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Hi, I’m really hoping someone here can help me figure this out. My 2005 Land Rover LR3 with 126,000 miles started acting up a couple weeks ago. It began with just a poor idle. I’d describe it as an occasional rhythmic “BLURP”…??? Kind of like a mini backfire that you can’t hear but you can feel. That progressed after a couple of days to a full blown rough idle with loss of power and rough acceleration. Thats when I started getting the DTC’s. Cylinder 8 at first. Changed the coil from 8 to 6 and drove it a bit. That’s when I got codes for 3, 4, and “RANDOM MISFIRE” followed shortly there after by the dreaded “REDUCED ENGINE PERFORMANCE” message on my dash. BTW, cylinder 8 never threw a code again. So I changed the MAF, reset the driver adaptaion log and reflashed the TCM. That seemed to fix the issue until I let it sit for a few hours. When I started her up… Same thing. Rough idle, random misfire and REDUCED ENGINE PERFORMANCE. I let it be for a bit because I’m trying to avoid throwing parts a the car in the hopes of fixing it. So over the past week I noticed that if I drive the car long enough the symptoms go away completly and it runs perfect. So I started collecting live data via the torque app and I came to find that when the engine approaches 170 degrees the engine starts to smooth out. by full operating temp of 190 or so it runs and performs perfectly. this is leading me to suspect a sensor that gauges temperature. I’d really appreciate it if anyone has any input on the subject because from what I’ve read anything gauging temp usually results in bad performance when hot rather than cold.
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Given you’re using Torque, what do your fuel trims look like at idle and ~2500 RPM? Be sure the car has warmed up to closed loop before taking the measurements.
Thanks for the response. I just downloaded Torque a couple days ago and I’m still learning how to use it. I’ll take a look and see if I can get that going then I’ll post results.
Hi again, first let me say thanks for taking the time to help. I really appreciate it. I configured the Torque app as best I could based off information online and YouTube. I uploaded a video of Fuel Trim and O2 sensors to YouTube here; https://youtu.be/MLqhFgOSOnw Once again thanks!
OK, I learned a little more on Fuel Trim and realized I’m monitoring the wrong one. Here is a video of a short road trip. Any help would be appreciated. https://youtu.be/ePG1TPnwIw8
That was done on a closed loop. The widget for fuel system status isn’t available on the video recorder plugin.
Thanks for the reply! I’ll get the trouble codes but I’m not certain as to how I can “freeze frame” the data
I’ll do some research to see if I can get that going. I don’t know if you’re if you’re familiar with JLR SDD but I have that too. Unfortunately all I’ve learned to do on that is pull codes, choose symptoms and reset my TCM
Try to determine:
Misfires on one bank only, cylinders 2/4/6/8, or mixture of banks?
Misfires at cold startup only?Fuel trim numbers posted at warm startup into closed loop look pretty normal at idle and higher RPM.
Just to not ignore obvious. Have you checked your coolant level and made sure there was no air in the system. I know Eric has mentioned that , that will mess with the Honda’s in the way you describe.
Bank 1 is; 1,2,3,4 Bank 2 is; 5,6,7,8. My first DTC was for misfire on 8. I swapped #8 coil with #6. The subsequent codes have been for #3 (only one occurrence a week ago) and random misfire. Random misfire happens not at startup but rather upon acceleration. This doesn’t occur once my engine temp is above 170 or so
I just changed out every hose/hose assembly on the car as well as the thermostat over the summer. There was only one I couldn’t get to because it’s under and feeds the intake manifold. The radiator was flushed and the system was filled and burped. But now that you mention it, I am getting a whiff of leaking coolant that I suspect is coming from the intake manifold. Also to note, the reason I didn’t change that one is because there is a bolt in the back of it that’s under the cowling and I was afraid I wouldn’t be able to get it back in and tightened. But I didn’t find out about that bolt until I removed the others and tried to lift the manifold. Could it be possible that my gaskets are no longer sealing properly?
“Could it be possible that my gaskets are no longer sealing properly?”
Yes, possible not sealing at startup but seals as engine heats up.Do a water spray leak detection tests around/over the intake gasket.
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