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Discussion Starter #1
Dudes, this site is awesome. Anything and everything Bronco. On to the problem... Traveller has been coughing?, Dying?, while accelerating or going uphill. It happens in the 1000 to 1500 rpm range. He doesnt die completely, just coughs, the rpms drop and then he catches again. It happens in overdrive and drive. Also, I just changed the TPS and now it wont idle unless I screw in the idle stop screw. Why would the auto choke stop working.
Any input would be welcomed.
Thanks dudes Denny
 

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When was the fuel filter changed last?

Have you tested your fuel pressure?

How bout codes? Have you pulled them?
 

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Discussion Starter #3
Hi!, and thanks for the reply

I changed the filter on the frame rail less than a year ago. Is there another one closer to the injectors? I havnt checked the regulator yet but I will. I checked the codes and it said the TPS wasnt giving enough volts,so I changed it. It had been running very rich. Now that it has a good TPS, does the computer need to readjust to the new condition?
Thanks again, Denny
 

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Anytime you replace a sensor its a good idea to clear the computers memory by disconnecting the battery for at least 10 minutes.
regards
rikard
 

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Discussion Starter #5
Yes Ricard, I did disco the batt after I changed the tps. It is just strange to me that after I changed the tps, it doesnt start at High idle and then kick itself down like it used to. Oh well, I will try to talk my girlfriend into helping me check the codes before it rains, and report what I find. I dont need her help, mind you, but asking her to help makes her part of the process. Thus she is much less likely to grow tired of my fooling with it! D
 

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If it sounds like its backfiring through the intake, and its doing it under a load like going up a hill, its usually due to preignition. You may have a sparkplug with crap built up on it thats igniting the fuel mixture while the intake valve is still open. That usually only happens under a load when it gets hot. I'd pull the plugs and check them since its an easy job and free just to confirm they are OK before you go puttting time and money in to other things.
 

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Discussion Starter #7
I have been troubleshooting it as time allows. Last night I noticed a clicking noise coming from the vacuum solenoids on the right inner fender well.
There are 4 or 5 of them, and it sounds like one of them is clicking on and off when ever I bump the throttle up or move the wires going to the idle air bypass valve. When I move the wire harness around, I can hear the idle change, or it will die completely.
Tonight I am gonna concentrate on the red wire going to the valve. It has continuity to all the red wires going to the solenoids. Hopefully that wire is bad and I can splice it and fix the prob.
Any help or advice would be gladly accepted. Sorry for the long write-up.
Denny
 

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Discussion Starter #8
Changed IAC, no differance. What the hell is causing this?!

High idle (2500-3000) after it warms up. Missfiring, skipping, caughing and then catching at @ 1300-1800 rpm. cleaned throttle body, replaced TPS and IAC. Still happening. Heeeeeeeeelp. Love Traveller, but damn it....
 

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How old are the plug wires? Mine would cough every once and awhile on the highway and at idle. Turns out one of the plug wires was wore through. New set of wires fixed it. :thumbup
 

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First go PULL CODES from the PCM - power control module, the vehicles computer to see what "fault codes" are indicated if any .....if you don't know how, www.fordfuelinjection.com for FREE code numbers and fault explanations..a plug in Ford Code reader - OBD1 would help....

A classic sign of loss of power is a vacuum leak, indicated by code: 44 (emissions) Thermactor Air System "fault".

If this is the case, go directly to the "Check Valve" that sits on top of the Exhaust Cross Over Tube bolted to the back of the cylinder heads...the valve will rust or burn thru from extreme heat and moisture causing it to suck air, creating what feels like an engine miss, bucking, ignition detonation and loss of power in stop and go traffic or going uphill until the RPMS smooth out......

You'll need to pull off the tube for closer inspection due to it's location....lol lol but you can get it from underneath the truck drivers side and top from the passenger side where there are 2 - 1/2or 5/8 inch bolts for the tube....the valve only costs around $20.00 or so....it's "pipe threaded" so put the tube in a vice grip for leverage to unscrew it...

The 86 302EFI XLT has another fuel filter inside a "reservoir" located on the drivers frame under the Transfer Case skid plate....in a black round plastic canister where the bottom unscrews from the top cap which has fuel lines attached along with a "pressure valve" inside to keep the canister full of fuel, say at cornering or extreme angles when Off Roading etc....the filter is a hockey puck style with a hole in the center going in hole up along with an O ring that fits in the bottom part of the canister in a track, filter kit costs around $10.00 but use a little grease etc., so the O ring stays in place when you screw the bottom half back on or you'll crush it, rendering it useless....pissing fuel out every where.....lol lol

Put a presssure gauage on the FPR = fuel pressure regulator located on the fuel rail towards the back.....

Check/test FREE the TFI module = thick film integreated located driectly on the distributor along with Ignition Coil if necessary ....

Make sure the ignition wires are appropriatley spaced apart eliminating cross over arcing which can contribute to loss of power, missing etc.

Check the timing for correct BTDC adjustment, the 86 302 EEC-IV -EFI is set to OEM 10 degrees stock.....there's a decal located on the top part of the radiator core support with that information, assuming it's still intact...

Last, definately get a HAYNES REPAIR MANUAL ASAP so you can better diagnose problems yourself FIRST.....

