996 Hesitation between 1600-2200 RPM

I have a 99 996 with a Tiptronic and when cruising steady around 1600-2200 RPM the car hesitates and I can watch the tach vary between 50-200 RPM, it is very annoying. The Porsche dealer verified the problem when driving uphill, but it did not appear to exist when going downhill. They suggested I buy 2 front tires to match the Michelins I have in the rear. I put new tires on, but it did not help. Next they want to change the fluid and inspect the transmission for problems. Has anyone else experienced this problem because our local dealer admits they have never heard or seen of this problem before but feel the torque converter may be to blame? Their only option is to replace the entire transmission if the inspection looks good visually. Does anyone have another suggestion?

what the heck does the tires have to do with the engine hesitating? I get the opposite, a slight boost but I think they said its the variocams kicking in or something..

The local Porsche dealer stated that the different diameter tires "may" be the problem, they said that the Porsches have speed sensors for each wheel and that they may detect a problem and cause the hesitation. I doubted it, but took their suggestion anyway because they are the "experts". Have you or anyone you know of ever heard of my problem before?

Finally, last night, I overcame my hesitation problem, however, it's not as low-dwon the rev range as yours, mine happened under full load at about 2500 thro' to 5000'ish. It manifested itself as jerky acceleration, almost like I would describe a VTEC or harsh VarioCam kicking-in would feel like if you didn't know better. Of course, it wasn't pulling as hard as it should either. Idle also felt "weird", in that if you come up to a junction, dip the clutch, revs would soar up to 1400 for about 5/6 secs, then eventually drop back to a normal idle of 800rpm. My usual Indy specialist ran PSTII diags on the car and came to the conclusion it was down to the two Lamda sensors (mine is a '98 C2 Manual)...which sounded plausible, as my Subaru's Lamda went at similar age....they all do. �430 lighter, and the prob is still there!! Spoke to another dealer who suggested it's *probably* the Mass Air Flow (MAF) sensor, as this item doesn't log an error code, instead the Lamda tries to compensate (over compensate), runs out of range, then trips an error code to be logged. Replaced it last night myself (friend works for Bosch, got me one for �89, versus Indy Specialist who wanted �395+Tax, plus 0.5hr fitting!!!)...Hey Presto, prob gone and I've got my old Porsche back again, and it feels SOOOOO much different! MAF is by far the easiest and cheapes item to try replacing, all you need is a security torx bit (one with a dimple hole in middle of star) to remove the 2 screws holding it in, gentle pull to break rubber O-ring seal, and it's out. You can't see anything (hot film type, not an element), but somebody on here suggested it can be cleaned and replaced. Hope this helps, Spen

Might be bad gas (petrol ), try a can of Techcron or other fuel additive. This just happened to my Expedition, ran like crap, surging and hesitating aftera recent fill up. Took it to the dealer, fuel analysis showed contamination with Karosene?? WTF

The tire diameter might make a difference if you have PSM but if you don't then it will have no effect. I also don't think you have vario-cam in your year so that wouldn't be a problem although even with it, the rough spot is around 3200 RPM. First try to figure out whether the problem is in the engine or the tranny. Is the car sputtering on slipping? That would help differntiate the source

I only use Chevron Supreme with Techron, always have but have added two different brands of fuel injector cleaner since the problem occured a few months ago, but will try a bottle of Techron. Thank you for the suggestion. I do not have PSM in my car so unfortunatly that can't be the problem. For some reason the dealer thinks it is in the transmission, specifically the torqe converter because the problem occurs when under a slight load. They have never heard of this problem before so I'm not convinced of thier evaluation and they want $400 just to change and inspect the fluid. There are no adjustmens in the Tiptronic transmission, nor can not replace the torque coverter by itself so my car would need a transmission replacement for approximatly $10,000. This is the reason I am hoping someone can suggest another problem area. Thank you, Steve

The first thing to do is find someone else to work on your car. Tires??? They must be morons. There are alot of possablities. You might look at the temp sending unit. A bad unit will cause a similar symptom. If there is no hestitaion at that speed on a COLD engine, that would indicate this sensor. It is located on the right side, bottom of the engine in the back below the AC pump. Remove the 4 wire connector, clean and reinstall. Variocam is not in play at that engine speed. Check all vacuum lines. What is your vacuum gauhe showing at idle. Is it steady and higher when hestitaion occurs? ? Hook up your scanner and take a close look at the O2 sensor reading while duplicating the hesitation. Also look at the long term fuel trim readings. What is the MAF reading at idle? Does the hesitation occur in all gears? Can you duplicate it in park? Before anything, I would disconnect the battery for a few minutes to eliminate any bad errors stuck in the computer. Much like rebooting you home computer.

