This is an odd one.

M

Mixpro

New Member
Jun 16, 2008
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Houston
Well I am confused. :nono:

The car temp gauge says it running cool and normal but when I get home from a drive and open the hood you can feel this thing cooking. The head gasket is good, had a leak down test done today. No probs there. No oil in the antifreeze or vise-versa. No white smoke, no nothing... But when I park the car its bubbling back thru the over flow. I checked the turbo and it is hot, I mean super hot... I think its running lean. So I replaced the temp guage sensor and the guage cluster and its a new harness on the motor. Still the same temp. I know my cold start injector sensor is bad. I was told that other than start up this also adds fuel under boost. Dont know if its true or not. Also my O2 sensor had gone bad as well.

Here is what has been done to the car since last week. Before this there were no problems.

Upgraded the CT26 with a 60-1 trim. I have a HKS 2mm head gasket, New Greddy timing belt. Head job with BBC chevy springs, 3 way valve job, new cams and shims, New seals on everything, new hoses on everything. New plugs, wires, SS turbo elbow, 3" down pipe. Hiflow fuel pump. AFM body from LS400 but supra electronics. Stock 440 injectors and I installed a hiflow electric fan. SAFC thais at defalut right now.

Fans are working and blowing like crazy.
 
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americanjebus

americanjebus

Mr. Evergreen
Mar 30, 2005
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how hot is it outside? and what is your coolant to water mixture? What is your elevation?

Mine does the same thing on really hot summer days or at high elevation, we have engines that run hot generally. You live in houston as it says in your ID so naturally its hot down there. When i get home i park and turn off the car but i can hear the coolant start to boil after about 2 minutes of sitting from the heat soak. If i leave my key in the ignition the electric fans will kick in and keep it from boiling over. This happens because there isnt enough coolant in the mixture from constantly diluting it by adding water to the overflow periodically. The lack of coolant to water mixture causes the boiling point to lower thus making easier to boil after a little bit of heat soak. Add more coolant, raise the boiling point, dont boil over and note the difference.

Lots of city driving? Let your car idle for a couple minutes after parking to let the oil and coolant lower in temps and help cool down your engine and turbo before actually shutting off their circulation completely.

I notice a huge difference in operating temps if i park immediately after a long highway cruise at low rpms vs stop and go traffic driving on a really hot day so idle time will make a difference.
 
Fozbo

Fozbo

7M Love
Apr 4, 2005
290
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Norman, Oklahoma
It might be the electric fan. I know some people on here have had problems with some types not cooling as well as the stock clutched fan. As a test, you might pull the electric fan and put on the stocker (if you still have it). It might be kind of a stretch, but it is possible.
 
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xarewhyayen

xarewhyayen

276 whp - 324 tq @ 13psi
Oct 3, 2005
959
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Philly
well as far as the turbo being hot, it should be. its a turbo. Exhaust gas circulates through it. You should let the car sit at idle for a few minutes after driving anyway to give the turbo some time to cool down a bit, but it'll still be super hot to the human touch or even closeness. Try replacing your radiator cap, if you're running normal temps and low cooling system pressure you'll boil. They're cheap enough to replace.

The reason a cooling system runs under pressure ( pressure is maintained in the system by the rad cap) is because raising pressure in a closed system raised the boiling point. Therefore if your cap isnt holding enough pressure excessive coolant is escaping into the resorvoir and causing boiling to occur in the cooling system..
 
Poodles

Poodles

I play with fire
Jul 22, 2006
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It's going to run lean with the lexus AFM as in your mod list you have NO way to tune it.

Get the stock AFM back on there, get rid of the electric fan and go back to a stock setup with a shroud and it should be fine.

Change the radiator cap and pressure test the system as well.
 
M

Mixpro

New Member
Jun 16, 2008
39
0
0
Houston
Well shit... Anyone got a stock fan and shroud?

The AFM is only the body of an LS400 with sthe stock supra electronics.
 
M

Mixpro

New Member
Jun 16, 2008
39
0
0
Houston
***UPDATE***​

I just did the 12v Pump mod for my Walbro pump and the over heating is gone. The lag is gone and its got shit loads of power again @ stock boost. It was running lean... I mean real lean...

Well shit!!!
 
hammerhead

hammerhead

Member
Sep 10, 2005
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Belize
i have had some similar experiences. If your rad cap is not holding the pressure, that will drastically bring down the boiling point. also stopped up rad will do the same thing.
 
Poodles

Poodles

I play with fire
Jul 22, 2006
16,757
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Fort Worth, TX
The 12 volt mod is NOT an answer to the lean condition that you where having from running the Lexus AFM with stock injectors.

TAKE IT OFF

Because now instead of going lean everywhere you're going to go lean up top and have a serious melt down.
 
shaeff

shaeff

Kurt is FTMFW x2!!!!
Staff member
Super Moderator
Mar 30, 2005
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Poodles;1084026 said:
It's going to run lean with the lexus AFM as in your mod list you have NO way to tune it.

Get the stock AFM back on there, get rid of the electric fan and go back to a stock setup with a shroud and it should be fine.

Change the radiator cap and pressure test the system as well.
Click to expand...
This.
Poodles;1084155 said:
The 12 volt mod is NOT an answer to the lean condition that you where having from running the Lexus AFM with stock injectors.

TAKE IT OFF

Because now instead of going lean everywhere you're going to go lean up top and have a serious melt down.
Click to expand...
And this.
 
shaeff

shaeff

Kurt is FTMFW x2!!!!
Staff member
Super Moderator
Mar 30, 2005
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Mixpro;1085327 said:
if i am running the stock electronics and the body from an LS400 is it still going to run lean?
Click to expand...

You have much to learn. Read this, and when you're done, you need to read it again. Make sure you FULLY understand what you're doing before you modify your car, otherwise the outcome can be disastrous.

http://rob.carlile.home.mchsi.com/lexus/lexus1.htm

I've posted that link countless times. A quick search would have revealed that.

In short, it's not the electronics, it's the AFM housing. It lets in roughly 25% MORE air than the stock unit. That housing, with stock injectors and no way to tune the car means that you have 25% more air than your injectors are able to handle (without fuel management). That's getting quite lean. ;)
 
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