VQ hesitation issue.
 

Every once i na while ill be sitting at a red light and the RPM's will drop a little and jerk the car and come back to normal idle. Funny thing is it wont do it if i have it in neutral, It almost feels like Excessive TC shudder. It will also do the same thing when im going into part throttle going uphills or in any kind of load situation, it will jerk for a quick second then keep going like nothing happens,
Nothing has been done to the car, but a Rear o2 code came up a after the problem has been occuring (couple of weeks or so), i replaced both front and rear banks with new O2's and to no avail the problem is still going on.

What year is it?

Maybe signs of early MAF failure.

that rear 02 code must've showed up because the cat was gone... y else would the rear o2 sensor fail??? thats what i think... but never too sure... wait for other comments...

could be MAF as well... take a small screw driver, turn the car on, and tap the maf lighlty... if ur car shuts off... change ur maf... it wouldn't throw a code for this prob... yet... until it gets worse... mayb a bad tb... or egr... lol check everything.

Because sometimes components just fail, they don't necessarily nead an outside reason.

The symptoms he describe could easily be (and likely are) a failing coil(s).

hey thanks for the reply everyone, The rear o2 as in the primary mounted o2 was replaced, not the post catalytic converter one, Also when the car does this, no check engine light comes on or flashes, and when i scanned for codes ....nothing stored, its really pissing me off.:mad:

Edit: ill clean the MAF just for the hell of it, got nothing to lose by trying that out, you never know

Pmhor: its a 96' max with a 98engine if it makes a diffrence.

bump

Have you checked out the coils yet? No real reason to bump until you do.

I had a similar problem with my 96. Mine turned out to be the plugs. It would "bump" at red lights and the idle would dip for a split second, but if i put it in park it would idle smooth. I put some ngk iridium plugs in and it runs much smoother without the missing and hesitation.

yea i just changed out the plugs with some new denso's, according to FSM specs all6 coils are within proper range, The plugs were changed in december but i suppose i could change em out and eliminate that from the list of ****. thanks for the replies

It's worth trying, good luck

maybe way off but if it's an auto it could be it goin out.

my car has the same problem, interestingly enough
when changing from first to second the car has a very stiff gear change (for an auto)

I've replaced all my coilpack. (i did have one go as well, however this felt much more pronounced) and the "hesitation" on light loads in overdrive feels different, its almost like changing gears (as apposed to the car running rough and loosing power).

also i get an occasional back fire through the IM, (although this only happened once since i replaced all the coil packs) and the car seems to idle rougher when warm (you can almost feel it drop rpms slightly, but only if you were actually listening to it)

i'm hoping its just the plugs. (haven't been replaced and i've had the car for a year) and if that doesn't fix it i might check the MAF, might also try injectors.

yea exactly we have the same issues. check engine light came on last night though, so ill see what it is this time, will post later

91parkave, I too think your symptom may point to coils, given that it occasionally does it under load while driving.

I believe "Torque Converter shudder" happens when the torque converter lock-up is activated, and this never happens in first or second. Lock-up is mostly used in 4th, and also in 3rd when you're easy on the throttle, and in any case, only after the transmission has warmed up.

The sharp 1-2 shift seems to be characteristic of this transmission, at least as it ages. But I never drove a 4th gen max while it was young. If it bothers you try changing your ATF to one with more friction modifiers. Three examples that come to mind are ATF+4, Castrol Import MV, and Amsoil. I make no claims of suitability for any of these fluids.

when in 4th and i put light throttle on (say going up a small hill) my car shudders a little and the revs jump up (after shuddering) and this only happens when the car is warmmed up?

for example. driving along a long straight road car sits around 1250 rpm (example only, i've no idea what the rpms are), come to a slight hill, squeeze the throttle slightly and the engine will feel like it misses untill it "catches" and the rpms jump up to 1500rpm.

is this the lockup slipping? and how would i fix this issue?

Same problem here, It is especially bad when the AC is on. Changed my spark plugs and it hasnt happened since.

PLugs changed...problem gone.......tears of joy:bawling: thanks everyone for your help

91parkave, nice to see you solved your problem.


mywhitewolf,

The rpms jumped because torque converted lockup released for that purpose, since you requested more power.

I haven't heard of torque converted clutch shudder upon disengagment. I suspect an engine issue first, it may be stumbling under low-rpm load.

Check tune-up items. Notice new spark plugs solved 91parkave's problem. There are many tune-up items, are any of yours overdue? Surely you can find details in the stickies and other threads.

funny thing is though i changed my plugs in december, and only had a issue recently, i guess **** happens, no other logical way to explain it, BTW the code turned out to a 02 code but i guess that was because of the spark plugs not igniting fuel properly and caused the 02 readings to go out of whack

Plugs, injectors and MAF are the only thing that it could be, i'm going to try the plugs when i can afford the money ($120 here in AUS :/) right now.

though it gives me hope that it fixed the issues with others. i'm hoping it does the same to me. i <3 my max when its cold. :D

plugs
...120?, cant be that bad down under is it? **** man

for all six, 120 is the cheapest to get the recommended. (i could spend $30, but i doubt i would have that much of an improvement in performance.)

mywhitewolf, I believe NGK copper plugs will perform as well as the OEM recommended NGK double platinum, they just won't last as long.

91parkave, would you tell us what plugs you took out (that caused the problem) and what you put in?