20 replies to this topic

[Mat Jackson]

All, Got the car running on ITBs and it's due to be mapped next week. The car runs really well, good throttle response at all stages, no pinging etc - but noticed the exhaust seems to be running hot. Might not be hotter than before, but just a guy feel. This makes me think it might be running lean.... Ecu is off another vx220 with homemade vvt, so the map has been tweaked from standard. Next week I am due to drive the car to the mapping session (90min drive at 60 on the m-way), but have a niggling question that if it is running lean could it cause damage in some way? I currently don't have any other way of getting it there (no trailer, or tow hook). I'm I worrying about nothing? If the car was running lean, would it show up in driveability? If it is running lean, would a 90min light run pose any risk? Mat Sent from my iPhone using Tapatalk

[fiveoclock]

Fit an AFR gauge 

[siztenboots]

more likely retarded ignition timing 

[Mat Jackson]

Either way - is it a risk to drive to mapping? Sent from my iPhone using Tapatalk

[fiveoclock]

Either way - is it a risk to drive to mapping? Sent from my iPhone using Tapatalk

Who can say. Fit an AFR gauge and you'll know exactly what its doing and can choose what to do

[2-20]

Have you checked your plugs ??

[gaffer1986]

If the exhaust manifold isn't red hot after 10-15 mins driving I wouldn't worry about it. My exhaust is red hot (only at night) despite meticulous mapping because it's such a high compression engine compared to most.

Edited by gaffer1986, 11 July 2017 - 06:38 PM.

[Mat Jackson]

If the exhaust manifold isn't red hot after 10-15 mins driving I wouldn't worry about it. My exhaust is red hot (only at night) despite meticulous mapping because it's such a high compression engine compared to most.

By red hot, do you mean glowing red??! Sent from my iPhone using Tapatalk

[gaffer1986]

Yes, if the exhaust is not glowing in daylight (will start to glow slightly at 400 degrees Celsius when dark) I seriously doubt there is enough heat to damage the engine. My engine runs very hot anyway and has done around 22,000 miles I think.

[gaffer1986]

One bit of advice I would give when it comes to mapping.. Turn off overrun fuel cut off; it's the single best thing I've done to this car so far.

 

The throttle positioning sensor is not the most accurate device as the throttle will never close to the "exact" position and is subject to how hard to let off the gas and therefore how much momentum the throttle spindle hits the stop screw. The alpha system has a basic TPS break point for when fuel overrun cut off will occur, depending on the temperature of the engine the throttle stop can produce a very slightly different TPS signal and when the signal is around the break point the car with go in and out of cut off causing the car to bunny hop, took me a year of figuring it out and a drive down the road with Northampton Motorsport watching live data to figure it out.

 

The alpha systems fuel cut off is crude and cuts in horribly when you get to the rpm specified for fuel to cut back in again and does so with a jerk, makes a very annoying drive around town.

 

As soon as he turned it off the throttle was instantly smoother, drops down to tick over really smoothly and pressing the gas from tick over is smooth also with out any jerks.

 

Then the big bonus, without fuel cut off, the engine pops and burbles really nicely when off the gas round town, let off the gas after full throttle above 5000rpm and you get some very distinct loud popping (not too loud though or artificial like f type) which makes me smiles every time I do it. Very close to carb sound.

Edited by gaffer1986, 11 July 2017 - 07:07 PM.

[gaffer1986]

Personally I've always hated the artifical machine gun style exhaust popping.

 

[gaffer1986]

Fast forward to 2mins 55 and 3 mins 10 to hear how exhaust popping should sound in my opinion.

 

Edited by gaffer1986, 11 July 2017 - 07:15 PM.

[Mat Jackson]

Ok - took the plugs out, cleaned them and went out for a 20 minute run, took them out hot and took a look:



Looked at the piston crowns through the holes and they all liked ok, but did have a light coating of carbon on them.

Plugs seem to look ok (maybe a bit Lean?) - only really looked for fouled plugs before....

Thoughts on the plugs?




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[Nev]

You can see the light brown of leanness starting to appear.

 

If you drive it at 20% throttle it would have to be badly out to do damage to the engine IMO, though still a slight risk.

 

Remember that cars on over run and very low engine load will happily run (and are mapped) at 15 to 20 AFR.

 

Putting an AFR wideband gauge in your car is a good pre-cursor to any sort of major engine/mapping changes BTW.

Edited by Nev, 12 July 2017 - 07:43 PM.

[oakmere]

Doesn't the engine run closed loop with the ITB's so as long as you drive gently the the oxygen sensor and ECU will control fuel mixture. It will be open loop foot down driving that could cause the issues. This is unless you have a more serious issue than a non optimised map.

[Mat Jackson]

Thanks guys - plan to drive to the mapping and an easy motorway run on light throttle so should be ok. The plugs above were after a 20 minute drive, with some sprites sections!!! Will have one last longer drive this weekend on light throttle and check the plugs again just to be safe... Sent from my iPhone using Tapatalk

[Mat Jackson]

*spirited sections* Sent from my iPhone using Tapatalk

[oakmere]

Careful removing the plugs when hot you don't want to end up with a cracked head.

[gaffer1986]

O2 sensor trimming has very little control. Will not right it if afr is far out, it can only trim.

[gaffer1986]

However, if you unplug the o2 sensor that should richen things up at bit. Another way to make it richer is to lower the airflow a kg per hour and put the TPS back to idle voltage. That will significantly make it richer across the band. I did this when I was worried about lean as a temporary measure and my exhaust temp went down a lot.

Edited by gaffer1986, 12 July 2017 - 09:22 PM.