Intake Dont Sound Correct

[madjack1369]

Hi guys. gotta start be thanking everyone involved with this form. Great wealth of info. here. OK... I have a 91 ls400.. It threw the belt due to a bad tenchener. Replaced it and belt. car would drive then die . start ,drive a bit, die. I Checked the crank position sensor . wires ect... for damage. saw nothing but when I put it back in. The car ran flawlessly for about 2 months. Now it runs , dies ect....... After reading the other post I am very sure that I need to replace the ECU. It has the series of #s that I hear were recalled from the factory. I machanic a bit but here is where Im stumpped. When the car started dieing. I started to hear this Sucking air sound like the intake (air cleaner ) assy had a leak. It would start and stop like it was controlled by vacume or a switch. It seems to lack a little power but now stays on the whole time the car is running. Could it be the MAF or VAf some call it? Its almost as if airflow were restricted. Guys. IVe checked airfilter,housing, rubber intake parts, vacume lines. I cant believe I havent figured this out. Also. No code but traction lite comes on. I think the check engine light bulb needs replaced.

[landar]

Even if there is no check engine light, I would still do the jumper trick to check for codes. If you hear a sucking sound then a vacuum leak could be your problem. Get a stethoscope at CVS, Walgreens, etc and start "sniffing" around the intake components. You can also use a short length of garden hose held up to one ear. Other ways are to use a propane torch around various hoses or intake ... you turn the torch on so that it is spewing gas without being lit then direct the flow around various intake areas. If you hit the spot where the vacuum leak occurs, the engine RPM should suddenly change.

From your description, it sounds like there is a vacuum leak after the MAF which results in a lean mixture and poor performance.

[1990LS400]

Get a stethoscope at CVS, Walgreens, etc and start "sniffing" around the intake components.

Mine looks exactly like this one and was dirt cheap when I bought it years ago at an auto parts store.

[madjack1369]

Good idea . However i have spent alot of time eliminating vacume leaks ect...I like the idea about the tourch. I cant help but wonder who the fellow that tries that and burns their car down. Ha ha... Not being mean but their out there. Anyway , my friend, I pulled engine codes 14 and 71. did all the tests for the egr and #1 igniter. Have any last thoughts. Im pretty sure the air sound is because the ECU isnt opening egr correctly. I have tested both the egr and vcv selinoids . The are both functioning as outlind by alldata. I really sounds like there is a exhaust blockage. not an intake restriction. The exhaust is only 2 yrs old.Its like it bouilds up preassure then wont run. havent noticed any foul smell,"rotten eggs " assossiated with catalist failure...... Anyway. after running through the egr seystem reall quick,"And did replace the filter on the egr modulator". It drove about & miles. Died , Restarted it . Did thius a couple on times about every 2 gto 4 miles. Then ..... When I start it it dies almost instantly.. It might run a minute or 2