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post #1 of 23 (permalink) Old 01-30-2004, 06:46 PM Thread Starter
 
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Engine cutting out/missing under load

The wife's '96 with less than 40k and the 4.6 has developed an issue.

First, the car has a few mods that were done when I got it. First, an open K&N cone on what appears to be a L-MAF, '98 Mustang plastic intake tube, underdrive pulleys, Dynomax cat-back exhaust and a chip. Unfortunately, I don't know who did the chip so this Spring Dennis will be getting an order for a new one.

Anyway, during the summer and fall I was getting a lot of detonation, even with mid- or high-octane fuel in 40 degree ambient air. It would ping at anything even close to or over 1/4 throttle in any gear. Suspecting the add-on chip and the programming, I made the wife was easy on it and new to downshift manually sometimes.

As it got down below freezing and the pinging became less of an issue, it started to act up during what I refer to as "tip-in." Take for instance, you leisurely get off a long off ramp, and when you get near the end of the ramp, and the tranny is still in OD with the converter locked, you ease back into the gas. Now, in this situation, the tranny really needs to downshift, but vehicle speed is fast enough and throttle demand is low enough that it doesnt do it. In this situation it would start "bucking" like a manual shift vehicle will do if you get into the pedal a little in too high of a gear. If you force a downshift, it stops it. It has quickly worsened and now I notice that under full throttle, I can feel it "missing" a bit, though it still pulls good. Otherwise, it runs and idles fine.

I started troubleshooting the pinging by cleaning the MAF and checking for pending codes, then left the battery disconnected (forgot about it and left it overnight, so it was long enough) to clear the computer. No dice.

Anyone have any ideas on what to start checking?

Last edited by Silkwood; 01-30-2004 at 06:56 PM.
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post #2 of 23 (permalink) Old 01-30-2004, 07:24 PM
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I would start by getting your battery and charging system tested. If your battery or alternator is dying you can get pining and etc…

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post #3 of 23 (permalink) Old 01-30-2004, 09:42 PM
 
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!.) Pull the chip... how does it run now?
2.)change the plugs.... better?
3.) replace plug wires... any improvement?
At 40 k the maf probably is still ok, but they can give up at any time and drive you nuts.... you may have a non stock maf, which is out of calibration for the chip, and some of your probs may be due to a vacuum leak, or leak on your induction plumbing, tho' that may be a stretch... good luck...
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post #4 of 23 (permalink) Old 01-31-2004, 12:50 PM Thread Starter
 
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The charging system is up to snuff, the battery is only about 6 months old and tests out just fine.

I can't pull the chip and see if it runs any better, the MAF is an 80MM and the chip was burned specifically for the MAF change.

Sparks plugs only have about 15k on them probably, same with the plug wires.

To cut down on the detonation, I should go with colder plugs right? I'll try plugs first and maybe temporarily move plug wires from my other bird to see if that helps.

Any other suggestions?
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post #5 of 23 (permalink) Old 01-31-2004, 12:58 PM
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i asked the same question on my post a few weeks ago, some people told me it could be a TC problem, or a bad throttle position sensor...my car does exactly the same thing as your car does, and as a matter of fact you have the perfect dercription of when the problem accours....my plan for now is to get a volt tester and check my TPS and then maybe change my tranny fluid to merc V...then pregap my spark plugs since they werent gapped to the specs i wanted when i threw them in...thats just what i got out of it...but im still in quest of finding the problem if its not these problems i described...

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post #6 of 23 (permalink) Old 01-31-2004, 03:36 PM
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The bucking thing, it's probably not the engine, it is more likely the torque converter clutch going bad. Add a trans cooler and refill the trans with Mercon V and that should cure it for a little while. When it comes back nothing except a new TC will cure it.
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post #7 of 23 (permalink) Old 01-31-2004, 03:46 PM
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I think your two problems are not related. I concur with the Mercon V posters. Do a complete flush. Let the TC drain ovenight and blow the lines clean. I still can not get over the difference it made. It was like getting a new transmission.
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post #8 of 23 (permalink) Old 02-01-2004, 12:25 AM
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so u guys recomend tranny flushes...i heard they arent the best thing to do for older cars...mine just hit 100k so i dont know what to do

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post #9 of 23 (permalink) Old 02-01-2004, 11:19 AM Thread Starter
 
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I somewhat doubting my pinging and bucking issues are related... however, I struggle with the TC theory for only one reason. If I push into pedal MORE when it starts bucking, attempting to draw a downshift, it will start backfiring into the exhaust.

