justintime Posted September 1, 2005 Share Posted September 1, 2005 The engine on my ’91 LS400 momentarily loses rpm and power, causing a jerk, or a sequence of jerks. This is not a shudder -- as in vibration related. It usually happens intermittently and is most noticeable once I hit speeds right at 70-mph. It is like the engine starts choking up whenever there is demand for power during acceleration - especially around 70 mph. Once below 70 mph, it again runs smooth. I’ve not tried to exceed 70 mph when the problem is present. The problem is not repeatable and I have not seen any correlation with outside temperature, humidity or gas grade selection. Again, it is intermittent - pretty bad one day, no problems the next day. I primarily use Premium Gas and Very Occasionally, I use Mid-Grade. I never use Regular. Though I am very far from being a mechanic, I suspect that it’s either a clogged fuel filter or a bad injector. I gather this because my fuel indication needle doesn’t read correctly. I discovered through the embarrassing way that my vehicle is on empty when the needle is on ¼ tank instead of “E”. Any advice or suggestions? Quote Link to comment Share on other sites More sharing options...
obergc Posted September 1, 2005 Share Posted September 1, 2005 Check your sparkplug wires and plugs. Gas gauge problem probably a bad part in the instrument cluster. Quote Link to comment Share on other sites More sharing options...
ko90ls Posted September 1, 2005 Share Posted September 1, 2005 congrats on the lex! sorry to hear about the engine problems though :( when my friend had his cutlass supreme(i know, no comparison) and his fuel injectors were clogged the car would just die whenever he put it into gear so that's probably not the problem. but if you really think it is just get a expensive(you get what you pay for) bottle of fuel system cleaner. the fuel injector is the same except the complete sys clean also does the valves. when i first got my lex and raced someone my car got pretty fast then did the same, the engine soorta locked and wouldn't acc. anymore. very strange sound also? sorta a jerking or spasm. what i did was a tune up with good iridium plugs and very high temp wires and have had no problems since :) might also wanna add the caps and rotors because on mine... very dusty. seriously there must have been a slight resistance in the electrical charge because of how dirty/dusty the caps and rotors were. not too expensive but not caried by toyota either(lexus only part) how you might check to see if the wires are it is when you got fast does the radio pickup more static? if so then it's the wires(RFI) good luck Quote Link to comment Share on other sites More sharing options...
sha4000 Posted September 1, 2005 Share Posted September 1, 2005 usually a tuneup can fix this i would suspect a clogged fuel filter Quote Link to comment Share on other sites More sharing options...
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