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lexus1995ls400owner

Problem Affter Throttle Body Cleaning

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I just finished cleaning the throttle body of my used 1995 Lexus LS400. When putting it back together, I noticed an unconnected hose from the bottom of the throttle body hanging which I didn't take off during the cleaning (I cheated and didn't disconnect the throttle body from the engine, I disconnected just enough to be able to move the throttle body out of the way to clean it). The other end of the hose is connected to a 90 degrees metal tube. It looks like the metal tube should go into the engine valve cover but it doesn't want to go in very far, so I'm wondering if this is where the hose should be connected. See my picture of where I've attempted to connect the hose to the engine. Can someone look at their 1995 LS400 engine and tell me if I've reconnected it up right (or a picture of where it should go). I've also got a MIL code P0170 which is Fuel Trim error, after the throttle body cleaning so these two may be related. I've also replaced the thermostat, flush the transmission fluid, changed the oil, replaced a very dirty air filter, all at the same time as the throttle body cleaning. Do you guys think the P0170 error code is related to any of these other activities. Thanks.

How does one attach a photo to a post ???

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Welcome to the forum.

To attach a photo, click on the Full Edit link, below the text box you should see an Attachments section. Browse to your file and click UPLOAD.

Once you do I'll compare with mine.

ADDED: This thread shows a pic of a TB:

http://www.clublexus.com/forums/ls400/3771...hange-pics.html

Here is a diagram showing the vacuum hoses connecting to the TB:

http://www.toyodiy.com/parts/p_U_199502_LE...EPGKA_2211.html

Since you did all that work, you may want to disconnect the negative lead to the battery for 10 mins to reset the ECU and see if it comes back to determine if you have a real issue or not.

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Welcome to the forum.

To attach a photo, click on the Full Edit link, below the text box you should see an Attachments section. Browse to your file and click UPLOAD.

Once you do I'll compare with mine.

ADDED: This thread shows a pic of a TB:

http://www.clublexus.com/forums/ls400/3771...hange-pics.html

Here is a diagram showing the vacuum hoses connecting to the TB:

http://www.toyodiy.com/parts/p_U_199502_LE...EPGKA_2211.html

Since you did all that work, you may want to disconnect the negative lead to the battery for 10 mins to reset the ECU and see if it comes back to determine if you have a real issue or not.

Thanks for the quick reply. Resetting the battery (and resetting the code using a OBDII scanner) did not help. The error went away but then came back after a few startups and short trips. I'm still unable to attach a photo. I see an "insert image" button, but when I click it, it wants a URL ("http:") location and there isn't a "browse to" file option.

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I'm still unable to attach a photo.
Hmmm. You may not be able to until you've posted a few more times.

Try this, click on the Add Reply button below this thread. Below the box where you enter your reply, do you see an Attachments section? If no, then you'll need to post more before you do. Forum rules I guess.

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Another data point ... I took off the MAF sensor and blew some air in there to clean it up. Also hooked up an ODBII scanner to get more info on the P0170 code. The engine is running rich, the short term fuel trim is at about +12% (it's lower now that I've cleaned the MAF), but the long term fuel trim is at +29.7% at idle. I think the trip point for the MIL is +30% so it's running very rich. Engine RPM is normal at 670 RPM. I've reset the ECU again. Hopefully, the MIL doesn't come back.

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That hose in question does indeed go to the valve cover, it's a breather. It connects to the bottom of the throttle body to a similar nipple.

If it's short, the hose may have been cut or more likely became brittle from underhood heat and broke off when last removed, you can just buy a piece of heater hose to replace it or leave it open, but put a filter of some sort on it, some oil blowby will come out of it and get all over the engine of left open. Mine is open but with a piece of hose draining into a small container that I use as a catch can because I don't like the vapors being sucked in and reburned in the engine, it gunks up the intake plenum.

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Would having an air leak in this hose causes a MIL of P0170 (Fuel Trim malfunction). Everything was fine until I cleaned the throttle body and replaced the air cleaner. I'm still having this fault after a MAF cleaning. What else could be causing it ? The engine seems to run fine despite the fault, perhaps slightly worse in fuel economy though.

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