above 4.5volts, wide open throttle)
(if computer sees above 4.5v from TPS and RPMs are 0, it will start "Clear Flooded Engine" mode)
("Clear Flooded Engine" mode, shuts off fuel injector pulses but leaves spark on, so spark but NO fuel)

Now crank engine
If should not start, it should not even fire, no fuel to burn
If it does fire or start then you could have a leaking injector.
(it could also mean throttle cable has stretched and TPS is under 4.5volts wide open, lol, Google: Ranger throttle cable mod)

If engine does fire, then you can use this test to find leaking injector.
Unplug the coil or coil pack, you want no spark

Repeat "Clear Flooded Engine" mode test
Pull out spark plugs
The wet one has the leaking injector
 

Shran

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Tried that test when I left work today and it failed miserably, started, revved up pretty high and promptly died when I let off the gas. Again very difficult to restart and sounded weird and ran rough for a mile or two.

I will check voltage on the TPS before anything else, I seem to recall checking it before and it was in spec but a double check won't hurt.

Pretty sure I did the zip ties on the throttle cable, it's pretty much the first thing I do to every new Ford I acquire, they all seem to have some slack. :D

Will also look at disabling spark and checking for wet plugs and will post the results.

I have to be getting close.
 

tomw

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You can pull the fuel rail along with the injectors, and then turn the key to ON. BE PREPARED for fuel spritzing all over the place if an injector is leaky. Pretty simple test, but with definite results. You may have to replace the injector O-rings, or at least lube them with motor oil or ATF for re-insertion into the cylinder head.
tom
 

Shran

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That only works if the injectors haven't been removed in many years and are more or less stuck in place... I did new O rings when I had the engine rebuilt a couple years ago.

If the injectors have been removed recently and you try that test, I guarantee that one or more injectors will get spit out of the fuel rail and gas sprays everywhere. Ask me how I know, lol.
 

tomw

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You'll know if the fuel pump works...

Use zip ties if needed to hold the injectors into the fuel rail. I don't think duct tape will do the job.

tom
 

Shran

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I ordered 4 injectors for it. If I am going through the work of pulling the upper intake off and testing them, I will just skip a step and put new ones in. A set of 4 reman injectors and intake gasket set was only $60 shipped from eBay. We'll see what happens, can't get much worse than it already is.
 

Shran

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I replaced the injectors on Saturday... it most definitely did not fix the problem. However it did seem to change how the truck runs once it's warmed up. It seemed to have some hesitation when pulling away from a dead stop before and the throttle response seemed to lag a little occasionallly. Those issues are better but the original problem persists, still have the cold engine sputter and after high RPM.

I didn't have time to take a fuel pressure reading after the new injectors and I am going to retest the throttle position sensor as well.
 

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The TPS I have in the truck tests marginal at best, it has one small maybe dead spot right off where idle would be... I am really struggling to find a replacement, though. None of the local parts stores even have one listed for an 88 2.3, the Ford shop had one listed but it is the wrong one. I don't even have a part number, the TPS I have actually has the part number filed off (!!! why!!!) The closest thing I have found so far is Walker #200-1018 and supposedly fits Merkur XR4Ti 2.3, T-Bird turbo coupes, 89 Mustang, some Aerostar vans, and several others but not the 1988 Ranger. It looks exactly like what is on the truck now though, and NOTHING else does, so I may risk it and buy one.

In any case I don't think the TPS will fix the issue, I don't know what I had it set to but it was wrong and now it's within spec, under 1 volt at idle and 4.65ish at WOT. Resistance is in spec at idle and about 50 ohms low at WOT. The truck runs like garbage when cold, pretty much the same as when I started trying to figure this out. I am still losing fuel pressure somewhere too.

Help? :) The deeper I get here, it seems like I am not making much progress. I am half tempted to just take it somewhere and get it fixed but I'd hate to make someone spend a bunch of time on it and not be able to get any further than I have.
 

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Must have been hitting the bottle or something the last time I had the timing belt off to replace the front main seal. :rolleyes:

Other than finding 4 missing bolts and two others broke off in the block (for the alternator/PS pump) I also discovered that the distributor had slipped, the timing was way off and the cam was off by one tooth. I don't know why the cam timing marks are not more user friendly on these engines, there are three lines and apparently the middle and left are the ones to use, not the middle and right. Makes no sense.

Anyway I fixed that and made a custom 17mm socket to really crank down on the distributor clamp. I have never been able to get it as tight as it should be because of where the bolt is. Even a shallow socket doesn't fit worth crap. Hope it stays set where it's at now.

So after fixing my hack job it does run a lot better. The original issue is still present although it's much more subtle now and limited to a slight hesitation on acceleration when the engine is cold. I am still bent on nailing down this issue 100% and will continue the updates as I work on it.
 

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I must have missed this recent update...thanks...good to know it is closer to finished.

I would imagine you have power steering in your truck if you can't get at the distributor hold down bolt via the space under the alternator. I didn't have PS so I could slip an 11/16" wrench up under the distributor and tighten/loosen that bolt in very small incremements...or pop the top off the distributor (unscrew it) and put a socket down there.

The "updated" brackets for the alternator (unless they moved it to passenger side that year) was big and bulky but much stronger than the ones used on the carbureted 2.0 (that I upgraded to a 2.3) and I managed to break one...I pulled one from a Mustang and was about to install it when I figured out how to fix the broken bracket...
 

Shran

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The alternator and p/s pump are definitely in the way. My solution was to take a 17mm shallow 3/8 socket and make it even shorter on the belt sander, then narrow the top half with a grinder so that it fits under the distributor and can still turn. Works great. The problem I had was not so much getting the hold down bolt tight, it was getting the socket off the bolt once it has been tightened. I'm sure there is a tool made for this purpose but I haven't seen one at the pawn shop yet so this will work for now.
 

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Cool! Another good workaround...:icon_thumby:

I didn't have access to a belt sander or even a grinder when I started driving the 88 2.0 but found the box end wrench worked well in my case...I still carry that 11/16 wrench around even though I will probably never get a chance to tighten another distributor...lol

But I do remember leaving my distributor a bit too loose and it took me a while to even look at that as a possible cause of the engine antics I was dealing with...my fault again...
 

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