lost, wot stutter @15 psi

[Breezio69]

Hey everybody, just got done tuning and everything went well during. I set the boost at 15 psi, cruise afr is between 14.5-14.9. When I initially tuned my wot I had a solid 11.1-11.3, ran great, decided to be safe and took a couple % off to get more in the 10.8-11.1 range.

After I made those adjustments under wot the car started stuttering at 3-4k and would drop to 12.5-12.7 afr.

I tried reverting back to the other values (had them written down) and now it does it with those settings too.

Already read through some stuff and found when you start going past stock boost you need to gap the plugs around .020, I have done that. Base fuel pressure is 43, wally 255, fic 650 injectors. I don't have a log and I'm at work so I can't get one till tomorrow...

Any thoughts on this?

Also, the last adjustments I made and did a pull the motor bucked and I thought the thing was going to drop out of the car... so I don't even wanna drive the damn thing


One last thing. My wideband is 4" upstream from the cat, my afrs are showing "normal" but my safc is only tuned at the most -8... with 650's... shouldn't it be in the -20's? Possibly more???

 

[Lambiablo]

It almost sounds like fuel cut you are describing, but it's hard to say. Are you still running a mass air sensor, and what are you tuning with?

 

[polarisamsoil1]

Highly recamend getting link
Test for boost leaks mine did same it was stretching a coupler under boost

 

[Breezio69]

I just replaced my couplers about two weeks ago, did a blt afterward and had great results at 20psi.

I don't think I'm cutting with the rewired 255 and 650's, also its an evo3gt turbo @15 psi... I should have plenty of room.

I'm tuning with safc and innovate mtx-l wideband. .. the weird thing is the safc is almost zeroed on my high points and only gets down to -8 on lo throttle to keep good afrs across the board... you'd think with 650's it would be some serious adjustments

**************

If I recall without looking (I'm at work) my safc is at the following hi throttle numbers

1k -1
2k -1
3k -3
4k -3
4.5k -4
5k -4
6k -2
7k +1

This is with my wideband reading 10.8-11.2 all the way through... well it did, now it cuts and read 12.5-12.7 at 4k +

Also, I can give it 98% throttle and hold boost at 14psi, the second I push it that last 2% it stutters and sounds like death.


Ps, I've hit fuel cut before, this is a whole different type of thing, the car WANTS to keep going, it just sounds terrible doing so... fuel cut when I've hit it felt like someone yanked the ebrake at 60. This is really different... maybe it will do it on the way home and I can post it while videoing my wideband? I don't know how many times it can do it before its catastrophic though, its done it 3 times.

 

[c2ypt1c]

I don't think I'm cutting with the rewired 255 and 650's, also its an evo3gt turbo @15 psi... I should have plenty of room.

Fuel cut is not caused by lack of fuel. The ecu has no way of telling that you've upgraded your pump or injectors. The only thing it cares about is how much air it sees entering the engine. That said, airflow is monitored through the maf signal and the SAFC effectively intercepts and alters this signal to "trick" the ecu into thinking there is less airflow. When the ecu sees too high of an airflow signal, fuel cut is then triggered.

As always, a boost leak test is probably the first thing you should do when diagnosing problems like this. Sounds like you have a leak, although you'd probably be running rich in that case. make sure your maf connector is plugged in all the way.

It could also be ignition related. How old are the plugs/wires?

 

[Breezio69]

So after work, while the motor was still cold I did some poking aroind at idle, found something that may or may not be this issue, but it is an issue. One of my pigtail connectors on my injectors was cracked, I took a screwdriver and listened to the injectors and that one sounded weak and I couldnt feel the "pulse" like I could on the other three. I took the pigtail off and slightly tweaked a prong (trust me this is 100% temporary, ordering pigtails tonight) on the injector and reinstalled, voila, felt the pulse.

Also, I decided to just try taking a few % on the safc, as I knew that wouldn't go drastically lean, but a tad leaner than what it was earlier before the car started this issue, ended up being between 11.2-11.5, pulled like a raped ape and broke the tires for a small chirp in 3rd which I've never done.

