FYI for Direct Scan Users

[V6 Beast]

Have any of you gotten the little spikes or data blips when looking at your runs in DS. They usually show up most in MAF and LV8. I used to get them all the time and it seemed worse as I added boost. I also used to get weird Boost DC readings, Instead of a smooth curve at the front then a basic flat line for the rest of the run, I would get a curve in the front then it would cycle up and down for the run. It made no change in actual boost because I am not using the selenoid to control boost.

Well I have gotten all of that to go away by shielding the ribbon cable. Here is what I did. I took the cable and and flattened it out. Then carefully wrapped the cable in heavy Duty Alum foil. Then taped the cable and foil using foil backed duct tape. (shiny silver kind)

This has made all the weird readings go away and now everything looks fine. I haven't had a single spike even at 27 PSI boost. (anything above about 22 PSI boost would give them to me every time) I also think it helped eliminate my stuttering problem I was having at 5000 RPM as I am now able to pull str8 to 5400 with no sputters.

Hope this helps

Sully

 

[BLACK6PACK]

Thanks for the info, I'm definately getting wierd readings. I'll try that out.

 

[Steve Wood]

Thanks for the tip...I know that shortening the cable usually helps but that is a real pain.

 

[Chuck Leeper]

DS WIERDZ??

That problem is written up on the DS website in the form of a service bulletin...www.chuengineering.com:cool:

 

[bruce]

Originally posted by V6 Beast
Have any of you gotten the little spikes or data blips when looking at your runs in DS. They usually show up most in MAF and LV8. I used to get them all the time and it seemed worse as I added boost.

One item to consider,
is MAF drop out.
When it occurs the injectors actually do turn off.
Adding that SHEILDING maybe be seriously adding capacitance to the cable, and hiding the drop out.
If you really suspect RFI interference, then shorten the cable.

There are two elements of MAF drop out.

If you're seeing little spikes downward at over 180 grm/sec., and it's not due to RFI, you're into drop out.

 

[V6 Beast]

>>Adding that SHEILDING maybe be seriously adding capacitance to the cable, and hiding the drop out.
If you really suspect RFI interference, then shorten the cable.

There are two elements of MAF drop out.

If you're seeing little spikes downward at over 180 grm/sec., and it's not due to RFI, you're into drop out. <<<

I wrapped the shiny side out to avoid capacitance gain.

lol.. seriously..I am not really sure how adding shielding to the outside of a ribbon cable could possibly add to it's capacitance but I am no expert in cabling. I usually deal with Network cabling and I know the only real difference between STP (shielded twisted pair) and UTP(unshielded twisted pair) is that STP has a foil shielding around all 4 pairs of wire (which is where I got the idea to do it). They both have the same capacitance and attenuation factors. STP is just more resiliant to EMI and RFI.

I don't think it is possible at a constant boost for airflow to go from 255 to 0 to 255 in 3/18ths of a second. This is basically what happens. I get 2-3 frames in an entire run that drops down to 0. DS captures at 18 frames per second which means each frame is basically an 1/18th of a sec.

If anyone would like to see before and after runs email me and I will be glad to send them to ya.

 

[TurboDave]

Originally posted by V6 Beast
>>
I don't think it is possible at a constant boost for airflow to go from 255 to 0 to 255 in 3/18ths of a second. This is basically what happens. I get 2-3 frames in an entire run that drops down to 0. DS captures at 18 frames per second which means each frame is basically an 1/18th of a sec.

If anyone would like to see before and after runs email me and I will be glad to send them to ya.

OH yes it can!!! If you're seeing MAF dropouts. It's what happens at higher levels of boost when the MAF is forced to 255 for a long enough periods (miliseconds).

It's what happens when the MAF buffer "is filled" and resets. The MAF reading drops to close to zero for a frame or two, this in turn drops the LV8 (calculated value using MAF), and also drops the injector PW to near zero (yes this really happens), (see archives about MAF dropouts) plenty of threads on this subject over the last year or so!!

Without getting into all the ugly details, it is a real.

 

[c&cgn]

Originally posted by TurboDave



OH yes it can!!! If you're seeing MAF dropouts. It's what happens at higher levels of boost when the MAF is forced to 255 for a long enough periods (miliseconds).

It's what happens when the MAF buffer "is filled" and resets. The MAF reading drops to close to zero for a frame or two, this in turn drops the LV8 (calculated value using MAF), and also drops the injector PW to near zero (yes this really happens), (see archives about MAF dropouts) plenty of threads on this subject over the last year or so!!

Without getting into all the ugly details, it is a real.

Some guys have been able to prevent the LV8 dropout and injector PW dropout in the chip, right? That's one of the things the Extender does isn't it? I see the MAF dropout in DS at higher boost levels but have never experienced any problems associated with it (as far as I know).

