Recently Purchased 1995 Ls400 Misfire?

[popcure1]

I recently purchased a 1995 LS400. When I test drove it, no issues. When I was driving it home, I was getting on the highway, kicked the accelerator down, and the car started sputtering and jerking, almost like it was running out of gas. It stopped when I let off the accelerator. No Check Engine light. The next morning, exact same circumstance with the same result. Later in the day, I took it to my mechanic to check out. I duplicated the problem, but this time, it sputtered no matter what the speed. The timing belt, water pump, plugs, wires, TPS, MAF sensor, fuel filter, and fuel pump were all recently replaced. Still no codes. Any ideas where to look? BTW, the check engine light does not light up with the key in the on position. Will this not allow a scanner to give code due to break in the circuit?

[Von]

My 93 was doing about the same thing (like 100 others) I read about a dozen things it could be, but since I didn't want to spend 2 or 3 grand on it, I started with the cheap stuff first. I replaced the air filter (that I thought was new) but when I removed it, the unseen side was filthy. The 2nd thing I did was remove the MAF and cleaned it with CRC MAF sensor cleaner ($7.50 in a silver can) 3rd I reset the ECU by pulling the 20amp EFi fuse. So far it has started and run/idled better than ever, but it's only been 2 days. I'll comment later. Good luck, and try these 3 simple things first. p.s. Don't assume everthing is new and right (like me), unless you did the work.

[Lucky13]

Dealt with this problem many times before with these types. If you are describing it right I would say Im 100$ sure about a fuel pump prob. Wireing sometimes but usually the pump itself. It comes and goes at first so sometimes it may seem that the problem is fixed after changing things. Like puting in a new ECM or Idle Air control Valve. But prob always came back till I dealt with that pump.

[eatingupblacktop]

I recently purchased a 1995 LS400. When I test drove it, no issues. When I was driving it home, I was getting on the highway, kicked the accelerator down, and the car started sputtering and jerking, almost like it was running out of gas. It stopped when I let off the accelerator. No Check Engine light. The next morning, exact same circumstance with the same result. Later in the day, I took it to my mechanic to check out. I duplicated the problem, but this time, it sputtered no matter what the speed. The timing belt, water pump, plugs, wires, TPS, MAF sensor, fuel filter, and fuel pump were all recently replaced. Still no codes. Any ideas where to look? BTW, the check engine light does not light up with the key in the on position. Will this not allow a scanner to give code due to break in the circuit?

If you have a timing light check each plug. You mention having done the TB. So, I would also check all wire, coil, dist cap, and sensor connections. Make sure the dist rotors are installed correctly. Check for arcing at the plugs, coils, etc. A weak coil will cause a misfire under load but could idle fine.

[Lucky13]

Does not really sound like a misfire. More like it is starving for gas. Did you check the electrical for the pump when u installed it? Did you use new wireing or use the old?

[90LS400Lexus]

My 1990 LS sputtered when I bought it... I ordered the dealer to install new spark plugs before I bought it, they did and then it ran perfectly. Maybe your issue as well?

[SRK]

One bad ignition coil would be my guess. Now diagnose the thing properly to confirm BEFORE spending money on parts. Fire your mechanic for throwing all those unnecessary parts at it.

[popcure1]

I recently purchased a 1995 LS400. When I test drove it, no issues. When I was driving it home, I was getting on the highway, kicked the accelerator down, and the car started sputtering and jerking, almost like it was running out of gas. It stopped when I let off the accelerator. No Check Engine light. The next morning, exact same circumstance with the same result. Later in the day, I took it to my mechanic to check out. I duplicated the problem, but this time, it sputtered no matter what the speed. The timing belt, water pump, plugs, wires, TPS, MAF sensor, fuel filter, and fuel pump were all recently replaced. Still no codes. Any ideas where to look? BTW, the check engine light does not light up with the key in the on position. Will this not allow a scanner to give code due to break in the circuit?

Thanks to all who have responded! I will check into everything simple, then go from there.

[Von]

Mine felt as if it were running out of gas, bucked and jerked then lost power. I assumed it was either lean or had lost a coil (1/2 power) Now I believe it was very rich (dirty air filter and MAF) and the ECU cut back fuel, defaulted to "limp home mode" which gave the false impression of lean with half spark. It's a theory, but makes more sense then saying you have to replace 37 parts to make a Lexus run properly. Don't OVERTHINK the problem !

[popcure1]

Mine felt as if it were running out of gas, bucked and jerked then lost power. I assumed it was either lean or had lost a coil (1/2 power) Now I believe it was very rich (dirty air filter and MAF) and the ECU cut back fuel, defaulted to "limp home mode" which gave the false impression of lean with half spark. It's a theory, but makes more sense then saying you have to replace 37 parts to make a Lexus run properly. Don't OVERTHINK the problem !

Great advice and I took it. Waited until it got dark, started her up, and found I have a plug wire with an intermittent glow. Tackle it tomorrow and see what happens. Thanks.

