SATAN STRIKES AGAIN! Surging/Power Loss, Part II

[Darkwriter77]

The tranny leaks, the rear end squeaks, and the motor likes to wheeze ... sounds like the beginning of a country song. Sorry, but the lengthy post is necessary to cover everything...

For those unacquainted with the saga that is my sordid love/hate affair with my 'Stang, here's the gig: no matter what engine/ambient temperature, humidity, gear, RPM, or throttle load, the motor likes to randomly drop about 30 to 50% power, surge/jerk, and pop a little out the exhaust. Comes and goes as it pleases without rhyme or reason. So far, I've thrown the following parts at it:

- EGR valve
- IAC valve
- BAP sensor
- TFI module (it actually cured the problem for a month, but when it started up again, swapping in another new one changed nothing)
- Motocraft plugs, Bosch wires, Accel cap/rotor
- Oxygen sensors
- Air filter (swapped K&N for paper Fram)
- (8) 19# Fuel injectors (newer 4-hole design, sourced from '95 T-bird)
- MSD ignition coil

I have cleaned/checked/tested/adjusted the following:

- MAF wires
- TPS
- Timing set to 12* (was sitting at almost 0* at one point!)
- Whole top end of motor (intake, throttle body, spacer, etc.) cleaned with CRC intake cleaner and Seafoam
- Fuel pressure is nice n' happy
- Every single little ground strap and wire I could find in existence on the car has been cleaned, sanded to bare metal, and coated in dielectric grease
- Alternator and battery are happy

That's the list as it stands at this moment. (I may have left a thing or two out ... just got home from work, my brain's fried.) Previously, it was throwing codes indicating a rich mixture. After resetting everything after all the above checks/cleans/replacements, I get NO CODES (except a standard pass code). I'm quite convinced it's an ignition issue, due to its intermittency and the prior running-rich codes. Only surviving suspects after this long war:

- Bad MSD coil?
- Defective plug wire(s)? (I get continuity on all eight plus the coil, but...)
- The whole friggin' distributor (namely the pickup coil)?
- SATAN HIMSELF!

Anyone care to offer up fresh guesses? Winner gets a cookie and much kissing of the feet ... and a round or two of beer, if you're local to Phoenix.

 

[Nutzy19]

just a stab but mine ended up being an o2 reading bad cause of a header leak which I barely heard

 

[DTT92LX]

Stretched timing chain? Think I remember hearing about 3.8 cougars having issues with timing chains resulting in similar symptoms.

 

[jrichker]

Does it feel like you turned off the ignition switch or is it a less dramatic event than that?

Does the power loss come and go in an instant or does in remain in low power mode for more that 5 seconds?

 

[darthcual]

Definately Satan. I'll take that beer now, Pilgrim.

 

[Darkwriter77]

Darthcual: C'mon, now. Not that easy.

It's not a complete loss of ignition. It feels more akin to a monkey sitting on the bumper and occasionally shoving a banana up each tailpipe for anywhere from one to two minutes, and then jerking them both out suddenly and thereby restoring normal power (heating up the bananas, perhaps?).

The only pattern I've noticed as of late: I leave work, and it's all wimpy and lumpy-idling 'till I get to the first stoplight (about 1/2 mile away). As I'm sitting there at the light, the car's idling almost like it has an E303 cam, and then suddenly the idle jumps up about 200 RPM higher and smooths out to a perfect purring, whereupon the power is all where it should be. Then, about a mile or so down the road, it does it again. If I keep driving 'round, it will go away sometimes for up to five miles, then come back for another one or two, and off and on again, etc. ... almost like it's some kind of a sensor cycling something. It seems almost too systematic in occurrance to be anything mechanical, as it would probably do it all of the time, if that were the case.

It was doing all of this before with the previous exhaust, as well, and hasn't changed one way or the other since I've added the UPR X-pipe (which is still rubbing the crossmember, grrrrr...) and the Dynomax cat-back (which has one tailpipe touching the bumper, grrrrr again...). No leaks anywhere, checked thoroughly for those at every connection right after installation.

Oh, forgot to add EGR position sensor (EVP) to the list of items already replaced.

Happy Halloween/Samhain, everyone! ... and happy B-day to me.

