fuel cut/what feels to be a speed gov.?

[bikerskater]

my car will rev fine in neutral and first gear but in second it will sometimes act like i hit the speed governor after like 4k rpm when flooring it but it rarely does it in second but in 3rd it does it a lil more but only when flooring it and 4th it does it at about 3700 rpm but it will do it if im flooring it or not and in 5th does it no matter what once i hit 3500 rpm and while its hitting this sort of gov./fuel cut the gas wont work but if i put the clutch in and it drops to 3k rpm it will accelerate again. also while in the gov/fuel cut on my safc 2 when i press the gas it shows the rpms going all the way up to 6k but nothing changes on the tach or in the sound of the car.

sorry for the paragraph trying to explain everything i can about it and for all the grammer errors

[onosqv]

Wow, lots of things going on here.

Did you do anything just before this started happening?

Since the safc detects rpm change, but nothing else does... check the safc wiring, then the speed sensor - your speed sensor could be bad -> causing your car to behave weird.

Have you tried removing the 5 gear sensor for diagnostic purposes?

Pulled engine codes (whether or not you have a CEL) to be sure?

Lastly, why do you have a safc installed? When things like this happen to me, I like to return the car back to as stock as possible to eliminate aftermarket parts affecting the car. If it is needed, then I can understand why you still have it installed.

[bikerskater]

safc isnt hooked up to the maf jus like rpm and and battery and throttle but according to my friend that had the car before said it doesnt have a speed sensor if that would cause it? and lately it has been popping outta 5 and not going in but just sometimes so i thought it was just a bad synchro

[onosqv]

1) if you have a speed reading (aka working speedometer and/or tach), then you have a speed sensor.

2) Seems you have a lot of possible issues that can't really be addressed until you do at least the basics.

I would suggest doing what I listed in my previous post first just to get those out of the way before tackling even more issues.

I would also personally completely disconnect the safc for now just to eliminate it from the equation since it is not needed. It "shouldn't" be affecting anything, but it doesn't hurt to simplify possible causes.

[bikerskater]

ok safc disconnected still doin it and i have a working tach so that means i have a speed sensor? i just wanted to clarify this before i go trying something but would taking the speed sensor nake it stop or make it worse? and whats the location of the 5th gear sensor and what does it do?

[onosqv]

For the 5th gear sensor, if you did any searching about speed limiter/governor, rev limiter, you will get the information you are asking. There's a search button, please use it.

Further initial diagnosis can be done via the FSM (factory service manual, also available via search).

EDIT: learn something new everyday - speed sensor affects speedo only, not tach. Thanks for the correction Vegascorbin.
Modified by onosqv at 12:25 PM 1/5/2009

[Vegascorbin]

Just a couple of points of interest.

You can have tach with out speed sensor connected. on the S13 the tach signal is from the ECU and it is from information from the distubutor.

The 5th gear switch is on trans. Check your FSM for more details.

Search for this problem. Another poster reported the exact same problem within the last 2 weeks and I hve been fighting this problem for over a year wiht my track car. The other poster (sorry I don't remember the name right now) was able to trace the problem to an exact set of circumstances as to when it started etc. It appears to be related to the speed sensior in the trans either giving wrong data or no data. I suspect no data as ours is not even connected.

Prior research did not show the speed sensior connecting to anything other than the speedometer but obviously it does feed back to the ECU someplace. Further research is required.

If you can, try swaping the speed sensior at the trans with a known good one.

Search and watch these boards for further updates.

[bikerskater]

thanks guys and sorry for not searching i did a lil on the problem but not for what i was asking so ill try the speed sensor and post back

[Vegascorbin]

Follow-up on Speed sensor wiring. I did find that the two wires from the speed sensor go to the speedometer and there is one wire that goes from the speedometer to pin 32 of the ECU.

I am guessing that if this signal is missing (ECU pin32) that the ECU will get confused and not operate properly possably causeing the cut out we have been discussing.

Does anybody know if we can just jumper the Speed Sensor signal to the ECU or does the Speedometer process or condition the signal somehow?

