Need help with stalling and rich on decel

[Agallington]

Ok, so I will try and explain best I can, feel free to ask questions if I miss something.
I have looked around at a lot of similar posts, but haven't really found an answer yet. I don't post much, just usually learn from everyone else's experiences on here.

The car runs great, fast, sounds good, with the exception of stalling after slowing down, and going rich and smoking at slow down. I am about at my wits end as I can't figure this one out....

I have been building this car for quite a while, like a few years off and on, had it out of the garage a few times before, but have taken it as far as I want at this point.
Also, the car was originally an NA auto, now 7mgte Manual
I have upgraded/replaced almost everything on this car.the following are my mods:
1. 550's, Lex AFM, walbro, afpr, j tube eliminate. 35 psi w/o vaccum
2. Egr eliminate
3. Built motor with wiseco pistons, aftermarket rods (I don't remember the brand), other arp...., etc...
4. Ported head
5. Six puck clutch
6. Fidanza flywheel
7. BBR kit
8. LIPP BOSS Sr. TO4E 61
9. 3.5" turbo back exhaust, no cat
10. Cooleeze ceramic intercooler piping
11. Cooleeze ceramic intake (between turbo and AFM)
12. Spearco intercooler
13. Greddy rs bov, recirculated
14. Hks fcd
15. Wideband
16. Aem truboost
17. Safc2( not much adjusted yet at all, but set up correctly)
18. Koyo aluminum radiator
19. flex-a-lite dual fans
20. 12 volt starter mod
21. Brand new motor wiring harness
22. Ngk coppers
23. New AFM sensor, tps,
24. I have the pcv system connected same setup as stock
25. MLS head gasket with arp studs
I'm sure I am missing some things here, but I think this should do. My thought has been that it is the iscv as it isn't making the clicking sound when the car is shut off. I ordered another used one and have the same issue. (The new ones are insanely expensive, and I don't know why, it seems like a pretty simple part). I have a spare computer, and that didn't fix it. Have a steady vacuum at idle, and holding a steady boost, so I don't think it's a leak. Turbo is new, Precision injectors are new. I did the test on the iscv per the tsrm and it checks out fine. Tps checks out fine. I have tried setting everything on the safc2 to zero and still same problem. I have no check Engine codes. Timing is correct.

Does anyone have an idea how to check the iscv further or have a known working one they would like to sell, like you've seen it work on another car that ran well or have any other ideas of what this could be?

Anyways, thanks for reading this long winded post, but I am at a loss.

 

[Nick M]

The car runs great, fast, sounds good, with the exception of stalling after slowing down, and going rich and smoking at slow down.

Fuel injection is halted by TCCS when you are coasting. It seems you are not.

 

[jetjock]

^ This.

Check for fuel cut RPM:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=125

If that pans out check the TPS and SPD input from the speedometer.

ISCV can be tested per the service manual.

 

[Agallington]

Tccs? Are you referring to the ecu? I have tried that and swapped with another already. I'd the I as iscv isn't clicking at shutoff does that definitely mean it is bad out could there be something else wrong causing it to not click. I tried another used one, but I guess it could be bad also, unlikely though.

 

[Agallington]

I will check this tomorrow. What does this mean if the results aren't as their supposed to be?

 

[Agallington]

Also, can you help explain how this would be relevant to my problem? I have checked the iscv per the tsrm and resistance is as it is supposed to be, just no clicking when the vehicle is shut off.

 

[Agallington]

I have checked my tps. What to you mean by checking speed input? By the way My speedometer ha been kind of off for a while. I had taken the dash apart to try swapping with turbo Gage's nd couldn't ever get them to work right, so I put my na ones bck in. The speedometer seems slightly off and drops down below zero when stopped.

 

[Nick M]

http://www.autoshop101.com/forms/h25.pdf

Start on page 10 if you "know it already", or page 16 if you really know it.

 

[Agallington]

That is some great info, but maybe a little over my head. If I'm understanding correctly, fuel cut off on decel is based on tps, rpms, voltage, and coolant temp.

I will check my tps again and try adjusting some.

Coolant temp sensors are new and no codes.

As I said before, I may be having issues with my gauges, battery which isn't displaying a voltage at all (I have an na dash). My rpm may be slightly off also. If my gauges aren't working correctly, is my ecu still getting the correct info?

 

[3p141592654]

The only gauge input the ECU cares about is the speedo. It has its own sensors for everything else. That said, a bad speed input usually sets a code 42.

Do you see code 51 when you step on the gas in diagnostic mode?

 

[Agallington]

I will check. I don't have any codes currently, but will check in diagnostic mode.

 

[Nick M]

I will check. I don't have any codes currently, but will check in diagnostic mode.

I am not picking on you but....how do you know you do not have codes currently if you have not been in diagnostic mode? If it is over your head, then you should pay somebody competent to deal with it. I mean that in all sincerity. The automotive business is full of people that don't know what they are doing. So choose the shop carefully. That includes dealerships that are far east of Torrance.

If you are smoking and stalling during decel, then TCCS (Toyota computer controlled system) is not seeing your deceleration.

 

[Agallington]

I know how to check codes, and yes, checked on a regular basis. NO codes.

I am going to try and reinstall my egr and see if that helps.

Also, from What I have read on here, could be turbo seals. I hope not, because I just spent a lot of money on this BOSS turbo, but I will check.

I have also heard that under high vacuum, the pcv system can sometimes cause these symptoms. Not sure what can be done about that though.

I will check all of the above, I suppose I could try the iscv replacement (being that it's not clicking), just want to make sure, as they are spendy.

 

[3p141592654]

Simple test of the ISCV. Start the car cold. It should have a fast idle 900-1200 rpm. Drive around to warm it up to operating temp (keep the car moving), then come to stop. After about 30 seconds you should see the idle drop down to 650. If you can see it do that the ISCV is working fine.

The most common cause of going rich/stalling after acceleration is a boost leak or BOV that is leaking or non-recirculated. I'd check that out. I know your list says recirculated BOV.