98 Chevy k1500 350, low oil pressure and misfire.

[name]

A 159k is not a lot of miles and when you see low oil pressure like this it could be something as simple as a week bypass spring in the pump , so don't be discouraged thinking you need a whole new engine. Does your truck have an oil cooler ?

 

[Cgbranch1]

Got some more answers on the oil pressure issue today. I took it to a local shop who does all my work on my work vehicles. They were able to find a broken spider line leaking gas into the engine, they replaced the spider and it’s gotten rid of the misfire and rough idle. I bought this truck literally 1 month ago and so I assume somebody has driven it with gas in the oil until it has hurt the bearings, hence the low oil pressure. Along with this, the shop pulled the p1860 code for the tcc pvm and replaced the TC solenoid and did a fluid change. They said all was good and when I went to get the truck the service engine light was on. Truck did not have TC lockup on my way home. Hooked up my scan tool and found the p1860 code again along with the p1351 code. From what I have read, these two electrical codes point to a bad ignition switch. The ICM was just replaced and the alternator passes the charge test on my scan tool. Just curious if this sounds legit, if so I will have my shop put a switch in it. When I clear the codes with my scan tool, the truck has lockup and works perfect until I stop and put the truck back in park and then drive again. I know somebody here can point me in the right direction, TIA

 

[Schurkey]

Download the service manual set for your vehicle from the links in the Sticky thread section of the Engine forum.

Follow the diagnostic procedure for those two codes. Especially if they have parts in common that would tie the two codes to a single problem. But be aware that they could be separate problems.



For the record, my '97 K2500 7.4L had no torque converter clutch operation when I bought the truck (very used.) Turns out that the computer disables the TCC when it senses misfire. Replacing a cracked spark plug fixed my TCC.