I have a 1994 Ford Bronco XLT with a HO 5.0 v8 and E4od Tranny (the build sheet for the engine decodes as High Output) This vehicle has factory tow package as well. The vehicle has 77,000 original miles on it. I have installed an FIPK, Flowmaster 2.5" exhaust, MSD Blaster Coil and A 1" throttle body spacer...I have removed the performance chip it once had in it.

The problem: The vehicle is hesitant with bucking in throttle when under load i.e. passing or just getting up to speed mainly in second gear. When it hesitates it does not want to downshift and there is a buzzing sound present on the pasengers side of the engine compartment that can be heard as though it is close to the firewall. When turning around corners (mainly turning left) the vehicle has a tendency to stall. I noticed the belt has been getting oil on it and see that it may be coming from the smog pump...I am not sure if it is failing. The fuel rail has pressure but the guage has been acting weird at times moving as speed is increased. It is drivable but it is not fun as it should be.

Parts replaced: I have replaced everything to do with emissions except TAD, EVR, TAB.

Note: The check engine light is not on and does not flash either as though there is a problem. This leads me to beleive that it is mechanical and not something electronic...but I could be wrong. The sensor in the rear is clean and new exhaust has been installed minus the catalytic converters (the stock ones are still there). It does, however have codes 33 and 133 locked as hard codes that I cannot get rid of in the memory as though they may be the issue...I am still scratching my head. My brain is sooo racked at the moment from all these darn sensors I can't even begin to think where this problem may lie mechanically.

Questions: How do you tell if the torque converter is bad? Does the Smog pump have any affect towards these issues of hesitation? Could the TAD, EVR and TAB solonoids be the culprit?

I am going to see if the ford dealer has the ability to put my truck on an asylascope to see if there is a leak of some kind present that I cannot see.

Your help will be greatly appreciated...I will even do an 11x14 original rendering for the person who has the answer to solve this crazy issue with my truck. I do renderings for custom vehicles and builds as founder of HighOctaneArt located in Maryland. Please help

 

I take it your talking about torque convertor shudder. You can tell by putting your left foot lightly on the brake just enough for the brake lights to come on and keeping your right foot just like it was. If the vibration stops it is the torque convertor. Hope this makes since. The best thing to do for torque convertor shudder is to replace ALL the trans fluid with mercon V. Fixed mine.
If it is doing it in second gear I would not suspect a problem with the torque convertor.
If I were you I would also check the motor mounts. My truck was bucking when pulling a trailer and I found I have a broken motor mount.

 

I would suspect the fuel regulator. It is close to the firewall and you said the pressure was fluctuating. My '90 F-150 was acting very strange, hesitant, no acceleration but good low speed performance. Turned out to be the regulator. I don't see how it would be the air pump as that does nothing but pump air in the exhaust after it leaves the motor. I don't think that would have any effect on performance.

 

The Thermactor fresh air pump (smog pump) pushes fresh air into the catalytic converter AND sends fresh air into the exhaust ports in the cylinder heads UPSTREAM of the O2 sensor which WILL adversely affect performance if the pump fails because it will throw O2 sensor readings off making the computer believe the engine is running rich. This will cause the computer to compensate by "leaing out" the fuel air mixture. There goes your performance.

Ok, the codes will be the place to start no matter what. First of all you have something really odd going on there because EEC computers generate EITHER two-digit OR three-digit error codes NOT BOTH. (Not exactly sure just what a Code 133 even is right off the top of my head).

Your stalling problem is most assuredly the result of a Code 33. Code 33 means that the EGR valve is not opening OR the computer is not getting ANY information indicating the operation of the EGR valve. Make certain the vacuum supply to the EGR valve is intact. Make certain the electrical connection the the EVP sensor atop the EGR valve is good. Clean or replace the EGR valve if it does not open when vacuum is applied to the port on the valve. If the valve appears to be functioning properly, there is a procees to test the EVP sensor if necessary.

 

Thank you all for the replies. I will certainly check all the items you have pointed out.

I have a new egr valve and sensor on the motor...both show that they are working properly but it may be one of the solonoids throwing vacuum to the egr valve that is causing a problem!?? Those darn vacuum lines are hard to chase though and check for cracks without cracking them. My vehicle is a Mass Air vehicle and the EEC-IV computer does throw codes in three-digits...unfortunately Ford has protected rights to most codes to which point I cannot find out what 133 is exactly unless I call in a favor. My Snap-on Super duper auto scanner cannot even tell me. I will be making calls Monday to see if I can get into this a little deeper. Where exactly the oil from the smog pump is coming from is my biggest question. The pulley has no drag or play in it and the stalling issue is steadily getting worse. I have even suspected that the sending unit may even be at fault but the gauge issue only happens a few times a week so when I check it, it is usually working properly. It is extremely difficult to get to the check valves behind the engine from the smog pump to see if they are cracked without removing the upper intake. If one should be cracked, could this be the location of my problem causing the rattling/buzzing noise when the engine is under load???

If I should determine a specific part fixes this issue and one of you great people that have posted here has it under their list. I will contact you for information on a vehicle to do a complete 11X14 rendering. I will post samples below:

 

I'm pretty sure you can get to those valves from an inspection plate inside the vehicle under the carpet ahead of the center console. Also I can't find a 133 code anywhere in my books. Sorry can't be of anymore help than that.

 

It sounds like the EXACT problem I had with my 86 ford bronco. Hesitation at cruising speeds, stall out on left hand turn, etc. I found it to be the Throttle Position Sensor (TPS). This is a very easy component to check.

