3.0 stumble/stall problem

[Bretsk2500]

Hi,

I'm new to the forum.. I recently picked up a '98 extended cab stepside (3.0) with an amazing body and frame for a song to replace my '02 reg cab short box (2.3) with a hopelessly rotted frame. anywho...

I'm not super familiar with the quirks of the 3.0, I know it needs heads or head gasket (which are on their way) due to combustion gasses in the coolant... The other issue when I start it... it will high idle just fine for about 30 secs then load up and die... it is like something is making the IAC just completely close, making it go waaay rich and stall... crank it again... runs just fine for about 30 secs, loads up and does the same thing.


Not trying to re-invent the wheel, on the 3.0, what are the most likelies? definitely acts like it isn't getting the right A/F ratio.

The only other 3.0 I deal with is an '04 Ranger shop truck at work.... and it's never required anything other than basic maintenance..

Also is the DIS for the 3.0 as maddenly weak as the DIS on the 2.3?

-Bret

 

[RonD]

Welcome to TRS

3.0l Vulcan engine was very reliable, used from 1991 to 2008 in Rangers, 1986 to 2008 in other Fords

Could the exhaust be partially clogged up, that will stall an engine?

Computer operated engines run a "choke" setting on cold start, rich mix, high idle and advance spark timing.
This is based on ECT(engine coolant temp) sensor data.
All engines startup with IAC Valve open all the way, cold or warm, then computer looks at ECT temp and adjusts fuel mix and IAC valve accordingly, for cold or warm engine temp.

There are two temp sensors on the 1998 3.0l, ECT sensor(computer only) and ECT sender(dash temp gauge only)

The sender used to be just 1 wire, sensors were always 2 wires, but after 1995 it could go either way with sender, 1 or 2 wire
SENDER should have Red/white stripe wire
SENSOR Green/red, and Grey/red stripe

ECT Sensors are usually under $10, they can be tested but...........up to you really, but check the wires for sure.

3.0l used a Coil pack after 1994, I thought the 2.3l Duratec used COP(coil on plug), so should have good spark
Firing order needs to be watched, 1, 2, 3 on one side and 5, 6, 4 on the other, NOT 4, 5, 6

Head bolt length changed in 1999, heads were the same, block had a recess and deeper threads
Good read here on the 3.0l changes over the years: http://www.therangerstation.com/tech_library/3_0-build.shtml

 

[Bretsk2500]

my '02 2.3 has a coil pack just like the 3.0 in the '98 minus 2 cylinders...

My knowledge base skews heavily towards GM products... My 3.0 when it loads up, it is literally like a switch.. or solenoid gets closed.. or whatever the hell is causing it... but if you persevere... it will eventually run on 5 1/2 cylinders. but that part of the program should be solved by new heads and gaskets... the head/head gasket problem definitely lies with #2 cyl in Ford parlance.... #4 in GM-speak.

It much more seems fuel/air related than exhaust... because it will come out of it eventually. if the exhaust was plugged it wouldn't..

 

[monstermazda]

Check fuel pressure I had the same problem my sounded like a drag car before it died.

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[Bretsk2500]

I finally got my scantool and the '98 in the same place and hooked it up... all three O2 are showing 0V and a +42% short term fuel trim on bank 1!!!

 

[RonD]

Have to ask, I assume that is after warm up, O2s don't work until they are heated up
I think fuse #13 in engine fuse box is the heater power for O2s, but should get a code if it is blown

+42 STFT Bank 1
What does Bank 2 show?

Engine off
Unplug and plug back in TPS and MAF sensors then restart
Loose connectors can put PCM in Open Loop

Yes, high fuel trims on both banks could mean fuel pump/fuel pressure issue

 

[monstermazda]

O2 sensor could be bad but pull the plugs on bank one and turn the truck on see if an injector is stuck open.

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[Bretsk2500]

Have to ask, I assume that is after warm up, O2s don't work until they are heated up
I think fuse #13 in engine fuse box is the heater power for O2s, but should get a code if it is blown

+42 STFT Bank 1
What does Bank 2 show?

Engine off
Unplug and plug back in TPS and MAF sensors then restart
Loose connectors can put PCM in Open Loop

Yes, high fuel trims on both banks could mean fuel pump/fuel pressure issue

yes, after scan tool showed closed loop. Bank 2 was at +17%, bank 1 also has a broken off stud in the exhaust manifold... farthest stud aft. I swapped the MAF with the known good one in the 2.3 (identical part #) VERY slight improvement, the old one was probably slightly dirty. I will unplug/replug the TPS. I don't have the 98's manual... but according to the '02's manual, the 20A maxi fuse powers the HO2S... that one is fine.

 

[Bretsk2500]

O2 sensor could be bad but pull the plugs on bank one and turn the truck on see if an injector is stuck open.

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#2 cyl wet fouls with fuel, all five other plugs were a perfect tan color. I don't think it's a stuck injector, as it runs perfect through the start cycle (the first 30 secs or so) and only loads up when it switches to stored trim data, which fouls #2...

#2's valves are also quite noisy.

I am pretty sure that the new heads will solve #2 cyl's issues, and in the swap process, the broken exhaust stud on bank 1 will be replaced which should stop any atmospheric O2 being sucked in through the exhaust flange..

I am concerned about all three O2's showing 0V... while giving trim data..

 

[monstermazda]

My 98 after rebuild show all three 0v this is with cheap scanner. Hooked up my 5000 dollar scanner I see voltage where it should be. You should check voltage at the o2 sensor ones 12v for the heater.

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[Bretsk2500]

found the problem:

notice the missing pushrod?

Found it:

and also dealing with cyl #2:

How the hell does a pushrod fall out????????

The pintle cover on #2 injector snapped right back on, so I am going to put it back in... at least #2 cyl is relatively easy to get at.

I've spent all day yesterday tearing the motor down to the short block... the head gasket had also eroded and failed between cyl's 1&2. a couple of the cylinders on bank two had recessed exhaust valves as well. I am glad I sprung for two reman heads.

I spent 5 hours today dealing with the sludgy mess that is this engine. now that the weekend is over... it's gonna be late nights after work putting it back together :/

 

[Bretsk2500]

Update:

the mechanical issues are solved... no more fuel fouled plugs. though I noticed a weird thing... it is still overfueling, but I have new O2 sensors waiting to go in.. anywho.. after I shut the engine off, it sounds like the injectors continue to fire for about 30 secs... is that even possible?

next on the list is a new coil/wires because it doesn't feel like it's got enough juice to completely fire the overly rich mix.... plugs are already new... and a new cam sensor and synchronizer because I think it's contributing to the fueling issue... and the tech pages say at 200k+... just replace it.

thoughts?