Where are all the sensors...

[fsa]

Could someone please help me find all the sensors on a 1.4mpi that I should consider cleaning to improve efficiency? MAP, butterfly, pre and post lambda, temp? Where exactly are they all located? Haynes index didn't have MAP or butterfly listed....... I'll do the engine flush when I'm next due an oil change....just want to exhaust everything else first. Any brand of cleaner I should opt for / avoid?

Had crappy mpg in today's commute and engine was more sluggish than usual at sub 3000 rpm. (I really hope it wasnt down to my air inlet upgrade).

Many thanks to anyone taking the time to help me!

Edited 2 September, 2011 by fsa

[Chris Coates]

Double post badness - read below

Edited 4 September, 2011 by Chris Coates

[Chris Coates]

The MAP is inside the intake manifold on the back - you can remove it easily enough without having the manifold off. Just look for the plastic connector on the back of the intake manifold and unscrew it. I've previously cleaned it with carb cleaner and just let it dry off and then put it back in, but if you're sensitive about it you could just use electronic component cleaner.

Whilst you're at it, you could remove the ducting to the throttle body and clean that too - carb cleaner would suffice for that.

I noted that all that oil going back to the throttle body from the crankcase was a bad idea - so just re-ducted it to a breather and a slight catch can. Works very well and I could physically see after maybe 500 miles how much effect it has, and how much crap goes back to the intake.

Note that the air inlet upgrade makes the engine more responsive, at the expense of economy unless you drive it accordingly - I noted that you get the bwarrrrp sound when you've got your foot in, but that also is accompanied by more fuel usage. It also kind of gives me away to the missus who then tells me off for booting it hahaha! If you drive the car just to the point before it gets loud, it's actually more responsive still and more economical.

On a run yesterday I managed 40mpg to Sleaford and back, with no lack of performance.

The lambda's are a common cause, and if your temperature gauge isn't responsive the thermostat could be another.

I've got a timing chain I need to sort - coming up to 120k so needs doing. Then again it doesn't really affect my economy much.

You might want to check your plugs too just in case if you're lacking power...

...And then also check your coolant for any signs of head gasket issues. Mine was so much nicer after I swapped the gasket out for the uprated temac set... But if you're doing that then disregard the haynes and tighten the head down properly - 50lb/ft torque recommended. Was recommended this by a friend who rallys an old estelle (and it's pretty much the same block/head).

[fsa]

Thank you so much for being so thorough. Gonna work through each one of them on my next couple of days off. How did you set the breather and catch can up? Must be really worthwhile protecting the intake from all the crap.

It's always tempting to put my foot down just to hear the growl, but am resisting the urge. I've definitely found it more responsive at the lower revs initially...then after this episode of slight sluggishness I started to doubt my amateur mechanics.

What sort of speeds were you doing to manage 40mpg? I found economy gets worse at over 60mph when the engine exceeds 3000rpm.

Going for Bosch spark plugs....i think the model no is FK47.

You might want to check your plugs too just in case if you're lacking power...

How much did the temac set cost you? No mayo deposits around the oil cap......any other signs of gasket issues I should look for?

[anewman]

Bosch super 4 FR78 (note NOT FR78X) are the ones I use. Main benefit from multi-electrode is longer service times though - they don't all spark at once. They're about £13 with a trade card from Halfords, £20 otherwise.

You may have the temac gasket fitted already, clean up the edge of the small portion of gasket showing on the right corner and look for the writing. Other issues to look out for, coolant loss/oil in coolant.

[fsa]

I have to admit, I got lost under the hood today and couldnt find anything at the back of the engine resembling a plastic housing for the MAP. At the risk of infuriating the pros, could someone annotate this pic to show where I should be looking? Is the throttle body above the MAP?

Edited 6 September, 2011 by fsa

[anewman]

I haven't made the location of the bolts too clear on the cover for the throttle body, basically they hold down the plastic prongs - one is visible just to the right of the right arrow. The hose on the end can be simply pulled off and pushed on.

I placed a red x to indicate the piece of metal the MAP sensor is on.

[Chris Coates]

I haven't made the location of the bolts too clear on the cover for the throttle body, basically they hold down the plastic prongs - one is visible just to the right of the right arrow. The hose on the end can be simply pulled off and pushed on.

I placed a red x to indicate the piece of metal the MAP sensor is on.

