Knock

[bjzq8]

Re: Knock

I'm not sure what pistons are in the motor (other than that they are forged)...could there be some weird interaction between the heads and pistons, as in the dish is in the wrong place or something? I'm trying to think of anything that could be basically wrong with this motor...it just doesn't make any sense.

 

[Quickstop [UK]]

Re: Knock

on Friday I had a bit of help and changed some really simple things - plugs and BIN and injectors.

It now runs ace but I have been getting fed up with mine.

You probably have a simple fix and you'll be over the hill. Don't give up on it - you'll lose all that money and feel robbed. Wrong time to sell as well unless you really need the money.

Good luck.

 

[WyoSyclone]

Re: Knock

I'm not sure what pistons are in the motor (other than that they are forged)...could there be some weird interaction between the heads and pistons, as in the dish is in the wrong place or something? I'm trying to think of anything that could be basically wrong with this motor...it just doesn't make any sense.

Do you have Datamaster, and if so, could you post up a log so we can look at it?
Pinging is either, too little fuel (sometimes too much will do it), too much timing, too much heat in the intake tract, too much boost.

If it was me, I would...

1) recheck the timing and timing mark on the balancer. 2) recheck fuel pressure (static and at boost). 3) pull the plugs and see what they look like. 4) do another compression test - the 135 is suspect if that was a valid test. 5) Recheck all the FAST parameters, and make sure you have the correct sensors for the calibration of the FAST (wideband and 3-bar for example). Then, if all those things check out,

...back the boost down to 8 or 10 lbs, and see if I could get it to run right at that level with no pinging (assuming a typical spark advance curve and no meth). At this point I would be careful to note what my IAT's are running at.

Then, inch the boost up 1 lb at a time till you just see the onset of KR. Then post back on here what that boost leve/spark advance/KR level is.

When the motor was rebuilt are you sure that you/they got all the air out of the coolant? Air pockets in the head can cause hot spots. What temp does the motor run at?

...just some things to check....

 

[bjzq8]

Re: Knock

It's a FAST system, the old-style, (not XFI) but I can certainly post a log if you'd like to look at it.

I checked the timing about two weeks ago, and it was right on with what the FAST thought it was.

I checked the fuel pressure about a week ago, it was about 50 static, and goes up appropriately with boost. I've tried fuel pressures between 45 and 55 static, with no difference.

I've just replaced the plugs with Autolite 103s. The old plugs didn't actually look bad, they had a bit of grayish stuff on them, and a bit of black. The truck has been run pretty rich in the past month or so, so it doesn't surprise me.

The 135 I got on 3 cylinders, it was getting dark and the air mosquito-filled. The engine was pretty cold at the time, if that makes a difference. But it was consistent across the 3.

The boost display between the MSBC unit and the FAST agrees, so I think the MAP sensor is ok. I will re-check the MAP part number just to be sure though.

The MSBC won't let me run anything less than 10 psi. If I recall correctly, that doesn't ping, but I will try it tonight and see.

I flushed the cooling system about a month ago, and carefully filled it, and burped air out of it for a week. It runs 165 degrees, and pretty much just sits there. It's never seemed to run hot, and never boiled over or anything.

Oh, and the O2 sensor is definitely a wide-band, but I can't say that I know it's in perfect shape, since its 4 years old. It does show appropriate swings in voltage when you force it lean or rich, though, and when turned on, closed loop does add and subtract fuel. If it was stuck at a particular voltage, I'd expect it would endlessly try to lean or richen the mixture.

Thank you again for the input. If I don't get frustrated enough to sell it to the junkyard, I might try converting it to E85. If it pings THEN, I know I've got problems.

 

[Maxtor]

Re: Knock

Post or send a copy to my email address of your LOG and GCT file and I will see if I can find anything.

 

[Try Me]

Re: Knock

Are you running in closed loop? Are you maybe maxing out your injectors?

 

[bjzq8]

Re: Knock

I am running it in open loop just for that reason; the closed loop seemed to overcorrect on the fueling, especially when things got weird with the timing. With open-loop fueling, I'm running right at 11:1, with an 85-percent duty cycle. I've tried backing off on the fuel a little and substituting methanol from the injector, but it doesn't seem to help either, at least at 15 psi.