I have 2 problems right...

First I have t3/t4
dsm 450's with a vafc

if i'm in nuetral and I hold the rpms let say at 3 grand....they will drop 400-500 rpms and move back up to 3000 and drop back down to 2500 and go back...

It just repeats this cycle...And no im not moving the foot...

any ideas?

2nd problem

my car is real jerky when lets say im driving 30 mph in 4th gear. Im just driving not getting on it; by any means...so lets say i take my foot off the gas to obviosuly slow down...im not putting my foot in on the clutch... but when i go back to apply throttle its jerky, and im not mashing the pedal....

so i first though well its prolly your fuel...

well right now my vafc is set for -35%...the only way for me to make it smooth is to dump in tons of fuel like -15% which is super rich...

any ideas?


-Dan

 

i am having the same symptoms with my engine, its just a b18a1 with the normal mods, i posted but didnt much feed back either, if you have any ideas gimme an email at Hurleypstar@hotmail.com , the one thing i heard mine could be is the TPS(throttle positioning sensor) because mine runs very lean(the colder the worse, the colder it is... the thinner the air), and i dont have a vafc or anything to increase it, i was thinkin about bigger injectors but i didnt know if it would do anything for me without a stronger fuel pump, or the fuel controller.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by citrus3000psi &raquo;</TD></TR><TR><TD CLASS="quote">my car is real jerky when lets say im driving 30 mph in 4th gear. Im just driving not getting on it; by any means...so lets say i take my foot off the gas to obviosuly slow down...im not putting my foot in on the clutch... but when i go back to apply throttle its jerky, and im not mashing the pedal....</TD></TR></TABLE>
common problem..dont know what causes it...maybe bad wires?

 

At other times does the car feel incredibly underpowered?
like its under load?

 

your running a turboed car off of a vafc only? Well thats a problem in itself... Sounds like a fuel issue - a sensor might be broken, or there may be a vacuum leak...

 

No the car never feels underpowered....

I think its something with the injectors since I switched to peak and hold injectors but im not tottally sure...thats why im making the post.

 

bump cause i have a similar problem

 

I made a data log today of my throttle positon, rpm. My throttle position doesn;t moving meaning its not my TPS...so that sensor is ok...

 

Did you install inline resistors with the injectors?

Sounds like a fuel issue to me. As for the idle problem, does it stay steady at regular idle (750ish)?

 

Yes I installed resisters with the injectors...


And yes it idles perfectly fine at 750 +- 50

-Dan

 

Your problem is common/normal. I had a turbod b18c1 running the VAFC hack, 440cc injectors and 255 hi flow pump. It has to do with pulse width of the injectors and messing around with map sensor (cutting fuel). The whole VAFC hack thing is just that..a hack and the computer does some funky stuff.

do a search on VAFC hack and you might find a thread on this. I believe "filetofit" (i think) wrote about this.

 

https://honda-tech.com/zerothread?id=571743

https://honda-tech.com/zerothread?id=251409

 

Had the same problem on my last 2 95 GSR's. Finally found out what it was on Friday thanks to this site.
On mine it was the "fast idle valve". THis is the "thing" under your throttle body. Pull your throttle body off remove the 3 8mm bolts and take this part off. "Shake it like a polaroid picture." If it makes noise you found your problem. You could buy a new one for 100.00 but I just took the flat end off with the 2 screws and screwed back in (all the way) the threaded plastic peice that is loose.

There you go all fixed.

PS this will take care of both of your problems the idle is causing your 4th gear issues.Every gear should be jerkey under 3000 RPM.