Bronco missing

Three possibilities come immediately to mind:

1. Sticking EGR valve
2. Loose catalytic converter core
3. Ignition module (don't know if applicable to this year/engine)

Is it a miss, or pinging? you could try a higher grade gas and see if it goes away, if that works then you might have some timing issues.

l8r, Jeff

Sounds like an ignition module breakdown from heat buildup. This can interrupt spark signal, only happens when warm, or hot.

Do you have the problem with the engine cold?

Spdloader

It seems to be a 'miss'. Couldn't hear a ping. I'm running 87, could try

89 and see what happens. I've always run 87 though.

: > Vehicle : > '92 Bronco; 5.8L, E4OD Tranny : > 178,000 miles : > Calif smog stuff : >

: > Problem : > Engine begins to 'miss' when pulling a grade and with about 75% throttle. : > It is worse with more throttle, better when backing off on the throttle. : > Tach not working so can't provide RPM number. Noticeable at higher : speeds, : > about 65-70 in 4th, 55-60 in 3rd. Independent of outside temperature, but : > consistent when engine has been working during long distant driving and : > heavy throttle. Temperature range of symptoms from 40F to 105F. Symptoms : > also show up on the level with AC on (105F outside) at Interstate speeds. : > Suspect this is just due to the extra engine load and additional throttle. : >

: > Repairs so far; : > New Platinum plugs : > New rotor and cap : > New plug wires : > New fuel filter : > Injectors cleaned at shop with special cleaners. : >

: > Took to Ford Dealer for diagnostic tests. Dealer claims that the vehicle : is : > 'perfect'. Took my $78 and said thankyou. : > Recently passed California Smog test with no problems and not even close : to : > a marginal spec failure. : >

: > So, with the above, my only hope is with the collective experience of this : > NG to give suggestions on how to isolate the problem. : >

: > It has been suggested that I change the O2 sensor. I don't know how this : > would affect the symptoms, but, I would have thought that the Smog testing : > would have detected a faulty sensor. Comments please. : >

: > I'm thinking that maybe there is a worn or faulty Injector. If so, how : > could that be isolated? : >

: > Could there be any Engine Computer sensors that are faulty?? If so, where : > are they and would a failure cause the symptoms? : >

: > Note, I'm not a mechanic. Just a retired Old Fart trying to keep his : Bronco : > running. : >

: > Your assistance is appreciated. TIA. : >

: >

: >

: >

: >

: >

: >

: >

: :

The only problem with a cold engine is that it is very slightly rough. Rougher than an 8cyl should be in my opinion and rougher than my recollection when all was well.

I think the heat buildup would have to be limited to the cylinder head temperature due to a long grade and heavy throttle. It immediately settles down when leveling out or when backing off when reaching the crest. I would think that the ignition module would continue to have an interrupted spark even though the throttle was backing off. I was wondering if a faulty Injector could be spraying fuel in an erratic manner with full throttle and with a higher cylinder head temperature causing the problem. What do you think?

Do you know of a test for the Ignition Control Module?

: > Vehicle : > '92 Bronco; 5.8L, E4OD Tranny : > 178,000 miles : > Calif smog stuff : >

: > Problem : > Engine begins to 'miss' when pulling a grade and with about 75% throttle. : > It is worse with more throttle, better when backing off on the throttle. : > Tach not working so can't provide RPM number. Noticeable at higher : speeds, : > about 65-70 in 4th, 55-60 in 3rd. Independent of outside temperature, but : > consistent when engine has been working during long distant driving and : > heavy throttle. Temperature range of symptoms from 40F to 105F. Symptoms : > also show up on the level with AC on (105F outside) at Interstate speeds. : > Suspect this is just due to the extra engine load and additional throttle. : >

: > Repairs so far; : > New Platinum plugs : > New rotor and cap : > New plug wires : > New fuel filter : > Injectors cleaned at shop with special cleaners. : >

: > Took to Ford Dealer for diagnostic tests. Dealer claims that the vehicle : is : > 'perfect'. Took my $78 and said thankyou. : > Recently passed California Smog test with no problems and not even close : to : > a marginal spec failure. : >

: > So, with the above, my only hope is with the collective experience of this : > NG to give suggestions on how to isolate the problem. : >

: > It has been suggested that I change the O2 sensor. I don't know how this : > would affect the symptoms, but, I would have thought that the Smog testing : > would have detected a faulty sensor. Comments please. : >

: > I'm thinking that maybe there is a worn or faulty Injector. If so, how : > could that be isolated? : >

: > Could there be any Engine Computer sensors that are faulty?? If so, where : > are they and would a failure cause the symptoms? : >

: > Note, I'm not a mechanic. Just a retired Old Fart trying to keep his : Bronco : > running. : >

: > Your assistance is appreciated. TIA. : >

: >

: >

: >

: >

: >

: >

: >

: :

I'm thinking of taking the Bronco to a local shop up here in the mountains after I exhaust any suggestions from this NG. I'll pass on your ideas. Maybe they will be able to isolate it.

