spark knock at high heat and various loads

[scotts90ranger]

ok, my truck has a bad habit lately since it's been warmer...

first off, engine has around 175K on it, '89 engine management system, haven't checked the codes lately (CEL is on, but I fixed the O2 problem since the last time I checked them so it's just still on I think).

problem is it pings like crazy sometimes no matter what gear I put it in to lower the load on the engine, it has been worse since the engine has been running warmer (heater core blew a while ago, just fixed it, wasn't much higher than it is normally), it's not happening all the time... an example of what it's doing is a hill on my normal commute I usually take it in 4th gear at 55mph (3000 rpm), but it was pinging, so I threw it in 3rd which is 4600rpm at 55mph since I figured that might help at the HP peak. I know the radiator on this thing is friggin tiny (about 1/2" thick), if I had to guess at what it's getting to I'd say 205ish degrees if it normally sits at 190

in the past I've gotten EGR position sensor faults on the KOEO test, and if I went out and tested them now I bet I'd get it again, might try tomorrow.

so, any ideas?

Thanks!

 

[scotts90ranger]

ok, pulled the codes at lunch today, got a code 34, CEL came back on on the way home...

so, you think the EGR position sensor is shot or the EGR itself?

 

[Wicked_Sludge]

pull the hose going to the egr and suck on it (a vacuum pump is nice too), if the diaphram moves then pull the valve off and check the egr ports for build up, and to make sure the valve is sealing when its in the closed position.

if all is well with the valve, replace the sensor.

a malfunctioning egr will definitely cause some bad pinging.

 

[scotts90ranger]

I should mention it idles great, nice and smooth, I know a bad idle is often a sign of a shot EGR valve...

I'll try to fit in checking the valve into the schedule... between moving and the tractor pull this weekend it could be interesting...

 

[scotts90ranger]

ok, I forgot I made this post, it doesn't really ping anymore, and the cause of my higher engine temp was a failed water pump gasket that I fixed a week or so after my last reply to this post...

the thing now is I have a arecurring code 34 (and only 34, on a KOEO test though), a couple months ago I grabbed an EGR valve and sensor and tube off of a 2.3L mustang that looked the same as mine, I replaced the sensor and noticed some black marks on the sensor side of my EGR valve and the sensor, which makes me think it's bad. with my lack of tools and nice work space at my new place I haven't pulled the valve off since it's a PIA with the clearance between the intake and the hood seal.

when I had my cab off a bit over a year ago I pulled the EGR off and cleaned out the tract into the intake manifold as good as I could with a drill bit and such.

it's more bugging me that the CEL is on and what could be wrong than anything, it runs fine but gets under 19mpg, which isn't helping anything