I still think I'm going to do these 3 things.
* new wires, mine are only 9 mo old but they were the cheapest ngk they had
* new pigtails
* new plugs, keep gapped @ .020, also 9 mo old

Maybe a new coil? Just to make sure everything is good.


New problem that's not a problem recently, its been over the last few months but I've gotten used to it and drive to accomodate it.

Bov flutter, this is what its described as I guess... the car is recirculated, it has tial bov, going from 0psi plus and just pressing the clutch in to neutral it spikes rich and wants to die... Any driving in vacuum it does nothing all is normal

There is a write up on how to cure this with a greddy bov, I do not have a greddy bov to fix. How would I go about fixing this with the tial? Btw, the fix on the greddy is taking out the small inner spring.... it also has a side effect of opening under low boost after the fix on that, catch 22 I guess...

I can perform another blt, that's not an issue. But like I was saying before I held 20psi like, 10 days ago after all new couplers and clamps. I'm thinking this is ignition or blow out related.

 

[c2ypt1c]

So after work, while the motor was still cold I did some poking aroind at idle, found something that may or may not be this issue, but it is an issue. One of my pigtail connectors on my injectors was cracked, I took a screwdriver and listened to the injectors and that one sounded weak and I couldnt feel the "pulse" like I could on the other three. I took the pigtail off and slightly tweaked a prong (trust me this is 100% temporary, ordering pigtails tonight) on the injector and reinstalled, voila, felt the pulse.

Also, I decided to just try taking a few % on the safc, as I knew that wouldn't go drastically lean, but a tad leaner than what it was earlier before the car started this issue, ended up being between 11.2-11.5, pulled like a raped ape and broke the tires for a small chirp in 3rd which I've never done.

Interesting. Well it sounds like the injector pigtail was the problem which would explain the lean condition but I'm surprised there were no p0200 codes being thrown...did the CEL come on at all? It's just weird how things started going lean once you enriched the SAFC settings...

 

[Breezio69]

Interesting. Well it sounds like the injector pigtail was the problem which would explain the lean condition but I'm surprised there were no p0200 codes being thrown...did the CEL come on at all? It's just weird how things started going lean once you enriched the SAFC settings...

No cel, its just odd that the stutter would only happen wot, you'd think a weak injector would also crap out under regular loads.

I was reading through threads and one mentioned that.... crap let me read it again.... it said, "rich misfires will cause a lean spike". So basically, a misfire would be faulty ignition causing the air to exit the cylinder unburned, basically just compressed air running through the motor.

That's what I took out of that statement, is that a correct way of interpreting that statement? Or is it false?

Edit: maybe my car just enjoys 11.5?

Also I was thinking, most setups I've seen safc #'s for, the people live in cali or elsewhere that's low... I live at 4300ft above sea level, would that explain the really low corrections on the safc?

 

[c2ypt1c]

you'd think a weak injector would also crap out under regular loads.

Well, in closed loop the ecu is getting feedback from the front o2 sensor so stoichiometric afr is maintained. The other injectors could compensate for the weak one.

I was reading through threads and one mentioned that.... crap let me read it again.... it said, "rich misfires will cause a lean spike". So basically, a misfire would be faulty ignition causing the air to exit the cylinder unburned, basically just compressed air running through the motor.

That's what I took out of that statement, is that a correct way of interpreting that statement? Or is it false?

Compressed air and raw fuel. I was initially thinking this exact logic myself. However, I thought back to how you can calibrate a wideband sensor by wrapping it in a rag soaked with brake cleaner and have it read rich...obviously, there is no burning/ignition occuring in this case, so I'm not too sure how valid that statement is. Hopefully a wiseman can chime in on it.

Edit: maybe my car just enjoys 11.5?

You could try richening it up again, now that you "fixed" the injector.

 

[habitatguy187]

Still something wrong if those are your safc settings for 650s. It'd be really helpful to know what your fuel trims are like.

 

[WES_393]

Compressed air and raw fuel. I was initially thinking this exact logic myself. However, I thought back to how you can calibrate a wideband sensor by wrapping it in a rag soaked with brake cleaner and have it read rich...obviously, there is no burning/ignition occuring in this case, so I'm not too sure how valid that statement is.

Yes, misfires can cause any O2 sensor to report a leaner mix.

