pugg57

ok, i've been reading on different sights (along with this forum of course) and i'm not sure i'm understanding what's going on... the car kinda stutter steps under hard acceleration at 3k rpm. i've seen ALL KINDS of explanations and don't know which one is it? for some reason the one that seems the most common, but least intuitive, is "bad grounding." lots of people suggested that a set of "hyper ground" wires would correct it. is this true? if it is, how does that only effect it at 3k? if its not, what is the culprit?

mad_7tist

from a mass of evidence higher fuel pressure and some better grounds seem to help most often

Kento

No one is absolutely, positively sure what the exact cause is, and the results from adding additional grounding to the electrical system have ranged from good to none at all. All that is certain is that when you install a standalone like the PFC that the 3K hesitation disappears.

pugg57

i intend to get a set of hyper ground cables (red, just because i'm trying to do red hoses, cables, etc. but thats not important) and would LIKE to go to a pettit ECY after i do a few modifications, does a new ECU ever fix the problem? its not like its driving me nuts, i love me car... all two weeks i've had it have been beautiful

mad_7tist

pettit unlimited ecu, still there somewhat

pugg57

mad 7, it did help though? do you have a set of hyper grounds installed?

Kento

Made no difference on my FD (the Pettit ECU). Luckily mine doesn't suffer as badly as some others I've driven...

DaedelGT

Made no difference to mine either, but from what others describe, mine is no where near as bad as it could be.

pugg57

so it sounds like, if its gonna bother me, i should probably plan on getting a PFC. i'm assuming you guys mean the Apex'i Power FC? does this act as an effect boost controller also?

mad_7tist

it is a marginal boost controler at best. profec b rocks

SpeedKing

iTrader: (4)

Is this 3K stutter symptomatic of the first year cars? I have a '94 and don't have this issue.

Mazda99Nikon

The current issue of Performance Tuner magazine seems to suggest it can be fixed by replacing and securing the vacuum hoses. It also gained the subject RX-7 something like 20+ HP, if memory serves me. They replaced every hose with silicon and secured them with super glue. Anyone try this and report similar findings?

cpa7man

iTrader: (2)

My 94 has a minor stumble, its worse when not fully up to temp.

mad_7tist

it's common enough that mazda has a service notice to dealers sbout it. along with some things that dont help it lol one of which is the grounding.

SpeedKing

iTrader: (4)

How do you replace just vacuum hoses and get a 20+ HP gain? Sounds like a load of BS to me.

Mahjik

iTrader: (1)

It just depends on the car. I have a '93 and no 3k hesitation. It's not an ECU problem; however for some, replacing the ECU seems to bandaid the effect.

user 9348703

grounds, plugs, wires, blah blah blah....

Its just one of those things, not just one part you can say causes that like mentioned above, its a troubleshoot problem.

Mazda99Nikon

Speedking: They reported the dyno (on a stock 93) showed only 200 HP. Upon extensive examination they found several leaking vacuum hoses. The article was basically trying to prove the point that with RX-7s, you're best bringing the car up to basic tune before you spend money on mods. The published dynojet charts seemed to prove their point, but hey, I'm only reporting what they said. On my FC, I can verify that if there are leaks to the 5th and 6th prt actuator hoses, you will definitely loose 15-20 HP. Still trying to figure how to fix those ports without tearing the intake and dynamic chamber off.

pugg57

I'm going to be replacing my vacuum lines with silicone ones shortly. is that difficult to do? do i have to pull the enginer or is just removing the intake manifold, etc. enough? also, could i secure the lines with just plain-jane worm gear style hose clamps?

cpa7man

iTrader: (2)

Try this link: http://www.rx7turboturbo.com/robrobinette/hoses.htm

and search on the forum.

You only need to pull the uim.

pugg57

thanks alot cpa that should help quite a bit

Kento

Negative, had no effect on the 3K hesitation when I replaced all the stock rubber hoses with silicone. Of course, when the stock sequential system has leaking hoses, it's gonna have so many problems with hesitation and bucking under throttle that replacing them to get the system to work correctly will make someone think they've solved the 3K hesitation.