View Full Version : Goes up to 25 mph, no faster
I have an 89 Ranger, 2wd, auto, A4LD. Been sitting idle for several years and I just can't seem to make it stay running. I got a reader and it coded out with a code 53 "throttle positioning sensor above max voltage," and a code 89 "AXOD Lock-Up Solenoid (LUS) circuit failure or Clutch Converter Override (CCO) failure." I noticed that the front bumper was bent, so I made sure the fuel cutoff (kill switch) was reset. I can get it up to 14 mph, runs great, shifts into 2nd and starts to surge. Keeps on surging till I let off the gas just a little bit and then runs great up to 25 mph. Starts to surge again and then won't go over 25 mph. On 2 separate test drives the surging just went away for no apparent reason, ran great. Stopped, started, took off fast, took off slow. It did great, but as soon as I put it back in park and drove it the next time the surging started all over again. It idles fine, BTW.
Partial list of new parts: Fuel pump, alternator, fuel filter, tank has been flushed out, ignition switch, steering column switch (slider), throttle positioning sensor, but it has not been set by a computer.
Before I was given the vehicle, it sat on the tarmac at the airport with a blown tranny for about 2 years. Transmission has been replaced by another mechanic. Numerous mechanics could never get vehicle to stay running. They all worked out on the tarmac on the vehicle over a period of 3 years on and off, with no special tools that I could tell. They all threw in many parts (i.e. rebuilt computer, mass airflow, sensor, throttle position sensor, one coil pack, maybe more?) just trying to get it to run.
HELP!! What should I try next?:dunno:
RobbieD
09-30-2007, 02:59 PM
Sounds like a real frustrating head-scratcher you've got there. Given the weirdness of the problem, the truck's history and all of hands that have been on it without resolution, have you checked all of the wiring harness grounds? The 1989 EVTM (wiring manual)would show all of them, but basically you're looking for loose or disconnected wires with ring terminals (usually, not always, black colored wires), which are screwed to body or chassis metal with a bolt. Check along the inner fender wells, in the kick panels (especially passenger side), the firewall and the radiator support. Also make sure that the battery has ground cables from its negative post to the engine, and body and/or frame. If for anything else, at the least this would get an ungrounded electrical system ruled out as the cause. Good luck with it, and welcome to TRS.
That TPS fault indicates the TPS, at least, is not grounded. Grab a voltmeter and a circuit diagram and see where ground got lost. There will be a voltage drop there -- with no ground, all three TPS leads will be at 5V.
That may not be all of the grounding problems, but it MAY lead you to something important. So, I'd trace that down first, fix it, and then reevaluate.
Wicked_Sludge
10-01-2007, 04:32 AM
if the TPS sensor was bad, wouldnt it have smiler symptoms in park (once the throttle reaches a certain spot, hesitation, stalling, what-have-you)?
i have to wonder if the tranny is the root of the problems.
I don't see any indication here of a bad TPS. I do see indication that the TPS is not properly grounded, perhaps intermittently.
I have been driving the truck around alot, it has messed up a few times. It seems the more I drive it, the better it shifts, so far anyway. Still have a ck engine light and the idle is not all that steady. When I am test driving and come to a stop and it is still in drive, it will run for a few min, then black smoke comes out the tail pipe and it dies. The TPS is new, and has not been set by a shop's computer. I have heard that it must be set that way. Is this true? I did a voltage test on the TPS; first wire on the left is 4.49, next is 4.99, last one is .032. THX for all your help!
Do you have any idea where I could find this ground?
IF you had your "common" connected to anything not on the TPS (engine block ground, negative battery terminal, whatever), then that TPS is ungrounded internally. I don't care if it's new; those are not correct readings. Especially if the throttle is closed.
Though to be honest, I'm really scratching my head as to how the signal can be higher than power.
RobbieD
10-01-2007, 04:22 PM
TWH- first of all, is there a thick cable between your battery (-) post and the engine?
