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(Slightly) "Lumpy" - 2,100 to 2,400 rpm.
https://forums.tipec.net/viewtopic.php?f=25&t=10169		 Page 1 of 1
Author:  Mark Allen [ Fri Jan 07, 2011 12:18 pm ]
Post subject:  (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Hello All

Even when warmed up to full operating temperature, my 944S seems to be running a little "lumpy" around the 2,100 to 2,400 rpm band width - not too bad, but, definitely noticeable. In all other areas, the car runs absolutely fine and all guages and fluids are as they should be.

Any ideas what the lumpy running around the 2,100 to 2,400 rpm band width might be attributable to?

Many thanks

Mark
Author:  ben944 [ Fri Jan 07, 2011 12:30 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Sticky MAF?

Someone will probably be along in a minute who might know more though.

Ben
Author:  Brett928S2 [ Fri Jan 07, 2011 2:41 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Hi :)

When were the plugs, dizzy cap and rotor arm last CHANGED ...not checked but actually CHANGED ?

All the best Brett :)
Author:  tr7v8 [ Fri Jan 07, 2011 5:08 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Poor running here will be MAF or possible air leak on some of the pipe work.
Author:  Mark Allen [ Fri Jan 07, 2011 5:28 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Many thanks for all your comments.

I wouldn't say that the car is running poorly - and my passengers have never mentioned it. I can just "feel" a slight lumpiness in the rev range desribed.

I think I understand the comments concerning the distributor and rotor etc. and I'll check the car's history in this respect.

When you mention the MAF Jim, do you mean the one on my car should is potentiallty broken and should be replaced or simply adjusted? Presumably an air leak would be due to a split pipe or poor connection between the air intake and throttle body?

Thanks again.
Author:  tr7v8 [ Fri Jan 07, 2011 6:24 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Mark Allen wrote:
Many thanks for all your comments.

I wouldn't say that the car is running poorly - and my passengers have never mentioned it. I can just "feel" a slight lumpiness in the rev range desribed.

I think I understand the comments concerning the distributor and rotor etc. and I'll check the car's history in this respect.

When you mention the MAF Jim, do you mean the one on my car should is potentiallty broken and should be replaced or simply adjusted? Presumably an air leak would be due to a split pipe or poor connection between the air intake and throttle body?

Thanks again.

Sorry not MAF Air Flow Meter or AFM, replacement or possibly fixing the one on it are what is required.
Author:  MisterGT [ Fri Jan 07, 2011 6:47 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
If the issue is caused by the AFM Clarks garage has a guide to adjusting it. There are also some good guides on YouTube.
Author:  J.J. [ Fri Jan 07, 2011 9:56 pm ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
Has it always been like that or is it recent? Loads of pipes that can cause a vacuum leak. Repalcement of the small pipes with a silicon kit costs around £25 & is well worth the investment. If it's always been like that it could well be fueling & a remap by Wayne Scholfield would be the way to go. Should pick up 15 hp & a load of extra low down torque as well. Will be as smooth as silk when done. AFM can maybe be bought new from euro carparts for around £200 if you give them the part number printed on the lid.
Author:  lindsayhbrown [ Sat Jan 08, 2011 1:20 am ]
Post subject:  Re: (Slightly) "Lumpy" - 2,100 to 2,400 rpm.
The flexible pipe just after the AFM is prone to splitting, easy to replace and about £20 from OPC IIRC
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