my nieces husband asked me to check out his truck. Reason is because it was misfiring cylinders 5-8. First thing I saw was when I opened the hood was cylinders 5-8 had excel coils and 1-4 were Minecraft. Also I checked spark plugs and they were in desperate need of replacement. So I went and got new ignition coils and spark plugs installed them and check that wiring harness damaged. Turned the engine on and I could still here the misfire and great loss of power. So, second thing I did (don't know if it's a good way to test) was poured small amounts of water on and around the intake manifold while the engine was running and listened to any change in revs indicating that there was a vacuum leak on manifold but nothing. I checked all vacuum lines and found rubber house connecting to PCV was cracked so I replaced. Engine still was the same. I cleaned out the MAF sensor turned engine on ran the same. With engine on. Disconnected MAF and engine ran the same. At this point I noticed the service engine light turned on which is obvious due the disconnecting MAF. So plugged obdii scanner and saw no DTC in stored codes but when I opened pending codes P1151 came up 3 times which is ho2s21. So I looked at live data and saw that ho2s21(v) was all 000.00 and the rest of the ho2s were showing voltage. What does that mean? Can that be what's causing the misfire on cylinders 5-8 and if I replace that o2 upstream sensor will it fix the problem?
Thank you,
Rob
The truck listed above is the Harley Davidson F150 model.
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Friday, July 19th, 2019 AT 9:29 PM
