wideband hooked up... is this normal?

[Arrest_me_red]

I have a piggyback on my car but it currently isn't doing anything, because i'm trying to see how it behaves stock.

at the moment boosting 10 psi, and it breaks up around 4000 rpm, and now i can see that its running lean at that point, while doing a pull it is mid 13's then shoots up to 15 or 16:1 before breaking up.

now i know i can add fuel through the piggyback, but would that really be fixing the problem? Is there something else i should be looking for ??

Edit:

I also have 440 cc injectors (not installed yet) because i wanted to get the car running right before i fucked with anything, but could this be fuel cut? in that case this would be the solution.

Stock 1jz and twins
3inch intercooler
3inch exhaust

 

[seoul4korea]

What kind of piggy back are you running? Have you noticed a change if you unplug the wideband?

 

[Arrest_me_red]

well, i've always had the breakup, sorry i didn't really make that clear, but over the winter i installed the wideband and the 14point4 uafc. i didn't know untill today what my burn ratios were.

 

[seoul4korea]

well, i've always had the breakup, sorry i didn't really make that clear, but over the winter i installed the wideband and the 14point4 uafc. i didn't know untill today what my burn ratios were.

Spark plug related for the break up but i'm not sure what to tell you about the AF. Is you O2 sensor bad/on its way out?

 

[f00g00]

Your probably running lean like I was after installing my 3" exhaust. I had to turn down my MBC to get it to run under boost as it shot up to quick for the stock injectors to program the fuel. If you have a silencer for your exhaust try installing it which takes a few seconds and see if it will run under boost with a restriction. If so then you will have to run less boost untill you get the 440's in or get more fuel with your piggyback but I would suggest getting a tuner.

 

[Arrest_me_red]

I researched this topic a more today. Last year i thought this was an issue with coil packs, as that seemed to be a common problem. i epoxy'd the cracks and put heat shrink over them, and this didn't really help that much, also i gapped my plugs to about .024 i believe. I read some posts that talk about a fuel damper bypass causing this issue, and i've read some other threads saying that an increased fuel pressure fixed the problem.

my piggyback doesn't read throttle position or manifold vacuum when correcting the map signal, should a good piggyback read the engine load to correct the map signal? I could design a simple circuit to modify the map signal based on throttle position with an adjustable gain and add this to my piggyback.

I think im going to go ahead and add the 440 cc injectors and scale back the fuel on my piggy back, then add some on the 3000+ range.

 

[f00g00]

Try and turn the boost way down with an mbc and see if it still breaks up.

 

[Radial]

10 psi, running VERY lean and breaking up...... your engine breaking up at AFR 16 is VERY logical, as the mixture here is SO lean that the knock-sensors WILL detect knocking, and the ecu WILL send your timing to heaven to save your engine... an Air/Fuel controller will only make things worse in your situation. Now, I think you have 4 possible faults here...
1: Fuelfilter is clogged, or pump is defective (Very realistic on old cars)
2: MAP-sensor is defective /Bad contact (Very realistic on and old engine/wiring)
3: defective o2 sensor... even though its only supposed to support the ecu with the mixture in Closed loop (Engine at idle and up to about 1/3 throttle)
4: Defective TPS sensor...the ecu does not know when you open your throttle, and wont supply enough fuel because its not logical to have Pressure in the manifold at low throttle

at full throttle your AFR should be something around 11... at IDLE and Criuse it can be 14-15 without issues, as there is no load on the engine (Saving fuel)

 

[hvyman]

Ya something is off. I saw 10-11 just below fuel cut y pipe and full 3 in exhaust and ic and pipes.

Have you checked for codes?

 

[MNBmk3T]

^+1. I'm only running 10PSI on my stock twins and when under boost my AFRs are around a solid 11. At idle they are around 12-13 and cruising on highway I see around 15-16.

 

[seoul4korea]

^+1. I'm only running 10PSI on my stock twins and when under boost my AFRs are around a solid 11. At idle they are around 12-13 and cruising on highway I see around 15-16.

I have stock twins and at 16psi we where still trying to pull fuel out as much as we could.

14.2-13.9 cruising and 12.3 af under boost.

I was actually amazed that the 270cc injectors out put that much fuel, but I guess my walbro helps.

 

[hvyman]

370cc.

 

[seoul4korea]

370cc.

thanks! I missed that!

 

[ifyouaint1sturlast]

I'm surprised nobody has mentioned this.

MANY 1JZ owners have had a 3-4k breakup when removing the fuel pulsation dampener (FPD), and the fix would be to retrofit the stock FPD into your aftermarket fuel system.

 

[MNBmk3T]

I have stock twins and at 16psi we where still trying to pull fuel out as much as we could.

14.2-13.9 cruising and 12.3 af under boost.

I was actually amazed that the 270cc injectors out put that much fuel, but I guess my walbro helps.

Wow still 12.3 under boost eh? Are you full standalone? Cause apparently (from what I've heard) the magical number is 11.3(ish).

 

[seoul4korea]

Wow still 12.3 under boost eh? Are you full standalone? Cause apparently (from what I've heard) the magical number is 11.3(ish).

Nope, emanage blue. I haven't heard anything about magic number as far as AF goes so I just went with my tuner's knowledge. Do you have any information on that?

 

[Radial]

the magical number is 11.3(ish).

11,3 is not a magical number.... thats a Toyota factory AFR-number, for safety... you can go all up to about 12,5 but then you realy need to watch the temparatures of your exhaust gases, and watch out for knock on warm sunny days.

Never ever heard about ppl struggeling with breakup because of removing the pulsation damper, a hole bunch of buddys are running without the damper just fine... but many ppl struggles when they forget/unintentionaly rips of certian vacuum hoses for the FPR and so on

 

[te72]

Try and turn the boost way down with an mbc and see if it still breaks up.

You can't turn DOWN boost with a boost controller, it will never be lower than the waste gate will allow, at least not at full throttle/load.

For what it's worth, I've seen solid 12ish AFR's on stock 370cc injectors at 16psi on my setup, stock everything. It sounds like you have a few things to track down and set right. Best to get it as close to stock, then go modding. Good luck.

 

[ifyouaint1sturlast]

Never ever heard about ppl struggeling with breakup because of removing the pulsation damper, a hole bunch of buddys are running without the damper just fine... but many ppl struggles when they forget/unintentionaly rips of certian vacuum hoses for the FPR and so on

From my research, it was pretty random. Some people had the problem and some didn't.

 

[seoul4korea]

You can't turn DOWN boost with a boost controller, it will never be lower than the waste gate will allow, at least not at full throttle/load.

For what it's worth, I've seen solid 12ish AFR's on stock 370cc injectors at 16psi on my setup, stock everything. It sounds like you have a few things to track down and set right. Best to get it as close to stock, then go modding. Good luck.

Well I guess that makes me feel better because I don't have any issues at 12.3 at 16 psi. And he's right you can only add not take away.