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On this 1998 ford ranger with a 2.5l engine, someone has…

Hey Ron. On this 1998...
Hey Ron. On this 1998 ford ranger with a 2.5l engine, someone has replaced the engine. it has a idling problem,at first start you have to keep feathering the gas to keep it running, then it will begin to idle on its own, but lopes up and down and smells rich out the tailpipe. but even thou it smells rich, I think its starving for fuel, after warm up, it seems to idle better. fuel pressure reads 50 psi.i think that's to low,i have vqcuum at the pressure regulator, but with the vacuum connected or not, doesn't seem to effect the idle, I took a hand vacuum pump and pumped it to 25 and didn't make a difference, do you think I have a regulator problem with this?
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10/12/2017
Ron
Ron, ASE Certified Technician
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Normal fuel pressure on this engine needs to be 56 to 72 PSI so 50 is on the low side for sure. On a properly working fuel pump should jump the pressure up about 5 psi when you pull the vacuum line off the regulator. With the hose connected it should drop. This dose not sound like you have a bad regulator . Is the computer setting any fault codes?

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Customer reply replied 8 months ago
no codes are present.

This to me sounds like you have a fuel pump issue providing the filter is clear. I suspect if you can get the pressure up it may straighten this out.

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Customer reply replied 8 months ago
ok, thank you

Your very welcome and thank you as well.

Ron
Ron, ASE Certified Technician
Category: Chevy
Satisfied Customers: 38,273
Experience: 35 years experience with ASE Certs
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Customer reply replied 8 months ago
hi Ron. I am still fighting with this vehicle, I have tried 2 new mass air flow sensors. the first sensor solved the idling problem, idle good , no rich smell, but when raising the rpms it wouldn't, it started to buck and jerk backfire, the 2nd one makes the truck run like the original 1 I took off. I can unplug the mass air flow and it will idle good, but will stall after awhile,since I went and put some gas in this thing that was almost empty, the fuel pressure has come up to 55psi.have you got some suggestions on this

Are yo till not able to get any fault codes to set?

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Customer reply replied 8 months ago
had my scanner on it last night and no codes except for the air temp switch that I forgot to hook back up
Customer reply replied 8 months ago
what about a crankshaft sensor, is this wired thru the mass air flow

Its seems pretty odd that its not setting any fault codes and the Crank sensor is separate from the MAF . I wonder if the timing belt is properly aligned. When the engine was installed was the belt changed?

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Customer reply replied 8 months ago
they had that all apart and I installed a new timing belt kit. I had all the gears aligned like they were suppose to be

Dose it seam to have proper power once you get it off idle?

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Customer reply replied 8 months ago
I can rev it up. after warm up ,the idle does get a little better, but still smells rich out the exhaust

Have you gone back in and made sure all grounds are in place? If you place a linking light on it what happens to the timing dose it advance smoothly?

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Customer reply replied 8 months ago
i'll check and let you know

Okay, Im here all day.

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Customer reply replied 8 months ago
since this has spark plugs on both sides of the head, which wire am I going to hook a timing light to or does it not matter?

You will want to hook it to the number one # 1 spark plug One the exhaust side .

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Customer reply replied 8 months ago
thank you

You bet, thank you as well.

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Customer reply replied 8 months ago
the timing advances when acc. it up

Okay then that should rule out a computer control issue. have you been able to get the computer to set any fault codes yet?

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Customer reply replied 8 months ago
just checked again and no codes. the little time I had it running, my eyes burn from the richness of the thing

If you fuel pressure is now with in specs I have to wonder if the computer is just bad, it controls the injector pulse. Was the computer matched with the replacement engine?

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Customer reply replied 8 months ago
probably not

I think because its not setting any fault codes that you should check and see if you have the correct PCM for this engine. You should be able to check this with the calibration number that should be on the door by crossing it over to the PCM number.

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Customer reply replied 8 months ago
my understanding is that the engine came out of something newer than 78
Customer reply replied 8 months ago
excuse me 98

That may very well be the problem, I would check and see if it has the correct PCM in it if you know the year of the engine.

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Customer reply replied 8 months ago
I just called the kid up and he looked at his receipt and he said the numbers from the vin are 170231. is that anything that you can tell me what the year is. also I had found where they had routed the alternator wires behind the exhaust and burnt the hot wire to the alternator in half and blew that 175 amps. could that go thru a circuit and hurt the ecm?

The charging system is not computer controlled but if you have a voltage spike that could have damaged the PCM. The number you have listed are not the vin number so I do know what they mean.

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Customer reply replied 8 months ago
I'm changing course . I pulled the vacuum hose off of the fuel pressure damper at the end of the fuel rail, it has 20 psi out of that hose, it isn't making any difference to the way its running, connected or not, does that mean anything, I thought the idle would change

Are you pulling the fuel pressure regulator vacuum line off?

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Customer reply replied 8 months ago
I would call it a fuel pressure regulator, its in the fuel rail, but oriellys call it a fuel pressure damper, which must be correct, I found where the regulator is in the tank and part of the sender assy

When you pull the vacuum from the regulator the pressure should jump up a few pounds and it will not change the way the engine runs. If your only getting 20 PSI of fuel pressure that is a problem, this engine needs 56 to 72 PSI .

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Customer reply replied 8 months ago
no, I have 20 on a vacuum gauge hooked to that vacuum hose

Okay the vacuum is fine. 20 HG of vacuum is good.

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Customer reply replied 8 months ago
but being plugged onto that valve, doesn't seem to change anything, according to what I found all that valve does is quiet down the injector noise, is that correct and it really doesn't have anything to do with fuel pressure to the injectors?

The vacuum line connects to the fuel pressure regulator and The only thing it will change is the fuel pressure should drop a few LBS and then when step down on the gas under load you loose the vacuum and the pressure should jump up a few pounds. The pules damper is just there to quite the injectors and has no effect on the way the engine will run. They are separate things as well.

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Customer reply replied 8 months ago
ok,thank you

Your very welcome .

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Customer reply replied 7 months ago
I'm still not getting any codes, but watching live data on my scanner, I don't think I have any oxygen sensor activity. I am going to post the readings for you and let me know what you think.HEATER CURRENT O2S12 1000mA / HTR CURRENT O2S11 1000mA /HO2S BANK 1 SENSOR 2V .02 V/ HO2S BANK 1 SENSOR 1V 0.00 V/ HO2S BANK 1 SENSOR 2 LEAN / HO2S BANK 1 SENSOR 1 LEAN. THESE READINGS ARE WHEN ENGINE IS COLD. shouldn't this be showing rich with engine cold?

Usually they will not start switching till the engine goes into closed loop. Have you checked to see if you have power to the heater circuit for the HO2S sensors?

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Its very odd that the computer is not setting any fault codes.

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Customer reply replied 7 months ago
the fuse for that circuit is good.with the engine cold, shouldn't that be showing rich and not a lean condition?

There are two fuse for the fuel control, fuse #9 and fuse #13 both located in the under hood fuse panel. Start with making sure both are okay then then check for power to the HO2S on the heater circuit . Once other thing to check is the Ground for the HO2S circuit and that is the G108 located at the top center of the left fender apron. See the Circuit wiring diagram in the link below for reference .

https://www.dropbox.com/s/znirp5h4gcjbnan/HO2S%201%20Oct%2024.pdf?dl=0

https://www.dropbox.com/s/aeq3ixgmtil4axn/HO2S%202%20Oct%2024.pdf?dl=0

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Customer reply replied 7 months ago
ok, I will give it a check

That would be a good idea.

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