[ryanom]

So I've finally got around to putting the twin cam out of a GTI swift in the hunting rig, got it all fired up (happy days) but I've got a problem. The performance is sluggish at best and the factory computer is throwing up an input fault code. Have checked the code and the fault is caused by not having a speed sensor. On the GTI this signal I believe is fed from the speedo head. I was wondering what everyone else has done to get around this
Cheers
Ryano

[Blkfxx]

Either viewtopic.php?f=17&t=38755

or

viewtopic.php?f=1&t=10121

[ryanom]

Thanks Blkfxx
You're a bloody legend

[Gwagensteve]

I don't believe the lack of a VSS signal will cause poor running- it will throw a CEL and affect fuelling on closed throttle whilst in motion.

This is the case with g16b's, I can't imagine the gti is any different. (Anyone confirm this?)

[ryanom]

Yep Steve. You're right. We believe that the lack of a VSS signal is causing the computer to restrict fuel delivery and therefore reducing performance.

[Gwagensteve]

But that's the opposite of what I'm saying.

On g16b's the VSS does not have any effect of fuelling under load, only under closed throttle when the vehicle is in motion. I know this as fact. I am unsure if the same is true for a g13B gti, but I bet it is.

Therefore the lack of an VSS is unlikely to be causing the poor running.

Many gti's have been installed without the VSS over the years, usually by the same people who also don't install a CEL.

My guess is you have a separate issue unless someone can confirm otherwise.

[lgp29]

I drove around for 12 months with no vss and no issues but the engine light.
After I fitted one I only noticed an improved idle.

[Gwagensteve]

Ok so the VSS doesn't throw a CEL, so there is another problem.

[lgp29]

Gwagensteve wrote:

Ok so the VSS doesn't throw a CEL, so there is another problem.

If CEL is check engine light then yes having no VSS hooked up will bring this on after 3k rpm is reached.
Bridging the diagnostic port will also give the appropriate blink code. 22 or 24 from memory.

After I retro fitted a vss the light stopped coming on and I no longer had a fault code but I did
not notice an increase in performance.

I daily drove it for a year with no VSS.

[fordem]

lgp29 wrote:

If CEL is check engine light then yes having no VSS hooked up will bring this on after 3k rpm is reached

Think very carefully about this - the Vehicle Speed Sensor tells the ECU how fast the vehicle is moving - not how fast the engine is turning - you can rev the engine to 3000~4000 rpm in neutral and it will not set the check engine light.

As far as I'm aware, a missing or non functional VSS will set a check light, but the logic behind it is not directly related to engine rpm - I believe it is based on the EFI system being in "fuel cut" for more than a specific period of time.

[lgp29]

fordem wrote:

lgp29 wrote:

If CEL is check engine light then yes having no VSS hooked up will bring this on after 3k rpm is reached

Think very carefully about this - the Vehicle Speed Sensor tells the ECU how fast the vehicle is moving - not how fast the engine is turning - you can rev the engine to 3000~4000 rpm in neutral and it will not set the check engine light.

As far as I'm aware, a missing or non functional VSS will set a check light, but the logic behind it is not directly related to engine rpm - I believe it is based on the EFI system being in "fuel cut" for more than a specific period of time.

You are correct. It did only come on after driving for a minutes. It may have been more a relationship with engine load
However it did also appear to come on around 3k.

[Gwagensteve]

Yes it's a simple check- engine under load but no VSS = throw the light.

Fordem's understanding is the same as mine- it's only there for fuel cut (different map for in motion or not)

It doesn't have any effect on fuel or timing maps and won't put the engine into a "limp" mode or anything. (Do suzukis of this vintage even have a limp mode? I've never encountered it)

Steve.

[rexhunta]

Gwagensteve wrote:

Yes it's a simple check- engine under load but no VSS = throw the light.

Fordem's understanding is the same as mine- it's only there for fuel cut (different map for in motion or not)

It doesn't have any effect on fuel or timing maps and won't put the engine into a "limp" mode or anything. (Do suzukis of this vintage even have a limp mode? I've never encountered it)

Steve.