: > Vehicle : > '92 Bronco; 5.8L, E4OD Tranny : > 178,000 miles : > Calif smog stuff : >

: > Problem : > Engine begins to 'miss' when pulling a grade and with about 75% throttle. : > It is worse with more throttle, better when backing off on the throttle. : > Tach not working so can't provide RPM number. Noticeable at higher : speeds, : > about 65-70 in 4th, 55-60 in 3rd. Independent of outside temperature, but : > consistent when engine has been working during long distant driving and : > heavy throttle. Temperature range of symptoms from 40F to 105F. Symptoms : > also show up on the level with AC on (105F outside) at Interstate speeds. : > Suspect this is just due to the extra engine load and additional throttle. : >

: > Repairs so far; : > New Platinum plugs : > New rotor and cap : > New plug wires : > New fuel filter : > Injectors cleaned at shop with special cleaners. : >

: > Took to Ford Dealer for diagnostic tests. Dealer claims that the vehicle : is : > 'perfect'. Took my $78 and said thankyou. : > Recently passed California Smog test with no problems and not even close : to : > a marginal spec failure. : >

: > So, with the above, my only hope is with the collective experience of this : > NG to give suggestions on how to isolate the problem. : >

: > It has been suggested that I change the O2 sensor. I don't know how this : > would affect the symptoms, but, I would have thought that the Smog testing : > would have detected a faulty sensor. Comments please. : >

: > I'm thinking that maybe there is a worn or faulty Injector. If so, how : > could that be isolated? : >

: > Could there be any Engine Computer sensors that are faulty?? If so, where : > are they and would a failure cause the symptoms? : >

: > Note, I'm not a mechanic. Just a retired Old Fart trying to keep his : Bronco : > running. : >

: > Your assistance is appreciated. TIA. : >

: >

: >

: >

: >

: >

: >

: >

: :

The other thing that immediately comes to mind is a weak fuel pump, might not be getting enough gas under heavy load. Might want to get it pressure tested. l8r, Jeff

The slightly rough idle doesn't fit with the symptoms. It does fit with gw's suggestion of sticking EGR valve, or it could be the idle air bypass valve needing a good cleaning, but the EGR sticking, and the bypass valve suggestion doesn't exactly fit your other symptoms.

You may have more than one problem.

A mis-firing injector will cause a low power condition on the cylinder it feeds, but I've never seen it cause a miss, not just one injector, anyway.

There is a way to test the module but you'll have to find someone with the proper equipment to do it. Some of the auto parts stores will do it, you'll need to ask around. Don't just change parts to find the problem though, that can be expensive. Being a '92 I don't know if it has it all in the ECM or if it has a separate TFI pickup. The TFI (thick film ignition) used to be attached to the side of the distributor in older models, but later moved to the top of the inside driver-side front fender. My '95 is setup that way. I can't tell you how to test it, but I can tell you the more fuel you put to the engine, the hotter the spark has to be to ignite it. Backing off the throttle eases your problem, as you said, so you still haven't ruled out the ignition module. I hope any of this helps you, Spdloader

I had the same thing with my 89. The number 7 and 8 plug wires were neatly loomed side by side. Moving them apart cured the problem. The ignition in one wire sets up crossfire in the other.

That is very good insight Spdloader. Let me digest what you said. I was just down the mountain and keeping with another suggestion, I put in some 89 octane. Only 10 gallons though as I was thinking that maybe some carbon build up might be the problem. I purchased some injector, carbon cleaner at a parts store and poured it into the tank. Then put in only 10 gallons. It'll take awhile to see if it helps. I'd sure like to fix the problem. I bought this Bronco new and it really fits my style, especially up here in the mountains where some Winters can be a real 'bitch'.

: > The only problem with a cold engine is that it is very slightly rough. : > Rougher than an 8cyl should be in my opinion and rougher than my : > recollection when all was well. : >

: > I think the heat buildup would have to be limited to the cylinder head : > temperature due to a long grade and heavy throttle. It immediately : settles : > down when leveling out or when backing off when reaching the crest. I : would : > think that the ignition module would continue to have an interrupted spark : > even though the throttle was backing off. I was wondering if a faulty : > Injector could be spraying fuel in an erratic manner with full throttle : and : > with a higher cylinder head temperature causing the problem. What do you : > think? : >

: > Do you know of a test for the Ignition Control Module? : >

: >

: > : > Vehicle : > : > '92 Bronco; 5.8L, E4OD Tranny : > : > 178,000 miles : > : > Calif smog stuff : > : >

