[007_e350]

I was surprized my car was pulling timing on certain cylinders, upto -7 degs, I usually dont even look at this parameter (cobb)

What factors cause DME to pull timing:
- IATs ? (dont worry 7" on the way baby)
- Bad Fuel, though I always put 93 grade

whatelse causes pulls ? I have excel file that datazap wont upload to send if anyone's good at analyzing

Below in the pic only cyl 1, 4 & 5 got pulled - Positive peaks are Boost PSIs

[Jeff@TopGearSolutions]

Octane and intake air temps can effect timing corrections.

A sudden 3 degree ignition drop is the DME's way of correcting timing as a result of knock or sometimes argued pre-knock correction.

Easiest way to find out of it's octane is to add octane booster, Lucas, NOS or Torco.

Only way to see if it's IAT is to get an FMIC and see if it goes away.

[007_e350]

Originally Posted by Jeff@TopGearSolutions

Octane and intake air temps can effect timing corrections.

A sudden 3 degree ignition drop is the DME's way of correcting timing as a result of knock or sometimes argued pre-knock correction.

Easiest way to find out of it's octane is to add octane booster, Lucas, NOS or Torco.

Only way to see if it's IAT is to get an FMIC and see if it goes away.

why on certain cylinders not on all ? Is anything wrong w the cyl

[Taskmaster]

How many miles, how are the coils/plugs?

[tc535i]

might be an injector flow issue as well, causing knock and timing pull

I'd start by switching coil and plug, seperately, into another cyl and seeing where the knock occurs after that

will give you better idea if it's ignition, fueling, etc etc

[007_e350]

Spark plugs are 500 miles old, coils/ injectors have never been replaced, 58k on the odo

[tc535i]

I'd start by swapping the coil on that cyl with another, then if no change swap that plug.... still no change, swap the injector

still nothing? nuke it from orbit.

[Jeff@TopGearSolutions]

Originally Posted by 007_e350

why on certain cylinders not on all ? Is anything wrong w the cyl

Some cylinders do run different then others based on a few factors.

Cylinder to Cylinder heat differences.

Coils / Injectors can also factor in as well as intake valve cleanliness.

It's hard to say blindly without going through the motions of eliminating each circumstance one by one.

Originally Posted by tc535i

I'd start by swapping the coil on that cyl with another, then if no change swap that plug.... still no change, swap the injector

still nothing? nuke it from orbit.

Good tip. LOL

[Allen@MOTIV]

Timing corrections are the DME's response to knock sensor feedback. Either through false knock or actual knock events. Hot CATs can make the fuel more likely to pre-ignite but unless there is knock it will not cause corrections. By far the most likely culprit for timing corrections is that the fuel is not up to snuff. Try different stations and see if you can find a better source.

Another thing to consider is the conditions in which the corrections occur. At part throttle and normal driving corrections are normal. It is under WOT conditions that timing corrections become important to monitor.

[007_e350]

Originally Posted by Allen@PTF

Timing corrections are the DME's response to knock sensor feedback. Either through false knock or actual knock events. Hot CATs can make the fuel more likely to pre-ignite but unless there is knock it will not cause corrections. By far the most likely culprit for timing corrections is that the fuel is not up to snuff. Try different stations and see if you can find a better source.

Another thing to consider is the conditions in which the corrections occur. At part throttle and normal driving corrections are normal. It is under WOT conditions that timing corrections become important to monitor.

its under WOT.. goodnews is my 7" gets delivered today wooooohoooye, will update

[shushikiary]

I've seen posts where its been said that if you have a true knock event you'll see it expressed as timing changes across adjacent cylinders, but I'm just reverberating what I've read and have no evidence to if that is true, though I'd say it makes sense that timing correction on a single cylinder would indicate the DME playing it safe even if there wasnt a true knock event.

I do know that the DME will retard the timing as the IAT's go up, especially once you get over 140 deg F charge air temp, but it wont show up as a timing correction I believe, and from what the guys who know their stuff above have said it appears to be true.