 

[BEATAV8]

I too have experienced issues with direct scan readouts at high boost levels. I often get MAF droputs and spikes, timing spikes, etc.... However, my extender chip ignores the MAF dropouts and spikes (LV8 is not affected, injector PW is not affected). Also, I do not think the timing spikes are real, occasionally I'll see timing spike from 21 to 51 degrees, but the car does not respond to it at all (no knock, no surging etc..). Last night after reading this thread I too wrapped my DS ribbon in foil and checked to make sure the connection at the ECM was not bottomed all the way. But... I can't test it till I get my downpipe back....

thanks guys.. the tech info on this site is awesome!

 

[V6 Beast]

>>>OH yes it can!!! If you're seeing MAF dropouts. It's what happens at higher levels of boost when the MAF is forced to 255 for a long enough periods (miliseconds).

It's what happens when the MAF buffer "is filled" and resets. The MAF reading drops to close to zero for a frame or two, this in turn drops the LV8 (calculated value using MAF), and also drops the injector PW to near zero (yes this really happens), (see archives about MAF dropouts) plenty of threads on this subject over the last year or so!! <<<


I guess we are talking about two different things... I was stating that I do not think it is possible for the actual air flow to change(255-0-255) that quickly (Which I still believe). I agree that it is possible for the MAF signal to drop. My injector PW is unaffecterd by these drops. Even though my chip ignores these little drops, I still didn't like them.

Since shielding the cable I have not had a single drop or spike that my chip has had to ignore.

After posting on here, someone mentioned that this was covered in a service bulletin on Chuengineering's website which I then checked out. It appears they have some shielding that they offer if you are having issues but I really don't see how it could be a lot different from what I have done. (I did find a newer version of the software that I didn't have.)

Anyway I am not telling anyone that they need to do this... Just passing on what has worked for me.

Sully

 

[bruce]

Originally posted by c&cgn


Some guys have been able to prevent the LV8 dropout and injector PW dropout in the chip, right? That's one of the things the Extender does isn't it? I see the MAF dropout in DS at higher boost levels but have never experienced any problems associated with it (as far as I know).

No, there are 2 elements to it.
One software, and one hardware.

The only way (when still using a MAF), to get around it is to run an extender chip, and Translator.

Once you know the elements of it you can design a non extender chip to use in a Translator to get around all of it

Just because it's not bad enough for you to feel doesn't mean it's not occuring. You can't miss it when starts turn off the injectors for over a .1 sec at time, but as it backs up the timing, it hurts performance. The amount of hurting one's performance is a relitive thing.

 

[Steve Wood]

Originally posted by bruce



No, there are 2 elements to it.
One software, and one hardware.

The only way (when still using a MAF), to get around it is to run an extender chip, and Translator.

B]

Not the only way. Once again, the pioneer was the MaxEffort which ignores the drop out.

I assume from your statement that the late model mafs also have this problem? Otherwise you would not have specified both an Extender and a Translator?

 

[TurboBob]

MAF dropout.

yes, Steve Y was the first to fix this problem. Kudo's to him.

The Translator will not experience MAF dropout with 'regular' chips
because it has a limiter switch to prevent this (DIP switch 3)

The Extender chips will not experience dropouts due to software enhancements
to bypass the dropouts.

(dropouts will still show up on the MAF display of DS but will not affect
the spark or fuel delivery).

HTH

Bob

 

[TurboDave]

Re: Re: MAF dropout.

Originally posted by AintGoinSlo


I have a Translator + with Extender chip and the 3.5" LS1 MAF meter.

You say that the dropouts will show up on DS, but wont affect spark or fuel delivery??

My car pops each time there is a MAF dropout (when using the Extender chip). Any explaination for this?

I have a file you can view if anyone wants to.

What position is your number 3 dip switch in? The little bank of 4 dip switches inside the Translator.

 

[TurboBob]

I replied to your other thread,

but, what version translator, what version Extender?

Send me your DS files and I'll take a look.

Bob

 

[bruce]

Originally posted by Steve Wood


Not the only way. Once again, the pioneer was the MaxEffort which ignores the drop out.

I assume from your statement that the late model mafs also have this problem? Otherwise you would not have specified both an Extender and a Translator?

Did you read my statement?.
I said when using a MAF.

There is a problem with the oem software, and with some of the oem/ oem replacement MAFs. A Translator and Extender take care of both problems. Actually I should say offer the best answers when using a MAF, ref Drop Out.

 

[TurboDave]

Originally posted by AintGoinSlo
TurboDave??

Sorry I didn't get back sooner. Been on and off busy

Switch is in the right spot.

Check TurboBob's questions. He can address the issues way better than I, after all, he's the designer.

 

[Steve Y]

MAF drop out:

John Spina has been in touch with a company that rebuilds MAFS.

There is no such thing as buffer overrun.

What he found was,.... the more air passing over the grid, the more current it takes to keep it up to temp.
After a certain point it drags down the power source in the MAF and everything screws up.

Talk to John about it. Interesting.

Steve

 

[TurboBob]

I'd still like to see the DS file.

Bob