fourthmeal

Hello folks, let me first preface that although I'm a new member, I've been lurking here since before I bought the car, and I have done my best to research and read nearly everything I can about this car. A big tip of my hat to the folks who did the audio how-to's, as I used them to safely and efficiently install my HU.


Now, like I said I looked before creating a thread. Here's my problem:

Randomly, if I put the throttle to the floor while already traveling, approximately 15-35 miles an hour or so, the engine will rev up, stutter, and BANG!, car jerks as if transmission fell out from underneath it, all hell breaks loose. I typically quickly shift to neutral as pure habit from owning manual cars most of my life, and observe the car in No lights, no symptoms of damage, nothing. If I let off the throttle and then come back on gently or even not-so gently, everything is fine. This only seems to happen when I am transitioning from a coast to a full-throttle event.

It has happened 3 times since I've owned the car, which is about 5 months now.


Thoughts?

piggylover1985

Check for broken mounts, you dont' beat the crap out of it every day i suppose ? Otherwise you will be looking for a transmission very soon.

fourthmeal

Will do on the mount check. I definitely don't beat on it, but sometimes you just gotta scoot out of someone's way, like merging. Its unsettling to not be sure about what you're going to get.

kika8806

i have an 02 and mine was making the same banging sound, it was when i downshifted...it ended up being a completely trashed motor mount. hopefully thats all it is for you too
oh and if thats what it is...i would recommend repairing it yourself, if you know how, or taking it to a local mechanic. my mechanic fixed both of mine for $150.....Acura quoted me around $450.

01tl4tl

the front motor mount is fluid filled and often fails- $150! for the part retail
DIY install see that section for help
Look under the front of the car for hydraulic fluid drops,
or looking up at the mount from below you will see a fluid trail-
looking from above it looks compressed- if you knew what it looked like new

some years are vac boosted and a blown mount will make a vac leak too!

01tl4tl

that 99- make sure the recalls have been done= ignition switch and egr port
call 1-800-382-2238x5
need the cars VIN number for that

plugged egr port makes engine run funny too

fourthmeal

I'll take all of that into consideration, thank you.

The stuttering thing just before the BANG is what intrigued me so much. I figured a trans issue would react much differently, like a softening of the torque made due to slippage, while under full accel.

I train techs how to diagnose for a living so I've got a decent amount of car knowledge, but man I've never seen a car do this.

Got some work to do!

01tl4tl

you have a 4 speed in the 99? those are way better trans- dont even sweat that

When a TL trans slips its just like the feeling a manual trans clutch with full wearout does- going uphill on throttle under load type situation-rpm buzzes to 5 grand and car doesnt accellerate- no feeling of positive downshifting to proper gear

or full throttle in top drive gear,, from 25 and 35mph-stand on it- if its going to slip it will do it then

if its a bad front mount with vac boost- that air leak could contribute to the shudder right as the engine slams against the end of the mount
Pass side mount often fails after front if left untreated,,then others follow- there are 5 total for eng and trans- only front and rear are fluid filled and expensive types

you train diagnosers- we share experiences on this car to help diagnose--the circle of life continues

01tl4tl

pull a spark plug- they will tell you whats happening

thewhitepearl

may also be fuel cut.

webmastir

i've had just about the same problem when only going from coast to basically WOT. i haven't changed my mounts in over 135k, which I hope is the root cause. i just had my tranny rebuilt like 15k miles ago, so i'm pretty sure it's not that yet. anyway, i'd be flippin amazed if my mounts were my problem this whole time.

fourthmeal

Yep, its a 99 4 speed.

I understand the BANG being caused by mounts, but why does the car pause, downshift, stutter/falter, then BANG? It is intense too, man.


At other times, while fully underway at highway speeds, there is NO problem hauling ass...full throttle delivers a clean downshift, and the surge of speed I expect of a decent running engine. I also have no problems coming from a dead stop, to whatever speed I want, at any throttle angle I want. It is only this very specific characteristic that happens rarely, randomly (4 times now since I've owned it), at a low speed coast, transitioning to full throttle.

It very well could be a form of fuel cut, as I would absolutely say it sounds like it, but why only then, and why with a bang?

BTW, this happened before and after I replaced the plugs with fresh Iridiums (old ones were just fine, I just didn't know their condition since the car was new to ME), and it happened before and after I did seafoaming, so I don't think it is either of those two changes.


Other than the trans, I have suspicions about the throttle position sensor or something in that realm.

03rejo

my 99 had a really bad time shifting when I first got it, it would also do the long pause between shifting while the revs would skyrocket, then dump it into the next gear with a violent thrust. I found that a full transmission fluid replacement (3qts 3 times) and a new transmission shift solenoid [tss] fixed my issue, although i've found much on the topic of the tss screens being clogged and causing hard shifting. Mine however were squeaky clean and just had a bad solenoid. Whatever you do, be careful putting the tss back in, making sure the o-ring is not out of place. If it is you'll be pouring tranny -fluid out and end up paying $28 for the new o-ring/filter

fourthmeal

Hmmm, very interesting!

Any codes pop up during all this, even if the CEL doesn't light up?