i am curious as my only diesel tuning experiance is with my current truck what the differance between say a fuel rattle and a timing rattle is, or just diesel rattle? i know the differance in adding a pilot injection to quite things down, but i am having an issue i want to try and figure out myself before asking for help. thanks joe
dumb question about rattles
- Thread starter stacks04
- Start date
they are the same rattle , timming rattle and fuel rattle ................. when timming rattles it because you are starting the injection spray too early ( too much timing ).
fuel rattle is the same just injecting too much fuel for the amount of air availible . both are knocking from too much fuel being injected on the compression stroke . if you post up the issue we would be glad to help .
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well i am getting a rattle if i put the pedal to wot or close to it from a low throttle condition like highway cruise. i am leaning to fuel as my timing never exceeds maybe 20* until the rpm are up there. i guess it is the greater fuel shot until boost comes up. not sure how to help that, it just flat sounds awful.
are all your limmiting tables maxed out ? the MAF limmiting table is the easiest place to fix this issue . basically it will limmit fuel till it see's X amount of air . alot of guys max it out because they dont like fine tunning it and untunned it will limit performance . only other solution is from a drivers stand point of rolling into it slower . i have it corrected in the MAF table myself . there are other ways to tune around it like fuel pressure tables or the base injection . it hard to tell without seeing the tune .
the maf was wide open, i made a change back to stock in the mid-up/left of the table to clear up some smoke at various throttle spots and its been raining men plus i have had no computer with efi until today. it is sunny now and hopefull for the day i guess i will try messing with the maf a bit. maybe i will get brave and use the map function to build a nice table.
just a FYI the base injection table will over ride the MAF table so if you lessen the MAF MM3 and the base injection MM3 is higher it wont show a difference .
base meaning throttle base 0727? if so then why the maf limiting table if the base table will just over ride it? that doesnt make sense to me.
I've been playing with fuel pressure, timing and torque limiting lately...Sometimes it's easier to go back and make baby steps...
base meaning throttle base 0727? if so then why the maf limiting table if the base table will just over ride it? that doesnt make sense to me.
there are plenty of ways to skin a cat and not saying mine is the best way , but in my "street tunes" were the MAF is used in the lower RPM's( 1600-2200 ) the base injection is low ( like 60 mm3 or so 100% throttle ) , by having it low it then references the MAF table for the "max " amount of fuel allowed .
Basicly the computer uses the base injection as what it is labelled as the "base" then several limmiter tables determine what the "max" fuel will be . the MAF is one of them . like Neens said take it slow change a table at a time and get a feel for them .
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That is good adviceDrop 5 mpa of the fuel pressure is useally enough,but that is just one way to do it
Grab a friend and log JUST the rattle area
I know exactly what you are talking about stacks and be damned if I can figure it out myself either. I make too many changes and seem to chase my tail with this same issue.
Unfortunately, it seems my "friend" (Cough Simon Cough)always has something better to do with his own truck so I have been neglecting my own!
Sooner or later though, I will get it figured!
Unfortunately, it seems my "friend" (Cough Simon Cough)always has something better to do with his own truck so I have been neglecting my own!
Sooner or later though, I will get it figured!
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thanks guys, i got some time to test this maf theory this am and it seems to stop the rattle. but it still doesnt tell me weather it is timing or fuel, because if it limits the mm3 that limits timing. i am going to max the table back out and make some changes in fuel first. go from there. i guess i am just getting frustrated. oh well. thanks for the help guys.
GMC_2002_Dmax
The Still Master
Didn't Nick tune your truck ???
If you are having problems with a rattle at low rpms it is most likely fuel pressure.
The tables are different for Federal, North East, and CA emissions trucks due to the EGR and air pump.
If you are running scripts for tunes you need to make sure things are not getting changed that should not be, scripts are indiscriminate, they do not care what they change.
If it is in one specific area you can make a MAP file and it will show you what is going on and what cells it is happening in as well as the frequency, etc.
If it's your own tuning go back to stock and drive the truck, if it goes away then change one thing at a time until the problem comes back.
Good Luck.
