Bogging in LOW rpms only when cold

[s13sr20detsilviastityper]

So ive had an ongoing problem with my car...

it will bog very hard in low rpms .. till around 3000-3500 when it is cold

but once it warms up its fine..

i had a knock sensor code, i rewired it but i believe its still giving me the code...

ive tried unplugging the hsoe from the FPR, and the o2 sensor no help

its hard to diagnose because once its warmed up it dissapears...

any ideas? thanks

[mrzabala]

sounds like what happened to my friends sr20det. We stripped out all the interior and unplugged most of the wiring for bedlinning. Than when we hooked it back together and started the car it started bogging, it could be that the ecu was re-learning its value like my friend explained.. I had to solder all the direct spliced wires, sanded to bare metal for the grounds in the car with dieelectrical grease, and made sure the ecu harness plug pins were cleaned and that the plug went into the ecu evenly while bolting down (I think the ecu was one of the main reasons it bogged). Than after a couple start ups (letting it run 5 min and turning it off resting for 5 min) I revved it a couple times and the idle went from bogging to normal. But then when we tried it the next day it started doing that but then went away when warmed up. After the first test drive (lowered the rpm to 850, it misfired an stalled a couple times. So we raised the rpm to 1250, and now it passed all test drives.

So overall check the ecu and ecu plug and make sure the pins are good condtion, clean, and evenly pushed in when bolting it to the ecu. Then do a couple test runs by changing your idle speed a little lower than higher if needed.

[s13sr20detsilviastityper]

Its been going on for a while, its not something that is going to clear itself unfortunately.

the ecu is code clear now, im thinking the engine temp sensor (red) could be bad, perhaps it is sending signal that the motor is warmed up so thats why it doesnt run decently until it is warmed up..

What RPM does the motor turn when you first start it?

[float_6969]

What RPM does the motor turn when you first start it cold?

[s13sr20detsilviastityper]

~1500

i unplugged the engine temp sensor (red sensor on intake manifold) and the stuttering is nearly gone, so i will replace it...

now it "cold" idles (~1750 rpm) for around 5 mins of regular driving and then drops to normal

but of course it wont run perfect with it unplugged, but since it runs so much better with it unplugged that means it is messed up

[fitch9014]

i'm going to stand by this, because i've said it before, i think this is just what these engines do when they're cold...it keeps you from planting your foot in it before it's ready...by the way, how cold does it get where you're at?

[eliterit]

Its been going on for a while, its not something that is going to clear itself unfortunately.

the ecu is code clear now, im thinking the engine temp sensor (red) could be bad, perhaps it is sending signal that the motor is warmed up so thats why it doesnt run decently until it is warmed up..

What RPM does the motor turn when you first start it?

can i ask what u did to get rid of the code you got? im thinking you possibly had a code for a knock sensor? correct?

[s13sr20detsilviastityper]

i'm going to stand by this, because i've said it before, i think this is just what these engines do when they're cold...it keeps you from planting your foot in it before it's ready...by the way, how cold does it get where you're at?

like 60 degrees??

[s13sr20detsilviastityper]

can i ask what u did to get rid of the code you got? im thinking you possibly had a code for a knock sensor? correct?

i had a code for knock sensor

wired it correctly and independently (had been cut at the ecu) with shielded wirei drove it up the driveway to the street and checked codes and it gave me maf, cas, kncok sensor

so obviously wasnt right

i checked it after driving to school the next day and got 5 5 (no problems)

either way, if it was the knock sensor, it wouldnt simply dissapear once it got warmed up