Question about surge on Highway

[Danman765432]

I have a slight problem that I am having now, its not major but its kind of annoying.

Some basic things:

-Car Has to Be Hot
-Mostly happens on the Highway
-Happens when just coasting
-My Car is also an AODE - Hissin thinks this could be important.

Ok well the thing that is actually happening is that I am getting a pretty bad surge. At first the rpms will be up and stay up high, as soon as I let off the gas. Then after 5 -10 seconds it will drop and surge until I hit the gas again and then they will go back up. Dont know if there is something to fix it or what not? Nothing really happens to the car its just annoying, the car actually takes off better when you hit the gas when it is surging upward in the RPM's.

Thanks,
-Dan

 

[final5-0]

I have a slight problem that I am having now, its not major but its kind of annoying.

Some basic things:

-Car Has to Be Hot
-Mostly happens on the Highway
-Happens when just coasting
-My Car is also an AODE - Hissin thinks this could be important.

Ok well the thing that is actually happening is that I am getting a pretty bad surge. At first the rpms will be up and stay up high, as soon as I let off the gas. Then after 5 -10 seconds it will drop and surge until I hit the gas again and then they will go back up. Dont know if there is something to fix it or what not? Nothing really happens to the car its just annoying, the car actually takes off better when you hit the gas when it is surging upward in the RPM's.

Thanks,
-Dan

Hey Dan

You see that a lot with modded Stangs that have cams, aftermarket mafs, larger inj, and the like.

I looked at your sig and saw none of those.

If you have verified the obvious stuff like v leaks, dirty maf electronics, faulty isc, and the like.

I do kinda wonder if the trans mods are contributing to the issue.

Form the pcm's perspective, you are at light load conditions and the spark can be quite high during those conditions.

The dad gum GT cal file is so high sparky & low fuelie (im sure thats not a word ... who cares anyway) so those two things don't help as well.

Is this something that has always been going on

Grady

 

[Danman765432]

No its hasnt really been going on until about 2 weeks ago when I noticed it. Recently I had idle problems but cured them by cleaning the MAF, IAC, Throttle body, ACT, and replacing and fixing all vaccum leaks and also my PCV. Before I put my intake and my new Transmission in I didnt really have an problems but after I started noticing idle problems. I just wonder if I just need a tune...I mean I already hit off the rev limiter when hitting the gas all the way because of the 3.73s but I dont really want to spend $400 on a tune before I do my other mods I want to do in the winter and next spring.

 

[final5-0]

No its hasnt really been going on until about 2 weeks ago when I noticed it. Recently I had idle problems but cured them by cleaning the MAF, IAC, Throttle body, ACT, and replacing and fixing all vaccum leaks and also my PCV. Before I put my intake and my new Transmission in I didnt really have an problems but after I started noticing idle problems. I just wonder if I just need a tune...I mean I already hit off the rev limiter when hitting the gas all the way because of the 3.73s but I dont really want to spend $400 on a tune before I do my other mods I want to do in the winter and next spring.

I suspect your Stang has always had an auto trans since you speak of rev limiter issues since the auto trans pcm has a rather low value rpm limiter.

If that is the case, the only way I know of upping it or killing it is with electronic help or pcm value manipulation.

I do understand wanting to avoid tuning as there is no cheap way out that I have been able to find

I finally decided to look at it ... kinda like this

Tuning to me is really no different than my set of heads, maf, rockers, or any of the rest of my combo ...
the interface is just another hot rod part
and
in some ways .........
its more important cause it allows me to get the most from the other parts that make up the whole combo

I don't know Dan ...

Sure seems like it has to be something that has been affected by all the recent changes

Grady

 

[Danman765432]

anyone actually have this happen to them before and fix it?