Combustion (in our case) is the reaction between Oxygen and fuel. Of course the O2 molecule is used up in the reaction, so the amount of O2 left over directly relates to the amount fuel burned. The wideband displays this as leftover Air per unit of Fuel, aka the Air/Fuel Ratio.

When a misfire occurs, the Air that should have been used up enters the exhaust and the wideband reads a higher concentration of Air. The gauge will then display an AFR that is leaner than accurate.

 

[Breezio69]

Well, it misfired a tiny bit on my way to work today @ 4.5k, not nearly as bad as yesterday. So I think I'm on the right track with the ignition. I'm going to go to napa after work and see if they carry the injector plugs... ill also go grab a set of plugs I had them special order from the dist. Center yesterday and hopefully have enough dough to get some wires, I have a vacation coming up I've been saving for so I can't get too crazy at the moment.

I also agree that the safc settings being low is an issue, I may swap out the front o2 and wire in the narrowband signal. It sucks though because I got the bung welded in pre cat to specifically avoid that but I don't know if its reading right in that location?

The only bad thing is I don't have a day off till my vacation next weekend and won't really have time to tinker, ill just have to cruise around... no big deal, but I'd just like to get it resolved, if ya know what I mean

*****

I may also throw my evo 560's in temporaritly to pull the 650's and send them off to get cleaned and flow tested. I don't know how old they are and haven't had them out longer than a couple minutes since I've had the car. I only took them out to verify they were j25-650 injectors.

 

[hotrodssnova]

Afr's in the 10's are way to rich. You have proven that by running in the mid 11's. Stay in that zone, gap your plugs at 18 and fix that pigtail.

Some might say you will shorten the life of the o2 sensor running it in the stock location, but my sensor has been working fine for 2 years now in the stock location. I tried running it down by the cat once fir kicks, and it seemed lazy and didn't read the same as in the stock location(no leaks either).

 

[Breezio69]

I've read and read and read about afrs and forced induction vehicles. At what point should i really start to worry about being too lean? Most articles I've read said tunes can vary between 11.0-12.5 @ wot... I was just going by what most have given for advice on here to avoid knock, 11.1, and the tune ended up sweeping between 10.8-11.2.

Ill get the parts and play around with it, I found out my logging capabilities are only for afr with the mtxl and cable it came with, so I need to figure something else out to figure out timing and everything else really.

 

[c2ypt1c]

I've read and read and read about afrs and forced induction vehicles. At what point should i really start to worry about being too lean? Most articles I've read said tunes can vary between 11.0-12.5 @ wot... I was just going by what most have given for advice on here to avoid knock, 11.1, and the tune ended up sweeping between 10.8-11.2.

Ill get the parts and play around with it, I found out my logging capabilities are only for afr with the mtxl and cable it came with, so I need to figure something else out to figure out timing and everything else really.

All things being equal (engine speed, load, temp, etc...), torque output is maximized between a range of about 0.80 and 0.90 lambda (11.8 and 13.2, respectively). Both ends of the spectrum are referred to as Rich Best Torque (RBT) and Lean Best Torque (LBT). Stray outside of this range and torque begins to decrease at an exponential rate. This "sweet spot" allows the flame to more efficiently propogate from one set of molocules to the next, increasing the burn rate. A faster burn rate generates more pressure within the cylinder and essentially has the same effect as advancing the ignition timing.

Now, why do most people suggest an 11.0 afr? Frankly, because pump gas sucks and it seems to generate the most torque while preventing detonation. So, to answer your question...don't knock.

 

[Breezio69]

That makes sense, I am going to just putt around till my vacation next weekend, after that ill be able to register my jeep and slowly go through the eclipse.

I have another symptom as of late. I changed plugs, gapped .020 (my gapper only goes that small) but I made sure it was super tight and barely fit on. It did this before last summer or when it was really hot outside and at operating temp... I get a slight miss when cruising and even at idle... now with my wideband installed I see when it does the tiny miss it jumps to like 15.2 for a split second.... it does this multiple times per minute. I have a video of my exhaust note for 20 sec that I will post to youtube later, you can hear the blip in the idle and see the little shake that it gives (can feel it in the seat)

I'm now beginning to believe this is fully ignition related and am going to try and find time to test all that out, and still keep the gf happy of course haha.

