Hesitation at WOT

Cougarfetish

Registered User
Hello all,

I'm still working on getting that mechanic of mine to properly adjust my Throttle Valve Cable, but I've got another problem I wanted to get your opinions on. My car is a 1990 Cougar 3.8L SC.

Out on the freeway last week, I decided to see what my new cat had for power. When I got on the pedal, I was getting a very sporadic bursts of speed. Boost meter wasn't going up and down, it just couldn't put out the power. It felt like a engine hesitation, and it felt BAD!

Car drives normal around town, and if I give it a bit, it drives fine. Only when I'm at Wide Open Throttle, or going up a hill with the gas slammed does it hesitate.

Could this possibly have anything to do with that TV Cable that needs adjusting? Or could someone suggest something else to try.

Thanks very much in advance!

Derek
 
Same here, its like a bucking?? i would definetly change those out, even if thats not the problem im sure it needed them soon!
 
Cougarfetish> Only when I'm at Wide Open Throttle, or going up a hill with the gas slammed does it hesitate.

I'd be tempted to suspect fuel supply. Perhaps it simply needs a fresh filter...maybe a new pump. Can you verify fuel pressures?

Have you checked for codes? See if any indication of a marginal coil pack.

Might even be clogged air filter, leaking injectors or plugged cats... Do the basics and get to know the car a bit better before going too far.
 
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Cougarfetish> Only when I'm at Wide Open Throttle, or going up a hill with the gas slammed does it hesitate.

I'd be tempted to suspect fuel supply. Perhaps it simply needs a fresh filter...maybe a new pump. Can you verify fuel pressures?

Have you checked for codes? See if any indication of a marginal coil pack.

Might even be clogged air filter, leaking injectors or plugged cats... Do the basics and get to know the car a bit better before going too far.

but the plugs and wires will run fine unless excessive boost ie wot or heavy loads going up hill, fuel filter is easy and also is verifying fuel pressure so you could also check those but im still sticking with plugs/wires
 
I had the same problem and spent about $300 on everything trying to measure were the Hesitation is coming from, the new wires that I put in had a little burn mark from lying on the manifold. It ran great unless at WOT then I could feel the Hesitation badly. I would start with the codes, plugs and wires.

Jerry
 
id start with the plugs and wires - if it's bucking, thats not a good thing, unless your ready to put HG's on
(borg wanrner -ch8651 8mm supermags) ,with a fresh set plugs, gap plugs at 45
 
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update

Update:

Was changing the starter last night (Found a Bosch brand new starter at a junkyard for $20!). Figured I may as well change the plugs.

It was a bit of a PITA, but we got it done. I didn't have enough money for wires at the moment, but I will get those done pronto. Accidently broke a spark plug wire while replacing plugs, boot ripped apart. I'll be going to the junkyard to steal a plug today after work, just to see how it's working.

If my hesitation is gone, great! But if not I'll be doing the plugs pronto. Fuel filter I just did last week, so that's not it. I'll keep you all posted, as I really appreciate the wealth of knowledge I've always found here.

Thanks again!
 
dielectric grease

When installing your new spark plug wires make sure to put dielectric grease on the inside of the boots on both ends of your new wires. This helped the bucking on my 94sc at WOT, keeps the plugs dry when it rains and will help if you need to pull the wires off the spark plugs again.

JT
 
maybe when taking off or replacing the wires, all-ways try to twist them back and forth on the plug, before pulling them off, don't just pull them off

as for getting plugs or wires from the bone yard - that could be a big hit and miss deal - i would'nt - but to each his/her own, do it right the first time round
 
Update

Went to the junkyard today, and found a set of wires that appeared to be recently installed, still looked new, so I took the whole set.

Replaced the one wire we broke, car still wasn't right. It now started to buck and shudder even at low speeds and not much on the throttle. Decided to put on the wires which we could get at easily (as it was getting dark) because the wires in my cougar were pretty old looking when I pulled them off. Even with 3 of 6 wires replaced, car still acted the same.

We're going to do the last 3 wires tomorrow because they look like they should work... Should. Hopefully these last 3 wires do it, and if not, I'll probably spring for a new set. I have a question if I gapped my plugs properly.

I gapped my plugs according to the haynes manual I have which said to gap them at .054

I really hope that is the right gapping? But I'm going to do a search through the forums right now.

**EDIT** Just searched, and since I'm quite sure there have been no mods done to the car (Just got it) I believe I'm ok at .054
The gapper I had only had a .050 marking and a .060 marking, so I did my best to get it in the middle of those. If it is out by a thousandth of an inch or two... that wouldn't cause it to buck should it?

