Fixed code 51 now im driving a prius

[Enano]

Hey supra enthusiasts, I have a small problem on my hands and was hoping some of you could chime in.

I started off with having a TPS issue ever since I bought the car. (It would not idle and I had to drive it home without getting off the gas)

After I got it home I adjusted the TPS a bit and the car ended up idling at 900-1100 rpm with a code 51 (TPS) After I got it to idle I started modding

Evo8/9 560cc Injectors cleaned/flow tested
57 trim ct26
Walbro 255
Lex afm
Authentic HKS SSQV
Turbosmart Boost controller
Cone filter
Wideband/boost gauge
Brand new o2 sensor
All new vacuum lines

So initially before I had the boost controller, I was at 8-9 lbs in 1st and 2nd gear and would pull up to 12 and hit fuel cut in 3rd and 4th gears. Car was pulling beautifully running full rich 10.0 at WOT and cruise 15-16 as well as idle full lean. (This was before I had the injectors/lex as well as after. Same psi. Still had tps code 51.)

With the code 51 and lex/injectors and boost controller on 16 psi, car would run full lean -.- on wideband at idle and if I went in on the throttle it would go 14.8 for about 2 seconds then start going up till it cruised around 15.0-16.4. 10.0 at WOT but I would be hitting some sort of weird fuel cut or misfire, car would hit a wall just like fuel cut but much less and it pulled like a goddamn beast.

Just yesterday I completely removed my throttle body, adjusted the tps to tsrm spec and cleaned it up inside and out. I also adjusted the throttle stop screw and dashpot because maybe an open throttle was what was causing the code so don't know what fixed it. Made my own homemade TB gasket and car is idling at 650 rpm very nice and quiet no misfires just like my last supra and now and my code 51 is gone.

So heres where the problem is... the car is slow as fuck. And I'm not doing 10.0 at WOT anymore, its doing 12's. It also dies alot I don't have any boost leaks that I know of, vacuum on my gauge is the same before and after I fixed the TPS and I didn't remove anything else that would give a boost leak. Unless my gasket is utterly fucked up, which I dont think so, even then I'm idling at 650 so I don't think theres a leak.

Just a question, does the ecu have different timing when having a code 51 as to when it doesn't have one? I messed with my cps and I haven't timed it yet but it seems to be idling smooth.

Also just throwing it out there, I pinched the hose that goes from accordion to IACV and nothing happened.

EDIT: I'm also backfiring alot now when switching gears, it seems to be dumping alot more fuel when switching? Might also be why car is slow when switching gears

Sorry for the long ass read. :] Any input help is appreciated

 

[suprarx7nut]

It sounds like you have a lot going on. All those efi mods make troubleshooting more difficult, especially when you had some issues even before the mods.

51 can indicate the tps is still not right and the ecu may not think you're idling.

The home made gasket, butt dyno results, and lack of timing don't help anything. Spend $10 on a real gasket, get a timing light, and see if you can clear the 51 code. Fyi, You can also get a 51 code by simply resting your foot on the gas pedal whole reading codes. The car may pull harder while running poorly. OEM fuel maps are made to be safe, not fun. So judging health by how hard the engine pulls isn't really correct.

 

[jetjock]

Set the timing after first fixing 51 because timing can't be set when IDL isn't working.

That said 51 can be caused by other than the TPS. Other than idle control and an emissions function (which may be related to your after-fire/muffler explosions) a TPS related 51 doesn't have much effect on EFI operation. It should still be resolved though.

With the ISCV hose pinched the engine should falter. It for sure should if the PCV system is then blocked since that's the only remaining source of idle bypass air. Sounds like your throttle plate is not fully closed. There may also be pirate air. That would cause unstable idle without an increase in idle speed.

 

[Enano]

I have already fixed code 51, thats when the car decided to become slow. I have no codes at all. But I will get a new gasket, and time it properly and update with the results, thanks guys.

 

[ForcedTorque]

Backfiring is Timing! Don't worry so much about the home made gasket. Get it timed first

 

[Enano]

So I timed the car today, it was previously at 15 BTDC... fail. So I timed it to 10 with the 2 connections in diag box jumped and when I took it off it went up to 12. So its pretty much at TSRM spec right now. After I timed it, it completely fixed my idle and AFR's now I"m idling at 650 rpm beautifully and at 14.7-15.0.

Now on to the next problem, under boost I am now going 11's and slowly creeps into 10's but I guess thats okay. I'm hitting some weird misfire or fuel cut or whatever it is but when it happens the motor appears to stop and I hear a loud ass backfire from my exhaust and then it keeps pulling. Could it be spark plugs? They are fairly new replaced about 1 month ago with NGK 5690's (I believe 1 step colder). Wires are also brand new NGKs.

I will be buying an Aeromotive FPR kit form DM soon hoping that will fix my issues but I do not think so.

Anyone have any input as to why its hitting that weird cut under boost? Could it possibly be a bad tps?

