sr20det Running Rich

[Garber]

Did some searching but i couldnt find anything.

1991 s13, sr20det mostly stock

At my last drift even I noticed the car was breaking up at high rpms... so i installed a wideband to try to figure out what is going on.

At idle: afrs 14.7:1
while coasting in gear: afrs max lean on gauge
while cruising or light accel: 10-11ish:1
while in boost: blinking 10:1 (max rich) and starts breaking up around 5k


i assume a boost leak would cause it to be lean while cruising (while in vacuum) ... I dunno.

any of this sounds familiar to anyone?

[cotbu]

Did some searching but i couldnt find anything.

1991 s13, sr20det mostly stock

At my last drift even I noticed the car was breaking up at high rpms... so i installed a wideband to try to figure out what is going on.

At idle: afrs 14.7:1
while coasting in gear: afrs max lean on gauge
while cruising or light accel: 10-11ish:1
while in boost: blinking 10:1 (max rich) and starts breaking up around 5k


i assume a boost leak would cause it to be lean while cruising (while in vacuum) ... I dunno.

any of this sounds familiar to anyone?

Yes, during part throttle/cruise, the throttle is open and you have vacuum in the intercooler pipes. So you may have a boost/vacuum leak.

It could also be an over fueling issue, and the plugs could be fouled, but that could also be the symptom of a boost/vac leak.

[rc1honda]

Try tightening your Intercooler piping. Could be a bunch of little leaks adding up

[Garber]

But wouldn't a leak while in vacuum cause it to pull in unmetered air and make it lean? Not rich...

[cotbu]

short answer no!
the reason why would be simply, closed loop.(02sensor)
but, if the ecu was only using the mafs and idle rpm and timing is correct you would see a lean condition before the ecu could richen the mixture. again if you jumped in the car and drove, or revved the engine, you'll miss it. So you probably missed it and the ecu has probably already learned, learnt learneddded anyway.:trogdor:

[cotbu]

So instead of me telling you how to prove this, just check for boost leaks, with a tester, and soapy water. or you could clear self learn restart your car and watch the rpm, temp and wideband for this to happen again.
also during idle, and engine warmed up if you pinch the pcv line closed you can probably verify a vacuum leak exists

[Danger_Dorn]

So heres what I think since I had this same problem. Check you're throttle position sensor and make sure it is between .35 and .65 mine is set at .50. Check for vacuum leaks too. If you have a boost gauge make sure its reading at least -8 psi which is equivalent to -.5 bar or -16 InHg. Your oxygen is dead after 3k from what I understand. Go check your voltages at idle of your MAF (1.8-2v at 900rpm idle) Check your timing (15 btdc) and check that all your vac lines to include the port under your throttle body is sealed.

[Danger_Dorn]

Short answer is check your tps

[cotbu]

The closed loop portion of the stock fuel map goes to 5600rpm, you need more understanding. WOT is a different story. So yeah you can be out of closed loop at 800rpm, if condition are met.

His issue wouldn't be the closed value of the tps, but .45v is my standard for tps closed as well as 4.120 wot, but it can very, just keep it under 5.00v for wot.

Again mafs voltage at idle can very, you should always be above .700v (so there isn't an enrichment trigger) and 1.150v at idle is normal for an 850rpm, but who cares, I don't know what your idle is. But If you increase the idle rpm sure it will raise the mafs voltage, and that's why you can't use vacuum as an indication of anything linear(healthy engine, etc) because the engine is using more air, vac should be stronger.(most people would bog with a high rpm idle the minute they leave vacuum) I said most....

Just as my previous post, it's to help you understand what may be happening. I'm not there to run multiple test and I wouldn't have you test things that don't pertain to your issue or questions, Just like I didn't address this... while coasting in gear: afrs max lean on gauge Becuase that is normal, The trigger to richen back up is IIRC 1800rpm. Don't quote me! Anywhooo, almost all of the procedures are the same when diagnosing a problem. The FSM can help everyone, Things it don't tell you are, Turbo engines hate boost leaks, add a mafs in and now they loathe them. There's more, but it's a secret!;)

So not really knowing what happened at this drift event, but based on the info provided, I say it may be a boost leak, you may have been bouncing off the limiter and the ecu may have pulled timing becuase of knock, but that is me speculating, which I can do all day,along with the test or repair procedure watch... you went wot and pulled the throttle cable too tight and the tps shifted, check/adjust tps voltage. whoa got another one, your plugs are fouled, pull plugs and look, smell, then replace, just because!;)

[Garber]

Very strange. I pull the plugs and they look like this

http://i21.photobucket.com/albums/b290/revlimityermom/Mobile%20Uploads/ResizedImage_1383403100287_zps7fd8d3b7.jpg

Which look fine to me... but I replaced them and now it seems to be running great but the afrs are reading the same.... I was expecting black plugs though... these don't scream rich to me at all

Bkr6e btw

[cotbu]

When doing a plug reading, you're supposed to pull the plugs right after an issue. That means don't let the engine idle before you pull them. Now the exception is a problem at idle. The porcelain tips look lean which coud be unburnt fuel from a number of issues, this could show rich on wideband, but ide expect raw fuel coming out the exhaust. Leaking injector, timing etc.
Can you pull codes, a knock sensor code, or cts code might be present.

Boost leak test, set everything back to stock setting, and preform routine maintenance. If you think the new plugs fixed the issue, oh and try 7's.

Sent from my Highly Tune Galaxy S3.4!!!

[Garber]

When doing a plug reading, you're supposed to pull the plugs right after an issue. That means don't let the engine idle before you pull them. Now the exception is a problem at idle. The porcelain tips look lean which coud be unburnt fuel from a number of issues, this could show rich on wideband, but ide expect raw fuel coming out the exhaust. Leaking injector, timing etc.
Can you pull codes, a knock sensor code, or cts code might be present.

Boost leak test, set everything back to stock setting, and preform routine maintenance. If you think the new plugs fixed the issue, oh and try 7's.

Sent from my Highly Tune Galaxy S3.4!!!

how do I pull codes on an sr20?

wouldnt be a leaky injector or it would be rich while cruising and become less noticeable when at full throttle...

I checked the timing and it is at 15 deg



It does not blow any black smoke at full throttle which makes me think somehow unburnt fuel is getting through.


It has always gotten around 18mpg cruising around town and highway... 24mpg highway which seemed low to me...

[cotbu]

Depending on the ecu, there's a diagnostic screw on the side, look up how to pull codes from a Nissan ecu. Or you could use the consult port, and software.

[JKTUNING]

How old is your wideband sensor?

What was the plug gap when you pulled the last set of plugs out?