1UZ-FE Posted July 19, 2004 Share Posted July 19, 2004 the conditions of my tests are as follows: temp:73° humidity:87% road condition:dry vehicle load: 1 driver, 0 passengers, no extra cargo. (just spare, and jack, and a few small items.) other info: A/C off, trac off, night, no aftermarket performance modifications. i found a nearly deserted flat, strait road with a speed limit of 50 mph. i tested my time to 60 mph from a dead stop. my best time was 8.2 seconds. my worst time was 9.8 seconds. all driver inputs in all 10 of my tests were exactly identical. i did not use left foot braking, went strait from brake to gas with my right foot and simply stomped on the gas. the weird thing is the large variation in times. the times were either right around 8.2 (-/+ .025 secs), or 9.8 (-/+ .025 secs). no inbetween. when the result was 9.8 seconds, i could feel that the car just didn't want to accelerate hard from a stop (0-20). once again, i gave the exact same inputs, so why the big difference?? i did observe the tachometer during all runs. i found that during the 8.2 second runs, the RPMs would sit at around 1900 from 0 mph to about 4 mph then go up from there. when the results were 9.8 seconds, the tach would register 1900 RPMs from 0-10 mph and simply didn't accelerate really hard until i reached about 20 mph. why?? im really confused about this. could someone please try to clear this up? thx in advance. Quote Link to comment Share on other sites More sharing options...
chips229 Posted July 19, 2004 Share Posted July 19, 2004 Well im glad im not the only one to notice this!!! Im going to have a look at the throttle sensor on mine when i get time,im also going to clean the butterfly inlet intake...hoping this might give the car more consistency. The throttle sensor might not be telling the ecu that your on full throttle. Quote Link to comment Share on other sites More sharing options...
1UZ-FE Posted July 19, 2004 Author Share Posted July 19, 2004 well i cleaned my throttle body about 3k miles ago. i know it helped with performance in general but thats it. please inform me on what you find out about the TPS. Has anyone anything to say about this?? Quote Link to comment Share on other sites More sharing options...
kazools400 Posted July 19, 2004 Share Posted July 19, 2004 I have a 93 LS400 and I've noticed this but I think mine is a faulty EGR system. I have it going in to get tests done soon. I'll let you know what happens. Quote Link to comment Share on other sites More sharing options...
1UZ-FE Posted July 20, 2004 Author Share Posted July 20, 2004 good to hear. i am really interested in finding out what causes this. i might ride up to the lexus dealer tomorrow and ask my friend joey in the shop. i'll let you guys know what i find out and am anxious to hear from u all. thanks chips and kazools for replying. Quote Link to comment Share on other sites More sharing options...
chips229 Posted July 20, 2004 Share Posted July 20, 2004 Yesterday i took the inlet feed pipe from the air filter box to the induction manifold off and cleaned the butterfly and intake with a spray can of cleaner i bought from me local car shop..if anyone else does this put a rag down in the breather hole or the *BLEEP*ty liquid will run into the top of the engine and mix with your engine oil :o You could take the breather pipe off buy its abit tricky cos of lack of room. The car took abit of turning over to get her to start,but now the engine runs smoother :) ....seems to pull better B) through the rev range....ive noticed it pulls alot better higher up the rev range....and the throttle response seems more crisper and the engine generally seems more urgent ;) So another job under my belt :D A job well worth doing guys. Chips. Quote Link to comment Share on other sites More sharing options...
1UZ-FE Posted July 20, 2004 Author Share Posted July 20, 2004 chips: so u said it helped the pick-up of your car, but does it fix the problem that i mentioned in my first post? Quote Link to comment Share on other sites More sharing options...
chips229 Posted July 20, 2004 Share Posted July 20, 2004 chips: so u said it helped the pick-up of your car, but does it fix the problem that i mentioned in my first post? Ive had my aircon fixed today,so i only drove the air over and back from the garage....i noticed all the comments on the way there as i was running abit late...on the way back i was just cruising with the air on B) Cars been parked up for the rest of the day as ive been surfing d net the rest of it Just for you 1UZ-FE...i will fire the old limo up and road test her now the roads are quiet ;) Be right back. Quote Link to comment Share on other sites More sharing options...
chips229 Posted July 20, 2004 Share Posted July 20, 2004 Well that was interesting... Its 9.30pm here..dry road...done the test on the same bit of road and theres no mods to me car...the car HAD a full tank of fuel with just me in the car..same sort of spec as on the 1st post...aircon off etc The 1st run was 8.88 sec then after 9.16,9.28 always in the low 9s done about 6 runs in total,but never under the 8.88 of the 1st run always in the low 9s. It almost seems the hotter everthing got the slower the car felt. Quote Link to comment Share on other sites More sharing options...
1UZ-FE Posted July 20, 2004 Author Share Posted July 20, 2004 It almost seems the hotter everthing got the slower the car felt. that makes sense. hot air does reduce performance. also, when u first got into your car for the tests u just posted, did the car sit for long enough that the engine cooled off all the way or even part way? if so, the engine was still choked, u get a higher idle, and a higher idle results in a better launch. as you car warmed up and approached normal operating temp, the RPMs dropped to a normal idle (~600 RPMs) and u got slower launches. my inconsistencies were not a result of heat thought. my slower runs were totally random. my first and second tests were 9.8 second runs, 3nd was an 8.2, 4th and 5th were 9.8, and so on. totally random. well thanks a lot chips for your helpful input. i appreciate it greatly. im still confused about what causes this but i guess i'll just have to live with it. Quote Link to comment Share on other sites More sharing options...
chips229 Posted July 21, 2004 Share Posted July 21, 2004 Hi........1UZ-FE I never like to drive any car hard when there not fully warmed up,the bit of road where i tested the car was a few miles from me,i drove the car around abit so it was up to temp before i did the test. I put the car into N to make sure it was up to temp and it was ticking over at 600 revs....i didnt hold the car on the foot brake,i just took me foot off the brake and nailed the throttle...i did notice like you said,some times the car didnt seem to get off the line as well as other times,sort of bogs down to start with like you explained yourself,but the 0 to 60 mph was nearly always around the same sort of times.. How much fuel did you have in your car when you tested...im going to test again when the fuel level goes down...im hoping then it will be abit quicker Im thinking of decatting the car,to give me abit more power...ive been told that should give me a extra 10 to 15 bhp Chips. Quote Link to comment Share on other sites More sharing options...
1UZ-FE Posted July 22, 2004 Author Share Posted July 22, 2004 Im thinking of decatting the car,to give me abit more power...ive been told that should give me a extra 10 to 15 bhp meaning removal of the catalytic converters? Quote Link to comment Share on other sites More sharing options...
chips229 Posted July 22, 2004 Share Posted July 22, 2004 Im thinking of decatting the car,to give me abit more power...ive been told that should give me a extra 10 to 15 bhp meaning removal of the catalytic converters? Yes mate.The catalytic converters Over here if the cars a 1993 or new then they must stay on the car and cant be removed as you will be breaking the law :o Mines ok its a 91 ;) Quote Link to comment Share on other sites More sharing options...
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