[nhra no 2]

I've been chasing this problem for awhile. New cap and rotor, plugs at .030, new wires. I've tried logging with two different computers. The Dataq keeps logging fine. No matter what I log in the payload, when the RPM hits 5400 ish no data coming from the EEC will climb any higher. I've enclosed a screen shot of a typical log. I'm lost as what might be going on.

[skunk]

Have you tried swapping usb cables between the DataQ and the Tweecer? My thoughts are it's hardware related. You can also try running with just the Tweecer to see if it's a software process issue.

John

[nhra no 2]

I have tried logging with the dataq turned off they BE. Still get the same results. I will try switching the USB cables. I'm not sure if this is just a logging issue, I'm pretty sure the engine won't Rev any higher than the 5400ish RPM also. I only have the stock tach on the car, so I don't have any other device to compare correct max RPM.

[skunk]

Ok ....if the engine doesnt seem to rev past the 5400 rpm..... It may be the tune. The name escapes me at the moment but there is a parameter for rpm that the ECU determains the pip signal as unreliable. Stock I think is 6500. I can't say for certain this will cause your issue but it's something to look for if you've been playing with rev limits.

John

[Paulie]

Can't really tell much from your picture, a screenshot would have been better. How high does load get?

[jsa]

I only have the stock tach on the car, so I don't have any other device to compare correct max RPM.

Can your DATAQ be configured with a hertz channel?
Have you got a multimeter that measures hertz?
What does logging only the RPM PID only show?

[nhra no 2]

Previously load was maxing out at 200. I have now set sarchg to 390 cid, instead of 308. But that has no effect. Still my 5400 issue.

[nhra no 2]

Jsa, I hate to sound like a newbee. But my Dataq device can log one channel as frequency, is this the same as Hertz? If it is, I'm how would I go about setting this up? I'm sure I would need a data table so that it would output the correct RPM? I guess I would need some have holding to do this.

[skunk]

Hopefully JSA will post up more info....I would like to know also. I know it can be done through logworks if set up properly. I attempted once for a knock sensor experiment but failed miserably due to the irregular signal amplitude. It might work for RPM since the signal is a much crisper square wave.

Look close at the tab for the DataQ in BE....there is the option but the checkbox will likely be greyed out (channel 9). Yes Hz is frequency.

If you have a multi meter with the Hz option it's alot easier to check free reving the engine measuring at the coil. I dont remember the formula but I do remember 400Hz = 6000 rpm. I'm sure Google can find more info.

John

[nhra no 2]

Skunk, were you able to log RPM in logworks? I have a LM-2, and I have never gotten it to work.

[skunk]

Sorry.....I did say logworks. I meant DataQ's Windaq. There is a sample in the software named AUTO.WDQ. You may be able to reasign the channel if your using a 4 channel version but you still need to get the signal to the DataQ.

I attempted a manual setup for what I was trying to do and never attempted to use the sample so I don't know if it works.

John

[jsa]

Yes hertz is the unit of frequency. It is a measure of cycles per second, so multiply by 60 to get cycles per minute or rpm. The assumption is you monitor a pulse that happens once every revolution.

If you monitored an injector that is sequentially triggered, it would would trigger every second revolution, so Hz×60×2=RPM

I don't have a DATAQ or any desire to study the literature, you are on your own there, until a DATAQ user chimes in.

Aside from an injector, signal sources such as coil low volts side, edis tach out, crank sensor, phase sensor etc can be used.

[Paulie]

Is it just the datalog stops at 5400rpm or does the engine actually not rev past 5400rpm?

[skunk]

I suppose I should warn you.....be careful where you tap the tach signal if your going to try and log it. The coil primary (low voltage side) will spike around 70 volts potentially messing up the DataQ. Easiest place to tap is back probing the TFI pip signal. It will produce a much lower voltage and a much cleaner signal.

I really don't see this as a physical RPM issue if your logs are flat lining and reporting the same data until you drop rpm. Maybe posting your tune will reveal something.

John

[85GT]

What sampling rate do you have in BE logging tab?

[nhra no 2]

Yes, I will post my tune when I get home from work tonight. Last night I had a little time to look through my tune. I was going through the scales and comparing to a stock A9L time looking for anything odd.

[nhra no 2]

I'm not sure of what sampling rate I'm logging with. I've never changed it, should be the stock value from when BE loads after a fresh install. Any suggestions of what the rate should be? That way I can set it after work. Thanks.

[85GT]

If memory serves, I believe it's 50ms. Anything faster (lower number) might be the issue.

[nhra no 2]

Skunk, and anyone else that would like to look over my current tune. Please have a look at my upload. Thanks

[nhra no 2]

85GT, the dashboard rate is at 100ms. Data logging rate is 50ms, and speed correction is at 1.00. So from what you had mentioned, everything is set correct. Thanks

[Paulie]

What is maf airflow when this is happening? The EEC has an airflow limit of 2350 kg/hr

[skunk]

Paulie..... wouldnt that just cause lean out? At 16# he may be close but not hitting the limit. 10 puts me around 1300.

Looking through the tune .... which looks pretty good .... nice and simple! I only noticed a couple of editing slips. I dont know that any of them will cause your issue but worth fixing to eliminate the possibility.

1, For some reason you changed System - Checksum Base Address.....set it back to stock 8192
2. Spark - Base Dwell ACT to ECT proportioning factor.... set it back to stock 0.8750. This is for use with black TFI module.
3. Go over you scaling.... I noticed your RPM scaling starts at zero. Maybe you did this for a reason but normally your first value in the tables is a valid RPM. Eg 400 rpm should be column 0. I didnt look too hard at the rest of the scaling changes but the same should apply.

John

[nhra no 2]

John, thanks for taking a look at my tune. I've made the adjustments you spoke of. I also looked at a log to see what my kg/hr is in a log with the 5400 problem. It was at 3.80 volts, which is around 1740 kg/hr. So the air flow to the EEC does not seem to be maxing out. I'll give it another test drive tomorrow to see if it's any better.

[Paulie]

Can you post a datalog? What distributor are you using?

[nhra no 2]

I will post a datalog after work today. I'm using a stock distributor, and it has one of the so called high output tfi modules on it. Iforget the name of it. The cap, rotor and wires have around 1350 miles on them, I replaced them this spring.

[skunk]

How about the coil? Stock type arrangement or aftermarket type like msd box. A failing pip, tfi or any part of the ignition system can act like a rev limiter as well.

John

[nhra no 2]

I have an MSD coil, around three years old. Also a MSD 6AL-2, the same age. I've have run the car with the spark box removed, no change. If I don't have to, I don't want to just start throwing parts at my car. I'm trying to diagnose a problem first. The other thing is my car is just a summer cruiser car. Never ever seen rain or snow (I live just outside Chicago). I only drive it around 1k miles a year. Just a little info that this is a well and clean maintained car.

[nhra no 2]

Oh and I have had a failing tfi in the past. The car starts having a no start problem when hot, or just no start at all. I've seen none of this. I always thought the electrical parts in the distributor were a go or no go type of problem.

[skunk]

They can fail intermittent as well.....usually with heat as you noted. You seem to have covered your bases with hardware so let us know what happens when go for rip with the updated tune. I am hoping the checksum addressing will take care of it since where you put it likely created an offset in the rest of the tune. Just a hunch..... hopefully it proves correct for you.

John

[nhra no 2]

As requested, here is a recent datalog.