Hard Miss, Smoking, Burning Rich 91 Ls400

[_mach_]

Hi,

I am having a odd problem. I own a 1991 LS400, with 176K miles. I moved to Massachusetts and purchased a new car for the winter time. The Lexus has been sitting for approx 2 months. I jumped it off yesterday to take it for a drive. The car idled just fine, no issues, but then when i got out onto the road the oil light flickered on, and then off. I pulled over, and was about a qt low. Added a qt, went for a drive. The light came back on. I added another qt, and the light went off. I drove for about 20 or 30 min (to charge the battery) and the light flickered on again, I shifted into neutral to drop the RPM's and the car died, and had a very strange odor, almost like burning antifreeze, but not quite as sweet. After it died the battery had no power. I tried jumping it off, but apparently the battery was completely dead. I put a new battery in it, and it started right up.....but it's got a HARD MISS now. The car shudders badly (feels like 2-4 or more cyl are not firing at all). Burning very rich, and smoking. I had it towed home, and I haven't torn into it, but was wondering if anyone had any suggestions on where to start. I was a technician for a number of years, but that's been a long time ago. I'm wondering if perhaps it could be a coil pack, or something along those lines, being that the electrical system could have been completely discharged, or over worked. Or could it have jumped time? do these cars have issues jumping time? any suggestions are much appreciated.

Thanks!

Grayson

[RDM]

If you can get it to run while diagnosing, start pulling injectors one at a time to see which cylinders are dead. From there you can determine if the dead cylinders are fuel or spark related by testing for spark with a screwdriver, if you have spark then it's fuel. If it won't run on it's own power, it is probably timing, the belt could have broken or simply sheered a few teeth off from age or wear. The battery dying may lead you to fuel pump damage too, trying to run on very low voltage can cause the pump to overheat.

Mine has had broken spark plug wires twice in it's life, once the OE set, another from a Ebay seller that I should have known was junk but bought anyway. Both times it was just as random as yours. Start with the basics and work out.

[_mach_]

If you can get it to run while diagnosing, start pulling injectors one at a time to see which cylinders are dead. From there you can determine if the dead cylinders are fuel or spark related by testing for spark with a screwdriver, if you have spark then it's fuel. If it won't run on it's own power, it is probably timing, the belt could have broken or simply sheered a few teeth off from age or wear. The battery dying may lead you to fuel pump damage too, trying to run on very low voltage can cause the pump to overheat.

Mine has had broken spark plug wires twice in it's life, once the OE set, another from a Ebay seller that I should have known was junk but bought anyway. Both times it was just as random as yours. Start with the basics and work out.

Dumb question, but are these interference motors? If it had jumped time, what are the odds that i had a valve smack a piston?

[RDM]

The 1st generation LS is not an interference engine. I have read the later VVT engines are but have never worked on one personally.

[_mach_]

The 1st generation LS is not an interference engine. I have read the later VVT engines are but have never worked on one personally.

Well that's a plus...even if it did jump timing, i can just replace belt and get her up and running again. Thanks for the information, will update as i tear into it. I actually just want to unload the car, so if anyone's interested, just let me know. Car is located just outside of Boston Ma.

[curiousB]

The 1st generation LS is not an interference engine. I have read the later VVT engines are but have never worked on one personally.

Well that's a plus...even if it did jump timing, i can just replace belt and get her up and running again. Thanks for the information, will update as i tear into it. I actually just want to unload the car, so if anyone's interested, just let me know. Car is located just outside of Boston Ma.

This car has dual distributor caps and coils. Apparently it’s pretty common for one side to fail leaving you running on 4 cylinders and a rough running engine. I'd search this forum for ignition and distributor related issues for more detail. Hopefully you’ll find it a much simpler solution than a timing belt.

[_mach_]

So...i tore the car apart today and i found something i didn't expect to find. The driver side rotor was broken off under the cap....the only problem is that the cam bolt has broken off too. The motor turns just fine, and it looks like the bolt just was defective or it was metal fatigue, but i've never heard of anything like this happening. I was able to get the broken portion out fairly easily, and am going to get a new bolt, rotor and cap tomorrow. Has anyone heard of this happening before? thanks for the help and suggestions guys!

[rickatups]

So...i tore the car apart today and i found something i didn't expect to find. The driver side rotor was broken off under the cap....the only problem is that the cam bolt has broken off too. The motor turns just fine, and it looks like the bolt just was defective or it was metal fatigue, but i've never heard of anything like this happening. I was able to get the broken portion out fairly easily, and am going to get a new bolt, rotor and cap tomorrow. Has anyone heard of this happening before? thanks for the help and suggestions guys!

Hi ..... I have a 95 LS400 that started acting just like your LS .... while driving in the middle of Los Angeles freeway system at rush hour and with no place to get off the road ..... I suddenly lost at least 1/2 engine power. I heard a "pop" sound also ... very weird. Then I started to smell exactly what you described. All I could do was to keep driving the car ..... so I did .... I finally found a place to get off the road. Once I lifted the hood, I could smell that odor you describe perfectly .... but I could not see anything leaking ... there was no smoke .... but that smell was strong.

I was 125 miles from home. I probably should not have done it, but I drove home anyway. The check engine light is on ... that happened shortly after I heard the "pop" sound ....

Anyways ... I parked the car for several months, but now I am ready to get into it ..... so I have been thinking that I lost one of the ignition coils

In your opinion ... how big of a deal would it be to dig into this and change-out a coil? My car has about 140,000 miles, so it would not be a bad idea to change the coils out anyways ... as well as to inspect the distributors, etc. I have some mechanical ability .... and I think I am up for it .... so ... what do you think? Is it major surgery to do a coil on this car?

[RDM]

95-up models are coil over plug, they don't have separate coils that fire the distributors. I'm not even sure if they sure ignitors either.