As my car does not have a dash it would be hard to install a speedometer.

Sugestions anyone?

[bikerskater]

after thinking about what you just said seems like it would do something but alot of ppl cut that wire to eliminate the speed gov. so i dont think that would be the problem im starting to think that maybe my maf is bad and judging air wrong and the ecu is getting confused thus causing fuel cut

[needhelp240sx]

thats exactly problem that im having with my car but it only happens to me when my speedometer is not working but when its working my speedometer the car works fine and i can floor it 100+ mph . what do you think guys what can cause this?? a malfuction speedsenor, but the thing is that sometimes my speedometer works but then quits working??

[Vegascorbin]

This is how I belive the Speed Limits work on a STOCK S13 with MANUAL TRANS. It is bassed on my research only. Please feel free to correct me.

There are 3 limits to our cars speed:1. Basic engine speed (Red Line) of about 6000 to 6500 at all times.2. Basic Car Speed of about 115MPH. I have heard of this being as low as 105 MPH3. Manual Trans also will rev limit at about 5000 WHEN IN 5TH GEAR ONLY. This is why there is a 5th gear sensor on the trans.

How do these work? Numbers 1 and 3 are based on the engine RPM as reported by the Crank Angle Sensor located inside the distributor. In the case of number 3 it also relies on the 5th gear sensor on the trans.

Number 2 is a little differant. The speed sensor on the trans send a signal to the speedometerwhich then OUTPUTS a signal back to the ECU (pin 32). This is the signal that tells the ECU how fast you are traveling. Go too fast and you get shut down. Searching NICO has told me that to eliminate any type of speed limiter you can change to an ECU from an Automatic as they do not have speelimiter in them. Still trying to verify what wiring changes may be required to do this swap.

The other option is to not tell your manual ECU how fast you are going or what gear you are in. How this is done depends on wether you wnat yoru speedometer to work or not. If you do then you cut the wire going to ECU pin 32. If not then just disconnect the speed sensor where it connects to the harness. Then just disconnect the 5th gear sensor and you should be good to go .

How does all this relate to our cut off problem? Hard to say. My car has not had the speed sensor or the 5th gear sensor connected from the time I bought it. For that matter it has not had a speedometer either. I think I may have a bad (shorted) wire in the lower engine harness. Further testing is in my future.

For those still running full stock wiring I would sugest disconnecting the speed sensor and the 5th gear sensor and re-testing. Please report back so we can all know what happened.

NOTE: Disconnect Speed limiting equipment at your own risk. They are there for your safety and to protect your engine. I rcomend disconnecting the above ONLY FOR SHORT TESTING REASIONS. (that should keep the lawyers off my back )

Comments?

[bikerskater]

that all seems to add up and make sense about what is happening but the thing is is that mine seems to happen in 3rd 4th and 5th sometimes even 2nd so i dont know how disconnecting the 5th gear sensor would solve my problem and i found out my theory about my maf was incorrect

[onosqv]

that all seems to add up and make sense about what is happening but the thing is is that mine seems to happen in 3rd 4th and 5th sometimes even 2nd so i dont know how disconnecting the 5th gear sensor would solve my problem and i found out my theory about my maf was incorrect

Like everyone & I have said, you should really search & read up on this stuff first...

When the 5th gear sensor starts going haywire, it doesn't matter what gear you are in - hence getting speed cuts in other gears --> your ecu thinks you are in 5th when you aren't.

[Vegascorbin]

Of course all of this makes the assumption that what we are experianceing is a "speed limit cut" and not some other problem.

Does anybody know of a way to tell if the ECU is doing a "Speet Cut" other than trial an derror?

[onosqv]

Nope, but that's why most people try the 5th gear sensor unplug trick first. Takes a few minutes, is a relatively common problem, and reversible and no cost if it doesn't help.

And as I stated in one of my previous posts, consulting the FSM is probably the best bet if the OP can't find the issue doing the normal stuff that everyone else does.

