BroncoII4x4.com

Hello there. First the specifics

88 Bronco II 2wd, 5spd Manual with 2.9L V6.
Fuel Injected
Either 86,000 miles, or 186,000 miles haha. Hard to tell.

Ok, Here is what is happening. The truck starts hard. usually takes 2-3 times letting it crank pretty good and some gas to get it up and running. At this point, you usually get a strong fuel smell, which is normal I imagine. when it does finally kick over, the motor will immediately jump up to about 3,500 RPM and then settle at an idle of about 900-1000 RPM. after 5-10 minutes of running, the truck will not hold an idle, moving between 3,000 RPM and dropping as low as 500 rpm, eventually when it drops it will die all the way. A version of this problem occurs while driving as well. Suddenly, the truck will lose all power and feel like its 'missing' giving you the jerky, sluggish acceleration, eventually you get a really strong gas smell and it'll die. wait 10 seconds to start it, starts fine, same thing occurs... Rinse and repeat. Since this started happening I have been getting about 8-10 mpg in town >_<

I am getting some indication from my Check Engine Light. It'll flash about 3-4 times occasionally, which I am told is an indication that it is running in self test mode. The fellow I bought it from said there was possibly "something minor" with the ignition but it wasn't a big deal.

My best guess right now is my ECM is failing. Maybe Ignition Coil? I am not a genius when it comes to Fuel Injection or Electronic Ignition. about this time I actually WISH I had Cap, rotor and good ol points lol Ignition Coil could be likely, given that it seems to do it more when it is wet outside (shorting and grounding elsewhere?) but realistically, I live in Seattle, its wet here more often than not.

Thanks in advance for the help!

Daniel

my first suggestion would be to take it to autozone and get them to hook up a scan tool to it if they will or if they wont for some stupid reason and there like the guys at my local autozone then if you have any mechanic friends they might do it for you what ever is causing this problem will probley be throwing a fault code telling you exactly whats wrong

When is the last time you did a tune upon its. but like 84_4x4, got to you local autozone and get them to run your codes. could be your EGR

Hmmm, it seems to me that you are discribeing bad injector!

they leak down when sitting and then spray way to rich when running

or your pressure regulator is shot
Is there fuel in the vacuum hose that attaches to it?

try unhooking the oxygen sensor. i had similar problems then i unhooked it and did better.

un hooking the o2 censor isent going to solve anything it will either way lean out the engine or make it run way to rich you cant just do away with them

The problem could be a bad idle air control (IAC). It is a solenoid valve fastened by 2 bolts to the passenger side of the upper intake manifold (plenum). It could be defective and/or the passageways in the plenum could be dirty. DO NOT clean these passages with the plenum on the engine. Remove the plenum to clean the passages.
An '88 Bronco II 2.9 does not use an EGR valve.
One or more defective fuel injectors could be the problem. A guy on Ebay sells reconditioned injectors that work excellently. A set costs less than one new one. He makes his living doing this and guarantees what he sells.
Another thing is to check for vacuum leaks. Also replace any old vacuum lines.
The first thing I would do is to purchase a computer code reader (available at any parts store) and check for trouble codes stored in the computer. Make sure you get the correcct code reader for your vehicle.
If you aren't comfortable with any of this, consult a mechanic, because you could make a bad situation worse.

84_4x4 wrote:un hooking the o2 censor isent going to solve anything it will either way lean out the engine or make it run way to rich you cant just do away with them

I did away with mine for a couple months with out a problem. Once it was gone, it idled much smoother. I later replaced it.

Trigger_2001 wrote:

84_4x4 wrote:un hooking the o2 censor isent going to solve anything it will either way lean out the engine or make it run way to rich you cant just do away with them

I did away with mine for a couple months with out a problem. Once it was gone, it idled much smoother. I later replaced it.

If you unhook the O2 sensor the computer goes into "Limp home mode"
and will run rich if unhooking it "fixes" your problem the the O2 sensor is bad
unhooking them long term can cause more problem

a cloged CatCon is the biggest problem

"a cloged CatCon is the biggest problem" that aint a problem if ya dont have one!

Hey there Mr Hair!!!!!

Long time no see or talk to! I didn't know you hung out here...

HEY MAN LOOK IM NEW ON THIS SITE AND I LOVE IT SO IM GONNA TELL U HOW TO FIX UR PROBLEM....MY 86 BII DID THE SAME SHIT THE OTHER DAY AND CONTINUED DOING IT. I REPLACED THE FUEL PRESSURE REG (2 BOLTS AND A FLATHEAD SCREWDRIVER) AND I DID AN INJECTION SERVICE ON IT....I WORK AT MEINEKE SO ITS AVAILABLE TO ME AND IT RUNS PERFECT NOW...SO TRY CLEANING ILL OF THE JUNK OUT AND PRESS REG AND UR GOOD.

sounds good to me but no use in yelling no one was hard of hearing before but not to sure now

OKAY, YEAH, ALSO THERE IS A LITTLE BUTTON YOU MIGHT WANT TO CHECK OUT TOO. IT'S ON THE LEFT SIDE OF THE KEYBOARD, KINDA IN THE MIDDLE; PRESS IT ah...that's better isn't it? no need to yell big papa!

don't forget to post some pics of your rig in the member's rides section.

welcome to the site!