Hunting Idle

S

supra-truck

New Member
Aug 25, 2010
8
0
0
Billings, MT
I finally got my 7mgte to start and it runs great no misses revs great only problem is it wont idle
im not sure on exact rpm because its a n/a tach and turbo ecu but it idles high and steady for a while
until it warms up then it starts hunting for a idle speed it goes from around 1000 to around 2000 to 2500 then back down. iv already searched for vac leaks adjusted cps and tps with no improvement. if i unplug idle air control it does not run any better or worse so i am thinking that is the problem but how do i check it to make sure? also does anyone have any other suggestions on what my problem could be
 
gottadiesel

gottadiesel

Flyin Low
Feb 16, 2009
459
0
0
Vancouver, Washington
^^ ^^ I second the motion of ISC as 1st place culprit

2nd choice - I would look, assuming as you said no vac leaks found, is to make sure the TPS is set correctly, I do not think it would cause that drastic of a idle hunt, as I know the ISC does, but if it is not sending signal to ECU that I should now be at idle (throttle position 0%) I am not certain what the symptom would be... IIRC you should be able to check, as you would throw a TPS code with the diag jumper in, if the ECU was being told that the throttle is off of idle position (anything 1% or greater of open position)

Also congrats on getting it started and running... that can sometimes be a mighty step in and of itself...

Hvyman beat me to it...
 
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gottadiesel

gottadiesel

Flyin Low
Feb 16, 2009
459
0
0
Vancouver, Washington
gottadiesel;1649262 said:
^^ I second the motion

FYI I used two AA batteries in series to make the 3vdc that is required for testing per the TRSM...

2nd choice - I would look, assuming as you said no vac leaks found, is to make sure the TPS is set correctly, I do not think it would cause that drastic of a idle hunt, as I know the ISC does, but if it is not sending signal to ECU that I should now be at idle (throttle position 0%) I am not certain what the symptom would be... IIRC you should be able to check, as you would throw a TPS code with the diag jumper in, if the ECU was being told that the throttle is off of idle position (anything 1% or greater of open position)

Also congrats on getting it started and running... that can sometimes be a mighty step in and of itself...

Hvyman beat me to it... I was seconding whitemike by the way...
Click to expand...

OOPS! In reference to the 3vdc.. I was mistaking my memory of doing the Igniter test with the ISC... ISC as I am sure you read in link from Hvyman uses 12vdc battery voltage... Sorry my mistake...
 
S

supra-truck

New Member
Aug 25, 2010
8
0
0
Billings, MT
So i have a update, if i take the main vacuum line that runs from the accordion hose to the ISCV and plug it on both ends the car idles perfectly.
any suggestions on what i could do to fix the problem? or should i just run without the ISCV?
also the reason i figured this out was from watching a youtube vid of a car with the same problem
http://www.youtube.com/watch?v=uWs3S3I3x24
 
S

supra-truck

New Member
Aug 25, 2010
8
0
0
Billings, MT
so i adjusted the throttle rod now i am def sure the throttle is closing all the way but the tab on the throttle linkage does not touch the idle adjustment screw when fully closed is there a way to adjust that so the screw will actually do its job
because now the car idles so low it stalls and dies. also it did not fix the idle surging problem. with the IAC connected it surges from 1500 to 2500 (i swapped in a turbo tach and now i have a way to monitor the surge) so im still chasing other problems
 
M

mk3-4-me

New Member
May 19, 2010
669
0
0
Milwaukee, WI
i am having the exact same problem. Same thing happens when i pull the ISCV hose from the accordian. Idk what is could be. The resistances between the terminals on my ISCV all are within spec.

I watched the same video and its just like that.
 
S

supra-truck

New Member
Aug 25, 2010
8
0
0
Billings, MT
have you figured out what the problem was? i have been working non stop but im gonna try to fix it again this weekend and i would really like to know what to try
 
M

mk3-4-me

New Member
May 19, 2010
669
0
0
Milwaukee, WI
no i havnt yet, on mine when i pull out the iscv hose and plug it up most of the way, it idle close to perfect. So im thinking i need a new one. Thats wat everyone else has been sayin and done.

So hopefully thats it. Did u try plugging the iscv hose when it was runing? it should lower the idle.
 
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Rollus

Rollus

New Member
Jun 2, 2011
593
0
0
Paris, France
supra-truck;1649462 said:
So i have a update, if i take the main vacuum line that runs from the accordion hose to the ISCV and plug it on both ends the car idles perfectly.
any suggestions on what i could do to fix the problem? or should i just run without the ISCV?
also the reason i figured this out was from watching a youtube vid of a car with the same problem
http://www.youtube.com/watch?v=uWs3S3I3x24
Click to expand...

Hello guys,

I'm new to this forum, read a lot but never posted.

I have about the same problem, idle is rough between about 5-800 rpm then it stalls. If I disconnect the hose between maf and isc, then it idle smooth but high (1500 rpm). If I close the ISC air pipe with my thumbs, it idles smooth at requested rpm.

I've swap my engine beetween my old 7mgte, to a new one, same year, same type.
I've put an HKS filter on the maf, because my stock Toyota filter was very bad... I've removed canister and egr recirculation, hoses for them are filled and airproof (sorry for my english).

Please, can you guys tell me what have you done to sort this issue?

Have nice drives ;)

RolluS
 
Rollus

Rollus

New Member
Jun 2, 2011
593
0
0
Paris, France
Problem solved for me, was my mistake...

On this engine, a Lexus AFM, iridium spark, and big injectors were mounted.
Lexus AFM has been remove, but big injectors remain...

I've put back stock injectors and sparks, the engine runs smooth and well now.

I've been told that iridium sparks may bring problems on a turbo engine, and that platinium are better...

++

RolluS
 
Rollus

Rollus

New Member
Jun 2, 2011
593
0
0
Paris, France
digihonk82;1724067 said:
Hahaha is this guy for real----^^^^
Click to expand...

Yes I'm real lol. BTW, I've bought this engine like this, didn't notice inj weren't stock even if I've changed the seals...

jetjock;1724075 said:
Strange, I've been wondering the same about you.

How is your French btw?
Click to expand...

Mon français ca va, je suis né avec, mais vais laisser digihonk82 répondre ;)

++

RolluS
 
kotu100

kotu100

Active Member
Nov 23, 2006
1,899
0
36
Easton, Ma
check the MAF plug, theres an oval gasket that goes in the plug. make sure its still there, sitting in the proper position, and not crushed.
I had a hunting idle problem for a couple months and everything tested good, its wasnt until i fixed this gasket that it went away.
 
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