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So I purchased my 98 LS400 around three weeks ago. Ever since there's been a ongoing problem. Starting it and bad RPM's. It worked fine at first then. One day I went to start it after letting it sit for about seven hours and it started and died instantly. Tried again gave it gas and it ran fine. Read some about it people said clean the throttle body and iacv so I cleaned the throttle body not the iacv because I don't know where it is on the 1uzfe vvti I now where it is one the regular 1uzfe not in the same place since the throttle body was relocated to the front. 

After cleaning the throttle body it ran great for a day or two then I had to give it a little gas when it started. Then it would start after giving it a little gas the first time maybe it would fire up the second or third time. Now it's gotten so bad that I get in try it and it stalls remove the key and inject it and remove it once more and then try to start it. I'm trying to get fuel in the engine, because if I don't do this routine it just cranks and cranks.  After several attempts it will fire up after more than five of these attempts. 

Ive notice that if it's a colder morning, sixty ish, it can start on the first go if I give it gas. And after running a little it just doesn't want to start like if it was warmer outside. 

Ive noticed a few other things, they might not be related. The security light does turn in when the car is unlocked and goes off when the key is injected so it's working I think. The touch screen and the clock turns off after the engine starts and resets the clock but not the radio settings. New battery and has had a recent oil change. Some of the vacuum hoses and either old or replaced. Power steering is out. And there is a brake problem. There was an engine light on but it's not know. Had it checked something about the immobilizer and the two o2 sensors. The timing belt was changed about 115,000 miles before the seller said. I have been putting premium gas in it. I'm not sure if the previous owner did or not. 

Should I check fuses, clean the idle air control valve (if so where is it located and what to use to clean it) or replace it. Make sure all vacuum lines are sealed. Replace the immobilizer and/or the o2 sensors. Or what do you guys think. I can't afford to take it to the mechanic. Anything helps. 

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Forgot to add that there is a cloud of smoke usually when it fires up the first time and then dies like usual. And the fuel gauge says about a quarter of a tank but the light is one and the eange says low fuel. When I bought it the car was below the empty mark. Maybe bad bad guel pump and sensor?

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voting throttle position sensor, or air flow meter/02 combo.

What makes you say that. Just wondering.  Because from other threads for iacv the problem is similar but not the same, they say when they start it they give it a little gas and it starts up I try it and it doesn't work. is it the throttle position sensor your thinking of. 

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a few reasons,

i had a similar issue with a Subaru. when the air flow sensor, and o2 sensor are not working right, the car can either "Lean out" causing detonation or fuel starvation, or can run rich, bogging it randomly. also check your plugs, sounds funny, but after running with bad sensors for a while, it ruins your plugs. replacing those, for good measure, and checking the fuel system is one angle i would start with,

- the other being a replacement air flow sensor,o2 sensor, and throttle position sensor. first using an electrical circuit tester with a voltage meter to check for drops or climbs in values. one by one. essentially seeing when they work, and how. (find the faulty one, or 2)

These engines are robust. however, the ecu can only run it with the information it gets. and i'd bet a punch in the arm, the ecu is getting the wrong information. and you have bad plugs as a result.

the only issue a friend has had with the same engine, is the Throttle position sensor. his car would suddenly drop out on him. fixed it, and has had no issues since.


so go back to basics, -spark,fuel, ecu inputs.

haha, might as well do a service while you are doing all this. :smile:


my own car is starting to act up. our issues could be mirrored. so i have a vested interest in this topic. keen to know what you find.

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