Hey all,
I have a stock d16y8 with the 15g greddy on 12 psi tuned with an s300.
I recently noticed my cruising afr (around 40 mph in 4th) is around 17.2. This causes my engine to bog down unless i start giving it more gas. Then as i release the pedal, the afr swings to around 12 before going to the 15s.
Because of this, im thinking it may have to do with clogged injectors or a bad fpr, as it did sit in my dads garage from 7/13 to 4/14 and was only started every 2 weeks or so. I think this may also be causing my engine to get excessively hot as i get a CEL if i drive around for too long without the heater blasting (also proves its not a bad o2?).
I have 550cc inj off an evo (8?), walbro 255, and stock fpr.
I am thinking about getting an aem fpr with possibly a press gauge as a start. Anyone have this issue before or know a good way to diagnose the issue?

Thanks in advance,
David

 

What is the code on the CEL?

 

Unfortunately, i havent been able to pull the actual code as it comes on only after a half hour of driving or so and doesnt come back after a quick restart (since i have to turn the car off before i hook up to the ecu). I tried checking the cel log on hondata, but it doesnt look like it stores the code. Im 99% sure its from heating issues tho, as i cant keep my hand over the vent for more than a few secs with the heat on blast. Most other things i can think of (e.g. bad O2) should keep a solid cel, hence why it didnt really bother me until i noticed how lean it was under light throttle.

 

car is probably throwing a cel for overheating

 

RIP D16Y8

 

You just need to add fuel to those few fuel cells. Download Smanager and connect to S300. Datalog while you are driving to see exactly what cells are lean. Add a few + to the fuel values and you should be good.

 

Ok thanks for the idea. Im a little scared to touch anything since i dont really know how to use smanage. Anyone have a good intro on the basics? Ive looked at hondatas site but they dont give you an easy how-to.

 

I suspect light cruise at a low rpm is driving in or near the idle cells causing the lean spot. Download the Smanager software and read the help file or contact a tuner.

 

I definitely think its the fuel system now. Its bogging down hard even when starting to let go of the clutch in first and it almost stalls unless i give it gas hard. So i guess now its injectors or fpr?

 

Got some pics

 

Check the fuel filter. if you didn't put any stabilizer in the fuel it has likely varnished and clogged the filter. I dealt with the same problem when I bought a car last month that was only driven like 7k miles a year.

I let the tank get totally empty and when I filled it up I apparently blasted all the varnish off the tank walls and completely clogged the filter 40 miles later.

It caused a lean condition, stumble, misfire, running hot, etc.

A 13 dollar part made me scratch my head for 4 weeks lol.

I would also recommend draining the fuel system and putting a fresh tank in with a bottle of the concentrated chevron fuel cleaner. I've had the best results using the stuff and I put a whole bottle in with fresh gas after I changed my filter and it cleaned the whole system past the pump in about 15 minutes of idling.

You might have to get your injectors cleaned depending on how bad the varnish is. In my case a lot was fine enough to pass through the filter. I got lucky and didn't clog an injector though.

 

Its also colder out now. If you were tuned in the summer you may need to add to overall fuel trim.

 

Fuel filter replaced, no luck.

 

Talk to your tuner, tell him its running lean at part throttle. I am sure he can touch it up for you.


How about in boost? Is the AFR the same there as it always has been?

If you cruise at an engine load/rpm OTHER than where its lean, does the car still over heat? Is your fan turning on? Have you double checked coolant level?



Another thing to consider, it might be a crack in the exhaust or loose part somewhere allowing air in. How is the AFR at idle? Usually that is where an exhaust crack will show its face and cause the car to run funny.

 

That is very true. Check for exhaust leaks or cracks before the wideband.

For a quick fix just go to Smanager, open up the Parameters window, Fuel Trim tab and add 10% to the Overall Fuel Trim value. Then save and upload the new cal to the S300.

 

Dont think its the exhaust, as it runs fine in idle. Coolant is topped off and the fan turns on. Im not sure how i could cruise long enough at a different afr as as soon as i lock in the throttle, it leans out. In boost or under acceleration, it runs in the 11s and 12s as it always has. I may try adjusting the fuel trim as it cruises at 14-15 while warming up but leans out once warm. I would take it to the tuner and call it a day if i didnt live 2 hours away now

 

The afr also goes rich before going lean when letting off the throttle, so does anyone have any experience with this phenomenon? It used to max out at 20.0 immediately after letting off the gas, but now has that hiccup, which is why i thought it may be a clogged injector/line or a bad fpr.

 

That is usually throttle tip out, throwing a bit too much fuel. Or the load column for max vac is tuned rich. Makes cool noises.

Double check you dont have corrosion in any connectors for the ECU, distributor, injectors, ect, if it all checks out, call the tuner.

Or like Muckman said, 10% fuel should make it drive better. Might even need more.

Ideally when you add fuel to the map, you dont want to target specific cells in the map and just add 10%. It makes the map jagged and harsh, and the car will drive the same way. (Thus why Muckman said to add 10% to the whole map, it will stay smooth. BUT that will also add 10% fuel where you dont need it, at idle and WOT... so what can we do about that?)

I see you can datalog and view "estimated fuel changes". So perhaps if you are feeling up to it, go ahead and apply the estimated fuel changes, and then smooth the map. Save-As a new file (always keep your original tune file so you can go back to it, in case you screw up) and then give it a whirl!

I would apply the fuel changes here.

 

So now it looks like its running lean when idle. I was staring at it on the way home from work today and when i first stopped it when to 15.4. Then, it started fluctuating between that and 17.2. The SAME EXACT afr i get when cruising. Gahhhh. Did a quick visual for cracks or loose flanges and i didnt see anything, but then again, i can only see so much without getting under it.
Called the tuner just to ask, but i obviously got the "it could be anything" answer.

 

The following are my fuel tables and fuel trim settings. Im still trying to find the units for the numbers on top under the "Col." numbers. Hondata's user guide it so bad .

I would say im a pretty quick learner, so if somebody could maybe explain what these numbers mean and how to do the 10% adjustment, or even point me to a good video of one, i would be very grateful.

Do i just raise all those numbers in the red on the estimated fuel enrichment pic I previously posted by 10%?

 

I honestly think, since things are appearing to "change" in your tune, that you have an issue somewhere that needs addressing. Not the tune.

I wouldnt make any changes.

 

Did you ever figure it out. I’m having the exact same issue except I’m not overheating

 

The user Herro Panda hasn't visited the site in 7 years, so I doubt he's going to answer. If you've got a lean spot, you need to tune the car. It could be that you need to add fuel to the cells which are showing lean, or you may have a compensation pulling fuel in those cells at certain conditions. Have a tuner look at your tune, or if you are competent enough, dive into it yourself.