Fluctuating Boost

[adarmo]

Hi,

Just got my first FD a 95 import.

Only had a short drive and I was impressed how smooth and seemlessly the power builds BUT it isn\'t as fast as I\'d thought - feels like 220bhp.

The boost gauge sweeps around to 8 or so but then flicks between 10-12psi on WOT rather than holding steady.

It has an Apexi controller, intake and exhaust but a std IC so I believe it should be set at 12psi.

It has had a completely flat battery for months as its been stood.

I\'m a decent mechanic but have never had an RX7 before so any tips where to start are welcome.

Thanks

[jamison1982]

hi, if i were you the first thing i would do is check all the boost pipes, in the rats nest, map sensor, bov and so one, do you have a commander for it?

[adarmo]

I\'ve just started reading up on all this... could take a while !

Yes I have a commander - just downloaded the instructions so now it might be of some use.

Most running 12psi seem to claim 300bhp+ - no way am I anywhere near that.

[jamison1982]

i took plenum off and replaced all hoses, and stopped any problems, plus its always a good idea the replace them all anyway

does it hesitate at all ? hold back when the boost fluctuates

[adarmo]

Bear in mind I\'ve never driven an RX7 before...

But no it seems to drive really well. I\'d seen a few dynos on here which seemed to show a massive flat spot when it switches from the small to the larger turbo - mines really smooth.

If I didn\'t have the gauge I wouldn\'t know there was an issue - except as I said it\'s also down on power.

[jamison1982]

if i remember right the standard boost pattern in 10 - 8 - 10 psi ( the 8 is the transition)

does it have a cat or has it been de catted ?

[jamison1982]

also have you checked the leads and plugs

[adarmo]

if i remember right the standard boost pattern in 10 - 8 - 10 psi ( the 8 is the transition)

does it have a cat or has it been de catted ?

No apparent boost dip or dip in performance (so may be modified)

Performance exhaust and No Cat.

[FD3S Efini]

Also the turbos are both the same size it\'s not a small one and a big one, impressive power for 2 small turbos though

Kris

[jamison1982]

they are very good turbos

i would be wary about changing things on the apexi commander bud,  

if i were you i would firstly check all boost pipes or for peace of mind replace them, check the leads and plugs and gaps

that way you have eliminated the cheap parts lol. also check the pipe going to the map sensor top right of engine bay i think ?

then see if this helps, as i have had this a couple of times, first was vac line had a small split in ( the map one) and second time was a lead failed.

[adarmo]

Thanks for the replies.

I\'ve been reading up on the rats nest and replacing all the hoses - doesn\'t look like fun.

I\'ll have a look at the weekend.

[jamison1982]

how did it go did you manage to have a look

[adarmo]

I spent most of the day replacing the pads... well I started doing the pads then thought while I\'m here I\'ll remove and clean the pistons.... then I thought I might as well change the flexi hoses.

But I did have a quick look then I took it out and it seems to have cured itself.

It isn\'t a rock solid 12psi but it\'s much better than it was.

I think I\'ll put it on the Dyno though as it definitely feels like its missing some power.

Power jumps up around 6000rpm  - I thought the 2nd turbo came it around 4800 ?

I have found out mine\'s been ported if that affects the power delivery.