Ranger5.0
10-01-2007, 05:29 PM
Higher then normal TPs voltage is caused by 1) a disconected sensor 2) An "open" in the suply wire, as in the 5V suply wire is damaged and 3) An open ground. Think of it thisway, your ECM is full of voltmeters, each meter is watching the suply voltage, and then the signal voltage, it then compares the two and makes a decision. If there is no path for the 5v referince signal to take,there will be no voltage drop, which then flags a active falt code. So, bottom line, new TPS or not, the tps and the tps circuit is where your looking. Disconect the tps, conect your Volt meter to the suply wire and the volt meter ground to the battery negative termanal. Get a buddy to mess around with the harness and watch the meter, if nothing happens, then conect the negative lead of the meter to the TPS ground wire, mess with the harness again and watch what happens. IF nothing happens with the meters ground lead is conected to the battery but the Voltage changes when its conected to the TPS ground, then thats a sign of a poor tps ground. If the voltage changes when the meters ground wire is attached then its a sign of the tps 5v suply wire is the suspect. This this, then report your finding. Also note that a "scan tool" doesnt help ya out most of the time. The DMM is your best friend when tracking electrical problems.
An open in the supply wire will give a grounded (too low) signal, not too high.
There is no way to make the signal wire read higher than supply in a resistive circuit, so something is wacky. Given that the signal is almost exactly 5V, I suspect the voltmeter just didn't make good contact when measuring the supply wire (and it's really 5V as well).
But I think the ground side is open. Probably within the TPS itself, or the connector (depending on how the test was done).
A simple ohmmeter will confirm. What's the resistance between the two outer pins, on the TPS with the connector removed? If it's open, you need a TPS. This is not a common wear failure. This is a defect in manufacturing or breakage during shipping or somesuch.
Ranger5.0
10-01-2007, 05:48 PM
lol, so your telling me everything i learned in electronic engine managment is wrong? The 5v referince signal is being monitored by the ecm as IT LEAVES the ecm and heads to the tps. IF THAT VOLTAGE does not make it to ground through the tps, it finds its way to ground internaly, through the ecm, which then flags a tps high code. if it it wasnt a missprint in a manual, and it REALY IS higher then suply, then somthing in the ecm is ****ed, and its time for a replacment Fred...... ****in ridiculous electronic device. I duno what some of you do for a living, but i diagnose this stuff at work, and learn about it at school.
Not everything, but you're going to have to explain how the computer monitors the 5v reference signal as it leaves the ecm and heads to the tps. There is nothing between there except for the supply wire itself. The computer has no way to know if it "got there" or not. There are precious few redundant systems in an automobile. Running a whole bunch of wires to monitor one might be called for in the Space Shuttle (where that wire failing might kill someone) but it just isn't in a light truck.
If it didn't "make it there," the signal wire is grounded. A resistor with no current is the same as a wire. That's Ohm's Law.
Ungrounded circuits can sometimes behave the way you describe (not one so simple as this one, though). But not unpowered circuits.
Ranger5.0
10-01-2007, 06:18 PM
lol, the signal wire is OPEN if it didnt make it to the tps, its grounded if it contacts a ground wire, or a grounded component of the truck. I can drag this out and explain how the ecm is monitoring the reference voltage and the signal voltage if you like?
The reference voltage doesn't change with an open. It would with a short to ground, but then you'll just burn out the VREF circuit and fry the computer.
You're confusing the signal wire with the supply wire. An open signal is floating and will read according to PCM internals. An open supply grounds the signal. It's not floating. Similarly, an open ground sets the signal to reference.
This is a very basic voltage divider circuit, which I'm sure you learned about in school. It's not at all a complex circuit. It's just a potentiometer with a 5V reference.
Ranger5.0
10-01-2007, 07:50 PM
shit, im an idiot. high tps voltage can mean that the tps ground is damaged. the suply wire needs to be working to get suck a code, correct?
Ranger5.0
10-01-2007, 07:51 PM
makg My mistake man, studying for the exemption test is makin my brain slowly turn to mush haha
Ranger5.0
10-01-2007, 07:52 PM
after a bit more thought, a bad tps wouldnt be the root cause of the problems tho..... a combination if that plus some other problems like fuel delivery could do it tho, no?
makg My mistake man, studying for the exemption test is makin my brain slowly turn to mush haha
Oh, BTDT.
