Rusty Posted March 14, 2012 Posted March 14, 2012 My '93 LS400 feels like it is running on 4 cylinders or about 1/2 power. The CEL is not on. The tachometer jumps up and down, usually in the 0 position when I drive down the street. There is the smell of electrical and fuel combined coming from the car. There is nothing leaking in the engine compartment or under the car. My guess is that it is a bad oxygen sensor but aging no CEL light. Does anyone have any suggestions? Thanks.
jaswood Posted March 14, 2012 Posted March 14, 2012 Replace or CLEAN the distributor caps and rotors.
jaswood Posted March 14, 2012 Posted March 14, 2012 Replace or CLEAN the distributor caps and rotors, check the camshaft position sensors/wiring, and the crankshaft position sensor/wiring.
landar Posted March 15, 2012 Posted March 15, 2012 Do any of the 'cats' glow red after driving in this condition? Number 1 suspect with your symptoms is the ignition coil(s).
jaswood Posted March 15, 2012 Posted March 15, 2012 Do any of the 'cats' glow red after driving in this condition? Number 1 suspect with your symptoms is the ignition coil(s). Tach bouncing symptom ruled out cat issue for me.
Rusty Posted March 16, 2012 Author Posted March 16, 2012 I drove the car for 45 minutes. It is only running on 1/2 power and barely makes it up a hill. I looked at the CATs and did not see a 'red glow'. I brought the car to a mechanic. There is no code being displayed so he is having trouble pinpointing the cause of the problem. What would cause the car to not display a code when the car is obviously running poorly?
jaswood Posted March 16, 2012 Posted March 16, 2012 Both... Even the slightest amount of dirt, fine dust, inside the distributor cap and then with a tad bit of moisture condensation overnight in addition and the engine will run rough until the moisture evaporates. Sometimes even worse, enough of the fine dust, metallic content dust, will get inside the distributor and you will see an actual arc path between one or 2 of the "connections" and the center power point. Mine had over 200k miles....
landar Posted March 16, 2012 Posted March 16, 2012 I drove the car for 45 minutes. It is only running on 1/2 power and barely makes it up a hill. I looked at the CATs and did not see a 'red glow'. I brought the car to a mechanic. There is no code being displayed so he is having trouble pinpointing the cause of the problem. What would cause the car to not display a code when the car is obviously running poorly? Wait...you took it to a mechanic and he is having trouble?? I know one thing I would do for sure. Time to find another mechanic. As good as we "think" we are on this forum, the reality is that we are just taking pot shots thru a straw. If you are not very mechanically inclined, find a good, trusted mechanic who understands the LS. They usually begin by isolating between ignition and fuel, then troubleshoot from there. Otherwise you will be throwing a lot of parts at it(think $$) in the hopes of hitting the culprit.
SRK Posted March 16, 2012 Posted March 16, 2012 There are plenty of problems that do not set a code - hence the term "no-code diagnosis" - especially on a '93 model year car. Tell your mechanic to check the coils and see if he knows how to do that by output, or by resistance. And he won't need a manual -one coil can be compared to the other. If he can't do this, then find a mechanic, because he ain't one.
dtwillis5 Posted March 19, 2012 Posted March 19, 2012 2 things to check: 1 see if any of your catalytic converter glowing red if so they clog up, take them off. They are bad cause you leaking gas into the exhaust (unburn fuel), running on 4 cylinders. 2 it's nothing dealing with fuel or air flow, it's an ignition problem. check the cam sensor, coils, and ignition control module.
jgray93ls Posted March 19, 2012 Posted March 19, 2012 Hi Rusty, This sounds a lot like what happened to my 93 a year ago. It ended up being one of the ignitions coils had went bad. You didn't say if it has been gradually getting worse, but mine was a sudden condition. There is an easy, albeit crude, way to check the coils. With the enging OFF, remove one of the coil wires. If the car will either not start at all, that is likely a GOOD coil. Replace the wire and remove the other coil wire. If the car starts and is still running bad, you likely have found the bad coil. They're only 50-60 bucks and fairly easy to replace yourself. There is one right on the top, front of the engine just to the passenger side of where the top radiator hose connects. The other one is a little harder to get at. Follow the lower small hose from your coolant resevoir down and it will pass right by the coil. It could definitely be some other issue, but this is pretty common and easy to check. Jeff
Rusty Posted March 22, 2012 Author Posted March 22, 2012 My car was running fine when I drove to work. I went out at lunch time and the car suddely ran on half power after I started it up. My mechanic replaced one of the cats that had deteriorated and clogged. He also cleaned out the muffler of any debris from the cat. He then replaced the fuel filter, which looked pretty old and put in new spark plugs. He checked the timing belt to see if it had slipped any. He checked the coils and said they were OK. It's been a week and the bill is getting larger. I think it's time to bring it to another garage. I chose this one becasue the mechanic has an LS400 and I see a few LS400's in his shop for repair.
