AFR 10s on idle / no exhaust fitted (NA-T)

[ballsdeep]

Guys I'm just wondering if its safe to drive the car to have my exhaust modded, it only has the downpipe loosely fitted.

 

The dp doesn't sit flush up to the turbo will this be why my AFR is at 10.7 on idle?

 

I'm in the finishing stages of my NA-T with only the exhaust and map to do will it be ok to drive it 7-8miles like this?

[David P]

Is that on cold start cycle or when up to working temp?

[FOSTA]

Have you had the battery disconnected? If so mine sits in the 10's for a few miles after I disconect the battery but after a few miles it sorts itself out and down to 14's

[ballsdeep]

Yeah the car hasn't been run since taking the engine out, just short idle runs.

 

I just started her up again here's what I got;

 

14s - startup dropping to 10.5 within seconds

10.8 - after 5mins idle at 850rpm

 

I took it down the road and saw 11s but only when I clutch to change into 2nd.

 

Once I get the exhaust fitted what rpm should I keep it under until I get it mapped?

[johnny g]

I know my TT used to idle around 10.8 to 11.3ish when cold, then upto 13.1 when warm and idle perfectly at 900rpm (this was with 272 cams)

[Fly]

Gaz. I was seeing 10s on cold start until she warmed up(water temp at 9 0clock pos) then i was seeing 11s. I changed my injector lag time which has psuhed me to 12-13s but you dont have to do that shes just running pig rich!!!

[ballsdeep]

Guess the old girl just needs to clock a few miles then, cheers guys

[Noz]

Cant you fit the downpipe and see how it runs when warm?

[ballsdeep]

It won't fit flush to the turbo! There's about 1cm gap at the top, but I have to drive it like that tomorrow to get it to topgear for the exhaust to be done.

[Fly]

incidentally does your car now idle really low? mine used to sit about 1500rpm and then back off when it got warm now it just sits at 1k and backs off when warm,

[ballsdeep]

Mine has always idled at a steady 850rpm when warm and it still does although I sometimes get a slight dip when I increase the revs??? Il be looking into this once my exhaust is fitted!

 

Isn't 1k a little high on idle?? I wonder what other na-t's are idling at?

[Chris Wilson]

A wide band Lambda sensor will give wildly inaccurate readings if it sniffs air, as in near the open end of the exhaust "system". What your ecu makes of it and how it reacts depends on the ecu and the way it is set up and mapped.

[bigbloodyturbo]

What ecu have you got? if your ecu has flagged your o2 input as 'failed' it will default to the failed sensor value, as standard this may be 18-19:1 which would make you run pig rich for safety all the time.

[Tricky-Ricky]

What ecu have you got? if your ecu has flagged your o2 input as 'failed' it will default to the failed sensor value, as standard this may be 18-19:1 which would make you run pig rich for safety all the time.

 

Don't you mean 10-11 AFR which would be the default for a bad lambda sensor,18-19 would be very lean.

[bigbloodyturbo]

Don't you mean 10-11 AFR which would be the default for a bad lambda sensor,18-19 would be very lean.

 

no 18-19 afr. If the ecu see's your sensor output as being outwith the expected values then it defaults the to 18-19 or whatever you set it to. This skews the map to always make you run rich.

 

-edit- should mention this was on a syvecs, I dont know if other ecu's operate the same, hence why I asked which ecu he had.

[Tricky-Ricky]

Sorry thought it was relating to std ECU which will like most std ECUs default to running things rich for safety if the lambda signal falls outside of the expected parameters.

 

And on rereading your post i think we got our wires crossed LOL!

[bigbloodyturbo]

Sorry thought it was relating to std ECU which will like most std ECUs default to running things rich for safety if the lambda signal falls outside of the expected parameters.

 

And on rereading your post i think we got our wires crossed LOL!

 

I get what you mean now. Nah, I only know that bit as it happened to me when I fed a 0-5v input from an LC-1 into a syvecs and wondered why it went stinking rich all the time, turned out because the lc-1 was 0-5v LINEAR and not the usual gradient response off the syvecs supplied wideband it defaulted when I blipped the throttle and told the ecu I was at 18.4afr(user defined default value) when I wasn't. ECU then dumped fuel in and I couldn't understand why. I got 9.5-10afr on idle and ran like a bag of spanners:)