At least it's only slowly....
Good luck.
after a bit more thought, a bad tps wouldnt be the root cause of the problems tho..... a combination if that plus some other problems like fuel delivery could do it tho, no?
Yes, I agree. My original thought was that a broken ground accounted for it all, but the TPS voltage measurement seems to isolate the ground to inside the TPS. I don't see how that could affect the torque converter.
The computer thinks the throttle is wide open, so it's probably very rich. That MAY account for the bad performance.
The right thing to do here is warranty the TPS (it's clearly DOA) and reevaluate. Check spark plugs for fouling and proper gaps.
RobbieD
10-02-2007, 10:28 AM
I hope that we hear more back from him on this one. I've seen people chase their tails trying to figure out weird problems, and it turns out to be something so simple it was overlooked all along. Ya'll all are making some good points and comments; I'd just like to be sure that the truck has both the engine and body well grounded to the battery, to get it ruled out as a factor.
It's true. I've seen some really bizarre behavior from hosed battery cables and especially body grounds.
My former Bronco II was once getting negative oxygen sensor readings at the computer (curiously, it didn't flip a lean code, though it really should have -- it just fouled plugs). Turned out to be a poor body ground that let the HEGO sensor float a little with respect to the PCM.
It's gotten to the point that a new-to-me vehicle gets its charging system worked over, first thing. The Exploder didn't pass and I ended up replacing both battery cables (voltage drop on cranking). Emissions tests sure work better that way....
Ranger5.0
10-02-2007, 04:01 PM
Ya, It would be good to get some input on how the trucks doing. Your right, if the ecm thought the TB was wide open all the time, it would make it run rich, and would for SURE affect drivability. If the tps went bad, the rich condition would foul plugs and could maybe(depending on how long its bee ngoing on for) foul the O2s and partialy plug the cat'...Thats a "pull out of ass" therory tho...its actualy somthing were learning right now, cause and affect type stuff
skippy
10-02-2007, 04:49 PM
It's true. I've seen some really bizarre behavior from hosed battery cables and especially body grounds.
My former Bronco II was once getting negative oxygen sensor readings at the computer (curiously, it didn't flip a lean code, though it really should have -- it just fouled plugs). Turned out to be a poor body ground that let the HEGO sensor float a little with respect to the PCM.
It's gotten to the point that a new-to-me vehicle gets its charging system worked over, first thing. The Exploder didn't pass and I ended up replacing both battery cables (voltage drop on cranking). Emissions tests sure work better that way....
i'll be damned,battery cables?i've been chasing grounds all around this thing while waiting for the ford tech manuals to get here.the original cables are on it and look ok,any idea what the risistance should be through factory cables?
Zero. But it's a lot easier to see if they work with a voltage drop test while cranking.
All the voltage drop should be at the starter.
Similar deal with the pigtails (though you don't need to be cranking -- but it might be a good idea to have it idling warm if it will do so).
RobbieD
10-02-2007, 04:55 PM
i'll be damned,battery cables?i've been chasing grounds all around this thing while waiting for the ford tech manuals to get here.the original cables are on it and look ok,any idea what the risistance should be through factory cables?
Hey skippy. As close to zero ohms, as possible. Measured between the engine block (or frame, or body, for that matter), and the battery negative post with a ohm meter (VOM).
I'm still looking for a procedure on checking the SPOUT circuit, you get my PM from Friday evening? Have you figured out anything else on yours?
skippy
10-02-2007, 05:56 PM
Zero. But it's a lot easier to see if they work with a voltage drop test while cranking.
All the voltage drop should be at the starter.
Similar deal with the pigtails (though you don't need to be cranking -- but it might be a good idea to have it idling warm if it will do so).
never occured to me to check the cables,truck starts with a tap of the key and maintains battery charge.i'll check it out.thanks.
