1999 Explorer -Intermittent rough idle, 4.0 L SOHC

20

Asked by Feb 02, 2016 at 09:28 AM about the 1999 Ford Explorer 4 Dr XL 4WD SUV

Question type: Maintenance & Repair

I have no Check Engine light or codes. During idle it
will every few minutes start to stumble as if it is
going to stall. I am unfamiliar with this Ford 4.0L
SOHC engine (not to be confused with the 4.0L
OHV engine) and the common issues that it may
have. It accelerates well and seems to have the
power it should have. I ran a live Elm327 scan and
it appears that an injector was being stuck open at
times but i do not have enhanced DTC's for this
vehicle to see anything more in depth. However, I
am also thinking that a possible cause may be a
vacuum leak coming from the intake manifold. I
am not quite sure why there is no code that is
being set in the PCM. Hence why I am leaning
towards a possible intake manifold leak. Are there
any mechanics that are experienced with this
engine that can give me some input? Thanks in
advance.

8 Answers

have you checked: - Vacuum leaks - Fuel filter - Spark plugs and Wires (to check wires, just spray mist over top of wires if see any sparks, change them) _ Fuel injectors (clogged (needs replacement)/dirty) - IAC Valve/PCV Valve - MAF or MAP sensor - EGR Valve - Oxygen sensors (upstream and downstream, you might have 2 or 4 O2 sensors)

Best Answer
20

-Vacuum leaks, Not checked -Fuel Filter, Checked (fuel pressure good) -Wires and plugs new -Injectors, Cyl 5 sticky -IAC, EGR and Map, untested -MAF cleaned but untested -o2 sensors, voltage output good on each -TPS, not tested Any common weak spots for vacuum leaks on these engines?

20

As far as the sticky injector goes, I will just clean, change filters, and test spray patterns and replace as needed.

i use a smoke machine to find vacuum leaks..

20

I cleaned the IAC which basically was already very clean, as is everything under the hood, fortunately. Judging from the various internet search results and posts, it appears to be a very common issue to have a vacuum leak at the intake manifold upper plenum. The other being faulty/clogged fuel injectors. Both of which I will repair soon. I will post my results which I hope will help others if they have a similar problem.

20

Update: I replaced the upper and lower intake manifold gaskets. I am still having the goofy idle. I checked the fuel pressure, which was at a stable 63psi. I changed the fuel filter and now I am running at 64psi fuel pressure. I was listening to the engine idle and I heard an injector stick and the engine stumble. The issue is only getting worse as the vehicle sometimes has hard start issues. I checked the fuel pressure leak down and it immediately dropped from 64psi to 0 after about 15 seconds. The fuel pressure regulator is not losing any fuel to the vacuum line. I will be cleaning or replacing injectors soon.

Fuel line on frame near exhaust at rear left side of engine and fuel line on front of engine going to injectors causing vapor lock I moved the line at both places and have not had anymore trouble got the idea from old ford and Chevy

20

It's been over a year now. I went through everything imaginable. I will perhaps give that a try. Currently, the 5R55E transmission gave up (second tranamission in 5 years). I'm not quite sure if I will be repairing this again unless I swap a GM drivetrain in place. That, or the scrap yard.

Your Answer

Add photo

Related Questions

  • 1999 Explorer -Intermittent rough idle, 4.0 L SOHC 8 answers

    I have no Check Engine light or codes. During idle it will every few minutes start to stumble as if it is going to stall. I am unfamiliar with this Ford 4.0L SOHC engine (not to be confused with th...

    1999 Ford Explorer 4 Dr XL 4WD SUV

    -

    Maintenance & Repair

  • 1996 Ford Explorer Rough Idle 2 answers

    Hello, I need some help with a 1996 Ford Explorer. The truck drives great on a cold start and continues to run good as long as it isn't shut off. But, if the vehicle is driven and shutoff, it runs...

    1996 Ford Explorer 4 Dr XLT 4WD SUV

    -

    Maintenance & Repair

  • rough idle 1 answer

    1999 Explorer V6 pushrod engine. 200K miles. Recent tune-up and run well. Now experiencing a rough idle, at idle only. Any ideas before the daughter drops it off for free maintenance and repairs...

    1999 Ford Explorer 4 Dr XLS SUV

    -

    Maintenance & Repair

  • 1993 Ford Explorer Rough Idle 3 answers

    I have a 1993 Explorer 4-Door 4wd and lately it has poor idle. It idles in between 500-750 RPM. It seems like its missing but no check engine light has come on. In park its alright idling but while in...

    1993 Ford Explorer

    -

    Maintenance & Repair

  • Ocassional Rough Idle 18 answers

    I have a 2010 XLT explorer 4.0 sohc. Every once in a while after I've driven it for a while maybe 20-25 miles then park it for a short time about 15- 20mins then go back to start it up I get a rough ...

    2010 Ford Explorer XLT 4WD

    -

    Maintenance & Repair

Explorer

Looking for a Used Explorer in your area?

CarGurus has 64,215 nationwide Explorer listings starting at $799.

ZIP:

Search Ford Explorer Questions

Ford Explorer Experts

#1 OJ
OJ
Reputation 10,530
#2 Tom Demyan
Tom Demyan
Reputation 4,220
#3 tennisshoes
tennisshoes
Reputation 2,430
View All

Related Models For Sale

Used Jeep Grand Cherokee
1,074 Great Deals out of 73,188 listings starting at $1,200
Used Ford Expedition
404 Great Deals out of 23,948 listings starting at $1,500
Used Chevrolet Tahoe
583 Great Deals out of 32,917 listings starting at $1,500
Used Ford F-150
2,126 Great Deals out of 193,347 listings starting at $290
Used Dodge Durango
264 Great Deals out of 21,138 listings starting at $1,500
Used Toyota 4Runner
227 Great Deals out of 19,353 listings starting at $1,500
Used Nissan Pathfinder
330 Great Deals out of 22,241 listings starting at $2,500
Used GMC Yukon
406 Great Deals out of 20,427 listings starting at $1,495

Used Cars For Sale

2017 Ford Explorer For Sale
55 Great Deals out of 38,493 listings starting at $22,712
2016 Ford Explorer For Sale
133 Great Deals out of 3,862 listings starting at $16,700
2015 Ford Explorer For Sale
169 Great Deals out of 4,809 listings starting at $12,997
2014 Ford Explorer For Sale
271 Great Deals out of 5,655 listings starting at $9,850
2013 Ford Explorer For Sale
77 Great Deals out of 2,704 listings starting at $9,750

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.