Idle going really low after giving it gaz

[nathan007]

Hello,

I run a h23vtec OBD1 swap (tuned ecu), Runnign idle is great (around 750rpm) and consistent recently, especially when the engine is warm, if i give it gas and let go of the pedal the engine idle will get very low (below 400rpm) and come back to normal.
Today while driving it became worse; i was running for about 15 min highway but when i came off to my Stop engine amost died. Runs perfect but when i clutch and let go of the gas engine idle is scary low..

Any idead of what to look for?

 

[HEADACHE CG6]

check your fuel pump and fuses

 

[dawg316]

how long has is it been running smoothly on a tuned ecu before the problem occured?

on a ecu theres is a taget idle ( lets say 800 rpm)

on hondas when you let go of the gas the injectors actualy turn off then turn back on when comanded to via the ecu.

take it to your tuner or who ever tuned your ecu and let them know the symptoms. sounds like an issue with the partial throtal fuel table

the iacv should also controll stalling issues. if you want you can clean it out and see if that helps the issue aswell

 

[nathan007]

It was running fine last season, even last week before I cleaned the iacv. At the same time I did switch out my iat (or map)?? Sensor (driver side of the intake manifold) because it was covered with oily residue. I will reswitch my original one tomorrow and see if it fixes my issue, then see from there..

Other than that no driving issues whstsoever, perhaps maybe a slight rough idle but its hard to confirm with poly mounts and no balancer belt...

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[nathan007]

It was running fine last season, even last week before I cleaned the iacv. At the same time I did switch out my iat (or map)?? Sensor (driver side of the intake manifold) because it was covered with oily residue. I will reswitch my original one tomorrow and see if it fixes my issue, then see from there..

Other than that no driving issues whstsoever, perhaps maybe a slight rough idle but its hard to confirm with poly mounts and no balancer belt...

Sent from my 6045I using Tapatalk

Edit; best example is with engine warm going in traffic, if I have to clutch and brake to some at a stop I am at near stall, then idle will progressively go back to normal

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[dawg316]

ahh sounds like an intake leak in that case.

the iacv hase o-rings thats are usualy flat AF. and when people clean them they dont relize the orings are already flattend. i usualy put a thin smear coat of RTV on em to insure a seal.

sounds like when the engine gets warm the oring gasket isnt sealing.

could be the same with the IAT sensor ( sensor on driver side)

that also has an oring so check that **** out

 

[nathan007]

Yeah I put rtv the first time when I assembled the engine, bit not this time.. Will definitely check it out!!

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[Rusty Accord]

It was running fine last season, even last week before I cleaned the iacv. At the same time I did switch out my iat (or map)?? Sensor (driver side of the intake manifold) because it was covered with oily residue. I will reswitch my original one tomorrow and see if it fixes my issue, then see from there..

Other than that no driving issues whstsoever, perhaps maybe a slight rough idle but its hard to confirm with poly mounts and no balancer belt...

Sent from my 6045I using Tapatalk

Try swapping the wire plugs between the MAP and the IAC. They'll interchange, and it IS possible to plug them into the wrong spots.
Just a heads up.

 

[nathan007]

Thanks for the advice, but the day i routed my wiring when i did the swap, there is no way to interchange due to wire lenght.
I did add atv sealer to the IACV oring (the obd1 8 shape one), and changed the oring on the IAT sensor, reset the ECU, still the same issue..

Perfect idle when cold, give it gas and returns right to target idle RPM, but when warm, will dip very low near stall and get back up to idle rpm..
I have a few other things to check (alt output, TPS signal, throttle body, possible vacuum leak, MAP ), just lacking time with a boat to prepare and help my brother whith his car.. Will keep you folks updated!

 

[Rusty Accord]

Perfect idle when cold, give it gas and returns right to target idle RPM, but when warm, will dip very low near stall and get back up to idle rpm..
I have a few other things to check (alt output, TPS signal, throttle body, possible vacuum leak, MAP ), just lacking time with a boat to prepare and help my brother whith his car.. Will keep you folks updated!

What are you using for a "cold" idle target? Just asking as my own car runs anywhere from 1200 to 1400 rpms depending on outside air temp. Once warmed up (operating temp) it's down to 750 rpm, unless the AC is on, then it drops another 20 or so rpm.