[rickatups]

I would be curious to know that IF it turned out to be a fuel pump starting to fail ... what milage is your '95' LS at now?

got my '95' LS with about 101,000 miles on it and have had to do much to reverse previous neglect ... however I got lucky with the timing belt as it was changed by Lexus before I got my car, thank God ....

anyways .... I have really been wondering for some time as to exactly how long one of these factory fuel pumps will really go ????????

[popcure1]

I recently purchased a 1995 LS400. When I test drove it, no issues. When I was driving it home, I was getting on the highway, kicked the accelerator down, and the car started sputtering and jerking, almost like it was running out of gas. It stopped when I let off the accelerator. No Check Engine light. The next morning, exact same circumstance with the same result. Later in the day, I took it to my mechanic to check out. I duplicated the problem, but this time, it sputtered no matter what the speed. The timing belt, water pump, plugs, wires, TPS, MAF sensor, fuel filter, and fuel pump were all recently replaced. Still no codes. Any ideas where to look? BTW, the check engine light does not light up with the key in the on position. Will this not allow a scanner to give code due to break in the circuit?

So...it actually ended up being a bad Engine Control Module. Got it rebuilt for $350. Now the check engine light is on and showing a bad knock sensor. I took a look under the intake and saw the lead wire on #1 knock sensor is broken away from the plug completely. Would this cause an intermittent "miss"?

[pishta]

I recently purchased a 1995 LS400. When I test drove it, no issues. When I was driving it home, I was getting on the highway, kicked the accelerator down, and the car started sputtering and jerking, almost like it was running out of gas. It stopped when I let off the accelerator. No Check Engine light. The next morning, exact same circumstance with the same result. Later in the day, I took it to my mechanic to check out. I duplicated the problem, but this time, it sputtered no matter what the speed. The timing belt, water pump, plugs, wires, TPS, MAF sensor, fuel filter, and fuel pump were all recently replaced. Still no codes. Any ideas where to look? BTW, the check engine light does not light up with the key in the on position. Will this not allow a scanner to give code due to break in the circuit?

So...it actually ended up being a bad Engine Control Module. Got it rebuilt for $350. Now the check engine light is on and showing a bad knock sensor. I took a look under the intake and saw the lead wire on #1 knock sensor is broken away from the plug completely. Would this cause an intermittent "miss"?

Knock sensors are pretty cool. They "listen" for preignition (knock) and when they hear one, they !Removed! the spark a little to correct the problem. The bad knock sensor (disabled) is most likely either causing a "knock" signal to be transmitted to the ECU and that is unneccessarily retarding your spark, cutting power and going to a default "limp" mode as it cant clear the perceived knock, OR it is never sensing the knocks and is allowing the ECU to advance the timing to a dangerous knock level that will eventually destroy rod bearings and pistons. With todays electronically controlled ignition timing, you need these sensors to work properly for designed performance.

[93ls400walt]

my 93ls ran as you described. When I picked it up after buying it 1500miles from home I would have stuttering and jerking on acceleration or when going up even a small incline on the interstate. After I got home I started with a tune up. Plugs and wires "looked" OK. But when I tried to remove the wires from the dist. caps. each side had one or more of the terminals just break apart. They were full of corrosion. So new caps,rotors, wires and plugs. This solved my problem.

[popcure1]

I recently purchased a 1995 LS400. When I test drove it, no issues. When I was driving it home, I was getting on the highway, kicked the accelerator down, and the car started sputtering and jerking, almost like it was running out of gas. It stopped when I let off the accelerator. No Check Engine light. The next morning, exact same circumstance with the same result. Later in the day, I took it to my mechanic to check out. I duplicated the problem, but this time, it sputtered no matter what the speed. The timing belt, water pump, plugs, wires, TPS, MAF sensor, fuel filter, and fuel pump were all recently replaced. Still no codes. Any ideas where to look? BTW, the check engine light does not light up with the key in the on position. Will this not allow a scanner to give code due to break in the circuit?

So...it actually ended up being a bad Engine Control Module. Got it rebuilt for $350. Now the check engine light is on and showing a bad knock sensor. I took a look under the intake and saw the lead wire on #1 knock sensor is broken away from the plug completely. Would this cause an intermittent "miss"?

Knock sensors are pretty cool. They "listen" for preignition (knock) and when they hear one, they !Removed! the spark a little to correct the problem. The bad knock sensor (disabled) is most likely either causing a "knock" signal to be transmitted to the ECU and that is unneccessarily retarding your spark, cutting power and going to a default "limp" mode as it cant clear the perceived knock, OR it is never sensing the knocks and is allowing the ECU to advance the timing to a dangerous knock level that will eventually destroy rod bearings and pistons. With todays electronically controlled ignition timing, you need these sensors to work properly for designed performance.

I am getting it reconnected today and will go from there. I really hope this is it...my boss (wife) is questioning me purchasing.