MAST Motorsports ECU situation

[Crawlin]

Background on the car -


Dad has done a swap with a 68 Camaro w/ stock (2009)LS7 and a 6speed. ECU is the Mast Motorsports and harness. It was expressed at purchase what motor and the swap, etc... and it is preprogrammed with the tune from what I was told. The tune has not been changed.


Only mods to the car are the long tube headers for the swap. The O2 sensors are located at what would be the 2pm(driver's side) and the 11pm(passenger side) on the collectors.


Finally got it running and now have a slight issue. So I will do the best to explain and show pictures of the UI to show what happens. I will say, that we've swapped o2 sensors from side to side and it doesn't matter what side they are on. In addition, the situation will go from 1 bank and then shut off car and restart and then it will go to the other bank sometimes. So it isn't just one bank of the engine, and it is not a specific o2 sensor creating the issue.

Apologize for the non-rotated images, they are rotated in my photobucket

When we turn the key -





Notice the UEGO 1 and UEGO 2 are off.


We start the car -





They are now warming and the car idles smooth as butter.


and then it starts... Soon as they switch to "Active"





can see bank 2 starting to go down


and even further down.....








At this point soon as it starts to go below the 1.000 value, the car will start missing and the idle becomes really rough. It will literally shake the whole car and we shut it off. The car has barely been driven because of this situation, but has let idle with trying to determine what is causing this situation. We have looked at coil packs, injectors, wires, o2's, etc... Like I said, it will switch to the other bank after restarting the car. It isn't a continuous back and forth, but the important information again is its just not one side doing it.




Any thoughts? He callled MAST this morning, and they haven't returned the call. I know people are busy so no biggie on that, we are all just going on a family vacation this coming week so have some time to discuss situation.


Thanks!

And a car pic for good measure since I'm proud of my pops for his effort in doing this swap in his garage. Pardon the cheap phone pic he sent me

[rchaskin]

I'm no efi guy, but I know a lot of builds have trouble because of a leak before the o2.
It shows the a/f at 23??
That would be the first thing I would look for.
Header cracked, gasket not sealing, header not tight, leak between header and colletor??

Second, I would verify that the o2 was correct for the computer.

Sorry, that is all the help I have.

Nice car by the way!!

[rennat_2006]

All of your grounds connected, clean unpainted surface, and nice and tight?

What kind of fuel system you running?
Fuel pressure?
fuel pressure regulator at the fuel rail, corvette fpr/filter combo?

[Crawlin]

Thank you so much for the input.

The grounds are clean. It is an immaculate car. Will definitely double check them though.

The air leak ahead of the o2 is interesting but they are brand new headers and there is no air tick that is normal from a cracked exhaust tube? And the switching from bank to bank randomly would then say that both sides would have that leak, so i dont think its that.

Fuel system is a narrowed DSE fuel tank with aeromotive 340 intank with an external adjustable regulator set at 58psi per Mast's instructions. It holds steady.

Thanks again!

[dontlifttoshift]

You swapped o2 side to side, what it looks like you need to do is swap the O2 harnesses side to side. You have the left hooked up to the right and the right hooked up to the left.

[Crawlin]

We will double check that. Thanks for the idea. The harness is labeled for each side so maybe mislabeled or just needibg that double check.

Thanks guys

[blitzer454]

I also think you're getting extra air in the system somewhere. The problem could be a leak somewhere between the MAF and the intake manifold. Or maybe the manifold itself has a leak. Are all the vacuum lines properly connected. You could try blocking them off and see what happens. Are you running open headers, if so that could also be a cause.

[icemanrd19]

spray some carb cleaner in the engine while running and see if the rpms change to track down a air leak

[dontlifttoshift]

There is not a MAF with the MAST system, all speed density.

Open headers could do it.

Don't spray carb cleaner on your headers.

I'll bet 3 dollars, some pocket lint and a rubber chicken that the harnesses are swapped side to side. I know because I have done it. We stretched a LS1 harness to mount the ecm under the backseat and crossed the O2 signal wires. Kept setting codes for out of range low on one side and out of range high on the other.

The ecm thought the left bank was lean so it would add fuel to the left and then the ecm saw the right bank was rich so it would lean the right but the left is still lean so more fuel on the left but the right is really rich now, so lets lean it way out.......vicious cycle.

[Crawlin]

Finally got back into town on Saturday. Pops looked through the couple ideas and started off with the swapping the harnesses from side to side. I got a text from him with the same screen and it looked like that solved the issue at this point.

It does make sense when you think about what it is reading and then the values in the cells that it would be switched.

I know the harnesses are labeled and were installed per the labels so will have to dig in deeper to the situation, but at this point the car is idling better according to him and staying steady/even through the warming and active phases

Thanks to everyone again for the ideas!