ALSO, since I leaned it out the major misfire at wot has turned into the same thing I'm experiencing at idle... so I have to be somewhat happy about that. I only get a small little blip at a couple rpm points after the spark plug change and leaning the safc a few % into the 11.3-11.5 range.

Thanks to everybody who has put a word in and tried to help me


*****

Well, just got home from fast 6, decent movie. Anyway here's the vid.

https://www.youtube.com/watch?v=OCrMn__07nE&feature=youtube_gdata_player

 

[WES_393]

I have another symptom as of late. I changed plugs, gapped .020 (my gapper only goes that small) but I made sure it was super tight and barely fit on.

What spark plugs are you running? Either way, a gap of .020" seem pretty small for your setup. I didn't have to pull the gap in that much (.019) until I was running E85 and pushing my Small 16g to over 25psi.

When I installed my Holset I swapped out the old BPR7ES plugs for the non-projected BR7ES which I gapped to .019" like the previous set. The result was misfiring/backfiring at idle and cruise, but no problems during WOT. I pulled the plugs, reset the gap to .024", and she's ran smooth ever since.

Long story short: Your obviously on the right track, but my next step would be increasing the spark plug gap.

 

[Breezio69]

Good stuff ^^^ thanks wes.

They are Autolite 63 plugs, bought yesterday.

I special ordered bpr6es plugs in and they never came in so I went with these.

***** I'm at a complete loss for where to go from here. Something else is going on.

I read another tech article on the safc and decided to start all over, my wideband didn't break past 14.0 on my idle setting till I hit +28% then. I went by the RRE article, they said richen it up till the idle the idle smooths out, then drop it back down till it stutters, add 10% fuel from there.

Why the hell would it take +28 to even richen up .7 points?

I think my injectors are messed up, if you saw in the hangout I posted I actually pulled the injectors and found out they were 650's already when I went to install my evos.... the base pressure was down 10psi to compensate to run stock boost, after I turned it back up to regular base pressure, issues galore... I think I'm going to install the evos and start over... or take it to a shop up the street from my house, this is a big let down...


Edit: wes, regapped to .024 and the stutter got worse again. I zeroed out my hi tables and plan on just putting around on my lo settings till I can check the coil and wires with my multimeter. I don't even want to drive the thing but I have to.

I'm also going to pull the ecu and check if its eprom (should be), every time I drive my car now evoscan sounds better and better... plus, if I'm lucky it will already be socketed, there is a very suspect cut out in my driver side kick panel about the size of a computer serial plug.... my thinking is since the car already had the 650's in it, at some point a tuning cable came through that hole? Who knows? Or maybe the things already chipped and tuned and I'm just screwing it up with the safc? I dunno.... I'm so confused

****************

Well small update at 2:45am. Just got done throwing in my evo injectors. Optimistic, I felt a strong injector pulse on all 4 injectors after the install, with the 650's one felt weak which I stated earlier in the thread, maybe it was stuck? Fired up and idled nicely... but I couldn't really free rev and tune so I set my safc at -10 across the board and will play with it on my way to work.

I also found a leak I never noticed till I pulled the fuel rail off, the pcv to I/m line had a tiny hole in it, like literally a pin went through it, would have never noticed it had a drip of oil not been seeping out of it, it was also probably a small enough hole to not affect a blt in a very big way. Either way, I'm going to throw the cap on the tb and check it out again, hopefully tomorrow? Or, I mean, later today.

Btw, that was a bi*** to do with the strut tower bar still on. What should have taken 20 minutes took about an hour and a half, haha.

 

[Breezio69]

************

Well, small update. The new injectors I think did the trick. The stutter in low throttle between 3-4k is gone. The car runs smoother. I've been focusing a lot on the lo throttle settings and think I have them dialed. Another thing is, these #'s add up much better to actual injector size, starting out at -13 @ 1k and end up at -21 @ 4k across.

My fuels trims have also zeroed out, my ltft after a 25 minute cruise only showed a min of -.8 and a max of -3.1.... which means its still just a tad rich correct? Runs like a dream though at low to mid throttle...

Hopefully I can get the wot stuff figured out, kind of nervous about it.