From all the threads I've read (and dealt with my self looking at data logs running the Cobb E30 map) the best route to fix, as everyone above has said, is to increase the octane by what ever means you choose best. Personally the knock protection on E85 is just insane, so that's why I switched to the E30 map and run an E35 mix with 91 octane as I can only get 91 octane gas here in colorado.

[007_e350]

If you wanna review the excel file I'll email it over, whats ur e-address ... the IATs were upto 114 I believe ... even yesterday it was cooler but the timing kept retracting upto -5 degs, even on the slightest pull ... IDK whats going on

Originally Posted by shushikiary

I've seen posts where its been said that if you have a true knock event you'll see it expressed as timing changes across adjacent cylinders, but I'm just reverberating what I've read and have no evidence to if that is true, though I'd say it makes sense that timing correction on a single cylinder would indicate the DME playing it safe even if there wasnt a true knock event.

I do know that the DME will retard the timing as the IAT's go up, especially once you get over 140 deg F charge air temp, but it wont show up as a timing correction I believe, and from what the guys who know their stuff above have said it appears to be true.

From all the threads I've read (and dealt with my self looking at data logs running the Cobb E30 map) the best route to fix, as everyone above has said, is to increase the octane by what ever means you choose best. Personally the knock protection on E85 is just insane, so that's why I switched to the E30 map and run an E35 mix with 91 octane as I can only get 91 octane gas here in colorado.

[shushikiary]

Post the log up on data zap so we can all see it, makes life much easier and the graphing is much better than excel IMO.... and I just saw you said it wouldnt take it. Save the excel file as a .csv and see if data zap will take it then.

What are all your mods, what map are you running, and what exact gas were you seeing this on? Have you replaced your spark plugs recently? If not I'd suggest the NKG's people suggest on here with a gap of .022. You might also have a weak coil pack, might try swapping the coil packs on the cylinders that have issues and see if it fallows the coil pack.

Have you had your intake walnut blasted? I've seen that help with this as well. First thing I did when I got the cobb was replace the spark plugs and walnut blast, then installed an OCC.

Quickest thing to do is to put some shell V-power 93 in, everyone seems to like that, log see if it helps. If not might try mixing in a small amount of E-85, like running an E-20 mix, let the adaptives reset and then do a log. I wouldnt go higher than that without swapping to the E-30 map or modifying your fuel scalars.

Note that I'm also assuming your data logs are under WOT 3rd-4th gear pulls like how the instructions on how to get a data log say.

[Tiago@VRSF]

Originally Posted by Allen@PTF

Timing corrections are the DME's response to knock sensor feedback. Either through false knock or actual knock events. Hot CATs can make the fuel more likely to pre-ignite but unless there is knock it will not cause corrections. By far the most likely culprit for timing corrections is that the fuel is not up to snuff. Try different stations and see if you can find a better source.

Another thing to consider is the conditions in which the corrections occur. At part throttle and normal driving corrections are normal. It is under WOT conditions that timing corrections become important to monitor.

This.

[mike@x-ph.com]

Factors for timing pull could be
IAT,Map too aggressive,Spark Plugs,Ignition Coils,bad fuel

[007_e350]

Originally Posted by mike@x-ph.com

Factors for timing pull could be
IAT,Map too aggressive,Spark Plugs,Ignition Coils,bad fuel

114 - Stg1 Daily Map - New - No problem - Probably fuel but what can I do abt it

[tc535i]

Originally Posted by 007_e350

Probably fuel but what can I do abt it

run higher octane, add e85, or back off timing on your tune

[mike@x-ph.com]

Originally Posted by 007_e350

114 - Stg1 Daily Map - New - No problem - Probably fuel but what can I do abt it

You can change the gas station if its fuel.
I run e65 and i get the 91 from Chevron and the 85 from Rebel.
Rebel's 91 sucks

[tbeam335]

What would cause timing corrections across all 6 cylinders?

[iqraceworks]

Originally Posted by tbeam335

What would cause timing corrections across all 6 cylinders?

Too much timing and/or boost for the fuel octane you are running and/or too high of IAT's. That's the main reasons