Mot Fail S16

[Jemehan 3 1 Cars]

So, I recently bought back into 205's and got myself a nice Miami blue 205 S16 on a K reg. I have lots of recipts with the car and from what i can tell its really good. Ran fine but had a few things that im not sure if are normal. Ill get to the MOT bit in a minuite.

 

When i drive the car, there seems to be power bands, like the car is cammed however i have no recipts saying that it is. Do S16 engines normally run with two power bands? Other than this she drives ok, could do with some new brakes etc but seems all ok.

 

When i took the car for an MOT today, the guy tells me that the car is running very rich, this doesnt honestly surprise me too much, however this meant the emmissions are miles over (i think at about 7). Does anyone know how to change the fuel air mixture and get this to run a little leaner so that it will AT LEAST get through the first stage of the MOT? Any help would be appreciated!

 

[Anthony 1,003]

Mixture is likely the lambda sensor being faulty.

 

The "cammy" feeling probabaly means that the ACAV on the inlet is broken, assuming the original inlet manifold is still fitted - a fairly common issue.

[Jemehan 3 1 Cars]

Lambda is on the manifold on these right? (Not had much chance to look over the engine in massive details).

 

Its a standard intake but i dont know what that ACAV is.

[Anthony 1,003]

Lambda should be on the downpipe somewhere. If it's missing completely then that would explain matters also!

 

ACAV is the variable intake runners that are actuated by the diaphrams on either side. Failure of one or both of these are common, and other parts of the system can fail as well but that's less likely (in my limited experience of S16's). A search should reveal details on the system and how to diagnose / repair it.

 

(I am assuming here that you're running S16 engine management btw - most are, but some are lashed up on 8v stuff or have been converted to use Mi16 management - big clue for either of the later two is the presence of a dizzy cap, as S16 management uses individual coil packs)

[Jemehan 3 1 Cars]

oooh no,no,no she seems to have had a good conversion done, its got full S16 ECU and diag plug in the car. Having listened to her, sounds like could have an air leak, this could cause the fuelling issue, its just so damn tight in the engine bay!!

 

Ill go outside with a torch in a min and have a look to see if i can see the sensor on the downpipe. How much would the diaphrams cost and how hard are they to fit?

[Jemehan 3 1 Cars]

I have had a look by torch light, the Labda looks pretty new, the plug isnt overly clean but the sensor itself is still shiny.

 

How easy should the actuators be to move? ( i will also search the forum).

[pugpete1108 62 1 Cars]

did they not continue with the mot then dan? or just stop when it failed the emmisions?

 

where did you go?

[Miles 331 1 Cars]

A air leak should make it lean, Rich is too much fuel, WTS could be the issue, But make sure the Lambda is wired up correctly or a OE one

The ACAV will move when you rev the engine,

[Jemehan 3 1 Cars]

It went to Ashford mot. Bernie down there is normally pretty good. I wasn't there when the mot was done but I was told that he stopped as soon as the co level went up to 7. Shouldn't be any other issues. Car had 1k spent last year to get it through mot and she hasn't done many miles in the last year. Iv spoken to the previous owner and confirmed this in hand with pug ecosse receipts for the last mot. I have a friend with a co2 tester so at the weekend will have a play and see what can be done.

In regards tothe intake and car feeling cammed that will need to be looked into, not sure if the power should come in bands or wether it should be a smooth acceleration....

[Jemehan 3 1 Cars]

A air leak should make it lean, Rich is too much fuel, WTS could be the issue, But make sure the Lambda is wired up correctly or a OE one

The ACAV will move when you rev the engine,

 

Do you have a wiring diagram for the lambda? It all looks fitted ok but I'm not an auto electrician... I don't understand that it passed mot last year and has barely been moved since.

[Vili 18]

The car should accelerate smoothly through the rev range. At least my and my friends 306 did when the variable inlet was working. Actually it should work just fine even if the manifold is not working. ACAV is easy to test anyhow. Just let the car idle and open the throttle by hand under the bonnet. You should see both diagrams pull when you give the gas and come back when you let off the throttle. (Could be the other way around, but there should be movement.)

 

If your lambda is not working you should get a fault code and engine warning light lit.

 

CO is partially burned petrol so you could have ignition problem. Failing ignition coil is very common fault in these engines. But this is unlikely if car was fine at the last MOT.

