96 T-bird 4.6L -- rough idle with new intake manifold

I failed to mention the stumbling is slight when the engine is COLD, but gets severe when it reaches operating temp.

Check for water/coolant in the spark plug holes.

Even better , pull all plugs out , check for carbon tracks on plugs AND wires/coils.

Or just put new plugs in, they don't cost a fortune, make sure the cables/coils are ok or you will end up with same problem

I've done a bunch of intakes and 70% of the time it had coolant in the holes and just a trace of coolant can cause a misfire

Thanks guys.

I yanked the plug wires after reading your posts but the holes/plugs were dry. Just to be sure of good contact, I sprayed the boots and plug connectors with zero-residue contact cleaner and let the holes evaporate dry before plugging the wires back on. The wires and coils are clean. The plug wire connectors at the coils are clean -- well, the factory silicone grease is still there. I could swap plugs, it's cheap as you say, but if fouled plugs were the prob, I don't think they would have coincidentally caused trouble immediately after the dealer repair, as they had no reason to yank plugs or otherwise expose the tips. I've read these engines are particularly sensitive to variations in wire resistance. I suppose it's possible the dealer tech(s) may have damaged a wire or three by leaning on them, dropping the old and/or new manifold on them, etc. I did move the wires and boots around a tad with the engine running and noticed no change. I'll check the wire resistance.

Been reading more on the subject and some owners have found that a dirty IAC caused their rough idle. I peeked at the innards through the front hole. It looked pretty clean, but I could yank it for a spray cleaning anyway. I suppose the dealer tech(s) may have knocked some deposits loose inside the IAC during the course of removing/remounting the throttle body. Other than that, any more ideas as to cause?

Thanks, Guy

I fear I am excluded in the covered vehicle class:

Not a clue whether your problem is due to defective ignition wires or not, but be advised that measuring their resistance is not likely to tell you much. Unless you find something radically different than about 10Kohm/foot, variations in resistance are not the problem. The typical failure is not the bit of extra voltage drop across the wire, but a microscopic defect in the insulation, causing arcing where it should not be and robbing the plug of power. Some people advise to watch for arcing in the dark, but I never had much luck with this method (not to mention the danger of messing around rotating parts in the dark!!!) So basically you have a choice: pay to have the ignition professionally tested ('scoped'), or take the plunge and replace the wires. I would do the latter -- if your wires are the original

resistance. I suppose it's possible the dealer tech(s) may have damaged a

them, etc. I did move the wires and boots around a tad with the

Maybe I missed it but, I don't see where you may have checked or cleaned the IAC. With the mileage you have and the loss of coolant into the system, it is possible (probable) that it needs a good soaking and cleaning. This is also true since you mention the RPM dropping with the air on which would indicate the IAC is not working properly. It should be able to maintain a steadt idle RPM even it it is a bit rough or stumbling on acceleration. A dirty/bad IAC would explain the inconsistent idle, the roughness and the stumble. Also, just looking at the MAF will not confirm that it is clean. You need to use a residue free solvent to clean it to make sure there is no oil film present.

Many auto parts stores will scan your ECM for fault codes. In my area, Autozone does this. You should write down the exact code and description from the scanner to post back here. In the worst case, you may need to pay the dealer or someone else a diagnostic fee to get the codes. A decent shop will apply the diagnostic charge toward the repair if you decide to have them complete the job.

There is a lot of knowledge here once you learn how to cull the BS. They may be able to help you avoid the shotgun system of auto repair. The shotgun is always loaded with dollar bills from your wallet.

BTW, it sounds like you either have a bad relationship with your dealer or they are incompetent - maybe both. You need to find another source of service for your car. There are quite a few competent independants out there. Check with your friends and co-workers for references.

Good luck Lugnut

After all that you've done already you don't wanna take the plugs out.........

Its your car

Good luck

...

