The unfixable mystery problem - Page 2

GettaRobo · 07-14-2009, 07:48 PM

I've definitely heard of them. I've also heard that they may not be so great to use as you can potentially bugger up your engine. I suppose that only happens if you're doing something super retarded though. I know that the mechanics have looked for a rev limiter in the ignition system and such and they haven't found anything. I guess the only way to know for certain would be to swap the other engine I have to see if it does the same thing. I'm about ready to throw in the towel and live with it for now, but we'll see what happens (I should know later today.)

carl johansson · 07-15-2009, 11:26 PM

First place I would look is the throttle position sensor - but to tell you the truth I don't even know if the supra has that. Alot of high performance shope sell a bogus "power enhancer" that is a throttle position switch that tells the computer that you are at full throttle - when you are only at 3/4. doesn't really add power - the petal still goes full - just no gain after3/4 throttle.

This problem sounds like the switch is working backward for some crazy reason! Like I said - it's a shot in the dark - but if someone burned a performance chip and it got screwed up - this could be the issue!
AFAIK - The Rev limiter on this engine is burned on the ECU chip! ( we hit it on occasion in the lemons racecar!)

Carl Johansson

GettaRobo · 07-15-2009, 11:28 PM

Well, to tell you the truth, the TPS has already been looked at. Unless the new TPS they brought in was screwed, it's working fine. Thanks for the suggestion though.

carl johansson · 07-16-2009, 02:30 AM

sorry,
didn't read all of the posts carefully enough. So if the TPS is OK - does this thing have a stock chip in it? Have you tried switching out the ECU with the one on the parts car?

GettaRobo · 07-16-2009, 03:00 AM

Yes, I knew I forgot to mention something! The parts car is a manual, but the ECU works fine with the auto and I think it shifts slightly better with the manual ECU. On a side note I'd like to point out that I started having these problems before I put the other ECU in, so I doubt it's the reason.

GettaRobo · 07-16-2009, 11:21 PM

So I talked to the mechanic today. Timing belt is fine, cams are properly aligned. Honestly, we are completely out of ideas. Since combustion requires three things: air, spark, and fuel, it's either not getting one of these things or perhaps it's something else. I know it's getting air, I'm reasonably sure it's getting spark (new wires, plugs, distributor has been checked, as has the coil wire,) and there is plenty of fuel pressure. Is there any way it is remotely possible that the tranny is dying on me? I mean the oil doesn't smell burnt or look brown and there are no metal shavings in it... The only tranny error code I'm getting is the speed sensor 2 error. So unless someone else has a revolutionary idea or something, I think I'm SOL.

carl johansson · 07-18-2009, 06:07 AM

Have you looked at the throttle cable? have someone sit in the car and floor it = while you watch the cable - maybe the cam lobe broke off or something stupid like that - so it's going back low throttle -

compare that to watching when you are at 3/4 throttle and it revs to redline.

I assume you took the fuel pressure after the fuel filter right?

It almost sounds like it's getting to much fuel at full throttle - did someone change the injector sizes? and isn't there an adjustable fuel pressure regulator? To much fuel at full throttle could be choking it off - while 3/4 is allowing enough air! It used to be a fairly common problem in carbed cars!

Just throwing out ideas - I don't know!

Carl Johansson

GettaRobo · 07-21-2009, 09:59 PM

Sorry for the long delay, was out of town and only had access to a dialup connection... Anyway, I don't think it's the throttle cable since it'll redline in neutral and park when you floor it. As for the fuel pressure, I wasn't the one checking it, so I don't know but I'll find out. I don't believe that anyone changed the injector sizes, but that could be a possibility. It was running rich at one point before I changed the AFM. The car is initially from the Los Angeles area, and now the car is definitely at a higher elevation here in Saskatoon, but you'd think that the other car that I have would run the same as this one if that were the case unless there's some elevation tuning differences that I don't know about. Apparently the mechanic had no clue about the speed sensor problem until I told him about it today... so basically he's going to see what all it controls and if it's causing the ECU to go in to 'limp mode.' It's a long shot, but I'll try some of the stuff mentioned here as well as the speed sensor issue and see what happens.

jcastro · 07-22-2009, 09:11 PM

try doing a smog check and ask to check ur vacume lines if it dosent pass the smog ull at lest have a better idea of wut it is and im pretty sure thell tell u whats wrong

86.5supra · 07-23-2009, 03:47 AM

i had the same problem after i had my 7mgte rebuilt. the shop couldnt figure it out so they took the motor out tore it apart and put it back in the car. It turned out to be a bad throttle body and mass air. hope this helps

07-15-2009, 11:26 PM	#12
carl johansson 3" Exhaust Join Date: Nov 2007 Location: Auberry, California Posts: 141	First place I would look is the throttle position sensor - but to tell you the truth I don't even know if the supra has that. Alot of high performance shope sell a bogus "power enhancer" that is a throttle position switch that tells the computer that you are at full throttle - when you are only at 3/4. doesn't really add power - the petal still goes full - just no gain after3/4 throttle. This problem sounds like the switch is working backward for some crazy reason! Like I said - it's a shot in the dark - but if someone burned a performance chip and it got screwed up - this could be the issue! AFAIK - The Rev limiter on this engine is burned on the ECU chip! ( we hit it on occasion in the lemons racecar!) Carl Johansson Last edited by carl johansson; 07-15-2009 at 11:29 PM.

