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92 Ls400 V8 Has No Power!


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My ls400 has no power i took it to the dealer they said it was the throttle position sensor and the mass air flow sensor,it it idles great but when you give it gas it is so sluggish so I just put it in the shop and had an entire new exhaust put on from cats to mufflers ,whith no change in the power i am at a lose please help.like i said it idals fine but when you drive it takes for ever to get 50 mph.i can smell gas and sombody at a stop light told me they seen alot of sparks coming from my tail pipes

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It's common for one of the two ignition coils to fail, and that will cause the symptoms you describe. Quick ohm check of the primary windings on each will show the bad one, or a timing light on the coil to cap wire will also show a dead coil. Cheap and easy to fix. I'm wondering if the dealer checked that before selling you an exhaust system.

The coils do not set codes, and if you did have one you'd have a check engine light on.

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I took it to the dealer to be diagnosedI replace the battery just before taking it to them there for erasing all codes on the computer

I would assume they had checked all that which they said they check the plugs and plug wiresbut their diagnosis was that I needed a throttle position sensor in a mass air flow sensorso I replace them myself with no change in the horsepower,i could smell gas and hear things moving around in my catalytic convertersso I took it upon myself to have a whole new exhaust system put in complete with true dual exhaust, the mechanic told me that my catalytic converters were completely toasted,so now i am wandering what toasted my cats

The car has 153k miles on it one owner and was just givin to me by a elderly couple

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Well what toasted your cats was the unburned fuel from the four cylinders that were not firing. The cats overheat when dealing with gasoline rather than exhaust.

Check the coils. It cost almost nothing to check, and then proceed. If you didn't have codes for the mass air flow sensor, or the throttle position sensor, then neither required replacement. Both will set codes when they fail.

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In the early time when I owned my 1990 LS400, I smelt ( yeah) gasoline, especially on start ups. Then the white smoke came. Mosquito trucks even avoided our area. Blocked off the power steering (super) assist vacuum lines (with golf tees and little hose clamps) and all was well.

Sold my LS400 to a friend and we changed the oil then washed and detailed. Ahhhh, still miss driving that car. Both my wife and I agree that the 90 LS was the best car ever.

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There are two coil packs, one for each bank. They are the roundish covered things in the front. Not sure how to check them other than no spark. I have never heard on people having problems with the coils but hey, anything can happen.

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So i cleard the codes and started the car rev it up a few times for a few minutes until the check engine light come on againnow I am only getting code 52

lOBD1 Codes

1 Normal Condition.

2 Air Flow Meter signal.

3 Ignition signal.

4 Engine Coolant Temperature Sensor signal.

5 Oxygen Sensor.

6 RPM signal (Crank Angle Pulse).

7 Throttle Position Sensor signal.

8 Intake Air Temperature Sensor signal.

9 Vehicle Speed Sensor signal.

10 Starter signal.

11 Switch signal.


12 Knock Control Sensor signal.

12 RPM signal.

13 Knock Control CPU (ECM).

13 RPM signal.

14 Turbocharger Pressure.

14 Ignition signal.

21 Oxygen Sensor.

22 Engine Coolant Temperature Sensor signal.

23 Intake Air Temperature Sensor signal.

24 Intake Air Temperature Sensor signal.

25 Air-Fuel Ratio Lean.

26 Air-Fuel Ratio Rich.

27 Sub Oxygen Sensor signal.

28 No. 2 Oxygen Sensor signal.

31 Air Flow Meter signal (Vacuum Sensor signal).

32 Air Flow Meter signal.

34 Turbocharger Pressure signal.

35 Turbocharger Pressure Sensor signal.

35 HAC Sensor signal.

41 Throttle Position Sensor signal.

42 Vehicle Speed Sensor signal.

43 Starter signal.

51 Switch signal.

52 Knock Sensor signal.

53 Knock Sensor signal.

54 Inter-cooler ECM signal.

71 EGR System.

72 Fuel Cut Solenoid signal.

78 Fuel Pump Control signal.

81 TCM Communication.

83 TCM Communication.

84 TCM Communication.

85 TCM Communicatio

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Your basically dumping too much fuel into the engine and the ECU is trying to compensate therefor triggering the code 25. Since you changed the throttle and MAF sensor I would check the O2 sensors to see if they are within spec as well as Plugs, wires amd coils. Something in your fuel management is not working correctly but it should not be too hard to figure out.

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I all so just found a pinched plug wire on the 2nd plug on the drivers side and a pinched coil wire on the drivers side at the coil.i am not shure if pinched means its bad or not but the coil wire is pretty floppy just below the rubber boot so I am wandering do I buy new wires first or the coil? there both same price but only have funds for one this week any sagestions?

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