If I tap the brake to release the TC clutch, it helps immensly since it starts multiplying torque, taking some load off the engine. What irritates me is that the damn thing will shift to overdrive at like 40 MPH. I think I'll see what Dennis can do about that when I get the chip redone. I'm thinking I don't want it to ever get into OD before 50-53 MPH, and downshifts should come around 45 MPH.

Throttle position sensor sounds like an easy step for troubleshooting since it's easy enough to test. I'll also get a tranny flush and Mercon V fill, it's due for one anyway.
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post #10 of 23 (permalink) Old 02-01-2004, 11:23 AM Thread Starter
 
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Quote:
Originally posted by smokymance
so u guys recomend tranny flushes...i heard they arent the best thing to do for older cars...mine just hit 100k so i dont know what to do
You heard right that a tranny flush might do harm to a high-mileage tranny. But I think that theory stems from the fact that a lot of people don't bother to have a tranny flush done until issues start to occur. At this point, they think that they can make up for their neglect and maybe dodge a bullet. The truth is, if they flush it at that point, it will usually fail within a short amount of time. Once you take all the friction-material laden old fluid out of the system, any issues with clutches/bands will worsen due to the fact that the new fluid starts cleaning things up and when there's not much friction material left, you end up expediting the inevitable.

If it's on a '97 with 100,000 with no current tranny issues, and you've done Mercon V flushes before at normal intervals, I'd say you'd be ok. If the tranny fluid has never been changed in that 100,000 miles, I'd be worried.
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post #11 of 23 (permalink) Old 02-01-2004, 03:52 PM
 
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1.)A tranny "flush" as sold by numerous dealers is not a good idea under any circumstance as the medium is more oil cycling in your transmission in the reverse direction...useing the same oil over, and over, and...... the only thing it helps is the dealers pocket book....Ford engineers designed the 4r70W in our beloved Birds with a rubberplug on the bell houseing, and a plug on the torque converter so a "complete atf change " is possible , and unique in that most cars will only allow about 6 qts. of the 13 or 14 qts to be drained and replaced, as the pan only can be drained on them.. of importance also is that about 15 years ago,or so,the ban on whaleing reduced the supply of whale oil which was used principally in atf, so manufacturers had to switch to rendered hog fat for an oil source, and not surprisingly it doesnt hold up like the old stuff that gave 100,000mi drain intervals . the new stuff has shorter service intervals. probably even the new Mercron V, which is a whole lot better than anything else available except pure synthetic such as mobil 1 atf
2.back to the shudder/ missing prob.....A stretch, but a possibility is the crankshaft position sensor may be failing intermittently causeing the symptoms that are being experienced.... altho its more probable that its a sparkplug failing tho they are still pretty new ....good luck
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post #12 of 23 (permalink) Old 02-01-2004, 05:02 PM
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wow, i dont really know what to do with my tranny. so far i have changed the fluid at 85k then at like 90k or so, and now i want to change to merc v....i have no idea what to do, but as i would image the best thing to do is drain everything, including the TC and just throw merc v tranny fluid in there, and NOT FLUSH it...


as far as the cranshaft position sensor goes, where would it be located, and is it an expesnive part...? thanks so far for all the help and good luck to you Silkwood, seems like we got the same problem, and i hope to fix it soon...

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post #13 of 23 (permalink) Old 02-01-2004, 06:15 PM
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If you are having issues with bucking and backfiring have you started with the simple things like check the plugs and how old are the wires?