If you are having problems with a rattle at low rpms it is most likely fuel pressure.
The tables are different for Federal, North East, and CA emissions trucks due to the EGR and air pump.
If you are running scripts for tunes you need to make sure things are not getting changed that should not be, scripts are indiscriminate, they do not care what they change.
If it is in one specific area you can make a MAP file and it will show you what is going on and what cells it is happening in as well as the frequency, etc.
If it's your own tuning go back to stock and drive the truck, if it goes away then change one thing at a time until the problem comes back.
Good Luck.
This is the condition sometimes referred to as "stomp rattle" isn't it??? Meaning, when you go from a roll (little or no boost and low throttle %) to stomping it suddenly, it rattles like mad.
IF this is what's going on, Craig had this issue with one of the versions of his tune and may offer up some help on how he eleviated the issue.
C-ya
IF this is what's going on, Craig had this issue with one of the versions of his tune and may offer up some help on how he eleviated the issue.
C-ya
Didn't Nick tune your truck ???
If you are having problems with a rattle at low rpms it is most likely fuel pressure.
The tables are different for Federal, North East, and CA emissions trucks due to the EGR and air pump.
If you are running scripts for tunes you need to make sure things are not getting changed that should not be, scripts are indiscriminate, they do not care what they change.
If it is in one specific area you can make a MAP file and it will show you what is going on and what cells it is happening in as well as the frequency, etc.
If it's your own tuning go back to stock and drive the truck, if it goes away then change one thing at a time until the problem comes back.
Good Luck.
it is my own tuning. nick made the tunes that came with my efi purchase, but i made my own dsp tunes. this one i am currently using is one i made brand new from when i got the heads done on the truck. great learning experiance thus far as i never took a stock tune and modified it completely on my own. it took alot trying to get all the limiting factors figured out.
i also have been looking into some other tunes i have and found one thing relative to all of them that was differant to mine. the throttle base injection table. i changed it and will test it tonight.
i guess that is what i would call it. spot on decription. no rattles anywhere else. see above for my theory in my tune. if do a slower roll into the throttle it wont do it.
GMC_2002_Dmax
The Still Master
TBIQ is a table that will cause a great number of unexpected changes to everything in the tune.
That reference table works hand in hand with the TLIQ table on the shifts and the base tq tables.
If you alter TBIQ you will have to alter TLIQ and Base TQ to make it shift properly.
If the rattle is at a specific area only I would log fuel pressure actual and desired and also main/pilot timing, maf, baro, boost, tq_dma, TPS%, Fuel_main_dma.
If you want a PID and Dash layout PM me your e-mail and I'll shoot it over to you, if you get really stuck I could offer you some help if you stop by.
Tony
GMC_2002_Dmax
The Still Master
When you are at low rpms, low MAF flow and dump a lot of fuel and timing in it will rattle.
If you are running DSP5 you only have two MAF limiting tables for 5 tunes, if you limit the big ones to work around the tip in rattle you will make the smaller tunes or stock ones weak turds for drivability.
Because DSP5 has limited space the fix for LB7 files would be to dump the boost table in favor of a MAF limiting table for each tune, I actually have requested that this happen some day if Ross decides to rewrite the DSP5 tunes files...........
Short of a limit table the way the ecm works the tradeoff on the smaller tunes might not be worth the hassle. The same tune on a boosted launch at the track at 1800-2000 rpms and a 10 psi booted launch will run like a scaulded dog with no noises other than screaching tires.
If you are running DSP5 you only have two MAF limiting tables for 5 tunes, if you limit the big ones to work around the tip in rattle you will make the smaller tunes or stock ones weak turds for drivability.
Because DSP5 has limited space the fix for LB7 files would be to dump the boost table in favor of a MAF limiting table for each tune, I actually have requested that this happen some day if Ross decides to rewrite the DSP5 tunes files...........
Short of a limit table the way the ecm works the tradeoff on the smaller tunes might not be worth the hassle. The same tune on a boosted launch at the track at 1800-2000 rpms and a 10 psi booted launch will run like a scaulded dog with no noises other than screaching tires.