Hey guys, after bragging to my wife that my K5 is the only bowtie we have that hasn't broke down it did just that last night... I almost did not get it home. Brakes going crazy trying to stall... check engine light on. Today I accessed the code and its a 44. I am guess I just need to replace the O2 sensor? 44 says lean 45 says rich... What do ya think?

While I am at this I was told the gearing in the rear and the front axles need to be the same. I am suspecting the PO switched out the rear axle when he put a turbo 400 in here.. How can I tell if they match? Thanks in advance guys have a great day

 

sounds more like a vacuum leak

 

137 views and one reply I am shocked!!! I have replaced the base gasket, it was in awful shape. I replaced the idle sensor, Vacuum sensor?, throttle position sensor, coolant temp sensor, cleaned the throttle body and injector ports, checked fuel pressure, (This all did start when I ran it low on fuel) Advance tells me MAP sensor not required on this model. Or I would replace it too... I have O2 sensor just have not changed it yet. How do I check EGR? I have read that can cause problems too. I have sprayed starter fluid/carb cleaner around all vacuum hoses, ports and intake gaskets no change in idle. Started truck and at first it would not idle, an audible whistle can be heard from air intake of air cleaner? After it warmed up a little it idled but higher than expected. Notice too that stove pipe from exhaust to air cleaner is gone. Battery had died from sitting so all codes are gone and it has not coded yet again. So, now what?

 

What is shocking is that it took you 3 months to get back here to check. Generally, when someone has been given direction, many people wait to see if the OP responsds back with what they have done.

Regarding the gearing, you can either just try to put it in 4wd with the front hubs locked in and see if it moves. If it doesn't, the gearing is different and that will need to be remedied. You could also pull the diff covers and check the actual tooth counts on both the front and rear ring/pinion combinations. If you do not know the maintenance history, doing an axle gear lube change would be good.

On the EGR valve, I have always pulled them off the motor whenever I suspected a problem with them. The EGR valve has two parts, the vacuum solenoid and the actual valve itself.

The vacuum solenoid can be tested by attempting to blow into the outlet. If you can blow through it without any power to the solenoid, then it is bad or at the very least needs to be cleaned.

For the EGR valve itself, I would clean it with some brake cleaner before trying too hard to test anything, but be sure to only clean the exhaust ports on it. Do not get brake cleaner on the diaphragm as it will soften the rubber and cause a leak sooner or later. Once it is clean, you can try to blow through it from the supply side to the outlet side. You will also want to apply a vacuum to the port and check it for proper motion.

A leaking EGR valve can cause a lean code as the exhaust gases would displace combustion supporting oxygen.

The "stove pipe" isn't really a necessity. You shouldn't have any adverse affects due to the fact that it isn't there.

 

Yes I have not had a chance to follow up on this problem for some time. Work and other car problems over rode this one. Daughters '85 Camaro, wife's mini van, blah blah blah... I bought this truck because it was straight and clean for an '87. Have been replacing parts for some time trying to get it back to original. Electric windows failing, seals dry rotted and the like. Someone put a turbo 400 with electric detent? shift switch but never hooked it up. (I found this while going to replace the cable in the 700R4 that was no longer in there) I suspect that the gearing is not a match either... Mount bolts for the axle were not torqued. Once I get it running back like it was I will pull the rear cover and look for the numbers.. Transfer case and front axle look original except for the lockers... Thanks for the reply..

 

Thanks new guy. I have been all over this truck and have replaced several things to no avail. I still have a whistling sound from the throttle body and a no idle problem.. This has me pulling my hair out, about tempted to post this blazer on craigs list...