 

If the car has been standing there is one bit more rare problem that I had and it's very hard to detect. You could have blocked fuel return line what is causing fuel pressure to rise. The fuel lines might seem perfect on the outside but be rusted on the inside.

[pugpete1108 62 1 Cars]

Should have got Phil to do it.

 

Odd that they stopped there though, I wouldn't have been happy about that. You paid for a full mot so should have had one.

[Anthony 1,003]

If your lambda is not working you should get a fault code and engine warning light lit.

In my experience, that's not the case, at least judging from the 306 S16 I had.

 

There may be a fault code logged, but the light was not illuminated when driving to indicate an fault.

 

The two biggest clues were high emissions (around 8% CO) and poor fuel economy (struggling to get 30mpg). With the lambda replaced, the emissions dropped down to around 0.5% CO (and then down to 0.0% when the CAT was replaced) and fuel economy noticeably increased.

 

CO is partially burned petrol so you could have ignition problem. Failing ignition coil is very common fault in these engines. But this is unlikely if car was fine at the last MOT.

High CO values are typically from running rich. High HC values tends to point to incomplete combustion from a misfire or similar.

[Jemehan 3 1 Cars]

Afternoon guys, thanks for the advise so far, this will all be checked out at the weekend, I believe that a Lambda sensor replacement may help? Is there any way to check if its the lambda sensor before i buy a new one? dont really want to replace what doesnt need to be.

 

Pete, They only did that test and as it was so high didnt carry on or charge me for the time it took to do that, figure they did this first!

[pug_ham 244 3 Cars]

The only tests listed on autodata for the lambda sensor are voltage checks & a resistance check of the O2 sensor heater;

 

 

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[nixonmi16 5]

to test the o2 sensor connect a volt meter to the supply to ecu norm the black wire on most sensors it should switch from 0 to 0.8v very quicky at 3000rpm.if stays still blip the throttle and it should shoot up then back down. an air leak before the o2 sensor can cause a rich mixutue as can a missfire all the sensor reads is air.

[Jemehan 3 1 Cars]

Am going to test everything tomorrow and check for air leaks on the manifold and lines. Just thought too, it has a leakin manifold gasket tick, could that be the cause of the issue? or would that just not help?

[Jemehan 3 1 Cars]

So, iv got it running better... Cleaned up the intake, diaphrams work fine. I changed air filter to astiffer one with more resistance. Best bit, changed the lambda and wow, it was literally cooked (will post up pictures later). Car is now however lagging in power, feels bit like a coil pak issue... Put my foot down and she bogs n then backfires. Anyone any ideas what could be the issue?

[dcc 855]

sounds like the fueling isn't right to me! not a like coil pack issue. Sounds like your getting too much fuel. Just because a lambda is 'black' doesn't mean it is dead. The one in my old Honda had seen 90k miles of used, and was very black, didn't mean it was dead

 

have you:

fitted a new ECU temp sensor?

fixed inlet gasket?

new sparkplugs?

 

Why the stiffer filter?

[Jemehan 3 1 Cars]

The Spark plugs are new ones in there, but they seem to be a little oily as i think the rocker cover gasket needs replacing. The inlet gasket seems to be fine, i took the inlet apart and put it all back together again and that all seems fine. Where would the ECU temp sensor be? I have not replaced that.

 

The Lambda needed replacing, it wasnt black, it had split and half of the internals had vanished. It needed replacing badly!! Now new one fitted, the car idles perfectly. Its just this bogging issue now. I had a feeling it was possible that its a fuelling issue, pretty sure its getting too much, but after replacing the lambda i thought it may re adjust itself - it hasnt. How can i change the fuelling?

 

I put a new filter on there as it was cleaner and seems to be better quality than what i had on there. In summary, the only think on your list there that i know i have not done is the ECU temp sensor.

[welshpug 1,657]

Is the map sensor connected ok?

[Jemehan 3 1 Cars]

Is the map sensor connected ok?

Little ambarrased to say this, but i havent the foggiest what or where that would be!

[pugpete1108 62 1 Cars]

Around the throttle body dan.

 

[Jemehan 3 1 Cars]

 

That's what's left of the lambda

[Jemehan 3 1 Cars]

Around the throttle body dan.

Took the whole intake system off yesterday to see if there were any cracks etc. Everything was plugged in correctly there. This bogging issue is really bad, i cant put my foot down