How to Richen Idle Mixture?

[Turismo]

I was wondering if there is a way to make my idle mixture richer? My A/F meter scans like it should but could use to be a little less lean, any tips?

Also, can you safely use a lower temp. thermostat and if so what temp is stock and what would you reccomend? I seem to get a little detonation before boost still but it only seems to happen after I've been to normal temp. for a while. Input would be great.

[VTeCno Geek]

Idle air-fuel ratio should be a little lean. You really only need 15:1 since load is almost non-existant. Extra air and fuel is added by the ecu when load goes up (ie A/C, or headlights are on). Also, this idle condition is compensated for by the ecu with an extra burst of fuel when you first press down on the peddle. The stock ECU configuration is why we have problems with elevated fuel preassure and bigger injectors. The ECU does not know how to compensate for this at idle. As for lowering the thermostat temp, here is the first question. Is your engine temp running over the half-way mark? If not, you really don't need to lower the temp. Pinging is is more likely caused by and inadequate fuel supply. Detonation could be caused by heat, but we are talking severe detonation. I would check a couple of things. A) do you have the new preassure switch. If you got your kit after June or July of 99 you shoul. This switch comes on at 1psi. B) with colder air, you may need to adjust the fuel pressure increase coming from the JR riser. This will increase the idle and on-boost pressure. THere is a locking "banjo" fitting on top of the riser, and then a hex insert. Stick a hex key in and keep the insert from moving while you loosen the "banjo" fitting". This will allow you to freely turn the insaert. Mark the starting position with whiteout or indelable marker so you have a reference. Then apply a 1/4 turn clockwise to up the pressure. Test. If this seems to resolve your problem, then great, if not, try another 1/4 turn. Repeat. Realizing that air temps can fluctuate dramatically from summer to winter, you may need to adjust this 3-4 times a year. It might be best to make marks at each spot for each season. This should hopefully resolve your problems.

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[Turismo]

I do have the new pressure switch. I also have a fuel pressure guage at the JR regulator and their is plenty of pressure (50-60psi) at idle. The temp guage doesn't go over 1/2, actually never gets past about 3/8, pretty standard reading. I guess larger injectors are calling me, wouldn't hurt anyway. VteCno, I went to the RC site to check em out after your last e-mail and their formula shows us using a LARGE injector for our power, 472.5 cc for 240 hp. What's up with that??? Any ideas?? (I did list for turbo app. instead of N/A but it seems closer to our FI setup). Would a lower temp thermo hurt? Only a few degrees? Also why would I get detonation before boost? It's kinda like the flat spot discussed at the Cartech FPR page and it happens regardless of load from 2nd gear on (minimal but annoying, plus I'm anal).

[VTeCno Geek]

Okay, if you are leaning out at idle (and I mean more than 15:1 A/F Ratio, then you may have a problem with your O2 sensor. If you are sure you are getting some ping off idle, and before boost, then you may have a problem with your injectors. As for the lower thermostat, It really shouldn't be an issue. Even when autoxing on the hotest day my temp gauge never passed half-way. As for the formula at the RC site, I am not sure it is setup right for the type of line preassures we are dealing with. I think there are some issues with that formula that may be big-engine specific. I called Russ and he personally recommended the 270's when I bought them.

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[Turismo]

OK, I kinda dropped the thermo. idea anyway after some of your guys input, it was just a thought. I guess I'll pull the fuel rail tomorrow and see if anything looks or acts strange. Anyone know if the non VTEC B18 uses the same injectors since I have a blown motor in the garage?

[zip]

To richen your idle mixture you adjust an epoxied screw on the side of the throttle body. You turn it counterclockwise to richen and clockwise to lean. After you've done this make sure to pull the ECU fuse for fifteen minutes and then reinstall. Good Luck.

[rjaffey]

Although it may not solve your particular problem, lowering the coolant temp and improving the efficiency of the cooling system can reduce knock by lowering the combustion chamber temps.

Check out:

http://www.redlineoil.com/wwti.htm

You shouldn't run too low a concentration of antifreeze if it gets too cold where you are. Also, remember antifreeze has other properties besides lowering freezing and raising boiling points. I also wouldn't use anything less than a 180 thermostat, but that's just my opinion.

[This message has been edited by rjaffey (edited January 09, 2000).]

[Turismo]

Thanks fellas, I'm going to try everything until I beat the detonation.

[VTeCno Geek]

The screw on the side of the Throttle body is for adjusting the baseline idle. It will not adjust the mix, just the point at which the IAC valve allows air thorugh to stabilize the idle.

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[Mr Rogers]

Turismo-I have my idle pressure set at 52-53 psi at idle and it seems to be working well with my 8psi setup. I get a little det in the midrange that the J&S removes but other wise it is ok. At idle the A/F gauge should hunt (dipping back and forth) between lean and 2 or 3 lights on the rich side. I have my timing set at 10 degrees and it is working great, but you mustn't forget that the air tmp here in Nebraska has lately been between 30 and 50 degrees, plus I have an AEM Well good luck figuring it out but it sounds like you are about there.

I just realized something after reading your post, and the ECU will pull all the fuel when at idle which takes the lights all the way to the bottom and off the scanner, then back up to rich alittle. So if this is what you meant by "less lean" your idle mixtur is just fine. I could have misread it the second time but this sounds like what you were talking about.

[This message has been edited by Mr Rogers (edited January 09, 2000).]