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post #14 of 23 (permalink) Old 02-01-2004, 06:28 PM
 
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One other thought: at about 100k, the stock accumulator springs have a tendency to go , and the accumulator pistons are trash.... the new retrofit pistons and GT springs, are much better, and worth looking into as a cause of bucking and acting up. Only thing is you need to take some things apart, and at that point , you might as well upgrade both the 1-2 and 2-3 springs and pistons.... check it out....
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post #15 of 23 (permalink) Old 02-01-2004, 10:20 PM
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how hard would that be...sounds pretty hard to me, i dont have the slightest clue about trannys

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post #16 of 23 (permalink) Old 02-01-2004, 10:34 PM
 
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I havent the foggiest idea what kind of probs were involved, but they charged me about $250 at the dealer, I got back the old partz , and they were lunched.this about two years ago on one bird, did the other a year later as I was pleased with the upgrade and both times was needed.....just over 100k....
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post #17 of 23 (permalink) Old 02-02-2004, 09:41 AM
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does anyone still think this might be a crankshaft position sensor problem?

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post #18 of 23 (permalink) Old 02-02-2004, 01:47 PM
 
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hey there's not much more to check.... the crank position sensor is down under the a/c compressor, and requires compressor removal to get out, not too bad, but kinda a pita.... once you identify it, first check to be sure its connected solidly, as the clip on the harness isnt too good sometimes and might be only making partial contact
Good luck.....
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post #19 of 23 (permalink) Old 02-02-2004, 03:52 PM Thread Starter
 
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Quote:
Originally posted by timb
If you are having issues with bucking and backfiring have you started with the simple things like check the plugs and how old are the wires?
The plugs and wires were replaced with two-step colder plugs and MSD 8mm wires, probably not more than 15k ago.

I wonder if those colder plugs are causing an issue while we're in this cold whether? I know those MSD wires can be a POS sometimes, I'm going to get a Ford set. Is there something better than OEM I can get from Ford?
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post #20 of 23 (permalink) Old 02-02-2004, 04:43 PM
 
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If they're copper plugs with 15,000 miles on them you might want to replace them anyway. My '96 had a similar misfire problem a few weeks ago that turned out to be a combination of coolant in two of the spark plug "holes" plus a bad plug. Since it was coolant it didn't want to boil/evaporate out like straight water probably would have. When I pulled the plugs (AWSF-12C with under 10,000 miles on them) I found I could hold the base of one plug and spin the insulator freely. Once all of the coolant was dried out and the plugs replaced the misfire cleared right up.

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post #21 of 23 (permalink) Old 02-02-2004, 07:29 PM
 
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Thr FRPP racing plug wires are the best I have seen,they are 10mm , I believe, and wont fit the tiny little wire holders on a bird, but they are good, and actually cheaper than buying plugwires from a dealer..... dont leave home without'em
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post #22 of 23 (permalink) Old 02-02-2004, 07:37 PM
 
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Another thing; pulling your plugs is a good diagnostic trick, and may reveal a problem in just one cyl...No sense in putting old plugs back in, just gap some new ones and replace them (BTW check gaps on removed plugs allways... anything over
.o60 is a ticket to problems...)it is often the little things that we just know cant be the cause of problems that turn arund and bite you inna .... anyhow, any variance in color , or wear, is a tipoff to further investigate....
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post #23 of 23 (permalink) Old 02-02-2004, 08:18 PM
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Quote:
Originally posted by Leland Jacobson
One other thought: at about 100k, the stock accumulator springs have a tendency to go , and the accumulator pistons are trash.... the new retrofit pistons and GT springs, are much better, and worth looking into as a cause of bucking and acting up. Only thing is you need to take some things apart, and at that point , you might as well upgrade both the 1-2 and 2-3 springs and pistons.... check it out....
The springs and pistons may be trash, but those are only going to affect the shifts, not cause the bucking at tip-in as described. After being sure your plugs and wires are good - the MAF I would guess is the culprit. It could also be the converter clutch, or a bad connection with the chip and EEC.

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post #24 of 23 (permalink) Old 02-24-2004, 11:07 PM Thread Starter
 
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The issue I started this thread about has been solved. It was the wires, and I can say that MSD spark plug wires don't have a good track record for longevity. These MDS plug wires are probably 15k-20k old. I expect more out of them. My OEM's lasted 90k on my 94 and the MSD's I put on that car are 30k or more old. I know I've read a lot of others hating their equipment too.

After I replaced the wires with FRPP wires and verified it ran correctly, I replaced the plugs since I was already under there. I still have pinging issues on warm days but I'm certain it's due to an aggresive timing schedule in the aftermarket chip.
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