 

[darthcual]

Well the only other thing i can think of is that you have a bad ground somewhere. Its one thing that I know of that can come and go like that. Pull your kick panel and check ur computer ground wires. Or maybe your computer is a Bad Bad Boy and is causing problems. In that case clean it with TAG body wash, 'Tis how dirty boys get clean'

Edit*Happy Birthday

 

[ihranotch93]

hey dark umm def sounds like a vaccum leak maybe or 02 sensors id try lookin for a vaccum leak under the upper intake . usually have to take it off to fix it. but pop the hood and listen for ne sucking noises and if its leakin find it. and for the 02 sensors replace em neway there only like 57$ bucks a piece lol i work at oreilys and advanced ap. nemore questions shoot me an email peace

 

[ihranotch93]

hey i read like right after i left that message that it has idling issues. if this sounds like ur car its 90% vaccum related . start it and it idles high for a sec then kinda of choppy u drive off and hit it a lil bit and its not there at all and it popp everynw and then when u get down on it a lil and then when u stop it idles like 2-300 rpm until u drive off. lol embarassin huh. had the same problem on my other mystang. peace

 

[Darkwriter77]

O2's are on the list of items I've changed, already. Also, I've already replaced every inch of vacuum hose in existence in the entire engine bay (I hate ugly brown hoses ... anal retentiveness at its finest!), and I've sprayed around to check for leaks on the manifold (upper/lower halves), throttle body, and related components. Still no magic bullet.

The idle issue is directly proportionate to the incidence of Satanic possession. That is, the idle is only lumpy when the motor's going through its wimpy power loss moments - whenever the "monkey" removes the "banana from the tailpipes," so to speak, the symptoms vanish instantly and completely. The surging symptom, at this point, is only really notable at low (parking lot) speeds and sometimes during take-off acceleration. Otherwise, it's just a matter of random 50% power loss and a sometimes lumpy idle ... and my gas mileage has taken a dive again, dropping from 19mpg (city) average to 15mpg average (city).

Assuming that it is the PIP (pick-up coil), and being that I'm a lazy bum that doesn't want to mess with pressing the gear off the distributor and whatnot ... would I be better off buying, say, a brand-new aftermarket unit like an Accel Billetech, or should I just get an OEM reman'ed unit? Presumably, the Accel will have a new pickup coil with it, but the reman dist. only runs about $90 (although the PIP in there is likely the original). I can afford either, it's just a matter of justifying that extra $150 for the Accel instead of the reman. (Heard the MSD's have crap TFI modules, so no go there).

Correction on the exhaust leak - I DID actually have a bit of one on the driver's side right at the flange. I dickered around with it for two hours today, but whomever at UPR bent that pipe got things a little too far to the left; no matter what, when I get everything all tightened down, the cat is pressed TIGHT against the tranny crossmember, so I can barely get a good seal up against the header flange because the angle sucks. (I did, at least, manage to get the tailpipes lined up evenly, though.) About the only thing I can do to solve it is to beat/grind the crap out of the driver's side hump of the crossmember to give myself about 1/4" to (I hope) 1/2" of clearance so I'm not feeling the exhaust through my feet/butt all the time, and so I can swivel the driver's side downpipe over enough to make it seal up nice.

So, I can't rule out the exhaust leak as a suspect just yet. However, since I did get it to seal up a lot better today (not an audible leak, now, just a tiny bit I can feel by hand near the header flange), and there's still that annoying power loss going on, I'm still leaning towards the ignition system and/or a sensor of some sort...

 

[Euphoric306]

damn.... we thought it was over


to every great epic, there is a better sequel


not really, but good luck, and happy birthday budday

 

[darthcual]

I just noticed the battery in trunk on ur sig. Is the wire grounding out somewhere? Also, how about your inertia cut off switch? Have you checked that? Good Luck

 

[Darkwriter77]

I thought only the newer models (90+) with airbags had the inertia cutout switch...?

Battery grounds are all good. Positive cable's not grounding out anywhere, it's all nicely tucked up against the framerail and wrapped in conduit. Voltmeter shows a consistent charge ... well, except for the usual dimness at stoplights with the headlights on, but that's largely a matter of my needing to upgrade to a 3g at some point.

I have cleaned all the other grounds that I could find, but I've never been able to locate this elusive ECM ground I've heard so oft mentioned. Is it right off the ECM, itself, over there in the passenger kickpanel? Otherwise, all others under the hood and off the battery are squeaky-clean.

Updated current list of suspects:
- PIP module/whole distributor
- Exhaust header flange leak (minor one on driver's side)
- ECM ground?
- Defective plug wire(s)

Plan of attack: replace plug wires and distributor, grind about a 1/2" notch out of the crossmember to allow the driver's side downpipe and cat enough room to swivel over to seal correctly, and then clean and add a second ground to ECM. Oh, and have a beer or two while sitting back and watching the director's cut of Land of the Dead.