I had the same hesitation and it was the MAF. Perfect smooth acceleration now. You could also try to clean the element with electrical cleaner for a cheap fix try. Just spray it on and let it air dry. Easy to remove. Will

I have a 3.4L and the temp runs around 220F when driving in town at 110F. The problem does not occur in park but does occur in all gears at that 1600-2200 RPM if the engine is cold or hot. It appears when just cruising not under heavy acceleration. Was your hesitation at that RPM range too? Can you tell me how to locate and clean the MAF? I would hope the dealer would have checked that first, but they only suggested transmission problems. It would be a cheaper fix that is for sure. Thank you, Steve

I have disconnected the battery for approximatly an hour but it didn't correct the problem. Is there a way I can check the O2 sensor or MAF without a PSII system, the dealer did not impress me with their first suggestion? Will I damage the O-Ring if I remove and replace the MAF unit for cleaning?

Just remove the 2 screws and pull out. I wet the o ring with spit when I put it back.

Can you recommend a good cleaner for the MAF?

The idea is to remove any oil, carbon or other grime from the sensor's surface. I use carb cleaner (really spray the hell out of it) and then follow it with a splash of rubbing alcohol. Electronic spray cleaner works well also. You can get a can at a Radio Shack.

Thank you for the suggestions, I'll try it on Friday.

Steve...I am curious if your problem got fixed? I am in Hong Kong now and I drive a 2000 c2. Same problem. So the cleaning of the MAF cleared out the problem? Can you describe your problem as there is 'hesitation' from 1500rpm...then when u press on the gas the rpm jumps to 2000 but then seems like no gear is being engaged....then suddenly the gear kicks in and the car just jumped to the front? That is my problem....very dangerous when in a traffic jam....suddenly it will accelerate more than needed...

Did you find the cause?

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Really? 14 years have gone by since the last post!

Lol.. Yes I know.. I have just recently purchased a 996 and it has that issue.. Can't find anywhere else with the issue.

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If you have a Tip like the OP, then test the transmission for fault codes for torque converter clutch, common problem. Also there is some new repair pieces for the ZF Tip, an improved pressure regulator that replaces/repairs worn out valve body bore for pressure regulator.

That's the problem I'm running into as well but this is the best I can describe itHey. I have a 1999 Porsche 996 Carrera 3.4l tiptronic and been having issues with accelerating up when I I'm on third gear cause then it makes this spitting sound from the passenger rear and loses 1500-2100 RPMs but still accelerating up but goes back down and up but still increasing speed but RPMs fluctuating up and down until I hit 61 mph it stops fluctuating and making those spitting kinda sounds. But behind passenger side catalytic converter. There is a wire or pipe with oil/dirt/sludge on it. So i know I'm losing oil as well cause I've had to stop it off on the dipstick already 3 times since my last pilot change at 92k and I have 96k now. What problems could it be?

There are spray MAF cleaners available at most auto parts stores.. Like carb cleaner without chemicals that can hurt a maf.. If the MAF doesn't help, a worn TPS sensor will raise hell with drivability.

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Variocam kicks UP at about 3200 RPM's then again at 5100. /X3

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Hello I have exactly the same problem 997 c2s tip s . I cleaned the MAF - didn't help I cleaned the throttle house - didn't help Fault scanning - No faults I replaced bmc air filter + silicone housing - didn't help The spark plugs were replaced with NGK about 4 years ago / 35 K. I am considering replacing new Bosch OEM spark plugs soon, but at the same time, I do not believe this is the source of the problem. in brief. What do you advise me? I'm very frustrated. Thanks

To me the rev range looks like where the lock up in the torque converter engages. 1st to do is reset the adaptation values of the tip computer. If the transmission never got serviced till now, might be the time to consider it. Less then smooth operation could also point to the valve body and the solenoids. Is not that much extra work to drop the oil pan of the transmission and check the valve body and the print plate and give it a thorough clean. Flushing the transmission is an option as you also replace the atf that stays in the torque converter and you flush the other parts such as the atf cooler. Might be it helps!

