Rough idle during cold start up.

[krmiller07]

I have an 89 Pathfinder SE-6 cyl. Manual Trans. that when cold, starts and immediatly goes into fast idle ( about 1300 rpm ) however it starts running so rich, that it runs like a carbed vehicle with a stuck choke. It idles rough, and shakes until the tempature comes up to the bottom of the gauge. Then as the temp continues to rise, idle settles down to normal and runs just fine. My questions are this. Has anyone experinced this ? And what could be the possible causes? I've done a thourough tune up. Plugs, wires, cap and rotor. Replaced all the vacum lines, checked for vacum leaks ( because that what it acts like ).However about 4 monthes ago, I replaced the O2 sensor and unhooked the battery while doing so. When I re-connected the battery and started the engine, this symptom starts. A few people have replyed in regards to resetting the ECU, and some have said that disconnecting and reconnecting the battery will reset the ECU. And others have said that cycling the starter or starting the engine at least 50 times, will do the same thing?

This rough idle and rich condition have been driving me nuts and I'm unable to read the codes from the ECU since I don't have access to a FSM.

Any ideas !?

 

Thanks,

 

krmiller07

krmiller70@hotmail.com

 

km@frozenrotors.com

Edited August 16, 2010 by krmiller07

[Specv1973]

FSM's are pinned at the top of this Forum. Not sure if there's ECU codes in there or not though. Good luck...

[MY1PATH]

the ecu needs several hours unplugged to reset.

do you have the stove pipe (intake heater) hooked up to the headder?

 

The TBI are commonly rich when cold, they warm up rich and with 5 deg retard timing so the fuel burns late and heats the engine more.

try bumping your timing to 15* then your cold idle will be ~10* and it may smooth out some.

[frecklecolouredbrain]

somebody else's link

i found this link after a quick search in here. check it out, but yours might be a switch on the right side and the light on the top and left side.

 

then look it up in a haynes or post it here, somebody will tell you what it is.

 

if it says 55, good luck.

 

just my pennies worth though. I had a similar problem int the cold(-20C) and it turned out to be my fast idle cam out of adjustment.

go to the 87-89 section of the forum and look at the TBI thread. and buy a haynes manual things like this are all in there.

[krmiller07]

the ecu needs several hours unplugged to reset.

do you have the stove pipe (intake heater) hooked up to the headder?

 

The TBI are commonly rich when cold, they warm up rich and with 5 deg retard timing so the fuel burns late and heats the engine more.

try bumping your timing to 15* then your cold idle will be ~10* and it may smooth out some.

 

 

Hi My1Path,

 

I do have a heat riser pipe coming up off of the exhaust manifold to the air cleaner snorkel. The valve on the snorkel is working as it should, and I've already set the timing @ 15*. How long should the ECU set diconnected ? I've heard several "arguments" or opinions about this ? This engine has about 45k miles on it, and is all stock. Except for a K&N air cleaner and no Cat.

[krmiller07]

somebody else's link

i found this link after a quick search in here. check it out, but yours might be a switch on the right side and the light on the top and left side.

 

then look it up in a haynes or post it here, somebody will tell you what it is.

 

if it says 55, good luck.

 

just my pennies worth though. I had a similar problem int the cold(-20C) and it turned out to be my fast idle cam out of adjustment.

go to the 87-89 section of the forum and look at the TBI thread. and buy a haynes manual things like this are all in there.

 

Thanks,

 

I have a Haynes Manual. And I cant find anything related to this problem. The link you posted is non-functional. My truck fast idles. It just runs really rich and starts to misfire while doing so. After it warms up to operating temp it's not as bad, but at idle it still sounds and feels like it has a miss.

[amo1dun]

I have an 89 Pathfinder SE-6 cyl. Manual Trans. that when cold, starts and immediatly goes into fast idle ( about 1300 rpm ) however it starts running so rich, that it runs like a carbed vehicle with a stuck choke. It idles rough, and shakes until the tempature comes up to the bottom of the gauge. Then as the temp continues to rise, idle settles down to normal and runs just fine. My questions are this. Has anyone experinced this ? And what could be the possible causes? I've done a thourough tune up. Plugs, wires, cap and rotor. Replaced all the vacum lines, checked for vacum leaks ( because that what it acts like ).However about 4 monthes ago, I replaced the O2 sensor and unhooked the battery while doing so. When I re-connected the battery and started the engine, this symptom starts. A few people have replyed in regards to resetting the ECU, and some have said that disconnecting and reconnecting the battery will reset the ECU. And others have said that cycling the starter or starting the engine at least 50 times, will do the same thing?

This rough idle and rich condition have been driving me nuts and I'm unable to read the codes from the ECU since I don't have access to a FSM.

Any ideas !?

 

Thanks,

 

krmiller07

krmiller70@hotmail.com

 

km@frozenrotors.com

 

dude...you may have a code stored so try running an ecu test see what code its throwing if any...

 

ecu test link

http://www.nissanpathfinders.net/forum/index.php?showtopic=21

 

 

 

let us know what you find

Edited August 23, 2010 by amo1dun