Car does not start after swapping ecu and swapping back

[yukioda]

I got a 1988 supra with a t61, cx intercooling, and 550/lex. I got a new motor and swapped it in with the same setup. The car starts fine and drove fine for a week but sometimes it would cut out at 3k rpm, I thought I was boosting too much but it barely hits 5psi before it cuts/ bogs out. Switch the maf and it does the same thing except it cuts out at 4k but then it would back to 3k rpm. I keep getting a code 14 and 52 so I switch the igniter and it still does the same thing, I switch the ecu to an 87 and its little smoother but it still cuts out. I finally did a Boost leak test and it seemed I was leaking from the intake gaskets. I put another intake gasket on with some gasket maker and put everything back together, I tighten it down and let it set in. I started the car and it idles fine but it STILL does the SAME THing. If i floor it the rpm stay at 3k bouncing up and down like a slow 2step or anti-lag but no flames.

| I try switching the ecu back to the 88 ecu just to see if it would change and the car just turns over and over. I switch back the ecu to the 87 and Now which ever ecu i put on it just turns over and over and doesnt start. I know I dont get spark becuz I dont see any Sparks from the coils when I take it out. I check the cps, and grounds and everything but all I did was swap the ecu. Do you think I might of fried the ecu? I dont get any check engine lights anymore and It seemthe ecu isnt getting power.I dont think I pulled the ecu plug pins out Its all still intact some what. I remembered when I swap the ecu I left my keys on on.Could that caused anything? I also switch the EFI main fuse and still nothing. When I swap the new motor I also got a high output alternator, could that over charged or send to much power to the components frying it? about a week ago I remember the car rpm was dying down and was bouncing around, it was almost like a clock ticking up and down fast,the car lost power and stalled, I started it again but it took a few tries .Im gussing mostly the igniter but once again all I did was swap the ecu and it does not want to start except turn over | Idk whats wrong anymore, I also remember the car did the similar thing about a year ago with the rpm thing but it wasnt as bad.

 

[yukioda]

I also forgot to mention I removed the egr

 

[plaaya69]

A high output alternator should not cause your problems. When i usually hear about the 3k rpm cut off from others, its usually the AFM and if it not that then it's usually followed by a bad TPS.

 

[hvyman]

52 is knock sensor. Which would cause the 3k and no full boost.

But kinda sounds like ou lost the ground for the shielded wires for the cow and knock sensors. Possibly go damaged when removing or installing the harness for the engine swap.


Also when replacing the I take gaskets if you cleaned both surfaces with a razor blade and scotch brite you shouldn't use any gasket maker or rtv

 

[yukioda]

Thats nice to know, I didnt think knock sensor would cause the 3k and no full boost guess ill fix/swap that , My afm and tps should be good because before I took my tps out and rev it and it does the 3k still, my afm is good from before idk how it would goe bad all of a sudden I mean I was care with it.I got other spare ones that helped it a little but it comes back to the 3k. How about the car not starting? it still turns over but dosent start, no spark, no check engine light pops up anymore.

 

[plaaya69]

If you are not getting spark and your igniter is good, how is your CPS? I just had the issue today and my CPS failed while driving. It dropped RPM's hard, sputtered then died and would not start. The thing is mine was a new remanufactured a1cardone unit too. I put my old one in since it was working and I took the remain CPS out and I found a shorted out wire inside the unit.

 

[yukioda]

I read this forum here : http://www.supraforums.com/forum/showthread.php?526597-no-power-to-ecu/page2

I did the same thing and I can hear my main fuse click when I put straight power from the battery to the main fuse but it still wont start, In the end he said his am2 fuse was blown,Mine was blown too! I replace my am2 fuse and right when I turned the ignition on it blew again. Where do you think the short is coming from? or whats the problem here man!

 

[f00g00]

Troubleshoot your IG2 circuit. Could be the EFI resistor or the igniter or a coil. You can start by disconnecting them both and seeing if a short still exists. If so then probably a shorted wire or noise filter pin 1 side.

 

[yukioda]

Alright so I disconnected both the plug for the coils and the igniter just to see if it works, I put a 40 fuse in the am2 even tho its suppose to be a 30, and all of everything worked for like 10 seconds. Then it blew but there was smoke coming from this plug thingy Heres a photo of it


What is that thing? I thought it was for the stiffness of suspension, but I dont have that anymore. It got real hot and smoked a little and then the fuse blew, well the fuse blew and I saw the smoke and touch it and it was hot

 

[yukioda]

Alright I did my researched and its the Turbo pressure sensor? But why is it blowing causing a problem???

 

[yukioda]

Ok.. So it controls nothing but the boost gauge...I got my aftermarket boost gauge right where the stock one use to be, Im thinking either my power wire or ground from the gauge is touching something behind the cluster and is causing a short? What do you think ima try to d/c it tomoro or somthing .

 

[f00g00]

That is your EFI resistor which is on the TCCS schematic and also goes to the same circuit.

 

[yukioda]

That is your EFI resitor which is on the TCCS schematic and also goes to the same circuit.

So Should I try replacing it? I d/c it it and it doesnt blow a fuse, but when I plug it in and when the IGN is on it blows that fuse, when i d/c it and try starting it , it wont start the car , do I need it plugged in to start? Im about to leave the supra game man, Usually I would know how to fix the 7m but now i dont know how or what cause this. Replacing this part might just might be the last thing, If it doesnt fix it, I might be done. I dont want to be done but dam, I Ran into a brick wall. You guys have been pretty helpful so Thank you for that. Very much appreciated, I will let you know how it goes after I replace it.

 

[f00g00]

Make sure that the wires aren't shorted together before you replace it and yes you need it to start.

 

[yukioda]

Alright so it STARTS! I left the ignition on on and it seems to be ok. I still have the 40 fuse in but ima see if a 30 would still blow or not, Im pretty sure it wont blow because I left it on for a while and running and everything is still good. Now I just gotta put a new throttle body gasket on and the turbo inlet back on and see how she drives. I took those off because I was going to redo the whole harness,Now I dont really have to or not yet anyways. Thanks again guys for the help,Right when I was about to give up I find the solution! Its odd how the efi resistor went bad , but hopefully when i put everything back together the car will run like a dream again.