88 B-II Hesitation/Power Loss (Updated 4/13/2010)

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Annie Oakley
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88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Annie Oakley » Sun Jan 17, 2010 10:05 am

Hi,
I've got an 88 Bronco II with the 2.9L, V-6, fuel injected engine and a 5-speed manual transmission. It's 4-WD. Air filter was changed about 3 months ago and is still clean. The alternator and battery are about 7 months old. Oil filter, oil changes and oil level are good.

A few weeks ago I started having trouble with a sudden hesitation/loss of power while driving down the interstate. It would start after 5-10 miles. No problem on the side roads where speed limits change or I have to stop occasionally. Then it started happening on side roads, too, though not as bad. I thought it might be bad fuel, so I ran 2-3 tanks of good fuel (including premium) through the tank, but the problem persisted. Pushing in the clutch pedal and coasting a short way or pulling off the interstate and idling briefly before getting back on seemed to fix the problem temporarily, then it would re-occur.

I had the fuel filter changed yesterday morning. Probably less than a gallon of water came out of the fuel tank before it smelled like gasoline, and the filter was pretty nasty. Initially, acceleration was better, and a trip of about 60 miles each way on the interstate was better on the way to Gastonia, NC, then a few miles short of our destination, the hesitation/power loss happened again. The problem was more frequent on the way back home. There was no problem on side roads or city driving.

The only other problem I've noticed that might be related has been an intermittent failure for the engine to drop all the way down to normal idle when the clutch is pushed in when shifting. It'll stay about 500 rpm higher than normal.

Any suggestions on what to look at next?
Last edited by Annie Oakley on Tue Apr 13, 2010 6:45 pm, edited 1 time in total.

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tekatlarge
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Re: 88 B-II Hesitation/Power Loss

Postby tekatlarge » Sun Jan 17, 2010 12:19 pm

Good details Annie,

Well the first check should be for any stored codes in the computer. If you don't know how to just take you rig to your local Auto zone or such and they can read the codes for you and 99.9% of them do it for NO charge. That could pinpoint the trouble but maybe not. My gut feeling says to me a fuel delivery problem. Check the fuel pressure at the rail and then run the engine about 2000 for a minute or two and see if the pressure is correct and stays at that value and doesn't bleed down until you let the engine idle and it should not drop significantly at an idle.

There are 4 common fuel related failures. #1 is fuel contamination (water rust etc) #2 Fuel filter. (you fixed that) #3 Rear fuel pump, #4 Front or hi pressure pump, and finally #5 the Fuel pressure Regulator.

Check them Codes and check the fuel pressure and regulation. Let us know what ya find out.
:cool:
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clem
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Re: 88 B-II Hesitation/Power Loss

Postby clem » Sun Jan 17, 2010 1:39 pm

I agree with tek on both accounts, well written and get the codes checked, sounds like fuel starvation. If the fuel filter was that bad I wonder if the injectors aren't clogged up a bit too, just a thought. :beer: :canada: :redneck:
'87 bII d44,9",np435/205and a 302 ( on hold)
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Annie Oakley
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Re: 88 B-II Hesitation/Power Loss (UPDATED 4/13)

Postby Annie Oakley » Tue Apr 13, 2010 6:34 pm

Okay, now for an update. I've also had the O2 sensor changed, a tune-up (shop said the timing was 10 degrees off), and various wires under the hood replaced that showed damaged insulation (to rule out an intermittent short). I've also run probably 8-10 bottles of Lucas through it. I thought that would clean up the injectors enough to let me know if that was the direction I needed to go.

Each repair has brought brief improvements but then it starts again. Overall, the problem is getting worse.

The idle jumps up around 600 rpm when the problem occurs. Two options seem to work the best......mostly pushing in the clutch and coasting until it drops back to about 900 rpm and then resuming driving, OR keeping my foot on the gas until it coughs a little and then takes off like a well-running B2 should. I cannot figure out why the engine rpm are suddenly increasing. At first I thought it was a cold-weather problem, but it is also happening on warm days. One thing I've noticed is that it doesn't seem to happen when driving in 5th gear at speeds that keep the engine above 2000 rpm (around 70 mph or a little less). As a paramedic, I'm not crazy about driving 70 without a really good reason, especially not in a 22-year-old, SWB vehicle with no air bags or roll cage.

