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Paul_13

Gti6 Misfire At Light Throttle Under 2K, I've Tried Everything

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camgti

The gti6 computer needs to read the VSS ( vehicle speed) to no malfunction.

 

To make this work in a 205 you need to get a VSS from an S16 or buy a new one pictured above that has both outputs. One output in the three (3) pin connector that the gti6 harness will connect to. This is the VSS connection to satisfy the ecu. The 306 uses an electronic speed where as the 205 uses a mechanical cable to drive the speedo. So. Fit a dual signal VSS as pictured. Plug the 3 pin connector to it and then plug your 205 speedo cable into it also so you have a speedo!

 

Make sense?

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jcsh

Hi, sorry for the delay in replying.. Yes this makes sense to me at the speedo sensor end - but what should I connect it to at the ECU end, I'm thinking that the guy who did the loom mods (its a 1985 205 Cti ...) will probably not have fitted a wire for a non-existent electronic VSS ;)

 

The other thing that 'may' shed some light on this weirdness is the following:

If I leave the car to idle, even when hot, the revs will very gradually dies away, until it almost stalls, then, (almost with great pomp and circumstance :) ) the engine will decide it needs to get itself in order and it will give itself a good bootful and raise its revs all by itself! its quite bizarre to witness it actually :)

 

3. Please advise on the correct p/n for the TPS as I'm not 100% sure its the right one (90%)

cheers

james

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Plumbob

If you are lucky then the wire that should connect to the VSS will be somewhere near the ECU plug tucked under the plastic conduit. Luckily for me on my car which has the exact same problem, there was approx 5cm of wire that had been left for me to tag a new bit on, this just needs to be extended down to the sensor. Its yellow on my loom and connected to pin 28 on the ECU plug.

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Slo

Sounds like the icv circuit has a problem to me but this is from autodata

post-21076-0-01974200-1407876640_thumb.jpg

post-21076-0-44647200-1407876848_thumb.jpg

Edited by Slo
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jcsh

Sounds like the icv circuit has a problem to me but this is from autodata

 

When I find out how to check that - I will do it - Thanks :)

 

2) I'm assuming that the schematic above is the ECU pinouts ..?

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Slo

yes terminal pins on the ecu, the icv will spin when you plug it in, so unplug it and see if it stops or even makes a noise when you plug it in.

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welshpug

its a stepper motor, icv doesnt spin.

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Slo

is it same one thats fitted to the turbo?

 

Just looked it up exactly same as turbo one, it just spins when its plugged in giving the engine a set amount of air to idle on, at least thats what it does on mine anyway. if i unplug it i get similar effects like the idling to nothing then zips back in again,

 

James do you know what year the car was the engine came from?

 

Part number for the tps changed in june 95 before this it was 1628 L1 which is the same as the turbo one and 1628 1E after this date

Edited by Slo

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welshpug

its a 4 wire thing.

Edited by welshpug

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jcsh

is it same one thats fitted to the turbo?

 

Just looked it up exactly same as turbo one, it just spins when its plugged in giving the engine a set amount of air to idle on, at least thats what it does on mine anyway. if i unplug it i get similar effects like the idling to nothing then zips back in again,

 

James do you know what year the car was the engine came from?

 

Part number for the tps changed in june 95 before this it was 1628 L1 which is the same as the turbo one and 1628 1E after this date

I dont know what year I'm afraid ...

Would the later TPS be backward compatible?

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Slo

I dont know but the earlier type is nfp now later one is available.

 

WP yes 4 wire connector same as mine is and yes it is a stepper motor

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jcsh

Is it Very important to use the OEM TPS or will a pattern part do? - cost is massively different (and if it makes no difference ..

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Slo

cant see any difference tbh, might not last as long as an oe one though if its a cheap part but certainly wont run any different its only a variable potentiometer inside

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jcsh

I'm wondering from the remarks above (thanks folks :) BTW ) if its a combination of the VSS and the ICV. ..

I'm discounting the lambda (thanks WP) for the moment as:

a) It has a new (albeit pattern) LP fitted.

B) The problem starts even before the engine is hot

c) I found one of the wires to the LP unplugged and replugged it some time ago and the problem was identical under both states.

 

Seems like the consensus is that the unruly idle could be ICV ; and then maybe exacerbating the ECU to go into its cut out state since it doesn't have a VSS feed ..

 

I'm wondering what else could be wrong, 'wiring issue' as suggested by WP .. I hope not! The guy who did the conversion is meticulous even though he had not come across this conversion before and in his defence there seems to be very little info circulating regarding loom issues of putting these engines into phase 1 cars..

Edited by jcsh

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dobboy

Surely you can write off the VSS for dodgy idleing as the VSS wouldn't be turning when the car is stationary? (Albeit there is a chance that the wires supposed to be to it are shorting wherever they are tucked away (but doubtful).

 

I'd be checking the coolant sensor first, from what i've read the ICV gets a lot of the blame for a dodgy one, and the coolant sensor is easily accessed and tested.

 

I replaced a knacked Lambda recently (which i proved to be knacked with multimeter), and the symptoms prior to changing it weren't as obvious as yours, it didn't have any affect at idle at all IIRC.

 

Also, regarding the TPS, i'm (almost) sure it was this sensor that i tried to swap from a spare i had on another engine, and although it fitted correctly the pins/plug were different from that on my loom and wouldn't marry up.....

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jcsh

Surely you can write off the VSS for dodgy idleing as the VSS wouldn't be turning when the car is stationary? (Albeit there is a chance that the wires supposed to be to it are shorting wherever they are tucked away (but doubtful).

 

I'd be checking the coolant sensor first, from what i've read the ICV gets a lot of the blame for a dodgy one, and the coolant sensor is easily accessed and tested.

 

I replaced a knacked Lambda recently (which i proved to be knacked with multimeter), and the symptoms prior to changing it weren't as obvious as yours, it didn't have any affect at idle at all IIRC.

 

Also, regarding the TPS, i'm (almost) sure it was this sensor that i tried to swap from a spare i had on another engine, and although it fitted correctly the pins/plug were different from that on my loom and wouldn't marry up.....

I'm thinking that there might be 2 problems. 1: the VSS which is absent and will be having *some* effect .. just not sure exactly what..\

Then 2: the Idle problem, which could be the ICV (or lamb or therm sensor, or .. or ...) these 2 sensor issues could be adding together to give these 2 strange behaviours..

Maybe ... ;)

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