Studder under boost & rpm

millhouse · Post by **millhouse** » Fri Aug 18, 2006 1:57 pm

I am running msns-e 029q with megatune v2.25 on a v3 main board.

The carâ€¦my 5.0l twin turbo mustang with mods as seen in my sig below.

Well...I've seemed to have develped a studddddder under boost. It's not really apparant under lower rpm/boost levels. The strange thing is this morning when I took a datalog the damn thing went away! Well...it's now back and can be seen in my second datalog.

If anyone has any clue as to what I check to help solve the problem....let me know.

Any and all help would be appreciated.

millhouse · Post by **millhouse** » Sun Aug 20, 2006 3:36 pm

And here is another datalog of a 1-4 gear wot run...and yes, the studder is still alive and kicking.

TT350chevelle · Post by **TT350chevelle** » Sun Aug 20, 2006 5:57 pm

From what I see in your datalog, I would suspect ignition.The datalog clearly shows lean AFR spikes when the engine stutters and this usually indicates that you have missed firing the fuel in 1 or more cylinders.What kind of ignition are you using?

Brad J.

millhouse · Post by **millhouse** » Sun Aug 20, 2006 6:17 pm

TT350chevelle wrote:From what I see in your datalog, I would suspect ignition.The datalog clearly shows lean AFR spikes when the engine stutters and this usually indicates that you have missed firing the fuel in 1 or more cylinders.What kind of ignition are you using?

Brad J.

You know...this is my #1 suspicion. My ignition is...well, stock. I had a msd coil but replaced it with a new stock unit as the resistance checked out a bit low.

I have my plug gap set down to .025 so there should be no problem there. The tach signal seems steady...although I did notice today it flaked out on me a bit (the factory tach).

I've had the TFI module checked 20 times to heat it up and it checked fine. I 'm beginning to suspect the distributer stator...but cant seem to find the time to tear the dizzy apart. I will say that the timing when checked with a light is dead nuts on at idle with no jumping around.

millhouse · Post by **millhouse** » Wed Aug 23, 2006 5:46 pm

Or not!!! It's back with a vengence. I need some input on the following datalogs please!!!

Also, more symptoms of the studder are jerking and bucking at wot in boost. This is really getting quite annoying...any and all help would be appreciated!

millhouse · Post by **millhouse** » Sat Sep 02, 2006 7:04 pm

Per Eriksson · Post by **Per Eriksson** » Sat Sep 02, 2006 11:59 pm

Try to go a bit leaner on the fuel in the affected area and also get new plugs, plugs seem to be short lived when having problem with weak spark which I feel you have problems with.

What lambda do you use?

millhouse · Post by **millhouse** » Sun Sep 03, 2006 6:34 am

Per Eriksson wrote:Try to go a bit leaner on the fuel in the affected area and also get new plugs, plugs seem to be short lived when having problem with weak spark which I feel you have problems with.

What lambda do you use?

I can...but I'm afraid there could be an underlying problem other than the tune. I'm also unsure if the VE table has anything to do with it.

As far as the lambada goes...it's an innovative lc-1

Per Eriksson · Post by **Per Eriksson** » Sun Sep 03, 2006 7:59 am

Try to back of the fuel quite a bit and test it, you may have it so rich the spark energy just isn't enough to ingite the mix and also gives you a wrong afr reading from alot of unburnt fuel.

When I run your log in MLV VE analyzer it changes it quite much in the bins it has values for.

millhouse · Post by **millhouse** » Sun Sep 03, 2006 8:42 am

Per Eriksson wrote:Try to back of the fuel quite a bit and test it, you may have it so rich the spark energy just isn't enough to ingite the mix and also gives you a wrong afr reading from alot of unburnt fuel.

When I run your log in MLV VE analyzer it changes it quite much in the bins it has values for.

Ahhh...tis an old .msq

I've ran it in the new one...and it doesnt change it that much.