More advice would be greatly appreciated.

Annie Oakley
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Annie Oakley » Wed Apr 14, 2010 7:09 pm

I noticed this morning that I had little or no trouble with it. The only difference that I can think of was that I backed into the driveway and parked the B2 with the nose facing up hill overnight. Is there a 2nd fuel filter that I don't know about that might be clogged?

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Ranger Dave
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Ranger Dave » Thu Apr 15, 2010 4:24 am

Annie Oakley wrote: Is there a 2nd fuel filter that I don't know about that might be clogged?



yup, in the dr.side frame rail
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damon
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bronco II help needed

Postby damon » Sun Apr 18, 2010 10:36 am

im having the same problem as annie, but mine runs like crap under load going up hills. ive dropped the tank and the fuel filter in the tank was ripped, replaced that and fuel injectors (pain in butt), an fuel filter, still having problems! lucky if i can go 30 mph down the road, this was a free vehicle cause my wife and i have not had a running vehicle in 2 years since my pops passed away, rotten luck, got 3 cars and not 1 runs, any ideas, please help!! damondinglenuts@yahoo.com thanx!

Annie Oakley
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Annie Oakley » Mon Apr 19, 2010 6:31 pm

Thanks for the tip, Ranger Dave! It goes into the shop tomorrow.

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Ranger Dave
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Ranger Dave » Tue Apr 20, 2010 1:09 am

let us know
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forman621
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby forman621 » Fri Apr 23, 2010 1:54 pm

yeah both of the filters on are on the driver side frame rail. I am having the same problem and i replaced the high pressure pump and the low preassure pump and bothe filters and it still sucks and wont run. but i have figured out that the low pump in the tank is running but not sending fuel. that was my problem.

Annie Oakley
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Annie Oakley » Wed Apr 28, 2010 11:27 am

Well, the shop tested the fuel pressure with the vehicle on and off, and everything came back within specs. He also feels that the fuel pressure readings would have told him if there was a problem with the fuel injectors. He says nothing unusual came out of the filters, so he thinks those are good, too. He runs an honest shop, so he doesn't want to start randomly replacing parts. We agreed to try running some premium fuel through it, which I started doing on about a 500 mile round trip for a few days off starting last Wednesday. There was a little trouble as described above for the first 10-15 miles, then everything ran smooth until yesterday evening on my way home from work. The same symptoms, but this time I kept my foot on the accelerator (mildly). At one point, it sounded like I got a backfire. (My hearing was damaged by an IED in Iraq and I can't pinpoint the source of sounds anymore.)

Could this be a problem with the exhaust system instead of the fuel system?

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Ranger Dave
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby Ranger Dave » Thu Apr 29, 2010 3:04 am

try a different computer
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KRE
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby KRE » Thu Apr 29, 2010 5:26 am

It could be the computer, but I'd check the Dist. trigger and TFI first. Do not replace the TFI w/o replacing the trigger. This requires the Dist to be pulled as the shaft has to come out to replace the trigger. Many times I've seen the timing to be unstable to a point that the engine will not run correctly, but it will not throw a code. Sometimes it will give a timing code, but many times not. Ford lost the TFI, class action law suit, because of all the problems it caused over the years.

Many times some of the best automotive folks in this country thought the unit had a fuel issue, which was only a TFI problem in the end.
Remember the base timing is set but unpluging the sprout plug, then after that, the computer takes over. The fuel system is 100% controlled via the computer which takes it's lead from the engine temp, map, manifold pressure, TPS an lastly the 02 sender. The TFI can change timing to a point that the rest of the system, can't comp for that change, which you now see as a driveabilty issue.
Engine computer, timing changes, are sent to the TFI. If the TFI does not respond, or runs wild, the other aspect senders return info to the computer which now trys to change timing even more. If you believe your having a timing issue, unplug the sprout this will stop the computer from making any changes at all from base. Then with your timing light recheck base timing to see if it's changed or jumping around at all, while the engine is hot. If it has/is, the TFI an trigger, needs replacing. You can drive the unit 5 miles or so with the sprout unplugged, as well. HP and fuel mileage will suffer but, you can see if theres any change.
The Bronco 2's biggest driveability issue was always the TFI an triggers.
The sad part was we just came from a carb world back then, an field training was not the best.

