Engine "stuttering" under full boost - see dm file

[Don W.]

Re: Engine "stuttering" under full boost - see dm file

Excellent article on reading plugs.

http://www.dragstuff.com/techarticles/reading-spark-plugs.html

 

[dgoodhue]

Re: Engine "stuttering" under full boost - see dm file

Makes it harder to justify advancing timing... The run was pretty clean, but sloooow. 1/4 mile in datamaster was 15.8..

I don't know how accurate DM is but 15.8 is slow for a typhoon. It should run mid 14's if you didn't boost launch it and if you did boost launch it properly it should be in the 13's. Nothing really stick out in the DM screen shot as being off to me. Maybe its running really rich at WOT or the timing is off.

 

[E.Murray]

Re: Engine "stuttering" under full boost - see dm file

In poking around last night, I may have found a serious problem. I can move the impeller on the turbo over 1/16" back and forth (axially). From what I've seen, there should be no play at all. Do I have a problem? If so, can I rebuild it myself? It's a stock turbo with the billet SportMachines impeller. What do I need to order? If I'm not supposed to have any wiggle, I don't want to run the truck until it's fixed. I'd rather not feed shrapnel through the intake...
Could that be why I'm slow? Besides one good pull, the truck hasn't run under 15 since I got it (according to DM). The power just isn't there.

 

[Don W.]

Re: Engine "stuttering" under full boost - see dm file

Did this thing ever start?

MALF 42 EST (Electronic Spark Control) .

The short version of code 42 is either you have something wrong with circuit 423 the white wire. Wire itself, ECM to conector or connector to ESC

OR, the same with 424 the tan/black wire.

OR there is something wrong with the connector itself.

Also with the connector separated check that 423 is grounded both ways by checking both sides of the connector.

There's more but try these things.

 

[E.Murray]

Re: Engine "stuttering" under full boost - see dm file

The first time I started it, I forgot to re-connect the tan/black wire. The CEL flashed at me, so I turned it off and connected it. I assumed that was the cause. I had also unplugged the ECM to connect the wideband O2. Do you think it's something else? I have to pull the ECM again to ground the O2 to it, so I'll double check connections then.

 

[Don W.]

Re: Engine "stuttering" under full boost - see dm file

The first time I started it, I forgot to re-connect the tan/black wire. The CEL flashed at me, so I turned it off and connected it. I assumed that was the cause. I had also unplugged the ECM to connect the wideband O2. Do you think it's something else? I have to pull the ECM again to ground the O2 to it, so I'll double check connections then.

The connector I'm talking about is at the back if the dist. Difficult to get to.

 

[E.Murray]

Re: Engine "stuttering" under full boost - see dm file

Thanks. I'll look at it. As far as the turbo, I talked to the previous owner and he said it was rebuilt by SportMachines (has their billet impeller). When he got it back from them, he noticed the play. He sent it back, but they checked it out and said it was ok. I called Tom at SportMachines and he said the .035" of play I have is ok as long as there is no contact with the housing (there isn't). I'm going to put it back together today and will run through all the stuff talked about in this thread.

 

[E.Murray]

Re: Engine "stuttering" under full boost - see dm file

Just posting the follow-up for posterity's sake. I always hate searching and finding a thread with no conclusion. :roll:
So I put the turbo back in, cleared the 42 code and re-did my wiring. Turns out I had a wiring issue from the WBO2 to the ECM. The gauge was right (i.e. was running rich) and the lean readings in dm were wrong. At the same time, I put in a fuel pressure gauge. Fuel pressure is 43 cranking and rises to about 62 when under full boost.
The run is below. I finally have solid boost control. No cat and free-flowing exhaust can, indeed, be fixed with the Forge wastegate and some conservative port work. Also, I found that the truck had been rich when I got it (hence the 120+ injector duty cycle). Now, things look pretty solid. Thanks for all the help. I have a few tweaks to make, but am calling the truck good for now.

 

[dgoodhue]

Re: Engine "stuttering" under full boost - see dm file

You way just want to lower the boost a tad to see if the spark retard goes a way.

 

[E.Murray]

Re: Engine "stuttering" under full boost - see dm file

That was first on my list. I lengthened the rod a half turn this morning (since everything was cooled down). Haven't hooked the laptop up yet, but it was a fun drive to work.

 

[Eric Sy GN]

Re: Engine "stuttering" under full boost - see dm file

Are you still using the factory wastegate solenoid, or did you bypass it? If you are still using it, could you send me that log (or post it)? I want to see how the ECM is interacting with that wastegate setup.
Good job getting things ironed out.

Eric

 

[E.Murray]

Re: Engine "stuttering" under full boost - see dm file

I'm not using the factory solenoid. I didn't think I could with the Forge??
Thanks for the great help, Eric.