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Throttle response from low revs

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pat bryant

New member
Dear All,

Just changed/renewed the air filter in my 2004, 2.7l, 986. I was hoping it might eliminate a reluctance to 'pull' from about 1500rpm when I floor the pedal. I first noticed this oddness when slowing for a 90degree corner, 2nd gear and then hitting the throttle on the way out; much stuttering and bumping. If I ease the power on it is fine but flooring the pedal, in any gear, from below 2000rpm results in the same condition. Otherwise it goes like a demon, no hint of misfire. I know there are limits to the torque you can expect so it may be that I should not drive it like that. Any views?

Pat Bryant
 
If the cars fully serviced and in fine fettle it might be the Maf needs a clean or more likely if pushing to hard out of a corner it might be the PSM.
 
That doesn't sound right to me Pat.

Other than the MAF sensor you could check for an induction leak.

Jeff
 
Dear Both,

Spent the morning cleaning a very clean MAF unit. Yes you guessed it; no difference at all. Fine if you ease on the power OR 'pedal down' at above 2000rpm, otherwise thumping and bumping.
Tracy: I do hope it is not the PSM system because (if it is) someone has hidden the switches on my car; though come to think of it I did once ride a little Honda motorbike around for about six months before I discovered it had a fifth gear.
Jeff: How do I check for an induction leak?
Next stop Porsche Wolverhampton which is quite close and they seem unusually helpful.

Thanks
 
Probably best bet to get a diagnostic plugged in to save time and money on things it may or may not be.
Good luck
 
The symtoms you describe are similar to those I experienced years ago on a Reliant Scimitar GTE. The technology is light years apart of course but the problem turned out to be a flexible petrol pipe that had lost its structural integrity and was collapsing and closing up under rapid aceleration but was fine when providing a flow of fuel even at speed. It was difficult to find but I had a great feeling of elation when I found it.
I‘m not suggesting that that is the cause of your problem but fuel starvation is a possibility. Have you checked your fuel filter for example? There may be "floaters” that are being sucked in during high and rapid demand for fuel.
As has been suggested, a proper diagnostic check is likely to identify what the problem is.
Good luck.
 
pat bryant said:
Dear Both,

Spent the morning cleaning a very clean MAF unit. Yes you guessed it; no difference at all. Fine if you ease on the power OR 'pedal down' at above 2000rpm, otherwise thumping and bumping.
Tracy: I do hope it is not the PSM system because (if it is) someone has hidden the switches on my car; though come to think of it I did once ride a little Honda motorbike around for about six months before I discovered it had a fifth gear.
Jeff: How do I check for an induction leak?
Next stop Porsche Wolverhampton which is quite close and they seem unusually helpful.

Thanks
Click to expand...


Tried cleaning the MAF a number of times when I had a 986. It doesn't do anything. In theory they are self cleaning (by the wire being hot). Putting a new one in solved the poor throttle response for me. Albeit that my issue was that it didn't like going over 4000 rpm when the MAF started to fail. BTW avoid cheap aftermarket ones. You need a Bosch or Porsche one. So not cheap. And make sure you get the right one because the 2.5 and 2.7 parts are different.
 
Update,

Porsche Wolverhampton, definitely not right (the car that is). No faults stored in ECU; vehicle in good shape (great); must, therefore, be something mechanical, ie not monitored by electronics/sensors. Somehow cylinder 5 is implicated (they did not say exactly how this conclusion was reached) sticky valve? I was presented with the option of paying more money to go to a compression test and, it seemed, they had spent quite a lot of time on the job for my initial £75, which included a general health check and you can have a walk around your car with a technician in the, immaculate, workshop. Close to end of day so I said I would have a think and book in for another session later. Personally and in an old fashioned way I suspect air flow/fuel but imagine they would have somehow picked this up.
Have to say that the service there is great AND they loaned me a Cayenne for the day (I want one) which was worth the visit in itself

Best,

Pat
 
Yes my dealings with Porsche Wolverhampton have been great
Little bit of a hiccup first time when I took the car in "Ive got a coolant leak from the top of the engine"
Paid my 75.00 and waited and they said you've got a coolant leak from the top of the engine!! (996 Typtronic)

I know that that's why I bought it in
I was hoping for a guestimate on how much it would cost from my 75.00

Took it to a guy who thought it was the oil cooler.
So went back to Porsche Wolverhampton who had agreed to check the Oil Cooler as it had a new Porsche one fitted 18 months earlier
Turns out the so called specialist in Horncastle had twisted the top pipe when fitting the new cooler This had fractured and was leaking coolant!!

Anyway three new pipes where fitted and I came away with a bill for about 300.00.

I do think you need to specifically ask then to diagnose the problem. Surely these guys should know what the problem is at 125.00 an hour



 
Dear Richard,
Yes, tricky really. I was speaking to another 'old boy' who was of the opinion that today's mechanic (sorry technician) only relies on standard protocols and e-diagnostcs rather than experience and an intuitive fault finding ability. Difficult for those of us who have quite a bit of knowledge but not the facilities.
I have sometimes seen a bit of smoke on start but do not understand your suggestion of 'leak' causing my symptoms? Grateful if you could clarify ahead of my next trip to W'ton.

Pat
 
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