Check FordFuelInjection.com for details. (SENSORS)

What you want to do is a voltage test on the sensor, while the truck is off. 1)TPS is located under the throttle body.
2)Use your multimeter (voltage setting) to test. Stick the probes in the back of the plug...this is called backprobing. Do not unplug to test.
3) Black probe either in the black wire or the negative battery cable.
4) Red probe in the green wire.
5) with the throttle closed the reading should be between 0.5 v and 1.0.
6) As you open the throttle (with your hand) volts should steadily increase. Wide Open Throttle (WOT) should be 5.0 volts.
7) Also...make sure you check your vacuum lines located on the passenger side of the vehicle. These have a tendency to come unplugged from the rubber boot which could affect performance.

I have a write up on this if you are interested with pictures. Please let me know if you are interested. Good Luck

 

I have purchased an aftermarket cheapo TPS from Autozone and then ended out paying the 8o bucks for the Motorcraft TPS. As for checking it...it checks out fine. It must be mechanical cause there is no code being thrown.

 

There should be no oil coming from the smog pump. Its bearings are sealed and the internals are not lubricated. Its an air pump and any fluid on the inside would have the potential to get into the air supplied from it.

A cracked check valve in the Thermactor system could certainly generate the noise you are hearing and possibly be a contribututing factor to the problem. Having one of them malfunctioning, will not generate error codes either. There is also the diverter valve hiding back there behind the passenger side cylinder head that does the actual redirecting of fresh air from the smog pump. It is controlled by the TAB & TAD solenoids via vacuum. There is a way to test for a dead TAB/TAD solenoid but its rather detailed and just a bit tedious to administer. If you want the procedure send me a PM and I'll forward it to you. The test can be performed with everything still in the truck and requires no handling of the vacuum lines.

Something you may consider doing is checking the mass air sensor to make certain it is functioning within parameters. I know you aren't getting any codes but the hesitation and stalling is a characteristic of a faulty sensor. This should let you test for the correct voltage at the sensor. You will need to actually drive the vehicle to perform this test. A voltmeter between pin 50 of the ECA and Ground will yield the readings you are looking for.

Idle - 0.8 VDC
20 mph - 1.1 VDC
40 mph - 1.7 VDC
60 mph - 2.1 VDC

These numbers are approximate and will vary with the load on the engine and the vehicle. But the varaince should not be more than a couple tenths of a volt.

 

I'll check my ford program tonight when I get home and find out what a #133 is.
I keep going back to the stalling when turning left???? The only reasons I can think of, and 1 of them is a stretch. Power steering pump and/or steering box is binding and killing the motor. And here is a creative guess, your master cylinder has leaked fluid in the booster which is getting sucked up the vaccuum hose, in particular on left hand turns since that would slosh the fluid closer to the hose.

 

That is interesting...The booster is possibly leaking. I checked the seal and there is a small crack around the hole where the pedal rod goes in...the brake pedal has been clicking with a very faint hiss as I apply pressure but the brakes are still there. The only thing is that there is no sign of leakage unless it is an internal leak of some sort. I have installed a new recon power steering pump when I first got the truck and a damper to help with dead spot in the steering. It's looking as though I'll have my work cut out for me with all this stuff to check out...unless I get it checked on an Asylascope first. Thanks for the replies and I look forward to seeing what code 133 is.

 

Code 133 is not listed in any reference I have been searching...possibly a bad PCM throwing faulty codes...Greystreak anyway to test for bad PCM?

 

First and foremost, I want to thank all of you for posting your thoughts to this issue...it helps having this board and you fellow Bronco guys and gals out there to aid others from experience and knowledge.

Well, through all my research with all vehicle brands...codes from computers are based on a main program so code numbers all across the board are typically the same or close. 133 looks as though it relates with the fuel system to some level, for what exactly is the question. I have had issues with the sending unit and the guage where the guage moves like the speedometer while accelerating telling me there is something strange here. I am going to have to check that first and foremost before moving on with steering issues.

Take note: I have noticed the truck shifting down into fourth gear at 30-35 MPH bogging the engine down as the rpms drop off cause it is the tow package. It has not ever done this before until these issues showed up. Maybe this can further pin point the issue to a direct cause.

Everyones help is greatly appreciated.

 

If the transmission is short-shifting, its getting told to do so by the computer. The E4OD relys completely on information from the computer for shift points. The only thing that would cause this is something erroneous being fed TO the computer OR the computer has gotten "eccentric" (Well they are worth far too much money to be crazy). The E4OD will shift as low as 33-35 mph sometimes but below that is anomolous.

Yes, you can test for a dead ECA. At pin #30 with the MLPS disconntected from the wiring harness, check for battery voltage (approx. 12VDC) at pin 30 of the ECA. If there is no voltage, make certain that the wire running from pin 30 is not "grounded". Once you are certain the wire is not grounded, check again. If there is still no battery voltage, the ECA(PCM) has had it.

NOTE TO ALL WHO READ THIS! This is an absolute LAST resort test! Not to be taken lightly nor is it to be administered unless EVERY other possible option is pursued. Of the problems synonymous with EEC-IV-driven engines a failed or defective ECA(PCM) is the culprit less than 5% of the time!

The change in fuel gauge readings as you described would tend to make one think something was shorting out the wiring to/from the sending unit which would cause the gauge to malfunction. Call me crazy but I friend had a Dakota pickup that would pop the fuse on the cruise control every time he put the clutch in. After chasing it for months, he was under the dash looking for a dropped fuse (to replace yet another blown one inthe cruise control circuit) and found a section of the wiring harness had fallen into the path of the cluthc pedal assembly and every time he poushed the pedal the wires would scrape against the bare metal edge of the pedal arm. He replaced the fuse and watched as the pushed on the clutch... instant sparks and "POP" from the fuseblock.

 

133 is not a valid code. For some reason there are no *33 (133, 233, etc) at all. Was this scanned on a computer or did you use a multi-meter. I think the universal codes wern't until OBD II in 96.