what would you check next?

[LittleHorse]

Here's the situation:

'90 Bronco II, 2.9 manual trans

Has been very low on power since I bought it a year ago. Can't make it up even slight-moderate hills without losing significant speed or downshifting to fourth. It also has to be cranked for about 3 full seconds before it starts, as long as 10 seconds if it's been heat soaking.

-replaced the fuel filter and the tank at the same time shortly after purchasing it.
-New plugs, wires, cap, rotor
-Discovered slight leak in left exhaust manifold to y-pipe connection. Haven't been able to fix because bolts are rusted on and completely round.
-Swapped MAP sensor and coil independently with my other (non-running) Bronco II and saw no change.

-Cleaned IAC valve and throttle body. No change except for it seemed to take a couple drives to work and back to relearn how to idle, but returned to normal.

At this point I just figured the 2.9 was a pig and have nothing to compare to prove otherwise. From time to time the CEL would come on while sitting in a long drive through wait, but would go back off as soon as I got out on the street. No codes stored in memory afterward.

Months later, started bucking/surging.

-Got lean code from KOER test.
-Replaced fuel filter again. No change.
-Manifold vacuum is steady at 17" Hg.

So is it possible that this is a result of the exhaust leak, or should I start looking at compression, oxygen sensors, fuel injectors, fuel pressure? I'm at the point where I'm gonna start having to spend more money on testing tools and/or parts and would like some guidance and I'm already in this thing for more $$$ than I'd like to be.

 

[Ranger Kip]

cylinoid for the start, battery for the start, compression levels for the power, clinders for the compression (might need to bore), and try checking the exhaust, you might have a leak that is killing your power.

 

[Original_Ranger84]

I'm gonna say maybe your injectors seeing as its a pretty old rig and trouble starting could be clogged or just old worn injectors, That would explain the long start periods especially when warm and the lean codes and lack of power. Also as you have replaced the fuel filter and tested the High pressure pump?

I can't imagine a small exhaust leak would cause all of that. Maybe a leak in the intake after the MAF sensor. And O2 sensors could be the problem but I would check the high pressure fuel lines to the injectors first and maybe have the injectors cleaned.

 

[triumphrider-1]

I'm gonna say maybe your injectors seeing as its a pretty old rig and trouble starting could be clogged or just old worn injectors, That would explain the long start periods especially when warm and the lean codes and lack of power. Also as you have replaced the fuel filter and tested the High pressure pump?

I can't imagine a small exhaust leak would cause all of that. Maybe a leak in the intake after the MAF sensor. And O2 sensors could be the problem but I would check the high pressure fuel lines to the injectors first and maybe have the injectors cleaned.

What he said. :icon_thumby:

 

[LittleHorse]

cylinoid for the start, battery for the start, compression levels for the power, clinders for the compression (might need to bore), and try checking the exhaust, you might have a leak that is killing your power.

the starter and battery were replaced in '09. The starter cranks PLENTY fast, the engine just takes a lot of cranking to start.

I'm gonna say maybe your injectors seeing as its a pretty old rig and trouble starting could be clogged or just old worn injectors, That would explain the long start periods especially when warm and the lean codes and lack of power. Also as you have replaced the fuel filter and tested the High pressure pump?

I can't imagine a small exhaust leak would cause all of that. Maybe a leak in the intake after the MAF sensor. And O2 sensors could be the problem but I would check the high pressure fuel lines to the injectors first and maybe have the injectors cleaned.

I've replaced the fuel filter (twice) and have checked for vacuum leaks by spraying starting fluid around vacuum connections and gasket surfaces. Mine is pre-MAF so it's a speed density system with a MAP sensor.

I have NOT checked the fuel pressure yet, because I don't have a fuel pressure tester. I thought about getting one the other day but saw they are nearly $50. Sounds like I may be buying one after all.

Thanks guys, I'll go in that direction.

 

[90B24wd]

You might have a clogged catalytic converter.

 

[LittleHorse]

hmmm...also an interesting idea. Not sure that it would cause the hard starting but would DEFINITELY cause the power loss. I could probably tolerate the hard starting if the thing had the power to pull itself.

 

[triumphrider-1]

the starter and battery were replaced in '09. The starter cranks PLENTY fast, the engine just takes a lot of cranking to start.



I've replaced the fuel filter (twice) and have checked for vacuum leaks by spraying starting fluid around vacuum connections and gasket surfaces. Mine is pre-MAF so it's a speed density system with a MAP sensor.

I have NOT checked the fuel pressure yet, because I don't have a fuel pressure tester. I thought about getting one the other day but saw they are nearly $50. Sounds like I may be buying one after all.

Thanks guys, I'll go in that direction.

Just rent one from AutoZone. Pay the deposit, and you'll get that back when you return the kit.

 

[BRUTUS_T_HOG]

Here's the situation:

'90 Bronco II, 2.9 manual trans

Has been very low on power since I bought it a year ago. Can't make it up even slight-moderate hills without losing significant speed or downshifting to fourth. It also has to be cranked for about 3 full seconds before it starts, as long as 10 seconds if it's been heat soaking.

-replaced the fuel filter and the tank at the same time shortly after purchasing it.
-New plugs, wires, cap, rotor
-Discovered slight leak in left exhaust manifold to y-pipe connection. Haven't been able to fix because bolts are rusted on and completely round.
-Swapped MAP sensor and coil independently with my other (non-running) Bronco II and saw no change.