Not with the naked eye, no. But an 8x magnifier provides a really good look at the individual turns of wire. That helps ensure every last speck is gone. I had cleaned the MAF a year ago. Black cake on the elements was so stuck the spray cleaner (as an electronics tech, I have a decent variety of quality stuff) wasn't enough; had to rake cotton swabs over it. That got rid of the CEL situation when a pro "Ford specialist" shop in town couldn't kill the CEL after replacing the EGR (twice), the fuel pump, the DPFE and all O2 sensors. They weren't even trying to rip me off, they were blatantly incompetent. If they had tried to scam me, they would have done all that work and THEN.. FINALLY.. EVENTUALLY fixed the prob. Instead, despite their "specialist" status and loads of costly test gear, they threw their hands in the air (and I do mean literally the owner did that), gave up and sent me away with my CEL light as a reminder of what idiots they are. Not bad enough? I discovered later they had left one side of a frame bar unbolted and hanging down at a 30-someodd angle towards the pavement facing forward! That move could have proven fatal: I had bolted it back on not long before I ran full on over someone else's road-killed deer at night. Had that bar been left down to snag the deer, I would no doubt have been thrown into the deep ditch or worse. So much for yet another pro shop that's been in biz for decades.

Both. But they set the terms for the relationship. Dealers have a bad attitude across the board, at least in these parts -- Nissan has treated me no better in the past, for example. They all behave as if they are doing you a favor just for putting up with your presence after the sale. The parts guys clearly hate their jobs. The mechanics can't or won't do theirs correctly. It's a generally "up yours" arrogance after the sale. Helluva way to garner future biz for their oh-so-cheerful sales personnel.

Thanks, Guy

Thanks for the input gang, but the prob was "none of the above". I'll give ya the scoop in case you'd like to add it to an obscure tip database somewhere. :)

Due to circumstances beyond my control -- i.e., hurricane Rita aiming straight for me -- I have to concentrate on prepping the house and myself for the storm. I don't have time to continue my easter egg hunt for the prob, so I turned it over to a nearby shop. Their ad says the techs are ASE-cert. and he's been in biz for 25+ years. That didn't seem to matter with other shops I've dealt with in terms of getting quality service but who knows, it's pot luck. Amazingly, the owner did the work himself -- usually, know-nothing grunts who should be flippin' burgers instead get the job, at least in my multi-decade experience with dozens of different shops who couldn't handle repairs. I can only cross my fingers this guy did the job to last. Maybe I'll have time for a cursory inspection before I split.

At any rate, as it turns out, the morons at the dealership jammed up the #5 injector lower seal and it was blocking the spray! This is the kind of stupid mistake one has to almost TRY to make. The _better_half of the seal was returned to me and it's a horribly squashed and chewed mess. sheesh.. So, one cheap injector seal and $140 later, the stumbling is gone.

The shop owner says since it was definitely the dealer's fault, I might recoup at least some of my repair bill from them. Hah! Right...

Thanks, Guy

Well Guy, You better take the bill and part of the seal down to the dealer and demand reimbursement anyway. You stand a pretty good chance of getting it. Only speak with the service manager, no body else can make this decision.

If they don't fork over the money make your call to the Ford Motor Company drone and file a complaint, you won't get any satisfaction from Ford, but the dealers HATE the negative calls.

Glad you got it fixed.

Good luck with the hurricane. Hope your preparations are not needed, and the beast ends up heading into some harmless void.

If you still have a moment to educate us, it would be interesting to know how he diagnosed that blocked injector. Was there a code stored for misfire? Was it for that specific cylinder? Or did he run a cylinder balance test?

----- Original Message -----

straight for me -- I have to concentrate on > prepping the house and myself for the storm.

Allright Guy, I hate to say this but I had EXACTLY the same problem on a 96 this spring and I got my help here. The problem was what shoe salesman said. Moisture in the plug wells. NOTHING MORE! It's hard to get them dry. They may look dry and not be. Your last mechanic MAY be a sheister as well. May have dried them out and sold you the injector part for the heck of it. As far as the recall, unless you have proof that you asked about it within the 7 years....forget it. BTW, I fixed my manifold myself for about $300. Wasn't that hard to do.