Good call.

The map is on the back of the intake manifold.

Take off the throttle body cover, then hand down behind the back... You want to basically trace back the plug from the throttle body to the Y-split, then trace behind the intake manifold - that's the MAP.

I did some epic photochopping to highlight this. From the left hand side of the throttle body (i.e. on the side of the coolant expansion tank):

[fsa]

THANK YOU THANK YOU THANK YOU!!!

[Chris Coates]

THANK YOU THANK YOU THANK YOU!!!

No worries

[fsa]

So far, it is a Temac, I've cleaned the throttle body and butterfly valve but I think I need a different sort of Torx screwdriver to get behind the throttle body for the MAP. The one I have is too long and I cant get any leverage on it. I've even gone through all my pushbike repair tools in vain. The throttle body wasn't as mucky as I would've expected on something this old...looked like a slight oil film which came off very quickly with a few shots of carb cleaner. Happy to report no mayo deposits around the temp sensor either...took that out for a clean.

Edited 8 September, 2011 by fsa

[Chris Coates]

Ok.

First thing: Is your head torqued down right? 50lb/ft torque is recommended... They haynes is a book of lies borrowed from Skoda for it. Re-torque from the middle outwards to be sure.

Second: Have you checked your plugs?

Third: What kind of mileage are you on? Timing chain can make a fair difference to fuel efficiency... Mine is set for a change as i'm rapidly approaching the magical 120k epic service mark.

It also could be injectors - when they get gummed up over its lifetime they do become less efficient.

Lots of ways that economy gets affected though. If vag-com isn't showing anything you could end up spending forever and a day tinkering to improve it - and probably spend a fair amount of cash doing so!

[fsa]

Chris, really appreciate your time, mate. I'm learning so much through this process.

After buying a little socket set from Halfords (luckily on sale), I got the MAP out and it was quite oily. Throughly cleaned, replaced, even a few squirts of electrical contact cleaner on the MAP electric socket. A quick 10 miles of mixed city start-stop driving and dual carriageway returned 37mpg! A far cry from the 31 I normally get. I really hope this lasts though. Advisable to do all that cleaning everytime I change the oil circa 10k miles?

I need to get hold of a cheapie torque wrench...ideally with 1/4 drive then my current socket set can serve both purposes.

I awaiting delivery of those Bosch plugs so will change them shortly...I'll compare the ones I take out with this chart.

64000 miles....so still halfway to go till that magical timing chain replacement point.

Injector cleaning needs that specialist ultrasonic device, does it not? I've been using redex every 2000 miles although whether or not it helps is debatable.

Edited 8 September, 2011 by fsa

[anewman]

Torque wrenches tend to cater to different torque ranges. A 1/4" one will give torques at lower end whereas 1/2" will give higher torques. 1/2" ones can usually be had cheaper too.

I'd be a bit unsure of re-torquing the headbolts on an engine where there appears to be no issues after the headgasket was fitted years ago. Besides I imagine 50lb/ft a torque wrench would click off straight away without undoing them first? If doing this and loosening each one first, I'd be tempted to get a new set of bolts.

[Chris Coates]

Chris, really appreciate your time, mate. I'm learning so much through this process.

After buying a little socket set from Halfords (luckily on sale), I got the MAP out and it was quite oily. Throughly cleaned, replaced, even a few squirts of electrical contact cleaner on the MAP electric socket. A quick 10 miles of mixed city start-stop driving and dual carriageway returned 37mpg! A far cry from the 31 I normally get. I really hope this lasts though. Advisable to do all that cleaning everytime I change the oil circa 10k miles?

I need to get hold of a cheapie torque wrench...ideally with 1/4 drive then my current socket set can serve both purposes.

I awaiting delivery of those Bosch plugs so will change them shortly...I'll compare the ones I take out with this chart.

64000 miles....so still halfway to go till that magical timing chain replacement point.

Injector cleaning needs that specialist ultrasonic device, does it not? I've been using redex every 2000 miles although whether or not it helps is debatable.

You can actually clean injectors with strong(ish) solvent-based cleaner - someone once mentioned varnish remover and leave them in soak overnight in a sealed container, then take em out and let them dry out... Ultrasonic devices are all well and good but not exactly easy to hand.

