Stuttering between 3k and 4k (197)

[FunkMotorsport]

Hi all, recently bought a 197 as a track car and am noticing that sometimes (not all of the time), I have a big stutter between 2.5-4k RPM. Pedal goes nowhere, just loads of pops and bangs. Then it will clear itself.

Alternatively, if I nail the throttle, it clears it, or if I drop a gear to take it out of this range, it will clear itself.

I’m sure this must have been a pretty common issue in the past, can anyone provide any insight?

Thanks

Ryan.

 

[glenn_adam_doble]

When the car is cold most of them do this here you have to ease the car up to temperature

Or if it’s all the time, there is water down coil 4 (timing belt side) causing a misfire,

 

[FunkMotorsport]

It seams to be at any temperature this will happen. And sometimes it will be fine, others it will hold back like crazy!

 

[glenn_adam_doble]

I know the hold back feeling mine does it usually after I have give it some stick, switched it off let it go cold then the next start up it will be horrific, kangarooing, spluttering misfiring, sounds like anti lag

The only way I get past it is just gently let the revs rise, 1/4 throttle max in second gear and you feel it lift and smooth out

 

[bloke]

Flat spot.

Flat spot can be terrible on some of them. I chased one once that turned out to be just the flat spot/map but it was that bad you could get it popping and running rough but as soon as you lifted even the tiniest on the throttle it would clear itself.

Map cured it, will see if I can find the graph as it was that bad it's comical!!!!

 

[bloke]

Red is standard map.

 

[FunkMotorsport]

Hi all,

Thanks for your input. This is my second 197, (years ago I owned an R27) and I am confident that this is not “the” 197 flatspot.

We are talking pretty much 0 load on the engine, and yes, a little like anti lag. Popping and banging.

Sounds more like an ignition error, or fueling error at this RPM. Like Lambda, crank timing or alike.

Also, this is irrelevant of engine temperature - cold or hot. Just at low revs, almost like the throttle pedal is redundant, unless you force it out of that RPM band (by shifting down), or by pinning the throttle to the floor gives it a little hesitation but then would accelerate as normal.

 

[bloke]

Yup, flat spot on standard map. As said some are pretty bad as you can see from the graph but lift ever so slightly and it will just about pull through it or accelerate hard before it and it pulls through absolutely fine.

Ecu is just getting confused and throwing a wobbler as it's a pretty quick ecu.

 

[welshname]

I got this for a few weeks until eventually it gave me a a light on the dash. I wish I could remember what the fault code was, think it was coil or injector but might be wrong.