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Fixed my flat spot!!!! Dyno result..

Robo

By Robo,
in Engines & Forced Induction

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Robo Community Regular

Robo

Posted
Posted

Hi There,

You may remember I had an issue with my R33 after I installed my exhaust..

The mods were:

Boost (10 psi) via bleed valve

Exhaust (3" from turbo & hi flow cat)

Air filter

FMIC (small - Medium size)

Oil/Air seperator

After I installed my exhaust I noticed a very bad flat spot (from 5000 rpm onwards)..

Had it dynoed and was not happy at all...

Did some research and worked out my AFM was faulty... Swapped it over with a mates and WOW..............

Check my dyno result (both have the same mods and same boost):

Cheers

Rob

Ps. Sorry about the small photo

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https://www.sau.com.au/forums/topic/22651-fixed-my-flat-spot-dyno-result/
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crooser Community Regular

crooser

Posted
Posted

I was having that exact same 5000rpm+ flatspot. it was pretty bad.

yesterday i swapped my afm for a mates to try. Bingo! fixed.

feels like a new car... pulls harder than a schoolboy at girls camp.

I'm pretty sure its just broken solder tracks in the old afm giving weird signals with strong airflow

good on ya robo :)

Robo Community Regular

Robo

Posted
  • Author
Posted

Sorry for the late reply..

Yeah my old AFM was always a little faulty... At one stage when you just touched it, the car would idle like a yo-yo (up down, up down)..

Yeah tried cleaning my old AFM with electrical Contact cleaner but did not do much..

On warm days the car felt alright (at low boost) and then as the nights got colder it would accelerate really well until about 4500 rpm then just dies...(well just felt slow) really really annoyinng..

I'll tell you when I swapped the AFM, I could even feel the difference in 1st gear... Happy days.

Regards

Rob

Ps. Lets hope this fixes everyone's flat spots. haha

Cubes Grand Master

Cubes

Posted
Posted

Usually when I first start mine in the morning it feels a little dead (like a flat spot) unless I give it a decent amount of acceleration.

Funny thing is when it is feeling dead boost also comes up quite quickly but doesn't appear to make the car go at all then I press the accelerator just that little bit more and it starts accelerating decently with a ever so slight hessitation. During this in first and second I can see a bit of smoke swirling around the arse end of the car in the revision mirror it looks like a real dark grey colour I can also almost see the black. Fuel?

This morning I didn't want that fuel cloud behind the car as a copper was right up my clacker as soon as I pulled out the drive way.

So i took off real slow not hitting boost in first or second and the car felt really dead..

Cruising on 60km's it requires more than normal acceleration when cold for some reason but this time maybe because I didn't blow the crap out by hitting a little bit of boost and making the cloud it started to miss and caugh.

I had to accelerate to just past 1/4 to where it started to take off and made the cloud a little.

It was then fine but still with a small flat spot or dead spot that can actually make the car make boost when cruising.

:) He didn't fix mine

JimX Grand Master

JimX

Posted
Posted

Joel, the grey/brown/black cloud of smoke is definitely fuel, nothing to worry about at all. But flat spots under mild acceleration or when cold sounds like blocked injectors to me. Try putting some injector cleaner in with your next tank and see if that makes a difference. If not, then maybe try getting them ultrasonically cleaned.

Mase Mentor

Mase

Posted
Posted

Robo quoted:

Sorry for the late reply..

Yeah my old AFM was always a little faulty... At one stage when you just touched it, the car would idle like a yo-yo (up down, up down)..

Yeah tried cleaning my old AFM with electrical Contact cleaner but did not do much..

On warm days the car felt alright (at low boost) and then as the nights got colder it would accelerate really well until about 4500 rpm then just dies...(well just felt slow) really really annoyinng..

I'll tell you when I swapped the AFM, I could even feel the difference in 1st gear... Happy days.

Regards

Rob

Ps. Lets hope this fixes everyone's flat spots. haha

Robo my rb20det is a dead replica of what you prescribed. I might go down to my import mate and see if i can swap afm's for a couple of days.

Thanks

gtstii Collaborator

gtstii

Posted
Posted

Robo, looking at your dyno run with the faulty AFM, you must have been feeling a massive flat-spot which was very much not normal - good to see you fixed it!

I think the flat spot most people are talking about above is the levelling out of the power line towards the end as shown on your latest (good) dyno run.

I feel a small "flat spot" also around the 4500-5000rpm area, but I think all r33's cop this. If I compare my dyno graph to yours, it is basically the exact same shape as your new dyno run (the better one).

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