92Lex Posted October 10, 2004 Posted October 10, 2004 I changed out distibutor caps, rotors, spark plugs, spark plug wires, air filter, checked alternator and battery and got deperate so I tried jump starting the car and it still wont start. The car cranks and dash lights all work but its not firing up... did I miss anything? I also checked valve timing and fuses. Any suggestions on where to look next?
Em91 Posted October 10, 2004 Posted October 10, 2004 Hi 92Lex. First thing you have to do is find out if you have spark and fuel. Spark is easy just unhook one of your wires from each side and put a spark plug in it and have someone crank while you are holding it up to a metal surface on the car. If you see spark on both sides of the engine with this check then you know that you have spark. Next thing you have to do is check if you have fuel. You can do this by disconnecting one of the lines on the fuel rale and having somebody crank the engine. Be careful and use rags so that fuel doesn't spill everywhere. If you have fuel and spark then you need to work on the next thing. Good luck.
92Lex Posted October 11, 2004 Author Posted October 11, 2004 I have fuel and spark. Whats the next thing?
Em91 Posted October 11, 2004 Posted October 11, 2004 Wow you checked that quick. Now things get a little complex. You can have anything from a vacume leak to a bad sensor. Sorry but those were the easy things to look for. The most common sensor for a car not starting is the Mass Airflow Sensor. That is the big aluminum sensor with a plug that attached to the air filter but, it is expensive and you don't want to play guessing games. I have been told that if you tap it a couple of times and the vehicle starts then you know where your problem is but, I would actually take it to be diagnoced. Sorry man.
92Lex Posted October 11, 2004 Author Posted October 11, 2004 If it was a MAF sensor malfunction wouldnt my car just stall or idle ruff rather than not start at all?
Em91 Posted October 11, 2004 Posted October 11, 2004 Any one of the three things can happen. I can stall, run ruff or not start. There are to many variable of what can be wrong. You should have the car diagnoced. Remember it can also be a vacuum leak.
VMF Posted October 11, 2004 Posted October 11, 2004 if it would be any kind of sensor, the engine light would come up. do you have the light? is your timing ok?
95LS400Bob Posted October 11, 2004 Posted October 11, 2004 I changed out distibutor caps, rotors, spark plugs, spark plug wires, air filter, checked alternator and battery and got deperate so I tried jump starting the car and it still wont start. The car cranks and dash lights all work but its not firing up... did I miss anything? I also checked valve timing and fuses. Any suggestions on where to look next? ← Let's go back here. Was the engine running somewhat normally before you changed plug wires, cap, rotor, etc. ????
92Lex Posted October 11, 2004 Author Posted October 11, 2004 There's no CEL on....the car doesnt even start. I checked my valve timing 4 times just to make sure everything is lining up correctly. The car ran fine before I did any of this, it had low power due to an extremely dirty air filter so I figured I'd do a comeplete tune-up. The car cranks but doesnt start up... I have fuel and spark for sure. The weird thing is that my instrument cluster turns completely black when I try to start the car up...it returns to normal and is bright as soon as I back off on the key. I tried jump starting it with another vehicle and left the jumper cables there for a good 5 mins. I torque'd everything down to specs. Spark plugs @ 13 ft lbs, even though the box said 1/2-2/3 of a turn once the base of the plug is flush...that wouldnt be it right? I went back and back tracked my steps to make sure I didnt leave any sensors disconnected and cleaned up battery post and connections. So now its just sitting in the garage.
blake918 Posted October 11, 2004 Posted October 11, 2004 Did you double check the wires at the plugs and at the rotors to make sure everythng matches up? Is this on your '91 or '95?
95LS400Bob Posted October 11, 2004 Posted October 11, 2004 There's no CEL on....the car doesnt even start. I checked my valve timing 4 times just to make sure everything is lining up correctly. The car ran fine before I did any of this, it had low power due to an extremely dirty air filter so I figured I'd do a comeplete tune-up. The car cranks but doesnt start up... I have fuel and spark for sure. The weird thing is that my instrument cluster turns completely black when I try to start the car up...it returns to normal and is bright as soon as I back off on the key. I tried jump starting it with another vehicle and left the jumper cables there for a good 5 mins. I torque'd everything down to specs. Spark plugs @ 13 ft lbs, even though the box said 1/2-2/3 of a turn once the base of the plug is flush...that wouldnt be it right? I went back and back tracked my steps to make sure I didnt leave any sensors disconnected and cleaned up battery post and connections. So now its just sitting in the garage. ← I don't have any diagnostic experience with the Lexus..but do with others. The only thing I can think of is possibly plug wires on wrong or perhaps the coil wire not in or in the wrong terminal, rotor not engaged correctly...something like that. We have spark but is it at the right time? that would be plug wire wrong, etc. Generally speaking...most cars...when the key is turned on..the computer turns the fuel pump in the tank on for a certain amount of time(approx 25 seconds). Then when the engine is cranked...the computer looks for a cranking signall..usually via a cam or crank sensor. If it sees this signal...it turns on the fuel pump and the ignition. Then the car will fire. Now to stay running...it looks at other sensors...but to fire...it should just be that. I know this is general but maybe that will help. Also is the engine cranking speed normal? Maybe the dash lights going out are just low battery voltage.
