leroy12

Hey, I've just finished my first turbo honda build and i have some concerns with the way it's running. The motor is a fresh build with less than 500miles on it. It was tuned by a very well known shop in my area and makes solid power in my opinion. (357hp/225tq at 9psi )

The question I have has to do with the A/F ratio reading. When i first start the car it idles at around 1200ish rpms until the car warms up and settles at 1000rpms. While warming up at idle the A/F Ratio reads about 14.5-15. When under accelerations it drops down below 12 which i believe is normal. However, the concern i have is that after driving the car in for a bit the A/F gauge starts to read 16.5-17 when I am cruising at low rpms(2000rpms). The cars A/F Ratio does drop back down to 13-14 A/F if i start to give it more gas.
The A/F Guage also reads --- when i come to a stop and just idle unless i pat the gas.

Is this typical or should I be concerned?


The cars setup is listed below:

B18C1

Crower Turbo cams
Crower valve springs and retainers
Skunk2 intake manifold
AEM tru timing cam gears
AEM fuel rail
Aeromotive FPR
1000cc ID injectors

BLOCK
JE 9-1 Pistons
Eagle rods
ACL racing bearings
Darton sleeves
All ARP hardware

Turbo

Precision 6262
Full race turbo manifold
Tial waste gate/ dumptube
Tial 50mm BOV
2.5 inter cooler piping

TheShodan

iTrader: (14)

It's getting close to stociometric because the car is not under engine load.

That's the one thing about running these gauges; if you don't already know when/how it's supposed to behave, it causes unnecessary panic.

That's pretty rich at 12.0:1 from 20-50 percent throttle

Nottheonion

12:1 under part throttle for me is too rich.

Id have it close to 14:1 for part throttle

As for it leaning out after it warms up thats your fuel enrichment settings.

Do a long data log. Then shorten it up to show just the parts youre concerned with and send it to your tuner

wantboost

iTrader: (2)

The idle AFR sounds right at initial startup. It should maintain that same AFR range at ilde almost all the time.

Part throttle cruise shouldn't be nearly that rich. You're just wasting fuel and I'm amazed it doesn't run like **** at part throttle.

What's the WOT AFR? That will really tell the story. Personally anything over 12.5:1 is just too rich and from what I've found is mostly done for safety and cooling effects.

Like stated above do a datalog of AFR vs RPM/MAP/TPS/Load etc. And post a screenshot of the graph at areas you think are an issue.

Although technically I think he would get better replies in the engine management forum right?

the171

The tune sounds proper except for the cruising part. 16-17 is too high. You want the ecu set on closed loop with a target of 14.7:1. So, the gauge will cycle from 15-14 back and forth give or take until you give it enough gas to turn closed loop off, when the fuel moves into the richer open loop range which you said it does.

Basically all you need to do is go into the software and enable closed loop. In my experience, the tune can be totally off and closed loop will still work fine, allowing the car to cruise efficiently. At that point all you need to worry about is medium to heavy throttle (open loop).

Flr Power

That is true but modern tune use close loop even at wot.

welfarepc

I would really closely inspect for exhaust leaks pre o2 sensor. Cracks, bad gaskets, loose connections, anything. These show as lean at idle more so that when there's greater gas volume and speeds. The low pressure zone behind each exhaust pulse will pull in air through the cracks.

96ekb20

the idle after warm up seems to be the biggest problem minus the cruising be so lean. 15.2-15.6 is good unless your trying to squeeze a lot of mpg out of it but seeing ur build i doubt that. but like welfarepc said check for exhaust leaks that will effect the gauge reading at idle.

LightningTeg

Depends on the EMS. But I dont think that's true unless its equipped with a wide band from the factory. Typically the ECU goes to open loop and just uses IAT, ECT, MAP and TPS to make changes.

If the tune is off that much in open loop, its going to be hell of a time for the closed loop control to bring it to nominal values.

850Fabrication

how is the exhaust setup?

leroy12

Exhaust is full 3" from the turbo all the way to a 3" virbrant muffler. no cat or resonators