01 SSEi Cough under throttle, FIXED! FINALLY!!!

[SSEiMan01]

My Bonneville has been doing something quite strange the past week or so. Under slight boost and more recently under WOT, there will be a quick little, cough is the best word. usually once maybe twice or more sometimes... Kinda seems like a misfire, but it has not thrown any codes. Along with a slight hesitation in rpm's, there is an audible ticking noise that happens at the same time as the "cough" I was at Lucas' (Wake) house last week and he saw this firsthand, so feel free to chime in Lucas... I have pretty much eliminated everything ignition related, as it has either been replaced or would likely throw a SES code. In terms of fuel, the pump is audibly good, though I only have a gauge I could use at idle. I replaced what Wake and I came up with as a likely culprit, the fuel pressure regulator, and still, no change. This problem is very intermittent, meaning that if you accelerated at about 3k rpm and held it there til the speed limit, it may cough at one but not the next light...
I am going to pull a few plugs tomorrow after the drags and see what they look like, they're NGK TR55's and they've been in there since 46k miles.
I am pretty much at a loss here, I don't have a camera that will take audio along with a video, otherwise I would post a vid. Hopefully Wake can add some things to clarify.
Thanks for your help

[wake]

this "cough" still has me scratching my head..ive never seen an L67 on a pretty much stock set up much less a stock pulley have this issue..and its such a weird feeling..it happens more on a gradual pull (think if you were on a dyno performing a torque curve) than it does zero to full boost

whats even more weird is like will said, it wont always do it..and its not like its falling on its face it just has a real quick choke and then its right back into its power curve,..the motor idles fine and is producing its true power..its just every now and then it coughs and theres no signs of whats causing it

we even took it out to the middle of nowhere and found that it will still cough up past 80..most of the the time the issue is right around 3100-3700 rpm not before or after

this whole issue has me dumbfounded

and the most messed up thing is that his L67 is smooth as can be, flowing fine and whining perfectly

EDIT: theres no noticeable twitch in the boost or RPM gauge when this happens

[Archon]

Check for vacuum leaks, and leaking LIM gasket? Does the 2001 still have the 2 speed fuel pump? Check in the trunk by the rear wheel well for the control module.

[Mechanical Mike]

The MAF sensor is another suspect.

[00Beast]

Replace the TR55's with Autolite 605's or 104's. From what I can tell, TR55's are either stock heat range or one range hotter, and my car didn't like them at all. It loves the current 104's. Just a suggestion from experience.

[wake]

i dont like to do this that often otherwise he gets used to it..but

[SSEiMan01]

LIM is not leaking as far as I know... I check it often enough...lol
I don't know if this car has the 2 stage FP, I took a quick look while at Wake's today and didn't see anything, but will look again tomorrow. Is it on the pass. side?
As far as vacuum leaks, it doesn't act like there are any, although I haven't officially checked.
I plan to change the plugs tomorrow, and I'll report back with what I find, If need be I'll pull the MAF and take a lookie at it, and see if its dirty or anything, and I'm sure there is a way to test it on here, I just have to find it...
It does make sense to me that it would be the plugs though, and after They've been on for a while, I think I should have just done AL's in the first place Live and learn...
LMAO @ Wake...
Thanks for all the help

[wake]

just pull off your FWI and put an eyeball up to the screen of the maf, youll know if its clean or not..

the MAF has a honeycomb screen on it just like the inside of a cat

[01bonneSC]

LIM is not leaking as far as I know... I check it often enough...lol
I don't know if this car has the 2 stage FP, I took a quick look while at Wake's today and didn't see anything, but will look again tomorrow. Is it on the pass. side?
As far as vacuum leaks, it doesn't act like there are any, although I haven't officially checked.
I plan to change the plugs tomorrow, and I'll report back with what I find, If need be I'll pull the MAF and take a lookie at it, and see if its dirty or anything, and I'm sure there is a way to test it on here, I just have to find it...
It does make sense to me that it would be the plugs though, and after They've been on for a while, I think I should have just done AL's in the first place Live and learn...
LMAO @ Wake...
Thanks for all the help

The fuel pump is in the fuel tank.

Also do you KNOW if the LIM gaskets have been changed to the aluminum ones?

[swampthing]

this sounds like my retarded issues, I also am running the ngk's let us know if it acts better when you replace them

[wake]

The fuel pump is in the fuel tank.

Will was referring to this post when he asked that question FYI

Does the 2001 still have the 2 speed fuel pump? Check in the trunk by the rear wheel well for the control module.

[SSEiMan01]

AFAIK, the LIM is untouched but who knows I havent ever really looked hard at it.
Gunnna change out the plugs, see what happens.
Does anybody have a part # from advance auto parts for AL 104's? Or a link from their website, or any others in south Chicago for that matter... I prefer advance. Also Napa lists two 104s but not as replacement for my car, one gaps at .045 and the other at .055

[bc21]

I "was" having a similar issue with my 2000 ssei untill recent when some kid tried to make a turn infront of me. Needless to say his ford focus was toast and my ssei is now out of commission for good.

Just taking a stab at it...I was leaning toward a bad TPS [Throttle Position Sensor] mine always occurred at 2500 rpm always. I had a similar problem on a customer's chrysler 300 where there was a bad spot on the sensor and as soon as it would cross over that bad spot on the sensor, the signal to the fuel pump would cut out and it would feel as if the engine was chocking for just a split second. You could hook up a scan tool and slowly press the gas pedal and watch the voltage steadily climb and at any point it drops to zero voltage you may of just found your problem.

Hope this helps.

[SSEiMan01]

That makes a lot of sense to me... Thanks for bringing that up, TPS wouldn't necessarily set a code right?

[SSEiMan01]

Well, In my case the TPS didn't change anything at all...
Next up is trying to find a parts store that carries the correct AL 104's
EDIT: Are these the correct ones? https://napaonline.com/Catalog/CatalogI ... 08387&An=0
EDIT 2: Just got back from the parts store, Got the APP-104s. Platinum. Gunna put them on after lunch, waiting for the (ungodly hot) motor to cool

[01bonneSC]

Id go with 605s. One range colder than stock plugs, which are 606s.

[SSEiMan01]

They tried to sell me the 606's and I told them either 605's or 104's and told them why, they didn't have the 6-5's so I went with the 104's...

[wake]

when installing said plugs..remember just how hot your motor gets especially that *dang* titanium oil cap

[SSEiMan01]

That's why;

EDIT 2: Just got back from the parts store, Got the APP-104s. Platinum. Gunna put them on after lunch, waiting for the (ungodly hot) motor to cool

[wake]

missed that post