92Lex Posted October 11, 2004 Author Posted October 11, 2004 This is on my 91. Yes, I checked everything, I also made sure the grooves on the rotors lined up with the groove cam pulleys. I checked the wires like 5 times and went by the wiring diagram, Ive been back tracking but without luck. Like Bob said, if I have spark and fuel it should fire up but I may have a driveability problem if it's one of the sensors. It turns over at the normal speed but its just not starting up.
dpeck Posted October 11, 2004 Posted October 11, 2004 This is on my 91. Yes, I checked everything, I also made sure the grooves on the rotors lined up with the groove cam pulleys.I checked the wires like 5 times and went by the wiring diagram, Ive been back tracking but without luck. Like Bob said, if I have spark and fuel it should fire up but I may have a driveability problem if it's one of the sensors. It turns over at the normal speed but its just not starting up. ← The check engine light should come on when key is turned to the on position and go out once car starts maybe something is unplugged to the computer?
99lsguy Posted October 11, 2004 Posted October 11, 2004 Torqueing the plugs to 13 ft lbs is perfect - the only way to do it Thoughts: Did you check the gap on the plugs? They should be okay outta the box but... Double check the rotors.......(oh yeah, you did this already) Disdonnect (for 5 min) / reconnect battery Also try turning the ignition on for about 10 seconds and then give her a crank! Dude - hope you find the problem
VMF Posted October 11, 2004 Posted October 11, 2004 the blackout of the dash makes me suspicious, there might be a shortage somewhere, check all the sensor connections on front of the engine. when you crank the engine dash should dim but definetly should not blackout. try to swap the battery may be? may b its just the bad battery, but i doubt it, but you should check it just to eliminate this possibility
92Lex Posted October 11, 2004 Author Posted October 11, 2004 The battery was disconnected the whole time I was working on the car. I also checked the gaps before I installed every single plug. I double checked the sensors that sit on the front on the engine...the one that sits to the left of the battery right by the fan bracket...(looks like a speed sensor?) seemed loose so I tighten up the screw holding it. I pulled the battery from my other car and threw it in there last night but still no luck.
99lsguy Posted October 11, 2004 Posted October 11, 2004 plug wires are all different lengths to match the "reach" to each plug from the rotor ???? So they are correct.....? And correctly matched in the rotor?? Could this have hosed the timing..........? I'm just throwing out ideas -- not trying say you've missed something :o
92Lex Posted October 11, 2004 Author Posted October 11, 2004 I pulled all the plug wires out last night and rewired them for the second time just to make sure everything was in place. Also took out the rotors and caps again and checked installation marks. I dont know why I keep doing this though...I guess Im just resorting to desperate measures. I also spun the crankshaft from TDC to TDC just to make sure my cam pulleys and timing marks lined up. ( Did this a total of 4 times ) If it were a sensor that was "knocked" loose then my car should still start but just have a driveability problem right? Its all good, Im just trying to get help and suggestions.
99lsguy Posted October 11, 2004 Posted October 11, 2004 I think the MAF sensor (malfunction or bad connection) wouldn't allow the car to start............ Does it ever smell like it's flooding out?
molocka12 Posted October 11, 2004 Posted October 11, 2004 Just a guess. Does you car have a timing belt or chain. Sounds like the timing belt to me.
95LS400Bob Posted October 11, 2004 Posted October 11, 2004 I think the MAF sensor (malfunction or bad connection) wouldn't allow the car to start............Does it ever smell like it's flooding out? ← Just for the heck of it, I just unplugged the entire mass air flow sensor and all vacuum lines I could find going. My 95 started right up. Just a test so we would know. If this had happened to me and I couldn't seem to find it...my next step would be to put the motor at TDC #1, remove the dist cap and make sure the rotor pointing at #1 on the cap. Or..rent a trailer...bring it over the Hill to Sparks, Nevada and we'll find it . Reading your posts a little closer..sure sounds like you are covering the bases. I still think all we need is compression, spark and fuel..and it should fire. To stay running a different story...but all we need to fire. I'll be reading the manual more tonight.
VMF Posted October 12, 2004 Posted October 12, 2004 MAF sensor would give u a check engine right away, tried that on mine.
92Lex Posted October 12, 2004 Author Posted October 12, 2004 Dont know what I did exactly but my car is running again. I just took everything apart then reassembled it and it fired right up. Too bad this couldnt of happen the first time I took it apart. My cluster still goes black when I crank the car though...but at least its running. I also flushed the coolant and since its been hot here lately I havent used the heater...I just found out that the damn thing doesnt work. Its starting to get chilly at night...I cant wait till December. I just wanted to say Thanks to everyone for all the advice and feedback.
95LS400Bob Posted October 13, 2004 Posted October 13, 2004 That's good. Just had a good laugh! Last night when we were talking about this...I went out and disconnected the mass air flow sensor so i could see if it would start as a test. Well, soon as it fired I shut it off. Didn't figure it would set a code for a check engine light. Connected the mass air flow sensor back up. Closed the hood. Wife just got home. She says "I got a check engine light on in the Lexus. Wonder what that is all about?" Ha! Ha!
99lsguy Posted October 14, 2004 Posted October 14, 2004 That's good.Just had a good laugh! Last night when we were talking about this...I went out and disconnected the mass air flow sensor so i could see if it would start as a test. Well, soon as it fired I shut it off. Didn't figure it would set a code for a check engine light. Connected the mass air flow sensor back up. Closed the hood. Wife just got home. She says "I got a check engine light on in the Lexus. Wonder what that is all about?" Ha! Ha! ← Bob, How is she liking the LS......I know you've worked on it A LOT !!!! since you've owned it to get the LS in great shape and your wife was a little leary.... SHe's gotta love the ride :D
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