Hesitation at higher rev's

[Dakkon]

Having driven my car for a while now I have noticed that occasionally when you accelerate past 5,000rpm it will 'hesitate', almost as if the power if gone for a brief second then its back again.

Only noticed this a couple of times, but was wondering if this was a feature of an older car, or something to investigate further?

[leosayer]

Could be a fuelling problem or a problem with the distributor. I would take it to a specialist, hesitation is the last thing you should expect at high rpm.

[Dakkon]

It had a new distributor at its last service (beginning of Feb)

[verysideways]

Paul,

If it's underfuelling at higher revs then you'll be hotspotting the pistons, this is v. bad for your engine.
Likewise if the timing's out you could do damage if you keep driving like that.

If you are able to get to somewhere like Northways, get one of their guys to go out for a drive with you and demonstrate the problem - they're very good at diagnosing this sort of thing.
(no affiliation, etc, just a happy customer)

Could be as simple as a fouled plug or a dirty fuel filter of course...

VS

[Dakkon]

Northway are not far from me, they are the guy's who serviced it, I will get them to check it over.

Thanks for the replies.

>> Edited by Dakkon on Monday 18th April 11:50

[DanH]

Dakkon said:

It had a new distributor at its last service (beginning of Feb)

Is that when the problem started? Could also be the HT leads.

[Dakkon]

Well car is in at Northway, they have replaced plugs, leads, distributer, air flow sensor and still not cured it, they are removing the alarm and immobiliser now.....

[guyvert1]

Cheap check then

[spenny_b]

...started reading your post and was about to say Lamda sensors, but then looked at your profile re age of car...maybe not then.

I've got EXACTLY the same symptom on my '98 996...took it to GT-One who diag'd it...2 sensors being replaced as I type...they only have service life of 5 or so yrs...

Not a dodgy engine earth, is it...corroded braided earth cable or affixing bolts?

Spen

[Dakkon]

guyvert1 said:

Cheap check then

Yeah, thats what I was thinking as the guy explained what he had done to try and find out what was wrong, along with new exhaust and MOT reckon that the best part of 2k spent...

[Jowda]

My 996 C2 1999 has exactly the same problem, through all gears at about 5250rpm. Just been in for a major service and guys there said the change of plugs should clear it - didn't work.

Would be interested to see if either of you managed to get it sorted as I did not realise that it could cause long term damage, let alone bug the hell out of me!

Thanks.

>> Edited by Jowda on Thursday 9th June 21:20

[Dakkon]

Well I should hear from them today, will suggest the dodgy earth (Thanks), thing is, im supposed to be driving to Le Mans next week....

[DanH]

Have they looked at the fueling side?

[Dakkon]

When the changed the airflow sensor they found it was running lean and adjusted it, so I assume they have looked at the fueling.

[Hammerhead]

spenny_b said:

I've got EXACTLY the same symptom on my '98 996...took it to GT-One who diag'd it...2 sensors being replaced as I type...they only have service life of 5 or so yrs... Spen

Spen,

How does the your car feel now? I occasionally sense this in my Boxster.

Cheers,

Steve

[spenny_b]

Steve said:

Spen, How does the your car feel now? I occasionally sense this in my Boxster. Cheers, Steve

Picked car up on Wed evening and took for a long "test drive" up to Manchester (from Surrey)...felt a lot better, almost *too* smooth! Generally sharper, better throttle response, and no puffs of smoke on cold startup from overfuelling...I returned yesterday, and have to say, noticed very occassional slight hesitation (nowhere near as bad) at c5500-6000rpm, maybe just clearing it's throat.

...then got pulled by plod on the M1, dagnammit...one video clip, "chat", 3pts and £60 later, I was taking it easy (read "driving like a fanny" back down sarf, so didnt test after that!

Ho-hum, damn expensive week all round really. All up just short of £400 with the dreaded...one of the sensors was a bugger to get out and boss needed re-tapping afterwards. Can't wait till 6.00 and waste a few more quid getting hammered! (car at home, of course...)

Spen

PS I also noticed that I got prob 30-40 miles more to a tank before warning light came on, so good result there.

[jowda]

just heard back from Porsche Center East London who have diagnosed it as a faulty Mass Flow Air Sensor and want £740 to fix it!

Got a quote from Design911 at £350 but does anyone have experience of them?

[spenny_b]

Hi Jowda,

Have experience of the MAF's on my Subaru....dead easy part to fix on them. It's the sensor that is situated on the inlet piping. Haven't looked at the Porsche one yet, but if anything like the Scooby one, it's just a single torq screw holding it in, plus a single plug...read "2 min job".

The Scoob one was about £100 for the part (on later models, earlier ones had to replace the whole housing at about £350)...£750 for the Porker sounds outragious.

Still got hesitation on mine, despite visit back to indy specialist and a reset of the diagnostics (which had flagged a Lamda error code).

Damn car, getting sick of it, tempted to part-ex this and the Scoob for an M3 CSL ....famed Porsche build quality/c£65k car when new certainly not impressive to date...