07-23-2009, 03:47 AM	#20
86.5supra 3" Exhaust Join Date: Jun 2009 Location: ny Posts: 83	mystery problem i had the same problem after i had my 7mgte rebuilt. the shop couldnt figure it out so they took the motor out tore it apart and put it back in the car. It turned out to be a bad throttle body and mass air. hope this helps

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07-14-2009, 07:48 PM	#11
GettaRobo 3" Exhaust Join Date: Apr 2009 Location: Saskatoon, SK Posts: 65	I've definitely heard of them. I've also heard that they may not be so great to use as you can potentially bugger up your engine. I suppose that only happens if you're doing something super retarded though. I know that the mechanics have looked for a rev limiter in the ignition system and such and they haven't found anything. I guess the only way to know for certain would be to swap the other engine I have to see if it does the same thing. I'm about ready to throw in the towel and live with it for now, but we'll see what happens (I should know later today.)

07-15-2009, 11:28 PM	#13
GettaRobo 3" Exhaust Join Date: Apr 2009 Location: Saskatoon, SK Posts: 65	Well, to tell you the truth, the TPS has already been looked at. Unless the new TPS they brought in was screwed, it's working fine. Thanks for the suggestion though.

07-16-2009, 02:30 AM	#14
carl johansson 3" Exhaust Join Date: Nov 2007 Location: Auberry, California Posts: 141	sorry, didn't read all of the posts carefully enough. So if the TPS is OK - does this thing have a stock chip in it? Have you tried switching out the ECU with the one on the parts car?

07-16-2009, 03:00 AM	#15
GettaRobo 3" Exhaust Join Date: Apr 2009 Location: Saskatoon, SK Posts: 65	Yes, I knew I forgot to mention something! The parts car is a manual, but the ECU works fine with the auto and I think it shifts slightly better with the manual ECU. On a side note I'd like to point out that I started having these problems before I put the other ECU in, so I doubt it's the reason.

07-16-2009, 11:21 PM	#16
GettaRobo 3" Exhaust Join Date: Apr 2009 Location: Saskatoon, SK Posts: 65	So I talked to the mechanic today. Timing belt is fine, cams are properly aligned. Honestly, we are completely out of ideas. Since combustion requires three things: air, spark, and fuel, it's either not getting one of these things or perhaps it's something else. I know it's getting air, I'm reasonably sure it's getting spark (new wires, plugs, distributor has been checked, as has the coil wire,) and there is plenty of fuel pressure. Is there any way it is remotely possible that the tranny is dying on me? I mean the oil doesn't smell burnt or look brown and there are no metal shavings in it... The only tranny error code I'm getting is the speed sensor 2 error. So unless someone else has a revolutionary idea or something, I think I'm SOL.

07-18-2009, 06:07 AM	#17
carl johansson 3" Exhaust Join Date: Nov 2007 Location: Auberry, California Posts: 141	Have you looked at the throttle cable? have someone sit in the car and floor it = while you watch the cable - maybe the cam lobe broke off or something stupid like that - so it's going back low throttle - compare that to watching when you are at 3/4 throttle and it revs to redline. I assume you took the fuel pressure after the fuel filter right? It almost sounds like it's getting to much fuel at full throttle - did someone change the injector sizes? and isn't there an adjustable fuel pressure regulator? To much fuel at full throttle could be choking it off - while 3/4 is allowing enough air! It used to be a fairly common problem in carbed cars! Just throwing out ideas - I don't know! Carl Johansson

07-21-2009, 09:59 PM	#18
GettaRobo 3" Exhaust Join Date: Apr 2009 Location: Saskatoon, SK Posts: 65	Sorry for the long delay, was out of town and only had access to a dialup connection... Anyway, I don't think it's the throttle cable since it'll redline in neutral and park when you floor it. As for the fuel pressure, I wasn't the one checking it, so I don't know but I'll find out. I don't believe that anyone changed the injector sizes, but that could be a possibility. It was running rich at one point before I changed the AFM. The car is initially from the Los Angeles area, and now the car is definitely at a higher elevation here in Saskatoon, but you'd think that the other car that I have would run the same as this one if that were the case unless there's some elevation tuning differences that I don't know about. Apparently the mechanic had no clue about the speed sensor problem until I told him about it today... so basically he's going to see what all it controls and if it's causing the ECU to go in to 'limp mode.' It's a long shot, but I'll try some of the stuff mentioned here as well as the speed sensor issue and see what happens.

07-22-2009, 09:11 PM	#19
jcastro 3" Exhaust Join Date: Mar 2009 Location: El Centro Posts: 113	try doing a smog check and ask to check ur vacume lines if it dosent pass the smog ull at lest have a better idea of wut it is and im pretty sure thell tell u whats wrong