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poor running lexus ls400

Old 10-08-18, 09:46 AM
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Exclamation poor running lexus ls400

So I've got a 1994 lexus ls400 currently with no engine codes but a solid TRAC light and is running horrible. Or rather it will idle but nothing more. If i depress the accelerator pedal it bogs down the engine and will not go above 1200 rpm's.
It ran for 2 months with no issues when i bought it and then one morning I went to fire it up and got a crank no start. No problem, as I noticed the fuel pump wasn't making it's usual noise so I figured I'd just replace it. I did the old Te1 to E1 since its an obd1 and came up with a code 24 (Bad signal to MAF) and a code 31(IAT improper reading) as well. I thought ok Ill clean the MAF and go through the other wiring and clean the engine up while I'm at it... It would need a tune up by now anyway so i replaced the spark plugs and found 1 that had a bad coil and replaced it. After hand cleaning the engine with cloths and rags, checking harnesses, replacing the fuel pump, spark plugs, and bad coil I found the MAF sensor to be not working and replaced it. Now the codes went away but the engine is still running rough. I thought maybe the ECM had blown so called the local yard and got one for around $50 used but tested ok. I took the old ECM out and yes it definitely had some melting resistors so I'm glad I caught that. I put the new one in and it took a few times cranking to get the car idling again...But nothing changed. Just for ****s and giggles I hooked up my quick connect fuel pressure kit off the Fuel Pressure Regulator rail and even while running if I depress the nipple on the quick connect I only get a teeny tiny squirt of fuel and then nothing.(my gauge isn't reading anything)
My gut is saying to replace the FPR but I don't wanna start throwing parts at it if I can help it.

Recap: Had engine code 24 and 31 but went away after replacing fuel pump, spark plugs, spark coil, MAF, and ECM.
The engine still runs rough and wont go over 1200 rpm while idling or 25 mph if I get it rolling.
I've read dozens of post's and believe not every car is the same so if you think I'm on the right track please let me know.
I'm just a do it yourselfer trying to do it right.
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Old 10-11-18, 12:57 PM
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I've got the same bogged down scenario, but only intermittently. Once a week, for 10-20 seconds. Stops me dead in traffic as I try to accelerate from a stop.
I had the fuel system chemically cleaned - no help.
I was going to try plugs and wires next. I'm not familiar with the sensors you mentioned - I'll have to do some reading.
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Old 11-12-18, 09:48 AM
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This is the IS forum, so the members in this section probably wont know the ins and outs of your car like the LS members would.

Throttle body gone bad maybe? Ive heard of the actuators overheating and crippling them, but not killing them.

Just throwing ideas out there. Might be wise to bring it in to prevent damage if any is occurring.
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Old 01-12-19, 05:25 AM
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Default Try cleaning your catlyne converters

It's a pain in the *** inust cut mine off Did wonders for my is
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