This should keep you busy for a while so let us know what you come up with......lol lol


Good Luck ~ :thumbup
 

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Discussion Starter #11
Thanks fellers

Thanks for your input. I quess I sounded rather desperate, LOL LOL!! Once the weather clears I will start fresh again. I have a chiltons, I have checked the codes before, but watching the blips on the meter is difficult and inconclusive. I need a better reader.
I will change the plugs and wires. I have changed that hockey puck filter and was careful with the o ring and it doesnt leak. That valve on the cross-over sounds interesting, but I have sprayed carb cleaner on vacuum lines and tree with no results. I will check that though.
When I do find what this is, and I will eventually, I will let everyone know what it was. This is why we love our Broncs!!!!:rockon
 

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I've tried using Propane, TB cleaner etc. etc. and none of them worked where the idle dramatically increased from the fumes, it took me a long time to figure out and fully understand code: 44, that the "check valve" was the culprit.

Most of the emissions system is easily inspected except for the C/O tube because it's slightly below the lower intake manifold right up againt the bloody firewall so you really can't see 360 on the valve for evidence except maybe using a decent mirror but then you have to sort of lay across the top of the engine uncomfortably in order to get positioned to gain access back there, PITA stretch...though you might consider removing the plastic fenderliner/s for access but IMO that just as much of a PITA....

IMO it's easier just to pull off the entire tube and inspect it and the "cheap metal" check valve, IIRC there's only 2 -C/O tube bolts and a rubber hose to disconnect...using my instructions it shouldn't take more then an hour to remove entirely, if that...

Kragen/O'Reilly's sells the Ford Code Reader (OBD-1) with diagnostic code book for around $35.00 and worth every penny, it's digital, quick and reliable as long as the batteries inside are fresh otherwise it won't trigger the PCM properly for fault codes.....

Good Luck ~ :thumbup
 

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Might wanna check if your new tps is good. My brother had installed one on his and had problems ever since. It wouldnt idle high on cold starts either. He changed it again, and its started running perfect.
 

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i had a similar problem and i narrowed it down to junk in my fuel tank and a clogged fuel filter. then i ran low on gas and it started again so i changed filter, but it didnt fix it the next time so i wound up getting some lucas fuel injector cleaner ran it for 45 miles and like magic its fixed.
 

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Discussion Starter #16
An update and a couple questions

Ok guys, first, thanks for all the inputs. I have learned so much about my PITA Bronc! Second, some updates.

I changed that fuel resevior and o-ring already. I changed the IACV, cleaned the TB very well, new plugs and wires. It idles better now, but that didnt fix the coughing and stumbling.

I checked the fuel pressure--40psi engine off--no leak down--30psi engine on with vacuum. 40psi engine on w/o vacuum.

I checked the map sensor. When I pulled the vacuum line off it died instantly. I disconnected harness and checked voltage at vref and signal return with key on and both showed 5 volts??? I moved wire bundles around to see if there was a short. didnt find one.

Questions
1. Is it normal for the fuel pressure to be 10psi lower with vacuum hooked up?
2. Is it expected that the engine would die when the vac line is removed from the map sensor?
3. Why would the MAP sensor signal return line be showing 5 volts during a key on voltage check

Thanks again. This site rocks!!! Broncs Rule!!!:thumbup
 

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Discussion Starter #18
Spark Plugs...

Yeah mikE2, I changed the plugs and wires a couple days ago. They all looked good and very similar except for one that had more carbon on it than the rest and it's white tower part was darker than the rest.

Another thing with the MAP sensor is that with key off, the signal return line(black wire) has continuity with the Battery. With key in run, it does not have continuity with the battery.???

The mystery continues......:scratchhe:scratchhe
 

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Discussion Starter #19
OK, its got me strait trippin' yo!

So checking the MAP sensor harness some more...
1. key off, black wire has ground to battery
2. key on, ground goes away.
3. key on, middle wire(green) has cont. to black wire on MAP harness, tps harness and egr harness.
4. key on, black wire has cont. to orange wires in MAP, tps and egr harnesses.
5. green wire has no other cont. to any other wires. have moved wire bundles around to find a short. havnt found one.

Do I have a bad wire, bad pcm, or is this normal behavior? I consider myself capable in most areas of automotive, amature, fix it on a weekend type of knowledge, but these @#$%^&*() EFI electrical systems, put together by 5 year olds with an etch-a-scetch drive me nuts.
Is it just me, or is this problem going to get worse as all cars age. Nobody will be able to work on them because they are to damn complicated. I say dont get rid of that simple early 70's car just yet, It may be the only thing running in a few years that you can afford to buy and maintain!!!

OK sorry brothers, just had to VENT:banghead:banghead:banghead:banghead
Oh and that word vent??? Why the #### does a BIG, TOUGH###, mud slinging Bronco need a solenoid vent?!?!
 

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Discussion Starter #20
Finally Fixed!!!

Well, Traveller is up and running good again. After all the drama and troubleshooting, it turned out to be a bad TPS sensor that i bought from auto Zone. To be fair, I cant be sure it was bad when I bought it. I installed it and removed it once or twice just to make sure it was right, so I might have messed it up.:doh0715:
The symptoms were that it would idle, but when it was put under a load, it would stutter and skip and run like crap. Hopefully this info will help someone down the road. Broncs rule!!! :thumbup D
 
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