SD2 Issue - ECM related parameters go to zero during a WOT run

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Mike Y

Active Member
Hi All,

Just looking for guidance/advice on a issue that we have been chasing. It was intermittent at first but now seems more frequent but we can't seem to get a handle on the cause.

We are running SD2 with a wideband. Car runs great but a on a few 1/4 mile runs we see the ECM freakout and all the ECM related parameters go to zero enough to shut the car down momentarily during a run.

What is interesting is that the non-ECM connected parameters like the wideband and MAP signals do not go to zero at the same time the other parameters do.

Attached is a snapshot of the WOT portion of the run. The log shows the dip down to zero around the 5700 mark of 3rd gear.

This is a pretty fresh build and we were pretty meticulous with the installation of everything since we have done this a few times already.

One of the early ideas was that this was an alternator issue. We swapped in a known good alternator and the issue was still there. We also removed the voltage booster thing. The logs show a steady voltage throughout the run as well.

The issue hinted as something electrical, so we swapped out ECMs to try and isolate where it is but the same problem occurred. We are about to go into the wiring next but was hoping this has been seen (and solved) previously. The case of the ECM is grounded to the chassis, and the engine ground are clean, we also used the casper's ground kit.

If it hasn't been seen before, then we are open to ideas on what to check or areas that are marginal and could be of concern.

Mike
 

Attachments

  • SD2 - WOT - ECM goes down.dat
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EricM

EricM

Administrator
Staff member
The ECM is crashing. This is most commonly caused by electrical interference. I usually see this with people using non-resistor plugs. Also the ECM case should not be grounded to the chassis, only the engine. Sometime different plug wires will affect it.
The last thing would be to try a new powerlogger board.
 
M

Mike Y

Active Member
Thanks Eric.

We use resistor spark plugs as we had a noise issue before that seemed to solve it.

We have two complete ECMs with powerloggers on both, so the swap was the full system and the issue was still there.

The case ground is interesting. One observation was that when the case ground was removed, the wideband started reading lean. We glanced by that at the time but will look at that closer. I think the WB might be wired/grounded separate from the ECM grounds.

As a check we will compare the reading to the stock O2, and/or hookup up the display gauge to see what the wideband is actually reading and compare it to what shows up in powerlogger/SD2.

I think with your initial ideas we are headed down the right path and hunting for an interference thing.

We are considering moving to ECUGN, but I think addressing this needs to come first.

Mike
 
T

TurboBob

Well-Known Member
Ground offsets are common with many widebands, the wideband companies don't do enough to explain how to avoid them. What kind of wideband are you using and where is it grounded?

as far as the ECM reset, ignition noise can come from bad coils, bad wires, bad module, etc. it can be tricky to chase down at times.

the ecuGN has some sophisticated digital filtering for these sorts of things, the stock ECM not so much.

Bob
 
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TurboBob

Well-Known Member
This could probably be its own topic, but my feeling on the subject is:
The ecuGN has a very capable digital filter system on crank and cam inputs, which is where the noise usually enters. So I believe you can make non-resistor plugs work. But I don't believe its worth the trouble. I have never seen evidence that non-resistor plugs will make more power.

So, we tell people to NOT use non-resistor plugs.

If you need some wierd, racy, super-cold plug for your application, we can recommend something.

Bob
 
M

Mike Y

Active Member
The car uses a TR6 ignition with the truck coils. Is that a powerful enough ignition that it could create noise events if say the car was marginal in terms of noise immunity?

We might be chasing something that we probably won't solve but if ECUGN is more resilient in this aspect, that is another reason to move to it.

When the car isn't hit with the noise event, it can run. We ran a best so far of 9.84@137 and were hoping to push it to 140mph but then this issue became more frequent.

Mike
 
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TurboBob

Well-Known Member
The truck coil is pretty powerful, if something in the secondary (coilpack towers, plug wires, plugs) is breaking down under load it can create extra noise. The ecuGN has configurable noise suppression filters as well as the ability to log the noise (part of logging the cam and crank signals).
 
8

87TR

New Member
thanks Bob,

it was more out of curiosity, we have no issue with resistor plugs.. tr6/truck coil/wires are all fresh from you, however plugs now have about 400 miles with about 20 passes and it may be as simple as a fresh set being part of the cure.

John
 
T

TurboBob

Well-Known Member
I run an old-school 6776BB, its one of the early PTE ones with the water cooled center, I think they were using Garrett bearings. (like in 2007).

Great turbos even today.

Bob
 
8

87TR

New Member
agreed....this one is 2006 water cooled center also, bought from Patrick at the Indy event....can't kill it!
 
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