Thread: Technical Question about Lean mixture

Originally Posted by Tank

To check for lean mixture, pull and read the plugs, if they are white to pale brown you are probably lean, should be grey towards black. I would also check that the vacuum advance on the dissy is working by sucking on the pipe and see if the top plate in the dissy rotates a few degrees. also check the 3 allen bolts that hold the IAC (stepper motor) on the back of the plenum chamber are tight, then pull it off and check the hose from the fuel pressure regulator has no fuel in it and while it's off clean the valve of carbon and it's seat in the plenum, all could be a source of running lean, Regards Frank.

Thanks Tank, ok I have already done, stepper motor, new vac advance, checjed dizzy rotation, ill check the regulator (I was thinking of changing it anyway) put some new plugs in regardless and check the plenum bolts, in the mean time ill grt a timing light and teach myself how to use it

url didnt work.

Ooops. I'll try again.
It's a good link for all tuning/EFI questions.

MoTeC > About Lambda > Overview

Originally Posted by nobbyclrk

Ooops. I'll try again.
It's a good link for all tuning/EFI questions.

MoTeC > About Lambda > Overview

Tuning with Lambda
The tuning objective dictates the target Lambda. Typical gasoline/petrol engines produce

peak power at Lambda between 0.84 and 0.90
best economy at Lambda equal to 1.05
optimal emissions at Lambda slightly lower than 1

peak power, 0.84 x 14.7 = 12.3. my sr20 under WOT is about 12.5

peak power, 0.84 x 14.7 = 12.3. my sr20 under WOT is about 12.5

Yep. That makes sense, on the rich side for WOT.

Ok well, I put a thermal thermometer on it and when the needle is at half on the dash it reads 76 deg at the temp sender, 78 deg at the thermostat, the hottest it got with needle at 2/3 was 86 deg, not as bad as I thought, ill intall a vdo guage now and change the sender and keep an eye on it till I get the radiator rodded