smog-guy707

iTrader: (11)

So ive pretty much ran out of ideas and you guys are my last hope. My little brother has a 90 Base model with no mods but an hks intake and a koyo rad, 30k on rebuild and 130k on car... heres my problem.

It has a lumpy idle, sorta sounds like it misses and it is very slow compared to other fc's Ive driven. If you were to give it full throttle it lags till about 4k rpm then it feels like vtec but still it feels like no power and it does not feel like it misses once your up and driving, only at idle.

heres what Ive tried

- a new MAF sensor

- new intake air temp sensor

-new fuel pump and filter

-tps is adjusted

-all new coils, plugs and wires

-compression is good

it had 2 codes when i checked it, one for a trailing coil and one for a 02 sensor and they both been changed and it still runs like crap. I took it to Ricks Rotary and he said it was the MAF and the IAT but ive tried that already and no luck.

now you gusy are all i have left, if i cant fix it myself i will sell it and put the money into my fd but i dont really want to because i bought it for my lil brother for his bday cuz he needs a car.

thanks for any help

SonicRaT

iTrader: (6)

get a DMM, check ALL sensors @ the ECU itself (there's a page in the FSM that explains how to do this and what the values should be). Check the wiring @ the Trailing coils. Make sure your auxiliary (5th & 6th) ports aren't seized in either open/closed positions.

Jims5543

iTrader: (2)

^^^^ Solid advice.

Just to add, make sure you have no vacuum leaks on the intake, that will make for bad idle and no low end power. An aftermarket intake screams vacuum leak to me.

These cars are famous for poor engine grounding, make sure you put a nice heavy gauge wire (think battery cable) from the bell housing to the frame of the car. Also make sure the ECU is grounded well.

FC3S_nataku

iTrader: (3)

^all sound advice. i was having the same kind of problem and it turned out to be something pretty dumb on my part. get the haynes manual and check the wire colors on your injectors. i had a crappy idle and it would drive fine after 3500-4000 rpm's. make sure you have the right plug wires going to the right injectors. hope that helps.

arghx

iTrader: (3)

i had those symptoms when one auxiliary port sleeve was stuck open and the other was closed

smog-guy707

iTrader: (11)

thanks guys, ill check for vacuum leaks leaks first just because its the easiest, as for the extra ground cables ive already added them

and i know this may sound stupid to ask but how do you check the auxiliary ports to see if theyre stuck ( ive only read in the third gen section till this happend)

SonicRaT

iTrader: (6)

They are two massive pressure actuators bolted on the side of the intake manifold (looking from passanger side), you'll see the arm coming out of the actuator attatched to a rod. That rod should be able to rotate/move open and closed with your hand. I'm sure you can find a whole lot more detail on testing those by searching though as it's been covered a ton.

smog-guy707

iTrader: (11)

^thanks for your help