91 LS400 Issues. Similar To Celsior But NOT
10-17-17, 08:41 PM
#1
Lead Lap
Thread Starter
91 LS400 RPM And IDLE Issues.
Hi guys. I just fixed an Idle and misfire on my celsior and It is getting ready to be turbod, Just finished fabbing the exhaust. I have 1991 LS400 that is running, as a parts car but I think I am going to fix it and sell it as I really dont need it. Its in pretty good shape, 180k kms. I was hoping it would be the same issue as my Celsior as it appeared, however, the same fix did not work.
It seems to be misfiring after it warms up. Start up is fine, a little white smoke at times and it idles and revs pretty much great, maybe a tiny bit rough. But the longer it runs the worse the idle and running becomes. Its almost as tho it is cutting out for a split second but it keeps running and doesnt stall. No CEL, No codes. I replaced both O2 sensors and the Coolant temp sensor will be here today. I thought it was the coils so I swapped them with the ones I just replaced on the celsior, no good.
I had a spare working ECU but sold it so I have ordered the correct Caps to do the ecu repair. On inspection the caps seem fine. I also tried the same ecu ripple test as I did on the Celsior but it doesnt have the same diagnostic ports.
There seems to be a PS leak which I will investigate further
Any other ideas while Im waiting for the sensor and capacitors?
EDIT- Also replaced thew spark plugs. Have not done wires yet.
It seems to be misfiring after it warms up. Start up is fine, a little white smoke at times and it idles and revs pretty much great, maybe a tiny bit rough. But the longer it runs the worse the idle and running becomes. Its almost as tho it is cutting out for a split second but it keeps running and doesnt stall. No CEL, No codes. I replaced both O2 sensors and the Coolant temp sensor will be here today. I thought it was the coils so I swapped them with the ones I just replaced on the celsior, no good.
I had a spare working ECU but sold it so I have ordered the correct Caps to do the ecu repair. On inspection the caps seem fine. I also tried the same ecu ripple test as I did on the Celsior but it doesnt have the same diagnostic ports.
There seems to be a PS leak which I will investigate further
Any other ideas while Im waiting for the sensor and capacitors?
EDIT- Also replaced thew spark plugs. Have not done wires yet.
Last edited by Moarpower; 10-23-17 at 12:59 AM. Reason: Inaccurate title
10-17-17, 11:26 PM
#2
Lead Lap
Thread Starter
Sorry. By caps I mean capacitor. There's and rotors on the other hand could also be at fault. I also have not replaced the leads but the resistance is is all good on them. Not to say that when they headed they don't have issues.
10-18-17, 10:08 PM
#6
Lead Lap
Thread Starter
No change after sensor. Will leave it for a few days until caps, rotors and coils arrive.the timing belt kit is on backorder. As are the leads
Last edited by Moarpower; 10-18-17 at 10:12 PM.
10-22-17, 09:38 PM
#7
Lead Lap
Thread Starter
Trending Topics
10-23-17, 01:01 AM
#8
Lead Lap
Thread Starter
Cap and rotor set along with coils should be here by wednesday. In the meantime I will double check grounds, relays, sensors and plugs. It could be a right bank injector, however the issue is not in consistent timing, its more like random Morse code beeps where the revs stutter.
Waiting to see what the outcome is with the new caps installed.
10-25-17, 04:20 PM
#10
Lead Lap
Thread Starter
Cap and rotors are due for delivery today! However the coils have been delayed til, worst case scenario, next Tuesday.
NOTE- I would usually not approach the issue this way. Its always better to diagnose and eliminate all possible non issues before throwing money at any car. However, in this case all these parts were going to be replaced anyway. At this point I am unsure as to which car to keep as my main project.
NOTE- I would usually not approach the issue this way. Its always better to diagnose and eliminate all possible non issues before throwing money at any car. However, in this case all these parts were going to be replaced anyway. At this point I am unsure as to which car to keep as my main project.
