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Old 01-19-2010, 02:50 PM   #1
ftwmotorsports
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Default 1989 turbo need help!

I joined this site to try and find some answers to a puzzle that can not be figured out. As by the name i am a Tech from a shop in Wichita,KS and I have a customers car here in the shop with a issue I cannot figure out. The car starts and drives pretty good but the only issue is when you try to make boost of any sort and let off, it will just die, unless you feather the gas a little. It had the tendency to go rich under boost, then extremely lean after letting off to the point where it would die. There has been several vacuum leaks found and fixed thinking that would solve the problem, but nothing. The codes were pulled and it came up with a code 51, which from read dealt with a couple things mainly being the tps which there was some wires found to be messed up and also it wasnt adjusted correctly. Now after playing with it some more there was a couple more codes that came up but that was due to playing with the maf. Now just so I am clear the 51 code has went away since fixing the tps issue. If anyone has any clue as to what is going on and a way to fix it would be greatly appreciated.

Thanks in advance,
FTWMotorsports

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Old 01-19-2010, 07:53 PM   #2
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Aftermarket BOV? Any other mods? Did anyone try to clean the AFM with any sort of spray or detergent?
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Old 01-19-2010, 07:56 PM   #3
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I had a hole in one of my vacuum lines going from the turbo to the wastegate or something and it did what you're saying, but it also was boosting insanely way too high at the same token, but vacuum could play a part definitely want to fix all those lines check the intake and intercooler lines for openings. There was recently another guy throwing a code 51 and he needed to replace his TPS switch... oh nm you got that fixed.
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Old 01-20-2010, 03:26 PM   #4
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Quote:
Originally Posted by cre View Post
Aftermarket BOV? Any other mods? Did anyone try to clean the AFM with any sort of spray or detergent?
i know it has a after market front mount and bov which wasnt routed correctly but that has been fixed and as for any other mods not to sure other then the noticable upgraded injectors and aeromotive fuel pressure reg. no havent tried cleaning anything yet.
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Old 01-20-2010, 03:29 PM   #5
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Quote:
Originally Posted by 916MKIIIx2 View Post
I had a hole in one of my vacuum lines going from the turbo to the wastegate or something and it did what you're saying, but it also was boosting insanely way too high at the same token, but vacuum could play a part definitely want to fix all those lines check the intake and intercooler lines for openings. There was recently another guy throwing a code 51 and he needed to replace his TPS switch... oh nm you got that fixed.
From what we cant tell we have fixed all the vacuum leaks that was on there, which was like 6 or so including the spot where new bov was mounted. as for boosting this thing didnt want to boost for nothing till all the leaks were fixed, it never tried to over boost.
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Old 01-22-2010, 12:44 PM   #6
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anybody else have any ideas? The strange thing about this is that when it dies after you boost, you can hear what sounds like a blow off valve coming back through the air filter. Sounds like the compressor surging in a sort, but its not the blow off valve, cause it will do it with it hooked up or unhooked. Also its not the idle air control, we unhooked it while it was running and blocked it, and I feathered the throttle to keep it going, while checking to see if the little orange valve in there was letting boost air creep by. Wasnt it. This thing has me baffled, and the customer is ready to get it back. Thanks for any help!

Ryan
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Old 01-22-2010, 09:03 PM   #7
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Quote:
Originally Posted by ftwmotorsports View Post
no havent tried cleaning anything yet.
Good.. DON'T! The AFM on the 7M-GTE is an optical unit, cleaning solutions tend to fog the optics and they're not user serviceable!

Quote:
Originally Posted by ftwmotorsports View Post
anybody else have any ideas? The strange thing about this is that when it dies after you boost, you can hear what sounds like a blow off valve coming back through the air filter. Sounds like the compressor surging in a sort, but its not the blow off valve, cause it will do it with it hooked up or unhooked. Also its not the idle air control, we unhooked it while it was running and blocked it, and I feathered the throttle to keep it going, while checking to see if the little orange valve in there was letting boost air creep by. Wasnt it. This thing has me baffled, and the customer is ready to get it back. Thanks for any help!

Ryan
A couple things. First off, half the people out there who run BOVs which are vented to atmosphere have issues with the car stumbling, backfiring and some have stalling issues. This is because the ECU is still expecting the air you just dumped to reach the engine so it's still delivering fuel. This can be tuned out with an aftermarket fuel controller. Oddly, the severity of this varies heavily from one car to the next.

Yes, the whistling sounds a lot like a severe boost leak.. check the usual suspects, this is routine... couplers, BOV, check valves (PCV system and ISC), and manifold gaskets... a leak somewhere further down the line can sound like it's coming from closer to the inlet ad the sound resonates through the piping.

Have you inspected the wastegate and made sure it's not stuck open?
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Old 01-22-2010, 10:29 PM   #8
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the wastegate is fine, it spools and boosts normally, its just when you let off that the problem occurs. I opened the throttle blade a little with the adjustment screw as it was totally closed off at idle. It made it a whole lot better and when I test drove it a little while ago it was great, I set the screw out about .020". My mechanic took it out for a test drive to confirm and it died twice on him. So just to test I taped a .025" feeler gauge behind the throttle stop screw and tried it again. This time it didnt die. I will have to adjust the TPS to the blade though. I may try another .010" and adjust the TPS. Ill report back.
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Old 01-22-2010, 10:54 PM   #9
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It's supposed to be fully closed off throttle...

Here, read this:
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/

ciao
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Last edited by cre; 01-22-2010 at 11:00 PM.
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Old 01-28-2010, 03:44 PM   #10
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we figured it out. We took the IACV apart and its all corroded and rusted inside. It wont move a bit. Does anyone have a good used one they will sell? Thanks guys!
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