[gledy2]

HI, i was wondering if anyone can help, my mini is tuned with a cai, 15% pulley, manifold and caback and intercooler, and used to run a max of 16psi on my boost gauge. Recently, i had problems with my spark plugs becoming unscrewed, so i tightened them up. Everything has been fine for the past couple of weeks, until the past two days. My car is now running up to 19 psi of boost, yesterday at 15.5 deg and today at 12.5 deg, and when the engine has warmed and i open the throttle up and drive harder, the emissions light comes on. The car seems to pull the same, and if anything it feels slightly faster. Does anyone have any ideas what is causing this, and am i doing any damage? Thanks, allan

[Paul Webster]

The map sensor is only 2.5 bar so thats why its come on. As for damage it all depends how your fueling is, its probably worth checking it out on a local dyno with the air fuel and timing monitored, just for peace of mind.

When you say 19psi does it spike to that or does it hold it there, what intercooler do u have.

[Loui]

Is it deffo the emissions light? Not the traction control? 19psi seems a lot of boost for just a 15% pulley am i right paul?

[Paul Webster]

I think we saw 17 with the stock intercooler so it might of spiked to that.

[roland2003]

Hi, The emission light is not triggered by hitting over 18psi (only the ASC/DSC light and PO108 code ).
High boost is more inclined to give higher emissions and trip the light though.
The stock sensor is 2.5 bar (ABSOLUTE PRESSURE) = 1.5 Bar guage pressure = 22psi, therefore although it flags at 18psi it still measures upto 22psi.
You wont get 19psi with a 15% SC pulley (and stock crank pulley). ,so either you have different pulleys to what you think or the guage is a bit out. Spikes with the SC are rare (turbos can spike quite a bit, a little of which can be beneficial)
Best Regards Roland GTT

[Paul Webster]

I must remind myself to read a title first.

I have seen a dyno graph on a Cooper S where the boost pressure is spiking so much that the tuner cant live map the car but like you said Roland it is proberly rare, espically if you haven't seen it with all the cars you've done, do you know how many you've converted??

Whats the most kpa you've seen Roland on the stock S map sensor??

[roland2003]

hi just about 20 psi which is approx about 235 kpa. (SC)
Best regards Roland.

[MINIMANIAUK]

As said the guage is possibly inaccurate, there is a slight possibility that there is a flow restriction such as the cat blocked or exhaust silencer blockage that is pushing up the boost ,maybe even bits of the cat in the exhaust silencer!! but one would expect some noise difference

[roland2003]

3 tuners helping all in a row , and on a sunday aswell!
Ony Mini2 gives this level of service.
Best Regards Roland GTT.

[k-huevo]

If the emissions lamp is intermittent then suspect an O2 sensor, most likely the post cat; pull the fault code to verify. Because you have dual symptoms, drop the cat-back and have a look at the exhaust manifold’s cat in case it has broken free (or collapsed) causing excessive backpressure as mentioned in previous posts. You didn’t mention the type of cat-back installed, if it has a resonator then that’s the next thing to check, and don’t rule out a prankster’s surprise stuffed in the tail pipe.

[Loui]

Other reasons for the emssions light could be map sensor at the front of the engine or the top wiring harness depending on age of the vehicle,

Possibly also a faulty bypass valve but ill know more about that tomorrow

[philly c]

i have a manifold and de cat and my fault light came on so i thought that it would be the o2 sensor but i was wrong as after fitting my o2 simulator the light is still on.

I need to get the fault code but at least i no its not the o2 simulator anymore.

My light didnt come on straight after fitting the manifold and de cat though??


Any suggestions?


Many Thanks


Phil

[gledy2]

Thanks to all for your help, i am away on holiday just now, so will check everything out when i get back, and drop the cat to check it out, and check the silencer for blocks, but there doesn't seem to be any change in noise. My car was running happily aup to 16psi for months before, only recently it has gone up, and might be a spike as roland says. I will also pull the fault code once i search on here how to do it, and see if it is the02 sensor. It isa 52 plate loui, so i will check where the map sensor is for that year. Don't hink it would be a faulty bypass valve as i had it out and fixed it before when it was jammed open, and have checked it since, and it has been closing properly. I will see what it is like when i get back, hopefully it will have cured itself sitting doing nothing for a week or so. Thanks again, allan

[ice man]

Hi, i have a jcw and also fitted the 4 banch and decat pipe and now have the same fault (cat inefficent) by disconnecting the post o2 sensor will it solove the problem?

Many thanks
Richard

[philly c]

no it will not cure the problem as the ecu needs to be told that there is no problem and disconnecting the sensor will not solve this problem. Th fault code given off can be rectified through the use of an o2 simulator. It simulattes the right current sent to the ecu letting it thnk that it is ok and operating well.

[roland2003]

Hi Actually, if the light is on due to 'cat below efficiency' (P0420 code) ,then removing the rear sensor completly from the car and using a bung in the rear hole will prevent the light. All you then get is P0036, but the light stays off.
Best Regards Roland GTT

[gledy2]

Thanks to everyone for helping, will get it sorted!

[sam_a156]

Hi Gledy2, any news on this, was it a faulty cat?

[gledy2]

Sorry been really slow to update this!! Yeah it was a faulty sports cat, it was so blocked it manages to blow through the flexi pipe on my janspeed manifold. I have now had the standard one on for a while and no faults, going to get the flexi pipe on the janspeed fixed and run it decat, to stop any future problems! Thanks to everyone for theor help.

[Paul Webster]

We have found that we nmake more power and trq with the cat in.