S16 Hesitation/bogging Down

[ASBGTi 9]

Afternoon all!

 

I am new to the forum and a first time 205 GTi owner. I have landed myself a cracking little 205 GTi with an S16 conversion. It was owned by a previous member of this forum a very nice chap called Dan. The conversion looks pretty tidy however there are a couple of issues, the main being the title of this thread!

The bogging/hesitation whatever you like to call it is driving me insane. I know there are a few threads that cover this issue however nothing I find that hasn't already been changed.

 

The things that have been changed are:

All sensors of the throttle body

Cam sensor

Vacuum and diaphragms on th pe ACAV system

Checked coil packs

Changed fuel pump and regulator

Idle control valve checked

The only other thing I can think of is the MAP sensor but I believe that it's in the ECU, so I ask what the plan is if that has failed?

 

I have a GTi 6 manifold on the way to me which I will swap over, to be honest I'd rather have it fixed before I change it though just for peace of mind. It has been intimated that I could change the ECU to a GTi6 but would that mean changing the loom?

 

A help would be greatly appreciated, I am a 205 virgin so all this is new to me, I have a general understating of mechanics etc but the car is pretty alien!

 

I'll post some pics of the car and my progress, thans for reading

 

A

[calvinhorse 870]

Can you see all the ACAV parts moving?

 

I had same with mine and was also told map sensor, never got round to doing it tho.

[welshpug 1,657]

Check the vacum pipe from inlet to ecu (i.e map sensor)

 

Probably running a bit rich at the moment.

[Miles 331 1 Cars]

Fitting the 6 inlet will only make the bogging down 10 times worse I'm afraid

[ASBGTi 9]

Hi guys,

 

Thanks for your replies. ACAV parts are moving, I'll check the vacuum to the ECU thanks and your right it's running mighty rich at the moment!

 

Miles - why will changing the inlet make it worse? Assume you mean if the issue is not fixed?

[welshpug 1,657]

the RFS throttle body is a fair bit larger, also the inlet flows quite differently, I have fitted one on an RFY engine a few years back and it did go very well, I don't recall any bogging down however it was a right faff to install with the different idle valve and oil hoses the RFY uses, the later RFS engine is far simpler with its oil filler into the cam cover and a directly bolted on ICV.

 

it was the first 16v engine I;d installed in a 205 and driven myself and was 6 years ago, so difficult to compare, the car was never put on a rr to my knowledge though I did see it on gumtree over in Bristol recently still running the same lump and inlet!

[ASBGTi 9]

Thanks for your input!

 

I'm about to check the vacuum hoses now so we'll see what transpires!

[ASBGTi 9]

Update!!!

 

Checked out the vacuum pipe to the ECU and whilst there was no splits or leaks it was kinked just before it connected to the ECU. Straightened it out and made sure it wasn't blocked and BOOM!! Instant result, much better!

 

However.........it's not all good news. At lower revs its still hesitant and a bit jumpy, could this be down to over fuelling? I can smell an awful lot of petrol when driving and when you rev at a standstill, on lift off theres a lot of popping going on suggesting un-burnt fuel in the exhaust.

What would cause this? Fuel pump? Inlet/exhaust manifold leak? Help!!

All help will be greatly appreciated. There are few other issues I'll need some help with but one at a time ay lads!!

 

For now here she is....

Edited August 20, 2013 by ASBGTi

[welshpug 1,657]

does it have the lambda sensor fitted and is it like that from stone cold or only when warmed up?

 

also check the coolant temperature sender, green on this management system.

 

[ASBGTi 9]

Yes it has a lambda sensor which I believe has been changed in the last 12 months. is it worth removing, cleaning and re-fitting? It's worse when its's cold and gradually improves as the temperature increases. The exhaust exit proper black!!

 

I'll need to get a new multi meter!!

 

Thanks!

Edited August 20, 2013 by ASBGTi

[welshpug 1,657]

If it gets better when it warms up then it sounds like the lambda is doing its best, they arent used for the first few minutes till they warm up.

 

You cant clean them.

 

Check or replace the temp sender i think

[Miles 331 1 Cars]

They run OK but to get the most out of it a remap is a must, too much Air otherwise. It does sound like the Temp sender has gone, Pig to change thou on these engine's. Be careful of back fires too, they can make the manifold explode

[ASBGTi 9]

Morning guys,

 

Right so coolant temp sender, I'll get that ordered today.

What about my over fuelling issue? Will the above go towards curing this?

 

If I did change the manifold and do need a re-map where would I take it/who does them? I'm in Manchester.

 

Thanks again guys

[welshpug 1,657]

Chipwizards are in your area, ish, cheshire/lancs, wayne can map many o.e ecus, you have a bosch mp3.2 ecu.

[ASBGTi 9]

Thanks bro.

 

What do you think to the over fuelling?

[jackherer 543]

Right so coolant temp sender, I'll get that ordered today.

What about my over fuelling issue? Will the above go towards curing this?

 

Yes, the coolant temp sender tells the ECU how much fuel to inject, if it fails the ECU sees very low temps and adds extra fuel to compensate.

[ASBGTi 9]

Thank you very much, updates to follow!

[ASBGTi 9]

Update.....

 

Right changed the coolant temp tensor and I'd thought I'd cracked it....Sadly not.

 

Still get some hesitation however I don't think it's as much and I still think its over fuelling.

 

Any ideas?

 

Cheers

[ASBGTi 9]

Hi guys, no updates at this stage. Can't figure it out.

 

My GTi6 manifold will be here Tuesday so with that installed we will see whee we are. My guess is that be internals of the AVAC are playing up intermittently.

 

If anyone has has any other ideas, please chirp it will be very much apreciated.

 

Cheers

[welshpug 1,657]

its a very simple setup, if you can see the vacuum pods actuating the quadrants then its safe to say the internals are just fine, its just two pairs of butterflies, nothing more to it.

 

there's the vacuum lines from the two pods to the solenoid, then hooked up to the vacuum pump if its from a 306 or zx, or an accumulator chamber if its from a 405.

 

 

give it a rev and you should see them moving.

 

 

I would check the inlet temperature sensor, the throttle sensor, and also try with the lambda unplugged.

[ASBGTi 9]

The actuators move when the engine is revved so I guess it's all working. I will check all the vacuum hoses to be double sure.

 

Could it be the the ignition amplifier? All the parts you have mentioned have been changed in the last months.

 

I've read a few more threads and it seems that it's not uncommon for the inlet manifolds to crack or indeed fall apart. Going to strip it all down tomorrow, see what's what.

 

Thanks again for your help.

[ASBGTi 9]

Update,

 

So I got to it this afternoon.

 

Removed the inlet manifold and assosiated parts, when I had the plastic part on my hands I could hear something rattling around. After removing the cover, I found this......

 

 

 

Could this be the root of the problem? I stripped it down in readiness for my gti6 manifold, I am now in a quandary as to put it back together to see of it works correctly or not.

 

Also I discovered a couple of connectors not connected, could anyone identify them for me....

 

There's a couple of other things put ill start a new post for those.

 

Thans guys

[ASBGTi 9]

Bump

[welshpug 1,657]

white and grey plugs are for the oil pressure switch and sender, should be one near the oil filter and one behind the starter motor.

[ASBGTi 9]

Ok great. Thnaks