Rusty Posted March 23, 2012 Author Posted March 23, 2012 Ok, my LS is finally fixed. The problem was the coil on the drivers side. This was suggested by many people and is written about in many postings on this site. It seems my mechanic may not have tested the coils thoroughly, as he said. After I brought him a printout of the suggestions in this posting string, he went back and looked at the coils again. So I have new parts, that I believe I did need, fuel filter, cat, spark plugs and he only charged me for 4 hours of labor, after the car was there for 1 week, but I still think I will look for a new mechanic. Thanks to everyone that contributed to my posting. This is a great website.
landar Posted March 23, 2012 Posted March 23, 2012 Thanks for the closure, Rusty. Not to knock those on this forum (including "yours truly") but the fact that you had to bring a printout of suggestions from this forum to your mechanic is a sad testimony. You may be correct in needing some new parts but I doubt you needed a new cat converter. Not cheap. You are right in thinking of shopping for a new mechanic. Glad you finally got her fixed...enjoy!
SRK Posted March 24, 2012 Posted March 24, 2012 Thanks from me too for posting back. As I mentioned in my previous post, I advised that your mechanic check the coils, as I suspected a coil from the start of this thread. Apparently he was unable to do this. Find another mechanic and beware those who throw parts at a problem, rather than diagnosing things. For sure you didn't need new plugs, or a timing belt check for an intermittent coil problem. Good luck with it!
jaswood Posted March 24, 2012 Posted March 24, 2012 Ok, my LS is finally fixed. The problem was the coil on the drivers side. This was suggested by many people and is written about in many postings on this site. It seems my mechanic may not have tested the coils thoroughly, as he said. After I brought him a printout of the suggestions in this posting string, he went back and looked at the coils again. So I have new parts, that I believe I did need, fuel filter, cat, spark plugs and he only charged me for 4 hours of labor, after the car was there for 1 week, but I still think I will look for a new mechanic. Thanks to everyone that contributed to my posting. This is a great website. Call me a "Doubting Thomas, but... A defective coil, defective to the level you seem to have encountered, but no CEL..??!! Doesn't seem probable. What else do the mechanic do that he "over-looked" telling you.
jgray93ls Posted May 8, 2012 Posted May 8, 2012 Jaswood, 'Thomas', I don't recall if my CEL came on then, but here's another related issue that may help some looking here. Just a few weeks after my post, my wife calls to tell the car is acting up, no power, thankfully only a block or two from home, but barely made it up our fairly steep side road. I get home from work and check it out. Acted just like before so I do the 'coil test' i mentioned before and, sure enough, with the coil removed from the driver's side coil it still runs the same, when removed from the top coil it won't start. I replaced the coil and....no change! Bummer. So I start thinking about it more and I remembered a key issue. When I had the coil wire off the 'bad' coil it was arcing all over, I was in a hurry and guess I thought that maybe the top of the coil was cracked or something. So I finally used my brain and started to check downstream, i.e. distributor and rotor. Well, when I started to remove the distributor cap, a bunch of little pieces and powder were falling out. I got a rag and tried to prevent as much as possible from falling down into the timing area. Anyway, the rotor had basically disintegrated. Sooo, same symptom of running on 4 cylinders, but different cause. Here's the kicker...no CEL. Hmmm. I think it works because is comes on at start up and it blinked rapidly when I checked for codes. Oh well, on to the next repair. Peace
VBdenny Posted May 10, 2012 Posted May 10, 2012 Seems unusual for no CEL but it is that. I had the vacuum plug I used to block off the power steering line come off and mine started running terrible. Popped it back on ( a little better than last time) and I'm good to go.
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