It's a good thing that manifold got replaced when it did and the subsequent misfire was cured when it was, because that poor car had to endure a 30-hour drive (I use the term loosely, as most of the time it was parked on the highway) for a mere 150-mile trip! I'd hate to have had the manifold blow in that massive traffic jam, likely forcing me to ride out the storm in the car. TX DOT is a joke and so are the local (Houston) meteorologists who spewed more hype than fact. They finally were blessed with a major storm to harp on after years of.. ahem.. dry spells. The constant barrage of alarming forecasts, all the prepping and careful packing -- I expected the house to be in ruins with all the weather gurus mouthing off about imminent 24-foot storm surges blah blah -- and the non-stop, 30-hour drive... for a grand total sleep deprivation of about 54 hours. I barely knew my own name when I finally arrived at my destination. And all that only to learn later that my destination was slammed with higher winds, more rain and more damage than I would have faced had I stayed put!! I was definitely not a happy traveler. Ok, enough venting...

I'm not the person who retrieved the car from the shop; fortunately, the shop owner spelled out what he did on the receipt:

"found cylinder #5 misfire at idle... performed balance test; all injectors are equal... unable to find vacuum leak... tested coil, plug wires and spark plugs... removed fuel injectors and found the rubber seal to #5 injector in injector port"

If he's an observant fellow, he probably suspected it initially from a visual inspection, though. I had earlier spotted a small bit of red rubbery substance poking out from the base of the injector. I chose not to pluck it out, as I wanted to avoid creating a problem -- I assumed it was just some kind of special factory cement or gasket maker material that the dealer techs had sloppily applied. I now know exactly what it was.

He doesn't list a specific code number (if any) obtained from the EEC. I could ask him, but I'm sure enough time has elapsed that he would have forgotten the number. OTOH, he may have it in his own records even though it's not on my receipt. If you guys are interested, I'll call him on that when I get a chance.

Thanks, Guy

I'm convinced he's legit and here's why: I had earlier spotted a small bit of red rubbery substance poking out from the base of the injector. I chose not to pluck it out, as I wanted to avoid creating a problem -- I assumed it was just some kind of special factory cement or gasket maker material that the dealer techs had sloppily applied. I now know exactly what it was.

I have proof I took the car back to the dealer in 1996 as soon as I received the recall notice. It also proves the dealer elected not to replace it at that time, which would have spared me this ordeal and saved Ford a customer -- until this manifold mess, I was perfectly content with my T-bird and with Ford as well. According to the dealer now, such proof is irrelevant; Ford WILL deny reimbursement due to the manifold failing after the 7-year mark. That remains to be seen. I still intend to pursue the matter. At the very least, I'll give Ford hell over it.

Yeah, it's a pretty simple job, which makes me even angrier that the dealer techs couldn't do it right. At the time I was under the mistaken impression that Ford would reimburse me, in toto, if their dealer performed the repair on this recalled part.

I always prefer to do my own repairs when I can, but hey, if it's a choice between $200 + S&H (cheapest price on this manifold I could find online) or $0.00 for a Ford dealer job, well... I won't ever make that kind of mistake about any car manufacturer again. I will just assume they are all intent on hanging their customers out to dry after the sale, regardless. In researching this Ford fiasco, I read quite a few horror stories about a great many vehicles. It seems the mindset of manufacturers and their dealers is only getting worse over time. I used mindset, singular, because they all seem to have the same one! bah

Btw, my insurance company is supposed to reimburse me for the towing expense, so yes, that $0.00 estimate above included towing. :)

Thanks, Guy

I'll definitely give the dealer negative marks to whomever will (or even won't) listen. I'll also revisit the dealer and try to score a refund. Will let ya know how successful it was.

Thanks, Guy