Lastly all automotive computers are no different in one respect than your desk top, garbage in, worst garbage out.

forman621
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby forman621 » Sun May 02, 2010 8:36 am

So does the bronco II cut out when going up hills or when heavy on the gas?
And how can you say there isnt a fuel system problem. they just didnt catch it, it only happens every once in a while right.
How long has it been acting up? My truck was acting up for several months and gradualy getting worse, because the low preassure pump went out and the high preassure was trying to do all the work and killed it too. so i had to replace both pumps to get it to run good again.
See if you can get it to start dieing when it is in idling. just need to test while the problem is occuring unless you wont find anything wrong with it.

BerryBros4X4
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Re: 88 B-II Hesitation/Power Loss (Updated 4/13/2010)

Postby BerryBros4X4 » Sun May 02, 2010 1:14 pm

You both, Annie and Damon, have had some good responses to the trouble you are having with your BIIs. I have read all the posts on these 3 threads and would like to offer a bit of my experience on these vehicles. It doesn't sound like an ignition or fuel delivery concern to me, more like a fuel CONTROL problem. The PCM in EEC-IV Ford vehicles uses look-up tables for fuel delivery and spark control based off of certain operating parameter information it recieves from sensors, the PCM uses the information in a specific order. The PCM has no way of knowing if a sensor is reading incorrectly if that sensor's information is within its prescribed limits, if it isn't in spec the PCM will set a code for it, and will set the check engine light. For instance; if the coolant temp sensor is sending a signal to the PCM indicating the coolant is 190 degrees, but it is actually 80 degrees, the PCM will not set a code and will not set the CEL, and the engine will run too lean, not have good acceleration/power, hesitate, missfire, and be hard to start when the engine is cold, (or won't start in cold weather). The PCM doesn't know the engine is still colder than expected and needs more fuel. If the ECT sends a signal that the coolant temp is out of the sensor's range to read, the PCM defaults the sensor input and sets a code for the sensor being out of range, and sets the CEL. The point of all this; Not every driveability concern will set a code and/or set the CEL, and not every fuel control concern is fuel delivery related, matter of fact, most aren't.

A couple of things, and no offense meant to anyone; the TFI module and/or pickup coil (trigger) probably won't be the problem here. In most cases involving the TFI and pickup coil, the engine stalls and/or won't start. Very seldom can they cause a performance/driveability concern not related to a "stalling and/or cranks but won't start" complaint. And PCM's rarely go bad, and more often than not, are replaced as part of the "shotgun" repair technique. :)
In all practicality, there are 3 sensor's on any EEC-IV controlled EFI engine (without MAF) that directly effect fuel control while the engine is STARTING, in order of PCM prioritization; MAP, ECT, and TPS. When the key is cycled to start the PCM updates the MAP reading and adjusts look-up tables for the ECT, checkes throttle position, adjusts Idle Speed Control motor, and determines injector pulse width, as the engine cranks to start.
After the engine is RUNNING, there are 5 sensor's on any EEC-IV controlled EFI engine (without MAF) that directly effect fuel control, in order of PCM prioritization; MAP (updated everytime the key is cycled, everytime the TPS reads wide-open throttle, and everytime the engine vacuum signal changes), TPS (updated everytime you move the throttle pedal position), ECT (constantly monitors engine coolant temp), AIT (updates everytime air temp at intake changes), and O2 (after PCM is in closed loop). The O2 sensors are considered for fuel trim (long and short term) and only effect fuel control for fuel economy and exhaust emmision fine tuning. In essence, the MAP determines all the look-up tables, the TPS and ECT determine there own tables based off of the MAP signal, the AIT doesn't change tables, and the O2 only effects fuel trim.

SO...(lol) this is what I'd do at this point, replace the ECT (the most common sensor to read inaccurately without setting codes or setting the CEL), then try either a known good or brand new MAP sensor.
Note; the ECT is not the same thing as the temp sending unit which is used for your engine temp gauge in the IP. ECT= Engine Coolant Temperature (sometimes called CTS for Coolant Temperature Sensor).

I hope any of this can help...

Clint Berry
BerryBros4x4
Anderson, Alaska


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