Hey all!
I've had some problems with spark knock (pinging) for a bit now. I thought it was a bad EGR valve at first since my 4Runner only pinged when it wasn't cold. I ran a vacuume line directly from my intake plenum to my EGR and my truck just about cut off. Since I think it is suppose to do that, I figured my EGR is ok. I then checked my vacuume on the line going to my EGR. There is hardly any vacuume at all, just a very, very slight vacuume at ilde. Now, somebody told me this was normal at idle, but when I give it some gas (up to about 3000rpms), the vacuume doesn't change a bit. Is the vacuume suppose to change once I give it some gas? Anybody have any ideas?

Thanks all, have fun.
Daniel

 

My 3.0 runs fine with hardly no vacuum coming thru the line to the EGR. One quick way to test an EGR valve is to start your engine..pull the top vacuum line coming off the modulator while its still connected to the EGR valve....while the engine is started suck on the vacuum line...I know as a kid you have stuck worse things in your mouth so this won't hurt! If the truck dies....good EGR valve. Oh...forgot to add that I just went out and tested the vacuum line coming to the EGR at 3,000RPM and very little vacuum...so you're fine on that end!

 

Thanks for the reply. I tried sucking on the vacuume line my engine did just about die, so I it appears that my EGR is ok. That hose doesn't taste very good. Oh well, I've had worst stuff in my mouth when I was little. (won't go there--it was quite a mess really) Well, back to figuring out this pinging.
Thanks for the help!
Have fun all.
Daniel

 

Hey man I had the same prob. with my 87' and it turned out to be streched timing chain. It would be fine at start and while cool but after engine heated up had a slight knock.

 

hey yeah it sounds like your egr is working fine it only has vacuum between decell and accell this is controlled bu the egr solenoid. but you say that it pings only when cold thats is probably a timing issue becuase if the egr wasnt working it would happen when warmed up when the egr opens it recurculates NOX back into the combustion chamber too keep temps down. you should recheck cam and ign timing. also a huge vacuum leak could cuase pinging it will give a lean condition which cuases ping anyways good luck

 

You should have an egr code if it is bad. Is your check engine light on at all?

 

I had a problem with no vaccum to the EGR on my 93 3.0 when I tried to get it smogged. Took it to the dealer and it was just some dirt in the vacuum line. Maybe try cleaning out the line/s with some compressed air and see if that helps.

 

Thanks all! I don't have a check engine light on. I checked it for codes though, and came up with a TPS/AC circuit code. (51 if I remember right) The lines don't seem to be clogged, but I'll double check that. A while back I noticed that my timing belt was half a tooth off on each of the cams, and I thought this might have something to do with the pinging. I tried to line it up correctly, but there was nothing I could do to make it line up right. So, I just put the belt on with it half a tooth off in the other direction. Maybe my belt is stretched a bit or something.

Oh, it only pings when the engine is warmed up, not when it's cold.

My timing is at 10 degrees right now, but when I was running it at 8 degrees, there was almost no pinging. There just seemed to be a bit less power at 8 than at 10, so that's why I would like to get this figured out. I'd really like to run with the timing at 12 once I get everything figured out. I use mid-grade gas too.

Well, thanks for the help all!
Have fun.
Daniel