S13 DOHC idle problems, I need some input please

[ak240mon]

Ok, I just had my auto switched to 5spd. The car runs fine, but when I get to a stop and press the clutch in the idle jumps to about 1800 rpm almost 2000rpm. Then if I sit there a few seconds the idle drops back down to a normal idle. But if I even touch the gas pedal the idle will jump back up to 1800-2000 and will then settle back down after a few second to normal idle. I had fuel issues right after I got it back from the shop but stuck a walbro 255 in and it seemed to have fixed the problem of not starting. So is my problem still fuel( pressure, injectors, rail, whatever) or could it be the distributor? Any feedback would be greatly appreciated. thanks AK

[JNM240]

Kinda sounds to me like your secondary butterfly valves are sticking open. I would check the vacuum to the solenoid, as well as all your vacuum lines on the intake manifold. Could be a small leak somewhere.

[ak240mon]

Ok, I'll check my hoses when I get home today. I need to go ahead and freshen up that stuff anyway. The problem is consistant though, it's not fluttering or anything like that. Thanks though for you info, have a great one, AK

[ak240mon]

Well if anyone still has any expertise to throw my way. The car still has the idle problem from above. My 240sx guru has never heard of the problem. Any help would be greatly appreciated.

[mmm240]

my 93 does the same, but only when i touch the gas, not when i push the clutch in.

i bought the car with the manual swapped in (used to be auto), so i don't know if it always did this. it doesn't really cause a problem, just curious

sorry i can't help, but free bump!

[ak240mon]

Well I guess me and you are the only people to have come across this problem. But like you said the car runs fine, it's just a little tricky in stop and go traffic. I would still like to see if there is anything I can do to correct this. thanks for the bump, BUMP.

[Jiggyfry]

hey guys, i have the exact same problem. When i come to a stop and push in the clutch the idle will jump up to aboot 1300rpm and after 5 secs will settle down to around 800 rpm. I recently rebuil;t the engine and checked every hose and cleaned everything, still the problem persists. Ive cleaned the aiv last week and its still there, anyone have some ideas???????????

[zero_gripS13]

im afellow auto to manual convert... and i got the same problem... not sure what it is...i thought i was the only one.. seems like its the converted 5spd people with this problem./..

[whiterps13]

It sounds like ap roblem with the ECU. Did you guys swap out the ECU when you did the auto-manual conversion. If not, does it need to be changed?

[Jiggyfry]

i have not swapped out my transmission like these guys ^. I still have the original 5 spd in it. I have checked multiple times for a leak and so far nothing. REcently im not having this problem, drove for aboot an hour last night and it never happened once, WEIRD! Could all this be related to my idle control maybe. Im starting to think it could be related to my "fast idle" control. What aboot spark plug wires? mine are toast i believe, could this be the cause? Oh well, ordered new wires, we'll see what happens.

[whiterps13]

My guess was correct.

zerothread?id=168658

[ak240mon]

Well that sounds about right I guess. I am using the auto ecu. So is there no way to reprogram my ecu to stop this or do I just need to swap out the auto for man. ecu? Thanks for your help and the link though MAybe Jet chip? thanks, AK

[mmm240]

Well that sounds about right I guess. I am using the auto ecu. So is there no way to reprogram my ecu to stop this or do I just need to swap out the auto for man. ecu? Thanks for your help and the link though MAybe Jet chip? thanks, AK

to my knowledge a jet chip is just that (a chip), not the ecu, it will connect into the ecu, but i don't even know if you can get one for our cars. i would just go with a reprogrammed one, my buddy put one of those jet chips in his ford contour (auto trans) and all it did was make half throttle feel like full throttle (and you can't do any better then full throttle anyways (made the car hard to drive smoothly)), it also raised the limiter to about 7.5 thousand, then a few months he blew the motor

and thanks for the find whiterps13 answers a lot of questions!

[Jiggyfry]

Anyone got any ideas, like i said i have the original 5 spd in it, no transmission swap done. Ive changed my plugs, dist cap, rotor and installed new wires, still slightly off idle. Say im driving, i slow down and come to a stop sign, push in the clutch, the idle will drop and stay at aboot 12-1300 rpm for aboot 5 secs then will drop down to normal, 800 rpm. Im now pullin my hair out on this one guys, the last thing i can think of doing would be a good injector cleaning. Any input would be appreciated!

How much deeper would the ocean be if sponges didnt live there?

[zero_gripS13]

borrow a friends 5spd ecu and see if itt still does it..

i kinda thought it was the ecu but it doesnt bother me too much... ill change sometime whever i feel like it

[Dustin240]

I had the same problem and my TPS needed to be ajusted.Dam TPS can really make a car idle like crap.

[ak240mon]

WEll to comment on the jet chip first, yes they do have one for a 240sx. Also all the jet chip is your ecu chip reprogramed to allow more air and fuel. I just didn't know if maybe when JET reprograms the chip it would help out.

So did the new TPS help? I know I was confused when I was told that the auto ecu will work just fine on a 5spd, anybody changed over to the man. ecu yet to see if that was it?