1UZ won't idle down while moving

[rmpig8]

Hi guys,
my problem is that my engine won't drop to low idle unless my car is sitting still. It doesn't matter how far I drive when I pull up it's still at high idle. If i sit still (like at traffic lights) it will drop down after about 20 seconds then be alright from then on.
Anyone want to guess at a cause? Cheers, Jay.

 

[gloverman]

Is it in a conversion? Or a factory car? Cheers

 

[samsdad]

Mine does this. Why coz most of the time it doesn't warm up enough and hit the magic 96 degrees C. Once it does and it does take a while it's fine for the rest of the time idling on spec rather than at 1200rpm.

How is your cooling system set up? What radiator are you using and does the fan run full time or part time?

TPS adjustment is also worth a look as is the throttle cable adjustment

Gloverman have another look at his post esp his signature

 

[rmpig8]

Yes this is the conversion in my 4runner. The problem was there in my Holden ute previous to this conversion so that rules out radiator and throttle cable as both are different. For this conversion I had Venom Cobras trim the loom down and they tested it but I don't know how hot they got it then.
To answer the questions though I have the standard V6 radiator and a pair of fans that run off of a temp switch.
Once I pull up and the idle drops it seems spot on so I doubt throttle position sensor is a problem either.

 

[samsdad]

Are you running a standard ECU or aftermarket?


Standard replace the thermostat with a stock one and go from there. Last one that had any issues like this idled at 2000 and was a crook TPS

 

[Bushwhacker]

EFI temp sensor?

 

[MX73 V8]

I assume your car is a manual now?

Mine does the same thing. (Manual 1uz).

(my other car) factory 1uz/automatic does it as well, but being an automatic it's not as noticeable.

 

[rmpig8]

Ok to answer the next round of questions: auto trans, standard ecu, on my third thermostat and second throttle body/tps. I swapped engines recently and swapped over a few things that didn't quite match (went from crown to soarer engine) so I'll check the temp sensor and see if that was swapped of not. I'm thinking more towards something speed related due to the fact it idles down as soon as I pull up.
Might give Venom a call and ask them what they think.
Samsdad, what system are you running if you can't get the car warm? My new engine runs cooler than the last one but still quite warm.

 

[4U2QUIK]

Mine does this. Why coz most of the time it doesn't warm up enough and hit the magic 96 degrees C. Once it does and it does take a while it's fine for the rest of the time idling on spec rather than at 1200rpm.

How is your cooling system set up? What radiator are you using and does the fan run full time or part time?

TPS adjustment is also worth a look as is the throttle cable adjustment

Gloverman have another look at his post esp his signature

exact same conclusion I came to about my car. it used to idle fine when i was moving, but then I installed a much larger radiator it idles high untill i've come to a stop for a bit.

 

[samsdad]

Ok to answer the next round of questions: auto trans, standard ecu, on my third thermostat and second throttle body/tps. I swapped engines recently and swapped over a few things that didn't quite match (went from crown to soarer engine) so I'll check the temp sensor and see if that was swapped of not. I'm thinking more towards something speed related due to the fact it idles down as soon as I pull up.
Might give Venom a call and ask them what they think.
Samsdad, what system are you running if you can't get the car warm? My new engine runs cooler than the last one but still quite warm.

UZZ31 Soarer engine with standard ECU, Manual trans, Standard diesel Surf radiator and 16 inch Spal cooling fan, just hits 96 deg on a 40+ day with the A/C on.

 

[rmpig8]

My setup uses the standard v6 radiator and a pair of Davies Craig 10 inch fans. The temp guage sits just a needle width below half guage on the standard dash most of the time but if I look at a long hill climb or a hotter day it goes up a lot more. I'm looking at fitting a 16 inch spal, a lot of people have recomended it.
My idle down problem only happens if I drive off. If I leave the car to run until it idles down it will be fine until I shut it down and it cools off a bit then the whole process repeats the next time I start it up. Hence my thoughts it was related to speed signal or something although my speedo works in this car and I used the whole dash and loom in the Holden ute and it had the same problem. Is my ECU the problem? It's the common part between both cars.

 

[samsdad]

The speed sensor in the 4runner is part of the speedo so as long as you have the wire from that (green with blue trace) hooked up to the ecu that won't be the problem. I think that the best thing for you is to check to see if any DTCs have been logged and go from there, reason being is if they do log a code they will "idle up". Another thing is to check for vacuum leaks as this will throw everything up the crapper.

I'm surprised that the V6 radiator cools it, those had enough trouble cooling the V6 and we used to change them to a diesel one to stop customers from cooking their V6 Surfs in NZ

 

[rmpig8]

I've never checked the codes so now might be a good time to learn how!
To be honest the radiator does struggle and I havnt driven it on a warm day with this engine yet. The old engine got very hot on hills etc but also ran warmer in general too. I'm only running on permits trying to get full rego so testing is a hard thing to do!
Out of interest, in my ute we sat the engine right back to put the centre bowl sump behind the front cross member leaving a 12" gap between radiator and engine. It ran like that with no fan at all for 5 years and only got hot once. And that was climbing Big Red at the end of Birdsville races weekend! Made it over too. Not bad for a 2wd with an open diff!