Stomping on the gas I usually get around 10 psi on the guage.
***
Thanks for all the help,

I'll post tomorrow
-Derek
 
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get a good set of wires and plugs -gap the plugs at .045

if the car is missing and or when going for a ride it bucks, your asking for trouble, if you keep pushing it, better fix it right or it just might cost ya more than you think

there have been other post of recent, that have talked about this

check this http://www.sccoa.com/forums/showthread.php?t=101436
 
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update

Ok here's the update:

Connected all of the "new" wires I got from the junkyard, still the same bad problem. Took out each of the plugs to inspect for cracks etc. the #5 plug's porcelain was broken. Finished checking and torqued up all the working spark plugs. While torquing the #4 plug, I heard a bit of a crack, more of a "ting" and stopped tightening it right away. Feeling the plug, it didn't feel wobbly, nor could I feel any cracks on it.

Went and bought a new plug for #5, and installed it. Car ran better, so we took it up the hill. Seemed to be running good, but still had a few shudders... I chalked it up to my TV cable still not being properly adjusted. Brought it back home and came in for a bit.

Went out for another drive, and car was missing badly in the driveway, figured we would try to pull out and see what happens. Going down the street, car misses HARD and guages start going haywire! RPM's going up and down like crazy, even though power to the engine was gone. I figured that #4 spark plug grounded out somewhere and caused the guage malfunction.

Car wouldn't start at all now... looking under hood, found that one of the plugs to the DIS was slightly unplugged. Plugged it back in and it fired up! Babied it on the way home and parked it just cause I was scared.

Worked up the nerve to take it for another drive around the block. Kept the car in 1st so that we could eliminate any chugging that the tranny could be contributing too. Car was driving pretty good! But we did feel a misfire here and there, so there's definitely some kind of spark problem.

While the car was in Drive, it drove really terribly, so I believe I still have quite an issue with the TV cable. It's getting hard to distinguish.

I guess the next step is to replace the #4 plug, if that doesn't work, then buy a new set of plugs. If that doesn't work then I'm totally clueless?? Bad coil pack all of a sudden?? I'll keep you posted, but would appreciate any potential other things that could be wrong.

Thanks again in advance!
-Derek
 
Regarding plugs and wires on the SC. Forget about torque values, the only way to torque the plugs on this car is when the engine is on a stand. Your best bet is to get a stubby ratchet and find a way to tighten each plug without using any u-joint sockets.
I've traced down a misfire one plug at a time before and the bad one was brand new with no visible cracks or deformities.
Start the car in Complete darkness, pop the hood, and goose the throttle at the throttle body while looking for arcs anywhere. For whatever reason, these cars seem to eat wires in my experience.

Good luck man,
MB
 
i just recently had a sumbling problem at WOT... it was my coil pack.. i swapped it out with another coil pack i had and the bucking was gone. No more WOT miss.

just a thought.
 
until you get a new set of wires and plugs for the car, you could be chasing ghost for a while, do it right.

as martinbob said - forget about torque-ing the plugs, theres just not enough room for doing that.

make sure you don't mix-up the firing order when changing the wires out - it's not hard to do
 
I've got a firing order diagram, it's not missing bad enough to be hooked up wrong.

what do you mean forget about torqu'ing the plugs? Am I to just leave them loose? I don't get it. I tightened them by feel, didn't have a torque wrench at the time.

Like I say, I'll replace the plugs in question, then try the starting in the dark method to see any arc'ing..

Thanks again all! Going camping to get away this weekend, so any more work on the car is going to have to wait till after the weekend.

Thanks
-Derek
 
Depending on the age of your wires and the used set you got, you still could be in the same boat.

When plug wires get hot and older, they are all prone to breaking. They could have worked perfectly on both cars until you moved/bent/straitened them. That is when a lot of what used to be working wires go bad.

Put in a new fuel filter. This is part of basic maintenance that needs to be done to any car.

The more you drive the car with a poorly adjusted TV cable, the more damage you could be doing to the transmission. Don't drive it until you know it is adjusted properly.
 
i did'nt say not to tighten them up, don't get carried away, i just dont see or use a torque wrench for doing plugs -let alone that there is not much room in there

as for going to a pick-a-part for plugs and or wires, i don't know that - that is such a good idea.

save up some bucks and buy these items new - your time is worth money as well - how many trips to pick-a-part will you have to make before you might get close

cheers :)
 
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