High idle 1GZ-FE

[cue340]

Hi, I have a 1gz engine conversion, the car used to have a large box on the bonnet for clearance. I modded the manifolds to lower the height of the engine. now my motor idles around 1200-1300 to rpm. I am not sure why. Most of the vacuum switches are no longer on the motor. The mod was removing the top two plenums and attaching the Tb's to the lower plenums. Thanks

[maccac__1590]

Was this the gz in the x90 that was for sale a little while ago? either way thats cool as hell haha.

Not a vacuum leek somewhere? spray some flammable contact cleaner around the manifold and see if the engine changes note.
What do these have for idle control? a stepper motor? could be stuck open or half open or something?

[cue340]

Hi Macca
yep its the one that was for sale just over a year ago. I have spent a bit of time looking for an air leak using a tube to listen and a can of CRC, no luck.

the 1GZ is drive by wire, so it has stepper motors on the throttle bodies to open and close the throttles and look after idle control as well.

I purchased a bluedriver obd2 device to try and do some diagnostics but I don't think it supports the Century at all.

[maccac__1590]

Cool cool, that thing was cool, glad you were able to get rid of the bonnet buldge cause it didnt quite suit the car haha.

MMMMMMM thats a weird one, the throttles should be shutting off to get the desired idle speed, so its as if the ecu is commanding high idle for some reason. if its a obd2 compliant engine any tool should be able to read it, weather it can get all the info out is another story, do you know what year car the engine came from? is the obd2 plug all wired up correctly to the correct pins in the ecu?

[cue340]

The motor is from a 1997 century, My understanding is all the v12 centuries had OBD2. The OBD2 reader i got is one of the more technical ones, I got it specifically because it was able to look at the fuel trim table which shows compensation from O2 sensor readings. This can let you know if extra air is getting in the inlet, basically if there was an air leak in a manifold. (The blueDriver website says that if your car is not listed it will not work at all... century is not listed)

I'll get hold of a more generic one to simply pick up error codes, maybe something is not working and as a consequence the idle is just not activating. Yeah the bonnet bulge also gave away the fact that there was a conversion, much more stealth now. Good point on the wiring for the plug, maybe its not wired up correctly or completely, i will check that out. I really was expecting 2 OBD2 connectors, but there is only one.
Cheers

[madmont]

I run a JDM 2JZGTE. I use a "LAUNCH CREADER VI+" to read error codes and erase them. You need a JOBD reader which the LAUNCH is. On my motor the Launch will not give me real time readings on the sensors.
For real time readings of the sensors and much more I use an app called "IN CAR DOC PRO" The pro version cost me $4.59. This app does not erase the error codes for me but gives me other info. Works off an ELM327 Bluetooth. Even works on a Mercedes which was here. It also has Toyota Century on the list of supported vehicles

[cue340]

Madmont
Thank you for the info! that is very helpful, I have ordered a Launch Creader VI and an ELM327 that looks just like the one you have pictured. cheers

[madmont]

Madmont
Thank you for the info! that is very helpful, I have ordered a Launch Creader VI and an ELM327 that looks just like the one you have pictured. cheers

Make sure you get the VI+ not the VI