Hits limiter at 4700-5500????

[CanuckSnake]

Hey guys I'm new so go easy on me. This is a new problem for me. On rare occasions under WOT the car will just stop pulling around 5000rpm like its hitting a rev limiter in any gear. You can keep your foot to the floor and it will just stay at that rpm. Its totally intermitten, fuel press good, good air/fuel, good boost(untill it does it), and then you go down the road for a mintute and it will be back to normal pulling to 6500 in every gear then next minute it will only rev to 4800 or what ever it decides to do. Just started doing this, had it at the track a couple weeks ago and it ran great all night, then messing around on the street a few days ago it started doing this. Thoughts?????

 

[racin4ds]

Mine is doing the exact same thing!! I just bought the car a week ago so I'm still really a newbie to the terminator stuff but I've owned many mustangs in the past. Hopefully some of the experts will chime in here. I was thinking I could be pegging the MAF but why wouldn't it do it all the time?

 

[cobracide]

The best thing to to is get a sct xcal3 and datalog. Check your spark plugs too.

 

[lgonz051]

mine too.

 

[CanuckSnake]

The best thing to to is get a sct xcal3 and datalog. Check your spark plugs too.

Plugs good. I have a sct Xcalibrator 2, can you datalog with this some how? I think its electrical(sensor) issue because its so random but no codes yet? What does belt slip feel like? The car is new to me:??:

 

[CanuckSnake]

O.K. just got back from a drive and its doing it all the time now. You can take it all the way up to 6000 with light throttle but get on the gas and it hits a wall at anywhere from 4600-5000. When it does this I keep my foot in it and it just stays at that rpm with boost staying at 15 but the air fuel goes big time lean like off the gauge. I don't think its sucking the pumps dry because it would stumble and fart more, I think something, somewhere is telling the pumps to shut off???? Would it be an issue with the fuel pump drive module??? I'm new to cobras.

 

[MY DREAM]

So wierd, mine just started today, go's like hell till I get to 5,200 rpm, then it falls flat on it's face. I am thinking FRPS, fuel pump or something to do with the fuel system. I havent done any datalogging yet. Yhought I would jump on here and see what's up first.

James

 

[CanuckSnake]

I changed the fuel pump driver and the sensor on the front left fuel rail(don't know what its called) Didn't change a thing!

 

[TVSCobra]

log the car and check your fuel pump duty cycle. see if the pumps are maxed out.

 

[MY DREAM]

Great! I went out to log it....log it...and all was good, no more falling flat, ran great. The only thing I did, was pull off the vacume line to the boost actuator valve located on the back of the Whipple and I sucked on it the tried blowing positive pressure into it aswell (please no gay comments) to see if it was holding or if it was leaking. All seemed fine. went to log, made a few runs up to 6,500rpm ish and all was good. Don't know what to say....

James

 

[CanuckSnake]

Great! I went out to log it....log it...and all was good, no more falling flat, ran great. The only thing I did, was pull off the vacume line to the boost actuator valve located on the back of the Whipple and I sucked on it the tried blowing positive pressure into it aswell (please no gay comments) to see if it was holding or if it was leaking. All seemed fine. went to log, made a few runs up to 6,500rpm ish and all was good. Don't know what to say....

James

Well I hope you figured it out. Mine started off intermittenly but now she won't rev over 5000 at all:shrug:

 

[MY DREAM]

I think it may be the vacume valve at the rear of the Whipple. I guess one of these days I will remove the Whipple to clean the intercooler, check/replace the vacume valve, and service the Whipple with fresh oil and a cleaning.

James

 

[turbotrail93]

I had this problem with my car, even though you think it might have gone away I wouldn't take it to the bank before seeing a tuner. I had exact same problems with mine at 5500 it was like I hit a limiter and car fell right on its face, and then sometimes i could hit redline. Well my new tuner dumbed it down to my level and what i got out of it was the M.A.F wasn't mapped just right to my injectors, intake, just air intake in general etc.... and he said some of them are really sensitive. As for it doing it sometime and not the others, he said sometimes you get bad air and sometimes you get good air, lol i guess there was more to it but It was over my head. So I'd check my maf counts on datalogging with what type of Maf i had.

 

[Stalker27]

Man PLEASE make sure it's not your pumps maxing out!!

I went through the exact problem you're having but ended up being a bad fuel pump so i was running off of one. Replaced them, & then a line popped off the fuel pump while it was on the dyno. I didn't want to drop the tank again so i went to datalog it & it would fall on its face. When they max out they can't send enough fuel for the air thats still comming in & then pop goes your motor

Also check to see if you have any water where the spark plugs sit. I washed my motor very easy & two weeks later i got into boost & scared the shit out of me the way the car was acting in boost. Hell i couldn't get in boost. I had water standing in cylinder #2. Cleaned it out put new plugs in & been fine since

 

[cobra=trouble]

i had same problem at 5200 rpms
i replaced the fuel filter both fpdm's with level 2's and the frps...same thing
so i went ahead and replaced both my fuel pumps ..that fixed it.

 

[nyjetsfan4lif3]

im having the same prblem , ever since i changed my pulley my car is doing exactly the same as u guys have described , went to my tuner and he said my pumps were ok , still havnt figured it out.

 

[BadDog04Cobra]

Check your coil packs...

You're describing precisely what I was experiencing...it was a bad coil pack. Started intermittently and got progressively worse. If nothing else has changed, i.e plugs, tune etc. my money's on a bad coil pack. Good luck.

 

[jimc04]

how do you test the coil? what ohms should it be?

 

[csilvers1984]

My car has done this a few times also,sometimes it will spin to a 7k cutoff but with traction it's like 6500. Every now and then if will do it around 5k and throws a overboost cel(cel might not be related) I dunno but it has done it twice in a race which really is inconveint.

 

[CanuckSnake]

Good suggestions guys but If I had to guess it would be something with the tune and MASS. The way it hits this wall feels like the injectors just shut off and its so consistant now. If it was spark or low fuel press you think it would hesitate and cough/sputter more randomly. I can drive the car all day long and runs like a champ as long as you don't go WOT and over 5000rpm or so. I'm waiting for some time to get it to a tuner/dyno but will keep ya posted.