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Hesitation / Bucking

R

RawBurt

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I first noticed it in 5th gear under WOT. Now it has seemed to move to lower gears. Its a slight hesitation / missing. Its pretty minimal, its not like itsfalling on its face or anything. My thoughts, plugs / wires / coil... Any other thoughts?

TIA
 
id say coil, and yur leads as well, u can try yur plugs and leads, check plugs are gapped right and the tips arent broken, no cuts in the leads, check to see if they spark, hope u sort it buddy :)
 
do you have a wideband installed Rawburt? i get something similiar occasionally. it appears to go really lean just for an instant and then back to normal like nothing happened. im thinking either the injector harness or the IAC. both are original on my car and need to be replaced anyways.
 
Ironically, I am experiencing this symptom as well.

stuttering/sputtering under 60-70% throttle or more.. any speeds, really, any gear (well. except first, really.. 2nd on up, though)

I started with new plugs..
then new wires
finally measured the coil and it was "technically" out of range so I swapped it out for another one.
no change

At this point, I'm thinking maybe my TPS is going out.

Then, I lowered the boost level to 3psi (just to eliminate all factors I could) and the problem went away completely. As long as my wastegate opens up before about 6 psi or so, I don't get the problem.
Now, I am thinking I am blowing out my spark at 6psi or higher and I am going to pull the plugs, and re-gap to 35 or 37 thousandths.
 
yeah i thought that too except that my plugs are already gapped to 30 or 35 thousandths :shrug: mine has done it occasionally (like once or twice) in 1st. it about throws me into the steering wheel when it does.

Ray do you have a wideband installed? if so, try to remember to look at next time it happens and see what it says. im almost certain it (mine anyways) has to be an air/fuel problem. it either gets too much air from the IAC or the injectors cut out for some reason (lack of power maybe?)

also if it was the TPS it would do it all the time at a certain throttle percentage. IDK about yours Ray but mine is not consistent with throttle percentage.
 
I could eliminate the TPS as the problem is removed when I lower boost below (what seems to be) a 5.5-6psi threshold.

the wideband does not fluctuate too much, but keep in mind that your O2 readings could be an secondary symptom, and not a primary one. (IE.. your O2 fluctuates, but only because of an underlying cause... )

In my case, blowing out spark would CERTAINLY cause a spike in mixture.. but I can't assume its my injectors flooding automatically, just because the wideband richens up. Again, just a secondary symptom to my primary problem.
 
yeah mine will be running about 13-14:1 and then suddenly it will jerk and the air/fuel will go to like 17:1. so its definitely something that is either making it go to lean OR its going really rich for just an instant (too fast for me to notice while i drive) and then it goes lean.

thats why im leaning toward the IAC. it could make it go either way as well as the injector harness if it had a loose connection somewhere. and since both the IAC and injectors are on the same harness i think im gonna try to replace it and the IAC (both are 10yrs old and have 246K miles on them)

Edit: mine does it mostly while cruising
 
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IAC not a factor during cruise.

Look at all your ignition system wiring, including the coil grounds, engine grounds, and pcm ground. Unbolt them all and clean them for corrosion.
Look at the fuse box and on the bottom for evidence of corrosion.
 
can a fault code reader point u to what is wrong with the car? I guess it would tell u its running lean or something like that, maybe fuel filter, dying cat? Hope yall sort it buddy :)
 
warmonger said:
IAC not a factor during cruise.

Look at all your ignition system wiring, including the coil grounds, engine grounds, and pcm ground. Unbolt them all and clean them for corrosion.
Look at the fuse box and on the bottom for evidence of corrosion.
Click to expand...

The thing is it didnt start doing this till after i put the turbo on so i dont think its the ignition system. it does not feel like a miss rather like all the injectors shut down for one revolution. i will check the grounds but im thinking its my injector harness. both the IAC and injectors get their power from the same splice. if there is problem with the splice (after 246000 miles) then the injectors may shut off and i believe the IAC defaults to an open position (correct me if im wrong on that one). i need to replace the IAC anyways due some idle issues so i will replace it an the harness as well as check the grounds.

fred22 said:
can a fault code reader point u to what is wrong with the car? I guess it would tell u its running lean or something like that, maybe fuel filter, dying cat? Hope yall sort it buddy :)
Click to expand...

a code reader will only tell me what code is stored in the PCM. since i have a scan gauge installed i can look at the codes anytime i want. sadly i have none to help me out. the fuel filter is fairly new (but i may just replace it anyways, cant hurt) and i have no cat.
 
striker2 said:
do you have a wideband installed Rawburt? i get something similiar occasionally. it appears to go really lean just for an instant and then back to normal like nothing happened. im thinking either the injector harness or the IAC. both are original on my car and need to be replaced anyways.
Click to expand...

