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Misfire, No Power And 10Mpg Please Help


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Well I purchased my 93ls 4k miles ago it has 170k miles on it. I went and took the family to a amusement park yesterday that was 360 miles away round trip yesterday. The car seemed to run just fine on the way there but when I started the ls to leave it started misfiring badly. I needed to get some gas so I stopped in the local station and filled up. I then found out I only got 18 mpg versus the usual 22-25. I will list the symptoms below.

* Running very rough

* Does not have any power, I would compare it to when you start a car in to high of a gear when trying to take off

* It could not maintain speed up any sort of hill

* My tachometer was not consistent, it would bounce all over the place

* Since the first day I bought it the speedometer has been 20mph slow but earlier in the week it magically started working correctly.

* When I first opened the hood, I saw some smoke coming off the rear of the engine.

* No check engine light.

*10 mpg

If any of you know where to start I would greatly appreciate it. I haven't had time to go pull a plug and see what it looks like so start giving me an indication of what might be wrong. It was a tough drive on the way back but we made it safe and sound. thank for any help.

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Sounds like you lost one bank of 4 cylinders due to ignition. These cars have issues where one side distributor goes dead either due to wiring, or coil. Understandably the car runs rough with only have the cylinders working and a lot of unspent fuel getting dumped into exhaust system.

I'd check that first.

If one bank is dead presumably pulling a plug wire (on the dead side) won't make any difference whereas pulling a wire on the good side will make a big difference as it will be going from 4 to 3 cylinders.

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Well I purchased my 93ls 4k miles ago it has 170k miles on it. I went and took the family to a amusement park yesterday that was 360 miles away round trip yesterday. The car seemed to run just fine on the way there but when I started the ls to leave it started misfiring badly. I needed to get some gas so I stopped in the local station and filled up. I then found out I only got 18 mpg versus the usual 22-25. I will list the symptoms below.

* Running very rough

* Does not have any power, I would compare it to when you start a car in to high of a gear when trying to take off

* It could not maintain speed up any sort of hill

* My tachometer was not consistent, it would bounce all over the place

* Since the first day I bought it the speedometer has been 20mph slow but earlier in the week it magically started working correctly.

* When I first opened the hood, I saw some smoke coming off the rear of the engine.

* No check engine light.

*10 mpg

If any of you know where to start I would greatly appreciate it. I haven't had time to go pull a plug and see what it looks like so start giving me an indication of what might be wrong. It was a tough drive on the way back but we made it safe and sound. thank for any help.

I agree that it may be running on one bank of cylinders but the symptoms could also point to the ECM operating in "Limp in Mode". I don't know for sure, just sayin'... keep us posted.

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How does a person check for a bad coil or bad ecm? Is there a range of ohm resistance that it should be in? An ecm sounds expensive how do I go about testing that?

thanks

There are two coils on the LS if you have a digital multimeter you could compare readings from both of them, the most common to fail is the one on the passenger side opposite the battery,also check the HT lead from this coil to the distributor as it passes under the plastic covers and the can get damaged if not routed correctly.

Other possibilities are the distributor caps and rotor arms.

The burning smell from the rear of the engine is probably due to the cat overheating due to non burnt fuel entering the exhaust as previously mentioned.

I would fix as soon as possible as the cats can be totally wrecked long term.

I would go for the coil first for what they cost new.

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How does a person check for a bad coil or bad ecm? Is there a range of ohm resistance that it should be in? An ecm sounds expensive how do I go about testing that?

thanks

Well as I said a simple test is to just unplug a HT wire from one of the plugs at the distributor. If that bank was already dead you should see no difference in performance. If that is the good side you'll suddenly drop from 4 cylinders to 3 and you should see even more stuttering and erratic running. This test is to prove or disprove the premise a bank of cylinders is dead and you are running on just 4 cylinders.

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  • 2 weeks later...

I don't know if this may be the case in your situation but something similar happened to me. I had replaced my driver's side valve cover gasket. When I was putting everything back together I crimped a spark plug wire under one of the plastic covers. I cut the wire coating exposing the wire. This caused a short between the wire and a metal bracket. I lost one bank of cylinders and had no power at all, car was in limp mode. Maybe check your wires to see if there is a short somewhere?????????????

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Well as an update to this thread. The driver side coil was to blame for the problem. I pulled the coil wire off and engine did not run any different. This coil was a pain in the butt to get out as it tried my patience cause I have bigger hands but finally got it. I also put new ngk plugs and wires on while I was at it. I have seemed to gain a mile per gallon or so. I had to go on a trip for work and drove 700 miles and average 22.9 mpg going 78-80 mph. I now need to fix my exhaust leak and the power steering pump and all will be good.

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Well as an update to this thread. The driver side coil was to blame for the problem. I pulled the coil wire off and engine did not run any different. This coil was a pain in the butt to get out as it tried my patience cause I have bigger hands but finally got it. I also put new ngk plugs and wires on while I was at it. I have seemed to gain a mile per gallon or so. I had to go on a trip for work and drove 700 miles and average 22.9 mpg going 78-80 mph. I now need to fix my exhaust leak and the power steering pump and all will be good.

This just happened to my wifes car on Friday, left it at a local garage over the weekend and did research(including this post). Today pulled the coil wire of pass side no start at all. Pulled off drivers side ran the same. Guess my patience will be tried a bit changing it tomorrow, but at least I'll save a bunch over the garage doing it. I'll update results. Thanks

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  • 4 months later...

Here is link to a message with detailed instructions on replacing the driver's side IC. Hope it helps you.

http://us.lexusownersclub.com/forums/index.php?showtopic=60609&st=0&p=389588&fromsearch=1entry389588

Sorry that eternity has passed by without an update. Thanks fsuguy. I wasn't able to check your reply before I did the repair, but that's a very helpful breakdown for others. Anyway to update, the coil was definitely the problem. While I was at it I changed the plugs and wires and cleaned the throttle body. By far the most time consuming plug change that I can remember. I've dealt with other issues since then, and now I'm having some others I'm currently trying to sort out. I will search other topics so I don't mess things up, but one that's somewhat related to this is a 'miss' or hesitation during moderate acceleration (mild pedal or flooring it it's ok). It was doing it before and after the coil change. Thanks!

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