As for a cheapy torque wrench:

El cheapo silverline torque wrench

Is what I use - bought the reducers from halfrauds at £6

And as for having to clean your map up every 10k... If you get rid of the crankcase recirc... You'll not have to again

I'll put something together over the weekend re: making a crankcase breather catch, and provide a piccy showing how much crap gets in if you leave it recirculating back to the intake.

As for re-torquing...

...Before having the time to change my gasket to rule it out properly (there was an oil leak along the gasket seal), I could actually still re-torque the head bolts - no loosening required. It was pretty scary how loose they were to be honest.

Also... MPI head bolts aren't stretch. So all good to re-use, provided you give them a look over first.

Edited 8 September, 2011 by Chris Coates

[fsa]

Thanks so very much for your thoughts. I appreciate what you're saying re gasket....no issues specifically with it so best leave it alone. Although the sealant tape is peeling off from around the gasket......normal plumbing white tape ok to replace? So higher socket sizes give more torque...understood.

On another note, the two rubber pipes going back into the throttle, near the Y junction of the cables by the MAP, were quite loose. They didn't have any metal clips securing them either. Are they like that on your MPI's?

I think I read that strong solvent cleaning method somewhere on here....will give it a close read and have a go.

That would be fantastic of you...anything to keep the MAP from getting gunky again.

VAGCOM did show:

16514: Check Oxygen (Lambda) Sensor Heating Bank 1 Sensor 1

16524: Check Wiring/Connectors from/to Oxygen (Lambda) Sensor Bank 1 Sensor 2

16825: something to do with the charcoal canister?

So somehow both lambdas are affected.....

[Tech1e]

Charcoal canister is probably dead, they don't last forever. Especially if someone is brimming the fuel tank, if you overfill the tank and this the overflow (common practice on the diesels) is backs up down the canister line and fills that with petrol, then it's knackered.

Probably needs lambda probe one if it's not longer heating, again the elements don't last for ever, worth having a look at the connectors on the second probe as it says but will probable clear one the first probe is sorted out.

[fsa]

Thanks, Tech1e....like this sensor?

Happy to report a conservative drive to Heathrow returned 41mpg and 37mpg on the return with a little heavy on the right foot

Very chuffed......thanks Chris and anewman!!

Edited 10 September, 2011 by fsa

[fsa]

Can't find charcoal canisters on Eurocarparts......is this a dealer only item?

Anything I should watch out for when removing lambda probes that's not in the Haynes manual? I realise it's a book of lies but it's the only guide I have.

Edited 11 September, 2011 by fsa

[rum4mo]

I don't know what everyone elses views are on buying aftermarket Lambda probes, but certainly on VW engines, factory fit NGK - or whatever NGK brands its probes etc maybe buy cheap buy twice? Probe could be easy enough to replace and new one should come ready coated with correct thread sealant, I bought the correct socket to replace the one on my wife's BBY engine - probably due to my ignorance and believing that the correct tool must be used, and found that with the manu-cat in place, this tool could not be used, so I used a couple of OE spanners (both different makes so that jaws were slightly different) as that area had bad access to spanners.

Edited 11 September, 2011 by rum4mo

[rum4mo]

Can't find charcoal canisters on Eurocarparts......is this a dealer only item?

I'd think so.

[fsa]

Are both lambda sensors the same part? Eurocarparts doesn't list pre or post separately.....

[fsa]

Is there any way of looking at a lambda sensor and figuring out if it's broken/damaged? I looked on lambdapower.co.uk (which does list probes more thoroughly than eurocarparts) and have just lifted my jaw off the floor after seeing the prices. Don't really want to spend that much unless I'm sure that's at fault. Guess I should've budgeted for this instead of splashing out on a RARB.

[Chris Coates]

vag-com should tell you...

Other than that I may have the voltages that it should be reading back in the epic amount of documentation i've got lying around - but i'd not fancy attempting to measure.

Your best bet is vag-com to find what it's sending back - i'll see if I can dig out what it should be reading for ya.

[fsa]

vag-com should tell you...

Other than that I may have the voltages that it should be reading back in the epic amount of documentation i've got lying around - but i'd not fancy attempting to measure.

Your best bet is vag-com to find what it's sending back - i'll see if I can dig out what it should be reading for ya.

As ever, Chris, you're a ledge! I'll find someone else nearby with vagcom as Nick who I went to last has gone back to uni.