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Discussion Starter · #1 ·
Hey members,
I have a 89 turbo auto that is bone stock. I need it to pass smog. Codes are 34 and 71. Abnormal turbo pressure and EGR temp sensor (calif). I removed the EGR and tested the temp sensor as per the manual. It is OK. Checked the VSV and vacumn modulator. Both OK. The EGR isn't carboned up and the diaphram works. Could a boost leak account for both codes? The 3000 pipe had a semiloose clamp but it was seated good. I'm going to reassemble it this weekend and clear the codes. Any ideas?
 

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http://www.cygnusx1.net/supra/techtip/engineerrorcodes.html

34 Turbocharger Pressure

Diagnosis
The turbocharger pressure is abnormal.

Trouble Area
Turbocharger
Air flow meter
ECU
Intercooler system
71 EGR System Malfunction
Diagnosis-
EGR gas temp below predetermined level during EGR operation.
Open circuit in EGR gas temp sensor signal (THG).

Trouble Area
EGR system (EGR valve, EGR hose etc.)
EGR gas temp sensor circuit
EGR gas temp sensor
VSV for EGR circuit
VSV for EGR
ECU
Whoops, My bad. I guess I didn't get all my post into the box before I hit Submit. My first suggestion would be to pull the Main EFI fuse for a half hour, and then see if the codes are still there.

The most common reason for the Cdoe 71, is a loost bolt causing a leak. Most people, however, choost to pick up EGR block off plates and never worry about that system again.

Code 34 is MOST often caused by hitting Fuel Cut Off at over 12PSI. It can also be caused by a large boost leak or the AFM being dead (which will have other symptoms as well (Not a code 71)).

For both codes, they will disappear if the memory is cleard (pulling the main EFI fuse) and will only come back when it's sensing either of those things.
 

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Discussion Starter · #3 ·
Thanks Jeeves
I guess I'm on the long list of 2nd owners that are repairing the abused/neglected of the previous owners. I should of tried reseting the ECU before I took it apart.Need to keep the EGR as I'm in Northern Cal. Thats 200 miles north of SF. Land of the redwoods and that funny smelling weed. The EGR system checked OK even ohming the wires back to the ECU. I'm checking for cracked pipes /boost leaks ,IC ect. BTW the Power Steering is repaired(previous post) The pump was burned up from lack of oil but the origional problem was that I found the pumps flow control valve wedged down by the block.
 

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So did pulling the fuse clear 'em up?
 

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Discussion Starter · #5 ·
Thx. Codes are erased.I found a blockage in the EGR. The little metal pipe that comes out of the EGR was carboned up. Boy the EGR is a PITA to remove/install with the motor in. Should be good to go now but I need to wait till after the holiday for insurance for road testing. Theses cars really drain the pocketbook. I fixed alot of the oil leaks and replaced 3/4's of the coolant lines. There is an electric fan wiretied to the radiator. Shrouds and fan assembly have been removed. No bottom inspection plate. All soon to be replaced. It's a labor of love though and gets my mind off of my divorce/holiday blues.I've been looking at the K &N filters on Ebay. I'm not fond of one size fits all. Maybe one from 935, also thinking of the cooleese hardpipes?
 
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