I can afford either one, but I gotta know for sure ... should I go ahead and order an Accel or Mallory distributor? ... or should I save $150 and take my chances with a reman'ed OEM unit? (Being that it's the PIP that I'm trying to replace, and most remans still have the original in there.) Other than looking pretty, is there any real benefit to having a new "performance" distributor to warrant that extra $150?

 

[jrichker]

The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire. The wire goes into the harness at the starter solenoid. It connects to pins 40 & 60 at the computer connector.

The secondary ground for the computer is by the computer itself. It grounds the computer case and the foil shield on the TFI wiring. This is different from the main computer power ground I just mentioned.

 

[Euphoric306]

im almost positive you can buy a reman'd dist with a new PIP, if not then a new PIP itself, just to figure out the problem id stick with the budget deal myself,

 

[Darkwriter77]

I agree, cheaper is definitely better. Trouble is, you have to disassemble the whole friggin' distributor to get the pickup coil in/out of there. Y'know, knock out the roll pin(s), have the gear pressed off of the shaft, replace the PIP, then have the gear pressed back on (or find a creative way of knocking it back on), knock in a couple new roll pins, grind 'em off flush, and so forth.

I dunno where the heck A-1 Cardone gets their reman dist cores from. The past three I've pulled off the shelf and taken a look at have friggin' RUSTED PIP's sitting in there. Given, the shaft has ZERO play in them and there's an obvious amount of magnetic drag I can feel in turning the shaft, but still ... who knows HOW many miles was on that core before it got reman'ed, and how thorough their "remanufacturing" process really is - looks like they just sandblasted it, pressed on a new gear (or cleaned up the old one), and threw it in a box. Gonna try for the exhaust leak, computer ground, and plugs wires, first, and see if maybe I can save myself that $100+ gig.

I almost had myself convinced today that maybe I just have some bum fuel injectors that periodically weren't firing, being that they ARE a used set (from a '95 T-bird), but that wouldn't jive with the fact that I was getting "system too rich" codes on both cylinder banks. UNLESS, of course, two or more of them were occasionally "sticking" and squirting too much fuel, which would cause it to bog down...?

 

[Euphoric306]

sounds pheasable (feasable?) **** that doesnt look right either way

anyway... up till now you've replaced your whole damned engine bay, and if i were you and had more than my minimum wage income, id be throwing anything i can at it to just get it to quit. maybe take a trip to the j/y and pull out an A9S or A9L(P?) computer, swap it in yours just to see if its your brain thats fudged

by the way... i wish i could change lanes by pressing the brakes, you lucky dawg

 

[Darkwriter77]

Well, my BRAIN for sure is most certainly damaged. It's probably what caused me to purchase this particular 'Stang, in the first place.

Seems to be spending more time lately in "banana in tailpipe mode" than in "banana out mode." Then again, I've been keeping the driving to a minimum in it, as of late, because it feels like such a gutless dog right now. Aiming for Monday as my next scheduled arse-whooping for the car, during which I get to tear off the crossmember, cut and grind the poopie out of it, fiddle with that driver's side downpipe, clean up the ECM ground, and throw on some Autolite wires.

Semi-related question: Since my UPR X-pipe doesn't use the usual hangers that poke into that double-loop-ended bar thingy (right above the tranny mount), and since that stupid little hanger just makes things a major PITA when dealing with the VSS/speedo cable, would there be any harm in just removing the stupid thing altogether while I'm at it? It doesn't really seem to serve as a spacer or anything, far as I can tell.

Also, can anyone verify my sneaking suspicion that grinding about 1/2" deep by 3" wide notch (mostly the front-outer lip) out of my tranny crossmember could perhaps weaken it enough to cause concern? I'm not pushing more than 250 horses (probably more like 200rwhp, if even that much), and I don't flog it at the track or anything...

 

[Euphoric306]

get that exhaust hanger out of there... that thing is the biggest PITA when trying to rehang your exhaust, getting the tranny mount to line up with it and the holes in the transmission... blah!

sorry... as for the weakening, i couldn't tell ya

 

[darthcual]

My catted h-pipe isnt hooked up and it holds just fine so I think you'll be okay. You may be right about the inertia switch but just to be certain mine is located in the truck next to the driverside tail light. Should be a little red button on top. Try holy water in the radiator. Be sure to put some in the overflow as well. Last resort, take it to a dealership and let them tell you what is wrong with it, then fix it yourself. Good luck