Yes, it's a hard limiter at 2-2500.

[Gwagensteve]

wow. Can't imagine what fault the ECU would have to see for that to happen. I've even seen a Baleno G16B with the MAP disconnected and I don't think it did that.

[JrZook]

VSS is not a critical sensor, shouldn't be triggering a limp mode

[ryanom]

Mine to seems to be limiting the engine at 2000rpm. Pulls like a train till then and then blahhhh. Anyway I've sourced a dash from a '94 vitara with VSS and hope to have it installed by the end of the week. I'll keep you posted

[Gwagensteve]

Note that 4 people have separately told you the VSS isn't what's triggering limp mode. By all means do the VSS, but it's not the cause of your problem.

Steve.

[rustyzook]

I've run a G16b for years with no VSS, this is not your problem.

I still don't have the vss hooked up and it still runs fine.

[MrRocky]

Ditto

[rexhunta]

Gwagensteve wrote:

wow. Can't imagine what fault the ECU would have to see for that to happen. I've even seen a Baleno G16B with the MAP disconnected and I don't think it did that.

Getting the gearbox loom caught in between the starter motor/block while doing it in the dark does it.


Yes, I found out the hard way.

[ryanom]

Well Steve. It's taken me some time to complete this project and also to consider your comment "note four people have told you". Well guess what.....fitted the VSS and she pulls like a freight train. 100km per hour at 6000 rpm in third. Completely different car after fitting the VSS. I appreciate that you are the resident expert in all things Suzuki but as we all know "X" is the unknown factor and "spurt " is just a drip under pressure.
This will be my last post on this forum.
Thank you to everyone who has helped me and contributed positive comments.
Ryano

[Gwagensteve]

I wonder what is different or unique about your GTi motor, computer or conversion?
I wonder if redline gti has more information about this? As you can see, none of the "experts" on here believed the VSS will trigger limp mode, including people who have proven this.

[rustyzook]

Wonder what else was touched while the vss was fitted (eg a loose connection in the loom that was bumped or moved while fitting) quite odd that just the vss would Cause/fix this problem! As it's really dosent do a lot anyway!

I have a feeling you may be coming back the this thread at some point,

also no need to get all butthurt over some advice, a lot of us here have done a lot of suzuki mods over the years, while we don't always agree with each other, it's still good to have the feed back and other opinions and ways of achieving the same end result.

PS my experience with sierra 1.3 gearboxes is 3rd dosent like to be flogged if you want your box to last. Just a heads up.

[Gwagensteve]

I'd agree rustyzook. I think there may well be some coincidence going on here.

[ZUZUKI]

The VSS must do some variously weird things.
A W/T Sierra we converted to G16B - the hard way (an engine and manual gearbox from here, a loom from over there which seemed to have the right bits, an air meter and computer that plugged into the loom, but otherwise didn't know each other previously etc) ran ok when it was all together, but had a stumble/stutter/miss-fire at about 60km/h (light throttle opening) in 4th.
Tried another TPS & air meter to no effect. Had previously wired in a CEL.
Pulled a Vitara dash apart & pinched the VSS to go into the Sierra cluster & away she went.
I hear what you all are saying & I would have said the same, but that is what the result was!.
Rgs, Michael

[lgp29]

Was the vss circuit simply just grounded in the absence of a vss?

[MrRocky]

Has zero effect on driveability on the coilpack baleno g16b
Done about 20+ harnesses for sierra swaps now all minus vss, infact those with vss swaps seem to return worse economy.

[Gwagensteve]

Ryanom- when he engine was in apparent limp mode would it free rev over 2k or would it only stop at 2k when in motion/under load?

[rexhunta]

unless theyellow sensor cable wasn't taped/heatshrinked up and just dangling in the cabin and shorting out on the wall/floor maybe ?

[jonno_racing]

Can 100% say vss is not required in mk1, mk2 or mk3 gti swift. Have done them all now. None with a vss. Im gonna say he fixed something else whilst he was at it