: > : > Problem : > : > Engine begins to 'miss' when pulling a grade and with about 75% : > throttle. : > : > It is worse with more throttle, better when backing off on the : throttle. : > : > Tach not working so can't provide RPM number. Noticeable at higher : > : speeds, : > : > about 65-70 in 4th, 55-60 in 3rd. Independent of outside temperature, : > but : > : > consistent when engine has been working during long distant driving : and : > : > heavy throttle. Temperature range of symptoms from 40F to 105F. : > Symptoms : > : > also show up on the level with AC on (105F outside) at Interstate : > speeds. : > : > Suspect this is just due to the extra engine load and additional : > throttle. : > : >

: > : > Repairs so far; : > : > New Platinum plugs : > : > New rotor and cap : > : > New plug wires : > : > New fuel filter : > : > Injectors cleaned at shop with special cleaners. : > : >

: > : > Took to Ford Dealer for diagnostic tests. Dealer claims that the : > vehicle : > : is : > : > 'perfect'. Took my $78 and said thankyou. : > : > Recently passed California Smog test with no problems and not even : close : > : to : > : > a marginal spec failure. : > : >

: > : > So, with the above, my only hope is with the collective experience of : > this : > : > NG to give suggestions on how to isolate the problem. : > : >

: > : > It has been suggested that I change the O2 sensor. I don't know how : > this : > : > would affect the symptoms, but, I would have thought that the Smog : > testing : > : > would have detected a faulty sensor. Comments please. : > : >

: > : > I'm thinking that maybe there is a worn or faulty Injector. If so, : how : > : > could that be isolated? : > : >

: > : > Could there be any Engine Computer sensors that are faulty?? If so, : > where : > : > are they and would a failure cause the symptoms? : > : >

: > : > Note, I'm not a mechanic. Just a retired Old Fart trying to keep his : > : Bronco : > : > running. : > : >

: > : > Your assistance is appreciated. TIA. : > : >

: > : >

: > : >

: > : >

: > : >

: > : >

: > : >

: > : >

: > : : > : : >

: >

: :

Hummm. That's interesting. I do have new wires and they should be isolated from one another. I say 'should be'. I'll take a look at them.

Good luck man, my '95 is my fifth Bronco. I've owned one of every body style, and I've got a couple of other Fords too.

Hope some of it helped, or at least put you on a path to finding the problem. Just some of the things I ran in to in 20+ years of mechanic work.

Hard to fix 'em in email, though.

Spdloader

That's supposed to be a problem in my old 360 too but never had it. So I read about it later and rearranged the 7 & 8 wires anyway.

But how exactly? What's the best way to do it?

They now criss cross over each other as opposed to running parallel, is that the right way to do it?

Alvin in AZ

On Sat, 29 Nov 2003 18:52:08 +0000, alvin rearranged some electrons to form:

Ideally they would be orthogonal (90 degrees) to each other, I believe.

I ran my 7 & 8 wires as far away from each other as possible, let them cross when they had to. It doesn't hurt for them to cross, just can't run parallel. Country people don't shine their boots very often, but they don't shine anyone elses either.

"Mellowed" wrote : Engine begins to 'miss' when pulling a grade and with about 75% throttle. : It is worse with more throttle, better when backing off on the throttle.

Two thoughts cross my mind, and mebbe neither are worth a darn... Is it a steady miss (like one cyl dropped/even spacing or rhythm between misses) or is it rather that the engine is running ragged (no particular rhythm? If it's a steady miss under load, then it can be isolated to a particular jug on an engine analyser by putting the engine under increasing load (while hooked up, of course) and watching the coil output on the screen. You'll see one cylinder's voltage to be much higher or lower than the rest. Once isolated, then you can specifically address the plug, wire cap or injector that's at fault. I know you already replaced those bits, but since you said you were going to visit a mech, I thought I'd mention it.

If it's ragged, a respected mechanic advised me once, and everything else seems ok (including smog/codes/etc) look to see if there's just a bit of crud on the air mass sensor causing an odd output to the computer and setting up a lean miss situation while under load. I've never had this happen, he just told me about it while we were shooting the shit.

Like I said - this is most likely of no help at all, but everyone else used up the good answers.

Dave

Those are good points, Dave

Spdloader

Thanks for your comments Dave. The 'miss' is not steady but comes on hard momentarily, but repeatably, under the stress conditions mentioned.

The Air Mass sensor seems like something to check further. The whole condition seems like a 'lean' condition. If the Air Mass sensor can cause it to run lean that could just be the problem.

Is it possible to physically see crud on the sensor? Is there a way to test this device or is it just better and easier to just replace it?

I thought I had it cleaned off my girl friend's 96tbird. But I wanted to see the little sucker, so I used what I usually use, a binocular eye piece (use it "backwards", about 20X) and saw a pile of crap still on there!

The main thing about cleaning the MAF sensor is it's cheap and easy and quick. You might need a set of "secruity" Torx bits tho. (swap meet! $5)

BTDT! It's really cool to have a mechanic that will charge you a small amount to tell you exactly what's wrong by using his engine analyzer for you. Find yourself one of those and hang on to him. :)

LOL! :)

Alvin in AZ