Hard launch = no rev'ing past 5000

[Karma]

I know there are countless topics about not reving past 5000RPM, but mine may be a special case.

Last year, on the last day driving my car a buddy bet me I couldnt spin all four tires(in the rain) I took him up on the bet and launched from 5K. I spun them though 1st gear, but the next shift I couldnt go past 5K. It sounded like a studderbox.

This winter I installed an EPROM ecu with a stage 3 chip and other things.(studderbox at 5K)
This year I still cannot rev over 5000. once 5K rolls around, no matter what gear, it sounds like a rev limiter, pops, and sends a puff of black smoke. It will do this in a free rev aswell. I thought it was my studderbox, but it still pops when im moving, revving in a free rev clutch both engaged and disengaged.

(Fuel filter was changed 500km ago)
I unplugged the MAF and the problem still persisted.
Going tomorrow to get new plugs.
Im also going to put back in the stock EPRPOM chip to see if that changes anything

Any ideas?

 

[ThingyNess]

Sounds like your clutch wire, or your vehicle speed sensor isn't sending the right signal to the ECU. Make sure to check both. The two (or three) step rev limiter uses both as input to decide when to engage which rev limit.

 

[Karma]

However, it did this last year, when I had no studderbox. Ill put in the stock EPROM chip to see if that is the problem.

 

[blazebolt]

Did you unplug your clutch switch? That may need to be plugged in depending on your EPROM configuration.

 

[T9S1i]

yeah id check the operation of your clutch switch. I couldnt figure out for a long time why my cruise control and NLTS wouldnt work, it turned out to be my worn clutch pedal assembly wasnt returning the clutch pedal all the way and wasnt pushing the clutch switch so the computer/chip didnt see my clutch as "out" and wouldnt let me put on the cruise control and would use my nlts rev limiter because it thought the clutch was pressed in.

 

[Karma]

Clutch switch is plugged in, and pedal assembly was just welded.
Note: did a boost leak test tonight, holds solid till 20 psi.
Went to check base timing, but I couldn't see the tic on the crank pully, im going to need to highlight it and check again.

 

[Karma]

Update:
Checked base timing today, it's between 5 and 6 degree's BTDC.
Also, valve timing is good, at TDC the ticks on the cam gears all line up.
I also know the clutch switch is working becuase I cannot start the car without the pedal depressed

Any other suggestions?

 

[Karma]

Another update:
I put in the stock chip.. and it rev's right up to 7000.
So now im currious as to why the studderbox is always on. I know the clutch switch is working, becuase the car won't start without the pedal pressed. How can I ensure the vehicle speed sensor is working properly.

 

[Turkish]

Sean, who did your chip? Was it done here or from Keydiver?

 

[Karma]

Steve did my chip. He contacted me today and is checking to see if he accidently put the rev limit to 5000RPM instead of the studderbox.

 

[toybreaker]

Sean, does the cruise work?

I think T9Si is on the right track.

It's possible to have the clutch down switch (starter interlock) switch working and the clutch up (cruise and stutterbox) offline.

This would still require the clutch to be fully depressed to get the starter to work, but wouldn't allow the cruise or stutterbox to work properly.

The clutch up switch is on the pedal bracket up high, and is opened by the clutch pedal returning all the way to the rest position. Take a peek and make sure it's plugged in and opening and closing when you cycle the pedal, and make sure the pedal is returning all the way up. A mis-adjusted clutch master can prevent the pedal from returning all the way.

Good luck!

 

[Zenja]

Also, the stutterbox works by checking the VSS to see if the car is moving. If the ECU thinks your car is always stopped, it will always put on the stutterbox.

 

[Black94DSM]

Also note that if you keep your foot on the clutch pedal while going through the rpms, you might be actually pushing it enough to engauge the clutch switch ( which will put you in nlts mode).

Quick test would be to just keep your foot on the rest to the left of the pedal and try to go past 5000 rpm.

 

[Karma]

Toybreaker: Your awlays here to help me! It appears that the clutch up switch is being pressed in all the way, IE the newly welded pedal of mine goes all the way up and hits the switch. Is there a way to test the operation of it? If it means anything my cruise control doesnt work either, even though it used to.

Zenja: My VSS is working properly becuase my speedo works.

Black94DSM: No matter if it the clutch is pressed, or not pressed. It wont go past 5K

 

[toybreaker]

If it means anything my cruise control doesnt work either, even though it used to.

Zenja: My VSS is working properly becuase my speedo works.

Sean, The speedo and odometer work from the cable directly. The vss is inside the speedo head itself.

This means the speedo could read fine and yet there's no vss signal to the ecu or cruise module. I've never dissected one, so I don't know how to test it. When I suspect a bad vss, I usually just swap in a known good cluster.

I have gotten a code for it once or twice, but there's usually some drivability symptoms present as well, such as a funky, irregular low idle that comes and goes. It generally won't turn on the check engine light, but it will be in the ecu memory if you pull the codes with a scanner or logger. It might be worth your while to plug it in and check for codes.

You can test the clutch up switch with an ohmeter. Just check continuity at the pins in the harness connector. With the clutch all the way up it should read one way, and with the clutch ever so slightly depressed, it should change state. (My humble apology, I don't have my manual with me, so I don't know if continuity comes or goes when the pedal moves...but I do know it's state will change.)

Good luck, and looking forward to your next thread.

When I.... then the car did...WTF and...