Ping???

[jbohrer8]

having a problem with my gn pinging. heard it as soon as i got on it at about 6 # of boost in first. Just hooked up the turbo link to get some numbers but need some help. cruising at 1725rpms in closed loop the mixture swapping back and forth from rich to lean. engine temp is 160 and mat is 126. tps is 1.31 and o2 is 55mv load is 94#. as soon as i get on it at 3550 rpms ret jumps to 13.4 degrees and scares to $$$ out of me. tps is 2.14v and o2 is 793 mv load is at 214# iac is at 79 and 31%... still trying to figure out what is wrong but don't want to blow my motor up trying to.

any help would be awesome
thanks

 

[Pronto]

How's your fuel? Could it be old or contaminated? Maybe a fresh tank of 93 or higher octain could be used to test if it's still pinging. My buddy had the same issue with his not often driven GN. Couldn't even get 2 lbs of boost with out the knock going crazy. Went and got some fresh gas and knock went away.

 

[Ormand]

The mixture will move back and forth from rich to lean as long as you are in closed loop. That's kind of the definition of closed loop. The ECM is trying to hold the "target" voltage, 0.45, and it keeps going over, under, over, under.
Check fuel pressure, make sure the filter is not clogged. Check that the air line to the fuel pressure regulator is attached and not split.

 

[jbohrer8]

i thought that it might have been the gas so a ran it down and put a fresh tank of 91 (highest octane at the pumps in ca) and it still pinged, maybe ill try to find some 100 octane and try that out. ill definitely check the regulator and the fuel filter.

thanks

 

[Pronto]

You could make some home brew 100 octain with Xylene. 1 to 3 ratio with 93 octain will give you about 100. So you could get about 98 octain with that mix plus a cupfull of Marvel Mystery Oil.

 

[Lee Thompson]

problem

I have the same problem and I believe it to be in the chip.

 

[Pronto]

Ya, if your running a 93 chip then it probably would ping. So, did the pinging suddenly start? Did it not ping and than started after a mod?

 

[jbohrer8]

ya it never used to ping, the motor only has about 5000 miles on it and it started not to long ago, im running the pitbull chip and haven't had any problems in the past. ive heard good things and bad things about the chip so im not to sure.

 

[jbohrer8]

well found a pin size whole in my fuel line that would leak if i tweaked with it. replaced it today and its still pinging the same. gonna check my fuel filter and pressure tomorrow.

 

[bruce]

im running the pitbull chip and haven't had any problems in the past.

Might be a signal that what was good in the past isn't true today. The Commanders, Turbo Tweak, and ME's all have code changes to make them light years ahead of the Pitbulls, and those like them.

If you don't have a Direct Scan this is a good excuse to buy one. It *can* be invaluable in helping find problems.

 

[jbohrer8]

haven't had much time to work on the gn but just got a chance to check the fuel pressure at idle, with a walbro 340 and a bosch 237 it is around 36 to 38 #. when i raise the rpms with no load on it it seems to drop a couple of pounds. Not sure what the pressure should be at idle with this regulator.

any help would be great

 

[Pronto]

Maybe you should try a remote fuel pressure guage and see what it's doing under boost. If it's not rising then there's trouble. I don't know about a Pitbull chip but most aftermarket chips that I have seen want more fuel pressure at idle than 38. It that what it was always set at?

 

[jbohrer8]

well checked the fuel pressure during a test run. it got up to 52 # while at 11 pounds of boost. still was knocking so didn't really want to romp on it all the way.

 

[Pronto]

Maybe you should try the idle line off press at 43?

 

[jbohrer8]

well checked the static pressure and it was at 43# everyone tells me the pitbull chip is no good so i think im gonna get a turbotweak.

 

[Pronto]

Eric's chips are great. Give him all your specs and the octane rating you'll be using. Don't know what else to look for is that doesn't solve the pinging. One wild guess, maybe since the engine has been rebuilt, the compression was shightly higher and now after 5000 miles you have some carbon buildup so the compression is too high for the Pitbull chip.

 

[jbohrer8]

never thought about that but i did raise the compression a little bit.

 

[jbohrer8]

well problem fixed. i see why everyone is anti the pitbull chips. Talked to turbolou and had an old chip set for stock injectors. slapped it in and knock is gone completely. on to the next step now!

 

[Pronto]

The stock chip with 36lbs will run rich but maybe the pb chip will screwed up and running too lean. Glad you aleast found the culprit.