constant boosting problem

supranutz · 11-24-2009, 05:39 PM

got my supra up and running after it sat for 10 years its a 87 supra turbo

it ran perfectly last night drove it around for an hour then took it on the highway had a good time hit 110 mph coulda gone way faster

now i get in it this morning it idles rough it misses/ runs rough thes=n sooths out at 2500 rpm and its constantly boosting

im not new to cars but new to turbos whats the deal /problem ????

MA70-3.0GT · 11-25-2009, 03:19 PM

Not sure about the constant boosting thing as the turbo shouldn't be getting enough exhaust gasses to make any boost at low revs, perhaps the sensor has gone haywire? Or if you mean it's overboosting & getting fuel cut then the wastegate could be stuck (or the actuator failed), probably stuck after sitting so long...

As for the rough running, have you got any fault codes when you do the diagnostic check? (making sure the light works beforehand)

cre · 11-25-2009, 07:58 PM

Begin with checking for error codes. Then start looking for vacuum leaks; An intake leak would probably cause you to run worse after 2.5K and not before.

Check for diagnostic codes: http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx

Why was the car sitting for 10 years? Blown head gasket? If so, the bearings have probably eroded and you may have some significant rod knock.

The stock turbo begins spooling around 2K and all turbos spool faster if you're running rich (it's a tuning trick actually)... cooler air is denser and richer air is denser.

dunewarz · 12-05-2009, 02:57 AM

Sitting for 10 years? Well there so many things you need to check. Especially after taking it up to 110 mph. I'd start with the simple stuff like spark plugs, wires, gaskets, filters, etc. Then more complicated stuff like fuel pump, head gasket, and cylinder head itself.

MA70-3.0GT · 12-06-2009, 02:57 PM

You still here nutz? What happened with the boosting problem?

*sigh* I hate not having closure on an issue...

11-24-2009, 05:39 PM	#1
supranutz Stock Join Date: Nov 2009 Location: texas Posts: 13	constant boosting problem got my supra up and running after it sat for 10 years its a 87 supra turbo it ran perfectly last night drove it around for an hour then took it on the highway had a good time hit 110 mph coulda gone way faster now i get in it this morning it idles rough it misses/ runs rough thes=n sooths out at 2500 rpm and its constantly boosting im not new to cars but new to turbos whats the deal /problem ????

11-25-2009, 03:19 PM	#2
MA70-3.0GT 12psi boost Join Date: Oct 2009 Location: Crewe, England Posts: 356	Not sure about the constant boosting thing as the turbo shouldn't be getting enough exhaust gasses to make any boost at low revs, perhaps the sensor has gone haywire? Or if you mean it's overboosting & getting fuel cut then the wastegate could be stuck (or the actuator failed), probably stuck after sitting so long... As for the rough running, have you got any fault codes when you do the diagnostic check? (making sure the light works beforehand) __________________ '89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit... '89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks... '83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks '95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it I'm not paranoid, they really ARE after me!!!

12-06-2009, 02:57 PM	#5
MA70-3.0GT 12psi boost Join Date: Oct 2009 Location: Crewe, England Posts: 356	You still here nutz? What happened with the boosting problem? sigh I hate not having closure on an issue... __________________ '89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit... '89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks... '83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks '95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it I'm not paranoid, they really ARE after me!!!

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11-25-2009, 07:58 PM	#3
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Begin with checking for error codes. Then start looking for vacuum leaks; An intake leak would probably cause you to run worse after 2.5K and not before. Check for diagnostic codes: http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx Why was the car sitting for 10 years? Blown head gasket? If so, the bearings have probably eroded and you may have some significant rod knock. The stock turbo begins spooling around 2K and all turbos spool faster if you're running rich (it's a tuning trick actually)... cooler air is denser and richer air is denser.

12-05-2009, 02:57 AM	#4
dunewarz 3" Exhaust Join Date: May 2009 Location: WhiteBear Posts: 54	Sitting for 10 years? Well there so many things you need to check. Especially after taking it up to 110 mph. I'd start with the simple stuff like spark plugs, wires, gaskets, filters, etc. Then more complicated stuff like fuel pump, head gasket, and cylinder head itself.