2-3 second lag on start with my 6.4

weekendwarriorfsw32 · #1 (**permalink**) 07-02-2009, 11:12 PM

Hello everyone,
Well the more and more I drive it, it seems to have a 2-3 second lag if I floor it to the ground its 1.... 2.... Go.... and the it launches same on the free way I floor it 1....2.... Then it goes. Any Ideas
Thanks
Nick

smotrs · #2 (**permalink**) 07-02-2009, 11:34 PM

There's a delay built into the programming that tells the system to wait until the turbos have spooled up before dumping excessive fuel into it. This helps prevent excessive soot buildup right off idle.

kane gray · #3 (**permalink**) 07-02-2009, 11:35 PM

That sounds normal to me, maybe a little longer than it should take. The turbo will give some lag, but it shouldn't take too long. I have found with my truck, that if I don't just floor it, and I "lead" into it if you will, that it takes off faster. Just my 2 cents though.

weekendwarriorfsw32 · #4 (**permalink**) 07-02-2009, 11:52 PM

What about the DPF being clogged would that do it?

ruschejj · #5 (**permalink**) 07-03-2009, 07:58 AM

My lag is the very same as you describe. I can count 2 or 3 seconds before I get the "go". It's normal and like smotrs said, programmed in to the PCM.

Some guys think that the Banks cold air intake help it out but not dramatically.

weekendwarriorfsw32 · #6 (**permalink**) 07-03-2009, 09:38 AM

So will a tuner and DPF delete help this out?

smotrs · #7 (**permalink**) 07-03-2009, 11:46 AM

Quote:

Originally Posted by weekendwarriorfsw32

So will a tuner and DPF delete help this out?

Yes, Spartan, SCT and Innovative all have tunes that will eliminate the lag considerably, not completely from what I hear, but considerably. What they do is is dump in more fuel to compensate for the turbos having not spooled up yet.

smotrs · #8 (**permalink**) 07-03-2009, 11:48 AM

Quote:

Originally Posted by weekendwarriorfsw32

What about the DPF being clogged would that do it?

If the DPF was clogged, it would probably throw a code or go into regen depending on the severity. Don't believe it would increase the delay though.

ruschejj · #9 (**permalink**) 07-04-2009, 07:52 AM

Another thing for you, when you are in a regen cycle, the lag is not as bad. Sometimes I get startled at how quick the motor jumps the truck forward while in regen.

I think the PCM compensates for lower boost by giving us more fuel. Try it some time.

weekendwarriorfsw32 · #10 (**permalink**) 07-04-2009, 09:08 AM

Quote:

Originally Posted by ruschejj

Another thing for you, when you are in a regen cycle, the lag is not as bad. Sometimes I get startled at how quick the motor jumps the truck forward while in regen.

I think the PCM compensates for lower boost by giving us more fuel. Try it some time.

That weird you mention this. Yesterday while I was driving around flagstaff I noticed this. Every other time I has gone into regen its been on the free way. I must say tho is sounds weird when you floor it from a stop and then let off.

smotrs · #11 (**permalink**) 07-04-2009, 01:20 PM

Yeah, I've noticed this as well. Shame it can't run this way all the time with the DPF without killing the MPG.

sbaset · #12 (**permalink**) 07-07-2009, 11:27 PM

As an FYI, I had a cracked DPF, smoke out my tailpipe, and no CEL at all and never saw a regen. Dealer replaced the DPF and it's all good now.

So you dont necessarily have to get a CEL, to have a bad DPF.

smotrs · #13 (**permalink**) 07-08-2009, 01:50 AM

Quote:

Originally Posted by sbaset

As an FYI, I had a cracked DPF, smoke out my tailpipe, and no CEL at all and never saw a regen. Dealer replaced the DPF and it's all good now.

So you dont necessarily have to get a CEL, to have a bad DPF.

True, but I was actually referring to if the DPF was clogged, then it would probably throw a code. If it's cracked, it just bellows out black smoke like normal diesels, not neutered diesels like ours.