-Cleaned IAC valve and throttle body. No change except for it seemed to take a couple drives to work and back to relearn how to idle, but returned to normal.

At this point I just figured the 2.9 was a pig and have nothing to compare to prove otherwise. From time to time the CEL would come on while sitting in a long drive through wait, but would go back off as soon as I got out on the street. No codes stored in memory afterward.

Months later, started bucking/surging.

-Got lean code from KOER test.
-Replaced fuel filter again. No change.
-Manifold vacuum is steady at 17" Hg.

So is it possible that this is a result of the exhaust leak, or should I start looking at compression, oxygen sensors, fuel injectors, fuel pressure? I'm at the point where I'm gonna start having to spend more money on testing tools and/or parts and would like some guidance and I'm already in this thing for more $$$ than I'd like to be.

if the truck has a MAF sensor i would try driving with it unplugged and see what happens. i've seen way to many vehicles have this same problem with a bad MAF.

i've also seen the same symptoms from a bad fuel pump. you def. need to know fuel pressure or you're wasting time.

and yes an exhaust leak can cause a lean code and cause the truck to run rich

 

[LittleHorse]

picked up a fuel pressure tester and some JB weld (for the exhaust leak lol) so I can get back to this thing as soon as I get my wife's F-150 running again.

 

[BlackBII]

First things first, What size Tires and Gearing?

Things I check when low on power:

Compression test
Fuel Pressure
Air/Fuel Ratio across RPM's, under load
Clogged Exhaust
Throttle opening all the way
Spark quality

Throwing money away on parts is wasteful, there are tests you can run to find exactly where the problem is coming from

 

[LittleHorse]

tires are one size wider from stock, same aspect ratio (equivalent to something like a 28.5"). Gears are 3.73 behind an M5ODR1, the M5OD was from an Explorer so it's got different 1-2-3 ratios but it's sluggish in every gear.

do you use a wideband O2 sensor to check your A/F ratio? Most of those I've seen cost quite a bit more than any of the parts I'm about to replace.

Also how do you check for a clogged exhaust? Can you check that by engine vacuum or do I need to fashion some sort of adapter for the O2 sensor port and measure the pressure upstream of the converter? Or pull the cats for a visual inspection?

As soon as I get my wifes truck fixed I'll be checking compression and fuel pressure. The throttle is opening all the way and the spark is healthy.

 

[cyco49]

my hard starting problem was the fuel regulator, caused other problems to. its about 25bucks at auto zone

 

[Angie]

post #2

"clinders for the compression (might need to bore),"

What is your logic behind this comment? my feeling on that would be rings need replacing and this is more promenant from blowing blue than anything else. boreing the walls is only for over sized pistons and this will actually cause more problems than I feel he is looking to get into. were you thinking of hone instead of bore?

 

[IMenriched]

Agree with checking the fuel pressure...note... the pressure as you goose the throttle.
does it drop more 5 psi or does it increase?

also the cats or overly restrictive muffler can cause the lack of ummff

 

[LittleHorse]

Fixed the exhaust leak Friday, no change. Will be checking fuel pressure tomorrow.

There is no smoke in the exhaust and my oil consumption is about half a quart in 4,000 miles so i think a ring wear problem is unlikely.

 

[LittleHorse]

Lol. Key on engine off, fuel pressure jumps to about 12psi and then bottoms out at about 2 within a few seconds.

Start the engine and the pressure climbs to about 32 and jumps as it should when goosing the throttle. Turn the engine off and it falls to 2 psi again.

I take it this probably indicates leaking injectors? lol


By the way, I forgot to mention I've been getting about 17mpg in highway driving and barely 15 city, and the thing shakes like crazy at idle.

Looks like I'll be shopping for some injectors. I was really hoping they'd be fine since the only place I've looked so far is AutoZone and they're about $60 each.

My thought is that one or more injectors is stuck open and/or severely leaking, causing the O2 sensor to pick up a rich condition, which then signals the computer to try to lean out - so I could have 2 cylinders running rich and 4 running lean. Sound logic?

 

[LittleHorse]

anybody ever had any experience with remanufactured injectors? Says they're flow matched with a lifetime warranty and appear to be legitimate.

 

[LittleHorse]

ok, I thought injectors made perfect sense given the behavior and the results of the fuel pressure test.

But I installed reman injectors last week and it made no change whatsoever. I also fixed the exhaust leak (again, first fix failed) but it made no difference, other than eliminating that annoying click sound.

Tomorrow after I finish installing a power steering pump and new front shocks I'm going to test the TPS and MAP sensor. I tried to have it done today at AutoZone, but much to my surprise apparently they don't do that anymore. I guess the bean counters must have figured out that they would make more money if people just bought new sensors without testing the old ones. So i'm gonna have to buy a vacuum pump to test the MAP sensor.

If those are both fine, I'm kindof at a loss. With my vacuum steady and in spec and burning less than half a quart of oil between 5k oil changes it's hard to see it being a ring or other mechanical problem. The only electrical things left will be the coolant temp and oxygen sensors, which I don't think would be the issue since the behavior is present in both open and closed loop operation.

 

[BRUTUS_T_HOG]

have you checked the ignition timing?

remove the SPOUT shorting bar and use a timing light to adjust timing to 10degrees BTDC