Can you run it with a wideband?

 

No, we didn't. But it ain't rich, it's LEAN, Lean, lean. Plugs are as white as white can get.

I'll pass it on though....at this point, try anything.

Not easily.

 

I believe you... I just wonder if the problem is timing related or if you're going screaming lean for some reason... That bog sure sounds like mixture over timing, but it's hard to tell for sure without being there.

Was this thing running OK in that RPM range for a while, or are these the new issues on the latest motor design?

 

Other than a little high EGT when coming off the throttle it's been running great...for a 3.turd that is.
Gets sucky MPG.

When I did the downshift/overrev/giant shake I think whatever was causing the high EGTs (and melted piston last fall) went from mildly malfunctioning to full broke.

Now if we can just find what's broke it'll run great again.


What about the pair reed valve? if that was fubar could it do this, bypass enough air to blow the AFM's reading?

Current list of 'what it's not'
1. It's not the TPS, changed.
2. It's not the AFM, checked with a known good one I have.
3. It's not the computer, again checked with a known good.
4. It's not fuel pressure related. Snap on remote gauge is still on there 38-42 psi.
5. It's not O2, changed.
6. I know the left cam has not jumped it's timing (distributor is driven from it and is still timed the same.)
7. It's not timing related. While normally this engine likes a bit more timing than normal, I've tried it at various settings and it?s of no help.
8. It's not plugs or wires, cap or rotor.
9. It's not compression (within spec across the board.)
10. It's not cam timing - checked.
11. It's not distributor or distributor timing - changed and checked.

 

It sounds like you have built the motor for more performance. If that is true, did you put in injectors that are big enough to provide the proper amount of fuel? You need a certain amount of fuel volume, not just pressure.

You could certainly have a serious vacuum leak. These are easy to find, using propane.

Lean and bog, is almost always fuel volume (to low) or air volume (to high).

 

I'd say the injectors are plenty big enough for the application. They were cleaned and inspected (thanks witchunter) during the last rebuild.

Under full throttle load EGTs are fine, it's when lifting off that EGTs spike.

Does that not tell us that the injectors are flowing enough?

When I was down at the shop this afternoon I suggested a vacuum leak and asked for ether...he said he has a 'smoke system' which works better and will test...

Maybe it's got a giant air leak somewhere and is not pulling the AFM's barn door open.

 

i still dont see were you opened the exhaust up to see if that helps....

 

Are you able to read the O2 sensor output?

If exhaust was plugged, the fuel would get in, but not the air, and it all gets high EGT with too much fuel.

Also, can you read fuel pressure, under load, going down the highway?
If fuel filter is plugged, you will have good pressure at idle; but not at speed.

 

Wow...best of luck on this.

 

well, sumbitch, you were right on the money.

This new Summit Cat w/ 2000mi on it was SLAGGED



It WAS an empty shell and I put a new cat in to do my part for the environment.
That'll teach me to be environmentally friendly...

 

.... no comment on that one..
well at least you know the problem

 

Wonder what caused that... in other words, was that a symptom, or a cause?

 

That would be my question too. Being as how it melted a piston last fall.
The burned hole was the result of towing a trailer some 800 miles thru mountain passes and I was NOT the slow guy on the road. Truck was WORKin. The only thing I ever found wrong with it was the knock sensor's plastic plug top was cracked.
Maybe I get some poor gas at the last stop and the knock sensor did not retard the timing.

But I've been watching EGT's very carefully and it has not gone over 1425 even once (until the very end when EGTs were spikeing.)

I ass-u-me 'd that the current high EGTs were the same problem that caused the piston melt. However, the cat was a new addition post rebuild.

Will high EGT continue to be a problem?
We will know shortly - I'm doing an Atlanta run (400 mi) this weekend and there's no guts in the cat now.

 

I guess we have to go with CAUSE.

Knocked all the stuffing out of the cat, cranked the distributor back to where it's liked it in the past - maxed out without going to the next tooth.

Ran to Atl for the weekend.

Run like a raped ape. Tons of power, has never run so good.

 

Great to hear! Love to see a dyno run on that thing some day.