[bikerskater]

ok so i disconnected the 5th gear sensor and it is still doing it but doesnt do it in 2nd at all now and 3rd it did it once and 4th still does it every time along with 5th but instead of only going to 4500rpm it goes to 5k

[Vegascorbin]

This sounds more like my car. On mine it will cut out at 4K in every gear consistantly.

My trans has never had the 5th gear sensor wired up from before I bought the car.

My thinking now is that I either have shorted wires for the 5th gear sensor some place in the lower engine harness ( the upper was swapped out) or possably some electrical noise being introduced on the line as it goes to the ECU.

As my car does not ever go on the street I am considering cutting both the 5th gear sensor and the speed limit input (ECU pin 32) at a location close to the ECU. That would eliminate shorted wires in the engine bay or bad sensors etc.

Yes the FSM can be a large help but if the standard troubleshooting charts dont solve the problem then it can be a real PIA to figure out how things are suposed to work so you can figure out what is not working.

I think those of us that are haveing this problem are getting close to solveing it. I am suprised no one has had this issue and fixed it that can report what their fix was.

[bikerskater]

seriously some one has had to of had this problem and solved it tomorrow ill cut the speed sensor wire and see wht happens then and tell you guys whats happens

[jetroy240]

we have this problem, found out the fifth gear switch wiring is shorted.

[bikerskater]

ya but if i have already cut it wouldnt it not be shorting out?

[Vegascorbin]

Wherre did you cut it? at the Trans or at the ECU? If at the trans then you need to check the wiring back to the ECU. If you cut it at the ECU then did you also cut the Speed limier signal coming from the speedometer? also be sure the cut ends are not shorting out to anything.

In our case I tried to trace the wires yesterday and found things that did not match the drawigns like I thought they should. I am going to be digging deeper over the next few days.

[bikerskater]

ok update cut both at the ecu still does it. found out today it does it in all gears and that i do have a speed sensor just not hooked up also tried 2 different ecu's to see if that was it but what the only thing that did is the one in the car the engine like would blink and with the other one it would also but with the third one it stays on so...? idk if that means anything

[Vegascorbin]

ok update cut both at the ecu still does it. found out today it does it in all gears and that i do have a speed sensor just not hooked up also tried 2 different ecu's to see if that was it but what the only thing that did is the one in the car the engine like would blink and with the other one it would also but with the third one it stays on so...? idk if that means anything

What do you mean by the engine would "blink"? When you say with ECU #3 it stayed on, do you mean it was fixed?

Are all 3 ECUs manual or are any Automatic?

[bikerskater]

sorry i forgot the word "light" after engine in the last post but no it didnt fix the problem but i found out that my sohc revs to about 7500rpm lol pretty intense

[Vegascorbin]

Sorry to keep bugging you for details here but I have been fighting this problem from when I got the car over a year ago.

Please correct me if I am wrong;

You have cut both the signal coming from the Speeddometer and the 5th gear sensor at the ECU and it did not fix the problem.

You tried 3 differant ECUs in the car without fixing the problem. ECU #1 and 2 only blinked the check enginge light but #3 had the check engine light on all the time. Were you able to get a code from ECU #3?

How are you able to get the car to rev to 7500? What ECU etc.

And just to backtrack, you have fath that your MAF etc is good.

I am sure if we work together we can find a fix for this

[bikerskater]

dude your not bugging me lol ill try and be more detailed ok for the 7500rpm thing i have absolutely have no idea and no i didnt try and see what code was being thrown idk where to bring it in or what to do. maf im about 87.987263647278176357463% sure its fine. and i sure hope we can figure this out

[Vegascorbin]

The only other thing I can think of is posably the Distributor is somehow failing and mesing us up. I can not think of how but I am runnning out of ideas.

Do you have another distributor you can try and swap in?

anybody else have any thoughts?

[bikerskater]

that seems be a legitimate idea but idk i mean i could try and find one and see what happens but i ihave to finid an alternator cause mine went out today

[Vegascorbin]

I doubt it will make a differance but try things as they are after you fix altinator and before trying a differant distributor. I have seen stranger things happen.