I was experiencing the same issue. After my dyno tune my cougar no longer stutters. The tuner dropped the "Time to delay open loop" down from 2 seconds down to around .125 seconds. If you have the SCT pro racer pack change this and see if it fixes it. It did in my case. :)
 
Blackcoog said:
I was experiencing the same issue. After my dyno tune my cougar no longer stutters. The tuner dropped the "Time to delay open loop" down from 2 seconds down to around .125 seconds. If you have the SCT pro racer pack change this and see if it fixes it. It did in my case. :)
Click to expand...



u know i thought of something like this, but i didnt post it because i thought i would get slated as u can say it doesnt fix the problem, it will hide it until it finds it again, so i didnt post it up here :(
 
I understand about the issue not starting till the install. With ignition systems on these cars that can happen because you are disturbing wiring whether it be the battery grounds or harness plugs. Sometimes once you move something it will change the resistance in the ignition circuit and that combined with other factors can cause stuttering due to voltage spikes on the coil pack.

Let me post this for the 100th time for people so they can begin thinking about the system in the big picture:

THe primary side of the ignition system runs from the [battery->Cable,fuse,harness->Coil-> harness-> PCM->Chassis ground] which fires the coil primaries.

The secondary side of the ignition system runs from [One Bank spark plug (front or rear I can't remember)->plug wire-> coilpack-> plugwire-> sparkplug->oppositebank cylinder head AKA ground]

When the coil fires it introduces spikes. The capacitor on the side of the coil pack must be clean and grounded well and operational to absorb those voltage spikes.

You guys might try getting a big 250 uFd capacitor and ADDING it or substituting it with the factory capacitor just as a test. Make sure its a higher voltage cap because the spikes do go much higher than twelve volts, at least a hundred sometimes even on the primary side.
Anyway, after all your grounds are cleaned up swap in a new capacitor with a larger value to see if you can clean it up.
This assumes your wires are good and plugs are gapped in a reasonable range. 0.035" is generally too tight in my opinion. .040-.045" will give good spark and easily sustain 12psi boost on our cars. The more gap the more energy in the spark so you only the minimum gap necessary to fire at the boost pressure you run. With the variations in ignition system performance between different cars that gap may fluctuate a bit but 40 thousandths is a good starting point if you are concerned.
 
Blackcoog said:
I was experiencing the same issue. After my dyno tune my cougar no longer stutters. The tuner dropped the "Time to delay open loop" down from 2 seconds down to around .125 seconds. If you have the SCT pro racer pack change this and see if it fixes it. It did in my case. :)
Click to expand...

It's certainly worth a try if a person has a sound ignition system then I don't see why not. I can't imagine the two types of stuttering to be the same though.
Maybe a slight stutter or buck when you first transition from open-closed loop but after that it should not be continual.
 
i was actually running 45 thousandths plug gap originally and then i went to 35 to see if it would help or hurt. it didnt change anything. im pretty convinced that the problem im having with my zetec is not an ignition problem but rather an air/fuel managment problem.

after i installed the turbo i left the intercooler to TB plumbing unhooked so i could drive up to chicago for a meet and to get it tuned (roughly 350miles plus an extra day at work). during that time i never had any problems. once i got to chicago i installed the last few pieces of piping and the injectors without disconnecting the battery, (probably should have just to be safe but i didnt) touching any grounds or the coil. the whole time on the dyno it ran fine and never had a problem. afterwards during my test drives it never had a problem. it only started acting up while on my drive back to Louisville.

now tonight i will go and check all my grounds to be sure. however since i need a new IAC and the harness anyways i am going to go ahead and replace them. we'll see what happens.
 
warmonger said:
It's certainly worth a try if a person has a sound ignition system then I don't see why not. I can't imagine the two types of stuttering to be the same though.
Maybe a slight stutter or buck when you first transition from open-closed loop but after that it should not be continual.
Click to expand...

The problem I had was a short lean condition every time throttle was applied in any gear causing a stutter but if you kept applying throttle it would jump back into range after a second or two. So it wasn't continual it was only on initial throttle tip in. It made sense to me in my case and the problem went away so if anyone has the ability to test it (has the prp software) you might as well give it a try.
 
Just an update on my "spark being blown out" stuttering problem.

Re-gapping the plugs to 35 thousandths solved the problem for boost levels between 6 and 14PSI. (I won't really go any higher than that), so.. my problem is solved.

EDIT: without removing anything other than the coilpack(and front cover, duh), I pulled, gapped and replaced all the plugs in 22 minutes.
yay!

What's more ego-boosting is that I did all of that without making a signle return trip to the toolbox. I just grabbed my 7mm, 10mm, and the right combo of swivel/extention(for the coilpack) that I needed and never came back inside. lol.
 
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I'll race you Ray... get your time down around 13 minutes and then you'll have a chance. :) Sounds like a great SZ 08 competition. STart training. :laugh:
 
haha.. you have to realize I did this while my daughter "helped" (held a screwdriver to the front grill screws, etc) and went in for a drink.

Rushing? sure.. 13 minutes... let's do it.

:D
 
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