DSMLink Communications Drop-outs during WOT run

[zippyshoe]

I have just started WOT tuning my car using DSMLink and have been experiencing a problem while trying to log WOT runs. With the boost set to 13psi I had no problem generating a WOT log. However, with my boost now set to 15psi, my car pulls smoothly, but communications between my laptop running DSMLink and my ECU appears to drop-out in the middle of the pull. If I let off the gas, communications then resumes. The test log appears to be missing data points during these drop-outs. I've tried to log a WOT run several times and this problem consistently occurs. After doing some searches on the DSMLink forum, I found that the two main causes of this problem are:

1) Connection between DSMLink connector and the ECU's connector is intermittent.
2) Using non-resistor type spark plugs can create electrical interference and hamper communications.

I think I've ruled-out number 1 - I have tried additional WOT pulls while holding the DSMLink connector firmly against the ECU's connector and still see drop-out in the middle of each pull. I also tried cruising and wiggling the connector and never saw any drop-outs. This leads me to believe that my problem is some type of electrical interference issue (from the ignition system possibly). Regarding number 2, I am currently using Champion RN9YC plugs which are advertised as "resistor"-type plugs, so this appears to rule out number 2. Has anyone else using DSMLink experienced data drop-outs while logging WOT runs? If so, what did you find to be the cause of this? Any ideas would be much appreciated.

 

[TSIMonsteR]

Have you tried a different set of plugs (NGK Bpr7es) just to be sure? Also, have you verified that the chip is properly in the socket?

 

[Staytuned]

Is it possibly a sample rate problem?

 

[zippyshoe]

I haven't tried replacing the spark plugs yet, but I was planning on replacing the Champion plugs with NGK resistor-type plugs anyway. The only reason I have Champion plugs installed is because I had some cylinder-head work done recently, and the shop performing the work installed the Champions (I had NGK's installed prior to this.) So replacing the plugs with NGK's may be worth a try.

When I installed the DSMLink EPROM into the socket on the ECU, I was careful to verify that the chip was fully-seated in the socket and that no pins were bent. However, it may not hurt to pull the ECU and verify that the EPROM is still seated in the socket properly.

I was wondering if a defective coilpack could create excessive interference - I have had a slightly "uneven" idle for some time now. It almost sounds as if the car misses occasionally. This problem seems to be more noticeable at higher temperatures. One of the resistance values I measured at the coilpack was slightly outside of spec. (spec. limits were 0.7-0.86 ohms and I measured 1.1 ohms. I am considering replacing the coilpack.

 

[zippyshoe]

Is it possibly a sample rate problem?

Is there a way to change the sampling rate in DSMLink? I know that you can change which parameters are sampled, but I didn't think there was a way of changing the overall sampling rate.

 

[daren_p]

What kind of laptop are you using, if it very old it may not be quick enough for the rate at which your trying to update in realtime. Under Edit then options you can chage the graph & text update rate. Does this only happen in real time or are the logs missing data when you review them? If this only happens in real time then this is probably your issue. Reduce the graph update rate first as it uses more CPU resources. If your saved logs are still missing data then you need to look else where.

 

[zippyshoe]

What kind of laptop are you using, if it very old it may not be quick enough for the rate at which your trying to update in realtime. Under Edit then options you can chage the graph & text update rate. Does this only happen in real time or are the logs missing data when you review them? If this only happens in real time then this is probably your issue. Reduce the graph update rate first as it uses more CPU resources. If your saved logs are still missing data then you need to look else where.

I bought my laptop brand-new about two weeks ago from Dell (Inspiron B130). When I review the log files, there is a large "discontinuity" in the graphs where the drop-out occurs. Also, if I move along the time axis using the cursor keys, I see the time value increment about 0.04 seconds consistently until I reach the discontinuity, then I see a sudden jump of about 0.2 seconds. Hence, I believe I am seeing a genuine loss of data during the log.

 

[zippyshoe]

Thanks for all of the quick responses everybody. I plan to take the following course of action:

1) Pull ECU and verify DSMLink EPROM is still properly seated in its socket.
2) Replace current spark plugs with NGK resistor type plugs.
3) Replace spark plug wires.
4) Replace coilpack.
5) Bang my head against a wall a few times.

Just for curiosities sake, I may try and connect my Pocketlogger (bought before I got DSMLink) and see if it maintains communication during a WOT run. Thanks again, and please let me know of anyone thinks of any other options I should investigate.

 

[daren_p]

Yes, doesn't look like a laptop issue. This is a stretch (since they usually work or don't work) but just another check, what usb to serial adapter are you using? There's a list on the DSMLink boards on ones that work properly. The strange part is that you say it only happens during WOT pulls.

 

[zippyshoe]

Yes, doesn't look like a laptop issue. This is a stretch (since they usually work or don't work) but just another check, what usb to serial adapter are you using? There's a list on the DSMLink boards on ones that work properly. The strange part is that you say it only happens during WOT pulls.

The USB to serial adapter I am using is a Radio Shack model (part no. 26-183). If I remember correctly, some other members of the DSMLink forum mentioned using a Radio Shack adapter without any problems. So far I have never witnessed any drop-outs while logging while simply cruising (when checking the fuel trims). The drop-out only seems to occur in the middle of a WOT run. It appears to occur at roughly the same time at each pull. Because of this, I was suspecting that some part of the ignition system is generating electrical interference as RPM's build. Does this make sense?

 

[TSIMonsteR]

Makes perfect since. Your thinking very logically, which is good. Quick question, do notice anything else going on in the cockpit at relatively the same time as the malfunction (ie. gauges, lights, anything out of the ordinary)

 

[zippyshoe]

Makes perfect since. Your thinking very logically, which is good. Quick question, do notice anything else going on in the cockpit at relatively the same time as the malfunction (ie. gauges, lights, anything out of the ordinary)

That's a good question. So far nothing else unusual occurs when the drop-outs happen - nothing unusual seen in the instrument cluster and the car runs smoothly throughout the pull. I'll just have to stay alert for any unusual events that accompany the drop-out.

 

[zippyshoe]

Go figure - I thought I would try a couple WOT pulls today and both times DSMLink logged without a hitch! I haven't changed anything that I am aware of from the previous unsuccessful pulls. I guess I will just have to monitor for this issue to see if it ever happens again. Thanks for all of the replies!