 

[hvyman]

check for codes. If you have 34 its fuel cut and most likely boost leak.
Could also be spark blow out which closing the plug gap could help but thats hard to do with iridium's.

 

[Enano]

So now i hav3 a new symptom. Car stays at whatever rpm i rev it to. And also upon releasing the accelerator while in a gear the rpms dont drop it acts as if its still accelerating or some sort of cruise control and its still being fed fuel.

My question is: can the tps stick if its bad?

Also: i have no codes. I will reset the ecu since i have not done so since i timed it. And im still backfiring when switching gears but thats because of the hks bov.

 

[hvyman]

Yes the tps can stick sometimes. replace tps. set according to tsrm and then clear codes.

 

[Enano]

So the tps stopped sticking and now after going to work last night and doing a few pulls, ive got a new set of problems... fucking supra.

Now my car only runs at 14.6 and goes down to 12.5 during cruise, sometimes it goes full lean at idle and taking off from 1st gear and it wont fix the afrs unless i step on the pedal hard. Also im still getting that massive backfire/cutout at high rpms. While this happened i wiggled the cps wires once and the car just died. But i cant recreate it.

 

[IndigoMKII]

Let me give you a piece of advise. Stop beating the fuck out of the car while its showing you it is having problems. Do you try to run a marathon with a chest infection? Stop asking the same of your car.

Now, don't just keep throwing money at the car while its acting up because you'll soon replaced everything on the car at a great expense and STILL have the problem.

Diagnose the problem first. You're having AFR problems, this can be a few things.

What type of fuel system do you have? Is it stock or modified?
Have you checked for a boost leak? All of these wonky AFRs and backfires can be caused by a simple boost leak.

 

[Enano]

I have:

560cc evo injs
Walbro 255
Lex afm

Afpr is coming soon.

No i have not checked for boost leaks but i doubt i have any. I think that cutout at high rpm is indeed fuel cut. Im at 16 lbs on a 57 trim. Fuel cut on a regular ct26 should be around 18 lbs no?

 

[supraguy@aol]

Fuel cut on a regular CT is usually around 10-12, but once you swap out to Lex and 560's, that all changes.
I wouldn't be trying to ask for more than 15psi out of any CT, regardless.
Check for boost leaks already. It takes all of ten minutes.

 

[IndigoMKII]

I have:

560cc evo injs
Walbro 255
Lex afm

Afpr is coming soon.

No i have not checked for boost leaks but i doubt i have any. I think that cutout at high rpm is indeed fuel cut. Im at 16 lbs on a 57 trim. Fuel cut on a regular ct26 should be around 18 lbs no?

I had my EBC boost spike randomly one night. PSI went to 21 PSI and my car never hit fuel cut. Mods in sig.

Fuel cut will cause a code 34(Abnormal turbo pressure) and the CEL will flash. If you're getting a higher RPM cut and no CEL flash, I'd bet on a boost leak.

 

[Enano]

Thanks for your input on mostly all my threads indigo.

My cel does indeed flash when the cutout happens although no codes are stored in memory afterwards. People watching my car tell me i shoot huge fireballs when the cutout happens and it sounds like someone is shooting a gun.

That would be ignition cut right? And the dumped fuel just exits and causes the backfire. I checked the resistance on my coilpacks they are all at .6 ohms 1 more than tsrm spec.

My coilpack wiring is shotty but i dont believe it to be the problem or maybe it is?

 

[IndigoMKII]

If its fuel cut, you will have a code 34 stored. The fireballs could also be from an overly rich condition aka doing pulls with a boost leak or way too much fuel pressure.

You said you have a walbro 255, did you bypass the jtube? Have you done a fuel pump rewire with a relay for more constant voltage? The old wiring causes a big voltage drop to a bigger pump.

If you havent bypassed the jtube, you're seeing excessive fuel pressure inside the rail. The stock fpr can barely handle the added flow of the 255, the jtube cant handle it at all. The original design of the jtube was to act as a restriction in the fuel system if the stock fpr ever died.

 

[Enano]

Yes, sorry the jtube has been bypassed. I am starting to think all of my problems are coming from my tps. I was idling at ~15 afrs. Unplugged TPS and went full lean. Car bogs upon pressing the accelerator a bit and then revs up but stays running full lean. Plugged the TPS back in and it continued to stay running full lean.

 

[IndigoMKII]

It isn't your TPS. The car will drive still with a TPS unplugged, it'll just be a little jumpy.

 

[Enano]

Well honestly, I'm waiting on new CPS plugs from driftmotion as mines are a little hacked up, and if that doesn't fix the problem its staying like so for a while because I am out of ideas. It just randomly starts idling funny, running lean out of nowhere. Like its literally running perfect in 2nd gear then I shift to 3rd and it runs lean as fuck until i step on the throttle hard. Just ordered a new compressor, TXV, and drier. Going to go at a r134a conversion by myself and see how it goes

 

[Another MkIII]

Did you check for boost leaks yet? Also, what are you tuning and monitoring your AFRs with? Are you tuning to VF?

-AM3