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1998 GST 6 bolt

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Its not really a build thread so much... it's more of a back from the dead thread! I bought the car in non running condition in February 2020!
Then I put some good tires and wheels on it, and had it towed it home 100 miles. Been working on it and driving it ever since!


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I didn't know much about DSM cars, other than they look great and the turbo versions are pretty quick..I had a '95 GST 25 years ago when it was new, but traded it in for a full size Montero when I got married and had kids...it was a great car! This one has some nice mods and was available for a good price so I bought it, planning to fix it up... so for the past 3 months I've been reading up, adjusting things and replacing a lot of sensors and other parts that were either broken, missing, or weren't the correct version. Its a 6 bolt swap.
 
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The original TPS was a 3 prong from a 1g. I replaced it with a 2g (4 prong) TPS to gain the function of the ISC idle control motor. The first one I bought wasn't working correctly and had to maxed all the way clockwise to trigger the idle control.
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I got another one and set it at .063v and works fine now.
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Ironing out the idle issues...the original ISC stepper motor was the earlier brown one.
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The advice from many here was to get a newer black one for reliability. OEM part was about $95 with shipping.
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Exhaust leak issues... I ordered a new set of studs and replaced the old ones which were a mishmash mixture of incorrect length bolts and stacked washers. Its better now, but I discovered one of the lower studs on cylinder number 3 was broken off inside the head! I'll have to tap and drill that one probably sooner than later....
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Vacuum leak issues... there must have been an aftermarket boost gauge at one time... I discovered the old vacuum hose to the non existent gauge was left open-ended underneath the dash, causing a vacuum leak... so I bought a new autometer boost gauge and secured the line at the fuel pressure regulator tee.
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I ordered the instrument panel bezel for mounting the boost gauge and a future wideband O2 gauge on the opposite side...
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Oil pressure gauge and dummy light not working.... I got underneath the car and saw that there was nothing hooked up to the sending units on the oil pump. I found the wires had been cut off the wiring harness...so I attached some new wires with some female spade clips that press securely on to the sending units...
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However, it appears as though the original Denso pressure sending unit for the gauge is mounted in the wrong spot in the front where the switch should be for the dummy light...
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The sending unit on the back of the pump does not seem to work....and both units appear to be oil pressure sending units. The switch for the dummy light is missing so I ordered a new switch.
 
Blow off valve not functioning properly...making a fluttering sound at deceleration... adjustments dont help...looked up the Greddy website and wow! can you believe it...a Chinese knockoff!
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The diaphragm and valve action is much smoother with the authentic Greddy BOV. The imitation BOV gets stuck slightly and doesn't open smoothly plus the internal is not machined very nicely with a lot of excess casting flash... The original Greddy has very smooth action without sticking and is very finely machined and has a gold metal seal around the valve on the bottom. Don't be fooled... There is no substitute for the real thing!
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I installed a new L pipe on the intercooler with a nipple in it for the wastegate actuator. This is ideal for a quicker boost pressure to the actuator and to help reduce boost spike... as opposed to making a tee from the vacuum line to the bov.
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New MAF sensor just for the hell of it... The original one was old and dirty... the new one was cheap only $50 and came with a new gasket... It's a Chinese made part but I wanted to see if it worked as good as the original... So far so good, plus I have the OEM for a spare.
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The new one is flat and flush behind the mesh screen where the little calibration screw was sticking out on the OEM version. Maybe a plus for airflow?(see left center area in pics)
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Battery and charging issues... I went downtown LA and got a rebuilt 2G alternator for $60 plus my old core, and a reconditioned stock size Champion battery for $30 plus my old Wal Mart POS trade in. New 4 prong alternator pigtail coming soon to clean up the wiring!
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Timing issues...the car has no power and stalls when letting out the clutch...The engine has a 1G cam angle sensor, doubling also as the crank angle sensor. However I noticed it was set all the way counterclockwise for max retarded timing. I advanced it by ear to get it to run better for now. This position feels pretty good when driving, but I have not driven it under wide open throttle or max boost yet. I'll install a knock sensor first. Also, there is no timing check connector on the firewall.
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I found a disconnected wire and discovered it went to the knock sensor on the back of the engine under the intake manifold. That's a good way to blow up your turbo engine... just disconnect the knock sensor and drive it around! Not smart...
The knock sensor looks bad with some black goo oozing out...
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I ordered a new 2g knock sensor from O'Reilly's and it saved me a few dollars over the Amazon listing for the same brand part plus shipping (Standard Motor Products part #KS32). I paid $80 out the door.

Installing the new one today!
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I've been adjusting the idle and trying to get it to idle ok with the big 272 cams in it... (No Dsmlink yet!)...The larger 1G throttle body and the front mount intercooler and piping makes it difficult to set the throttle stop properly....It seems to work best approximately one-half turn past the point where it touches the throttle cable stop... I cannot get it to idle higher than about 600 RPMs with only 8 to 10 inches of vacuum... cold starts are still a problem too. I'm going to install a bypass plate in the throttle body for the FIAV (coolant based cold idle air valve).
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The front mount intercooler on the car looks like it's been hit on a curb and it's kind of dinged up...
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I bought a new tube and fin intercooler for better efficiency!
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And some new T bolt clamps,
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Here's my new boost leak tester with a liquid filled gauge! Time to do some leak testing...
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I want to keep the factory temperature gauge in the instrument panel functional. So I came up with this method using the stock connectors that came with the gauge, and a 5/8" brass tee off the heater hose...this will be hidden behind the intake manifold, as opposed to the ugly ones in the upper radiator hose... this will be for my Autometer full sweep temperature gauge. I'll mount this gauge on the gauge pod. My heater core is bypassed since it's SoCal...
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That temp gauge may end up being a little off (probably not by much though) since it's situated where it may not see proper flow? Just a thought. Me personally, I'd drill and tap the t-stat housing for the sensor, I do have spares however if I decided not to use the sensor or something. Just know, I'm not saying this is bad, you made a good solution.
 
Hi thanks for checking out my thread! I thought about tapping the thermostat housing but my sending unit is pretty big (are there two sizes?) and I couldn't see it working out very well... this location is at the heater inlet hose just a few inches away from the thermostat. These Autometers are a bit slow to read temps anyway...but I still have the stock gauge too. Photo coming soon.
 
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I was going to replace the rear seats with my new black ones, and in combination, install my new 'WalBro 255' fuel pump today...
Until I discovered it was a fake!!
The Walbro logo is not even correct!
Compare images...the fake one...with a faded hand stamped logo missing the notch at the bottom...
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And the REAL one! The 'W' logo has a notch on the bottom and its hydraulic pressed accurately.
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