Ranger5.0
10-02-2007, 06:49 PM
as fas as the positive cable goes, the voltage drop is most crucial during cranking, thats when it(and the ground cable) are seing the most amps. Check from the center of the batt term' to the center of the B+ term' on the starter, then crank it over. Grounds on the other hand can be a bugger. A bad ground hear, bad ground there and life can get a bit frusterating. Sensors need a good ground to operate properly, the ecm needs a good ground to operate properly, tho, it has some redundent grounds internaly/externaly to compensate for ground issues. Lose damaged and corroded conectors are usualy the ones to blame for many "gosts" in an electrical system. The voltage drop on a ground cable/wire should never be more then like .5 volts, and on a power wire it should be no more then like, i think .o5 volts. I know half a volt doesnt sound like much, but when you add them up through out a circuit then it doesnt take long to cause some problems
I do have a broken blk wire on the pigtail from probes. The other two wires are damaged also. I will get a new pigtail. Will the new pigtail being spliced in cause voltage to drop?
(p.s. you guys are cracking me up!)
Then you found a broken ground. Good! FYI, one of those pigtails grounds the oxygen sensor and the other grounds the computer. If either is poor, you'll get wrong mixtures and false mixture codes.
Wires and direct connections should have no voltage drops. Voltage drops should occur at loads only (the starter in the cranking circuit example), and in reverse at the battery and alternator.
Those pigtails often come with battery cables. I recommend getting them that way, rather than splicing, for this particular application. Splices are hard to seal from the elements and are very vulnerable near the battery. But if you do splice, solder the splice (you'll need a VERY POWERFUL iron or a small propane/butane/whatever torch to solder 2 or 4 gauge cable) and seal it up with heat-shrink. Use electrical (rosin core) solder; the plumbing stuff (acid core or solid) will corrode connections.
The clamp-type battery connectors will work for a time, but they don't last.
RobbieD
10-03-2007, 11:05 AM
(p.s. you guys are cracking me up!)
Nothing wrong with that! Good luck, man, and let us know how this turns out.
skippy
10-03-2007, 03:16 PM
i'm going to start over saturday and with the battery cables,and i'm going to check every ground i can find.i know,supposed to say (fixin to)in the south.hope to find something,we'll see.thanks guys.
Ranger5.0
10-03-2007, 03:20 PM
sounds like a good plan. Damn'd grounds can cause a lotta issues...and intermitent problems caused by bad conections are an even bigger pain it the arse.. Once ya start looking at your wireing, take your time, gently pull on some conections, see if anything looks bad. IF you cant solder and heat shrink the new conections, you can use crimp conectors that are coated with heat shrink tubing...They work well, we use them at Deere if/when we cant solder conections.
The ground wire that is bad is on the TPS pigtail. Have a new one on order,should be in town in a few days. looking fwd to putting it on! you guys are great thanks so much. I will let ya know how it comes out all so may antilockbreak light come on as well as the emerg.light and stays on most of the time, every now and then they go off at the same time while it running, they go on and off as if they are wired together. If I unplug the wire on the emerg break peadel the panel light stays on as well as the antilock light. If I trun the engine and key on emerg light gose on and off as it should as I set the break and release it thanks.
RobbieD
10-03-2007, 10:31 PM
Thanks for checking in, and letting us know how it's going. You're making progress, for sure. I think you've got two idiot lights on that thing; one for the emergency (or parking) brake, and a second for the anti-lock brakes (ABS). Probably can get that sorted out, too. Do keep us posted, and good luck.
Ranger5.0
10-04-2007, 06:54 PM
hey, try playing with your ebreak release and the pedal, that might fix the e break light. or take a look at the resavoir for the mastercylinder, some wires might be lose there
hdtv27ew
10-09-2007, 06:40 PM
I just posted a new thread that talks about some of the ground issues you may be experiencing. Check it out.
87 Bronco II Grounding Problems Solved
Good luck!
I put the new pig tail on the TPS. Every thing is working great now thanks so much for your help.
RobbieD
10-16-2007, 06:35 PM
Awright! Good deal. From your first post: "Numerous mechanics could never get vehicle to stay running." You did real good, man; CONGRATULATIONS! Now you can just enjoy your new truck. But be careful hanging around here, or else you'll get the bug to start modding it.
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