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Thank you How can I reset the adaptation values of the tip computer? My tip s got service before I purchased the 911. On October 2013 Transmission electric plate + transmission oil was replaced in ~100,000~ km. Now, ~170,000km~.

Disconnect the negative terminal of the battery long enough would reset ECU and TCU. Take a sample from the ATF to get an idea how it looks and smells. Further check if the ATF level is good. At 70.000km I would certainly consider to do a filter ATF refresh again. 140.000km is the workshop set interval. My advise is to do it at every 50.000-70.000km. Take into account that with the normal procedure only half of the ATF gets replaced. You could plan to redo the refresh once or twice more after short intervals in order to get most of the old ATF left diluted. Ideally would be to flush or to empty the torque converter manually. If the problem lies in the transmission you will need to get the valve body checked, cleaned, if necessary refurbished or replaced. After that you might want to check the torque converter. For this the transmission will need to come off ... additional labour. maybe there is no problem at all ... and it is the lock-up you feel engaging (maybe somewhat unsmooth).

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Thanks bro I will definitely incorporate in my next service replacement fluid transmission and cleaning as much as possible of the things they have access to (without disassembling the transmission). I hope this solves the problem and I hope I do not have to dismantle transmission. If you have any other ideas, I'd love to hear. This hesitation is very frustrating. Especially in traffic jams.

One further question before you start spending money on servicing. Is the hesitation there also when you drive the car in �manual� mode? Or is it different? Any difference under different throttle application? In manual mode the TCU is in its most sportive mapping which als changes the engaging behaviour of the gear changes and lock-up. More direct. If the hesitation is not there in Manual mode it might be that an irregular slipping behaviour of the lock-up in drive mode is causing the hesitation. Controlled slipping of the lockup is used to improve driving comfort. But if the slipping starts to become irregular (due to problems in valve body or worn torque converter, lock up friction) it could cause the sudden load and unload on the engine which could be the hesitation described.

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This also happens in M mode. There are certain (rare) situations that this does not happen at all and everything is smooth. Sometimes I feel it has to do with the power of the statement I give. But it's really hard for me to point out anything specific. I've read a lot that happens to both manual transmission and TIP S owners. My hesitation is only at the beginning of driving, first or second gear. No matter if the vehicle is cold or hot. The RPM falls and comes back, like engine braking, a knock on the back and then everything works smoothly. By the way: I always only drive in M mode with Chrono Sports In D mode the TIP S is very disappointing (unlike PDK which responds well to both D and M).

Mmmm difficult one ... based on your experience I I would then keep looking at the engine side for finding a cause. A log of multiple variables from the ECU could shed some light on it. It will require a durametric. log misfire counters and see if any appears and on which cilinder, when the stumble occurs.

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Thank You for searching !

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Hello Friend My mechanic told me that in terms of diagnostics and engine everything looks great. Porsche Authorized Senior Diagnostic Mechanic. Is this phenomenon recognized and can it be resolved as a result of TIPTRONIC oil replacement? Could this be related to spark plugs? (As far as I know my spark plugs went 40,000KM and replaced 4 years ago, non-original NGK spark plug and no BOSCH). Could it be related to MAF. I cleaned up my MAF and nothing changed. I realized that MAF also does not "throw" a fault and sometimes just replace it. I have to solve it. It really hurts my pleasure.

Cleaning a MAF is not always a solution, and most of the times only a temporary. Check the Hot Film Voltage with ignition on. Any value outside the 0,95-1.05V range I would consider the MAF as ready for replacement. Don�t forget it is one of the most important sensors in the car. it wears out and needs replaced so now and then. My previous MAF sensor lasted 30-35k miles. if you have no records of when it was last replaced I would advise to buy a new one.

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Thank you! To my knowledge, it has never been replaced. Buy Bosch OEM Replacements Right? The original is the same as one Bosch one right?

Yes Bosch more details can be found here: https://www.pelicanparts.com/techart...low_Sensor.htm