Merc63

I'm on the highway today going up a slight incline in manual mode and I roll on it a bit at around 3000rpm. The car starts hesitating slightly cutting on and off, it's not too noticeable, but it's there.

Mods in sig. Stock spark plugs... I'm going to check AF on the road with a wide band. I'll also check plugs when I get home... Anyone got any other ideas???

Pit-Pony

Check for codes.

Merc63

no CELs were thrown. Stopped at a store for a bit and did a few more runs down the freeway. I couldn't duplicate the hesitation now.. Weird..

Ordered new plugs a week ago, we will see what these look like when I switch them...

peh-amg

Mine was doing a similar thing. I had K&N air filters and no charcoals. I replaced the K&N's with OEM air filters, left the charcoals out and cleaned the MAF's. Problem solved and car runs great now.

Merc63

I have KN as well.. Weird.

I've been running them for over a year though with no problems.

Just recently put headers and a new tune on
Tho...

I'll check MAFs when we do
The plugs.

alicefrerichs

I couldn't duplicate the hesitation now

RNS-11Z

its o2 sensor issues.

1st amg

I had BMC filters and the car on a highway in fifth gear, when I rolled into the throttle in would hesitate and leap, not a smooth acceleration at all, never a code when it did that, so removed the filters and it never did it again, apparently the filters created a vacuum leak of sorts, like they never sealed in the airbox completely and the MAF would react to this.

hhughes1

I had a similiar issue that would occur every couple of weeks at the same spot which happened to be an uphill ramp to get on the interstate near my house. Accelerating at about 3/4 throttle the car would hesitate just before it got to the shift point at about 60 mph. One hesitation, felt like momentary fuel starvation then it ran fine. Within a couple months I had a serious misfire issue in the right bank. Changed plugs and switched the coil packs left to right. The plugs on the problem side were burnt to a crisp so i thought problem solved. Acted up agian a few days later and it turned out to be the upstream 02 sensor from the problem side. It never threw a specific code, just general misfire codes but the voltage readings were crazy erradic and replacing the sensor solved the problem once and for all.

khmergod

I sometimes get hesitation on right yields heading towards highway feeders. The problem was having a lead foot and tires skipping/not gripping. That could be the issue with you.

Merc63

So replacing the First o2 sensor before the cats solved your problem?

Did you order the sensor from MB or another source? $?

I don't think it's the air filter cause I've had these in forever with no problems..

But like I said I just did the headers and a new tune so I'm thinking it's plugs, o2s or mafs are dirty...

I'll post back with updates, thanks guys.

Merc63

Why do u say this?

BerBer63

had hesitation, idle issues, bogging at idle, really rich exhaust smoke....upstream passenger O2 sensor. Changed and everything tip top now. btw I threw the code tho.

Merc63

Car seems fine today.. Maybe its on the way outs...

Do you have any work done to the car or is she stock?

BerBer63

headers

RNS-11Z

i have had this issue several times and its just happened again.

Merc63

So you have had to replace the O2 sensors a few times now? Does the hesitation get worse or stay the same, can you explain your experience a bit more pls.

RNS-11Z

Yep had them replaced previously, fixed everything up. Basically the car feels like its stuttering. Initially i noticed it when the car was on slight throttle input going up a hill. Then it eventually got worst and engine light came on.

Merc63

That's exactly my experience..

Should I wait till it gets worse to get new O2 sensors? Or get them now?

Would they be sending false readings and causing AF ratio problems?

RNS-11Z

My car started running real rich, and performance wise it lost a few hp. I swapped my o2 sensors over and this fixed the problem for several months but its come back again. Try swaping them over, if not you may need knew ones like i do now.


h.

Blown63

Merc63, I have been having the same exact issues, I was experincing this when i had kleemann shorties, a catless midsection and running k&n filter with charcoal delete.(which had no o2 sensor)

I now am back to stock headers and midsection with cats and o2 sensors but still have k&n filters and a charcoal delete and it still happens occasionally. I feel as though this is caused by the k&n filters and not having a tune designed for them. I don't know if I am correct but I feel as though the hesitation is caused by air/winds from high speeds entering the intake which causes the throttle to hesitate when a gust of wind flows through the filters.

But now my only question is when i didn't have o2 sensors why was I still experincing the hesitation?

Merc63

How did you not have o2 sensors? Aren't they needed for EFI?

Blown63

I was under the impression that because i had no cats there was no o2 sensor but now looking back at pictures of the midsection there was a spot for an o2 sensor, i am not sure though.

Merc63

Ya you had O2 sensors. They are the ones before where the primary cats would be. The ones after the cats are the emissions sensors.

I haven't had this come back yet.. Haven't had a chance to hook up my wide band AF yet, but I will soon...

_timothy

This just started happening to me after months of smooth wot action

I can reproduce this at 3/4 throttle in 4th gear at hwy speeds
It feels like the fuel shuts off and it lurched. No codes or dash lights

From searching it looks like I need to clean the MAF, check the spark plugs and possibly reseat the air boxes, yes?