Crazy EGT temps. What's up?

[laser92awd]

Lately I've been playing around with my boost controller and driving the car pretty hard. What's got me puzzled is that if I make a WOT run through 3rd gear, my EGT's peak right at 900C which is pretty high. THIS HAPPENS AT 10PSI! If that's not weird enough, it happens ALSO AT 20PSI! That's crazy. Why would running such low boost make it run as hot as twice the boost?

I have a VPC/550's/fuel pump. I've even tried turning the VPC GAIN knob up and down and it doesn't seem to make any difference.

The car seems to also be running low O2's (around .80 to .82), but I'm not getting any knock, the car pulls hard, and my spark plugs look totally fine. It's almost like I can run whatever boost, set whatever VPC settings, and get the same results.

Somebody was following me the other night when I was testing at 20PSI and they said when I shifted from 2nd to 3rd a huge flame came out my exhaust, but I did not hear any backfire. I also notice when I run at 20PSI it seems like black exhaust smoke poors out the back of the car during the run (like a mist, not like clouds). At 10PSI I don't see it.

What's the deal?

 

[L2RTSiAWD]

Sounds like you are running extremely rich.

 

[MustGoFaster020]

What kind of timing are you getting? Sound like it's rich but retarted timing could cause high EGT's also. My friend's Galant ran high temps too, crused at 1400ºF and made it to somewere around the M on the Autometer guage, the wideband said 11.8:1 A/F's too, it had a lot of knock but we are 99.9% sure it was machanical, no matter how rich we went it knocked (720's and a ETE12).

 

[laser92awd]

You mean running rich can cause high EGT's? I thought it was lean that I was trying to avoid. I've also got a GCC that I haven't fully dialed in yet. I could put the VPC gain down to minimum and then start leaning out on the GCC?

My base timing is 5 degrees BTDC with the terminal grounded.

I guess I should clarify that when I put in my 550's I also put on a fuel pressure regulator and at first the car would barely run and was puffing big black clouds. I set the FPR to 43psi (@ idle) and leaned out the idle rpm on the GCC and it started idling fine. But all the other GCC knobs are not in use yet. The GCC lets me lean out a lot farther than the VPC so if I'm running rich I should be able to lean it out quite a bit.

So does everybody think I'm running rich and should start leaning out across the rpm range? What about the relatively low O2 numbers I'm getting - do I just dismiss that since every car seems to read different? The O2 value is steady through the run when I log it.

See I guess I was confused because with the low O2 and high EGT values I was thinking I needed MORE fuel. I'm really trying to get the car dialed in without blowing something up.

Jonathan

 

[doug]

I've been told that if you're running really rich, that you're dumping burning fuel out the exhaust manifold, which WOULD cause your EGTs to skyrocket (I hope I'm remembering/explaining that right-- someone jump in if I'm hosing it).

 

[DSMafia]

doug youre right....its called a secondary ignition.... basically like he said excess fuel gets ignited in the manifold....

 

[4pistons]

I've been told that if you're running really rich, that you're dumping burning fuel out the exhaust manifold, which WOULD cause your EGTs to skyrocket

Exactly...Your cylinders can actually be running cooler from the excess fuel but it burns in the Ex. manifold at your EGT probe and registers a high temp.

The car seems to also be running low O2's (around .80 to .82), but I'm not getting any knock, the car pulls hard, and my spark plugs look totally fine.

No knock is a good indication that you're not lean even though the O2s seem to be low. Are you datalogging the O2s?

I shifted from 2nd to 3rd a huge flame came out my exhaust, but I did not hear any backfire.

A "Backfire" comes up through the intake....Those flames are another good indication of running rich.
I'd start backing down your fuel settings little by little and notice when things start changing. Or get to a dyno and put a wideband on it.

Rick - '91 GSX

 

[laser92awd]

Thanks, I'm going to start tweaking with my pocketlogger and gradually move it towards the lean side.