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New GTP, questions, concerns and hello :) !

B

BigNelson76

New member
Evening gentleman, and the occasional lady I suppose.

i've just purchased a new to me 1998 gtp with 128,000 miles on it for a mere 1000, now yes as you may have already guessed it isn't immaculate but it's in pretty darn good shape all things considered.

First off, zero experience with turbo cars. I understand (now) that i'll be pumping premium from now on at the station... I also know the poor thing needs a turbo coupler (Got that good old rattling rocks noise).

Here's what I don't know:

this thermostat seems weird. it'll gush up to 200+ and a little more then open and slide down to a cool 185 ish I suppose. Being used to mini vans and a 24v taurus it weirds me out to not see that needle dead middle of the temp gauge...

Car... well... smells funny. I don't THINK it smells feline to me... but rather a little exhaust and even rich at times. I smell that 91 octane once in a while, usually after a throttle kick then letting off (typical???) but also smell kind of exhuast like smells but Maybe the cat? A touch oily? Reading old threads I see the LIM gaskets go seemingly frequently and will look into that I guess, but other ideas?

It threw me an engine light the other day and it stuck--- this was before i knew about the 91 octane requirement... I believe the PO would not have known about the 91 requirement either but didn't seem like the guy to go smokin tires anyway. .... engine runs great still, no loss of power, no NEW smells or sounds (besides turbo coupler). I will go get it scanned sometime soon and report back with codes. Recommendations for a good home use scanner? I'd like my own eventually....

OH and the damn radiator is full of.... water... or super diluted coolant that's kind of sludgy... not oily, sludgy... and yes I checked the oil for water-it's innocent.



So theres a couple things..... The important ones first, then the silly little things that bug me will come later :)!



I was glad to see there are good forums behind these cars, when I buy a car I check the engine, feel the transmission then click around for the forums.
 


Its called a supercharger coupling. several of the vendors have heavy duty ones as well as kits. https://zzperformance.com/3800/superchargers-eaton-parts.html
rockauto.com is a great place to buy replacement parts. great priced and fast shipping.

Maybe time to replace the thermostat and flush the coolant. Since it needs an intake you can just drain it and clean the LIM while you are at it.

the resonators on these leak. That may be your issue.

Put in a new cabin air filter to try and help the smell. there are some that are carbon infused.
 
the sludge may be the factory dexcool that went bad from being proned to air. I'd drain/flush the coolant out completely and refill with prestone yellow coolant or anything besides the dexcool. might as well throw in a 180 t-stat while you're there. also you would need to bleed air out of the system after you're done filling it. the bleeder is on top of the t-stat housing.

try and fill 92octane and higher.

scanner, you can use the Bluetooth OBD2 adapter with torque app if you have a smartphone. another idea is a aeroforce gauge, laptop and hptuner combo, if you can find it on the forums the LS1M scanner w/palm pilot.
 
what part of Idaho are you from? if you live in Boise you can run E85 in your car if you change your injectors. I wouldn't worry about the thermostat, mine does the same thing. the smell of fuel could be the evap purge solenoid. I would recommend also changing the supercharger gasket, and lower intake manifold gaskets, and probably would be beneficial to drain and flush the coolant and then to replace.
 
Whoops My mistake on the supercharger.. I DO know that, but posted this thread around 3am...

I will be flushing the coolant and thanks for the link to the couplings, is there a large benefit of going for a 180 thermostat over the stock? I'm in NORTH Idaho so we rarely get too hot though on rare occasion we break 3 digits
 


a cooler system lowers heat and in a force induction setup lowering any amount of heat is a good thing. an example is lowering heat soak, preventing detonation a re a couple that springs to mind. too low though hinders gas mileage and heat during colder weather. so there's a decent medium where to not deviate from one end to the other.
 
Be sure to (if you plan on keeping it a long time) to address the downpipe restriction. If you don't plan on going to a smaller pulley or modifying it much...then everything else is fine; but a 3" catted (or catless) downpipe from ZZPerformance would take care of the tiny downpipe along with getting rid of the horrible U-Bend. On a stock car it'll pick up probably 15-20~ WHP if it's in a warmer climate. Toss an intake on the car as well when you do the 180* and get a mail order tune (you can PM for more details on that if you'd like and I can put you in touch with a guy here that'll toss a DHP file in your PCM...because you'll need a tune to take advantage of the lower fan turn on points...a 180* won't do much until you have the fans kicked on lower)...that'll pull it together...give you the supercharger whine under throttle, and take care of the factory flaws on these cars.

Flipping your upper dog bone mounts 90* is free, do that too to limit engine movement.

If you're doing a coolant flush and t-stat...I'd probably do plugs/wires at the same time if you haven't. Autolite 605's gapped @ .050" and some OEM replacement wires.

I typed this awhile ago...it's a little outdated but if you haven't read it, feel free: http://www.grandprixforums.net/threads/17482-Safely-Modding-Your-3800-Powered-Car!!
 
Well i've heard reasons for a 180 thermostat, and way hand raised against it but i must ask why?


On another note, engine light went off !
 
Because some people don't think it's beneficial and can't ever back up anything other than: IT NEEDS TO BE AT "X" RUNNING TEMP BECAUSE PEOPLE AND ENGINEERS SAID SO.
 


blueguy91 said:
Because some people don't think it's beneficial and can't ever back up anything other than: IT NEEDS TO BE AT "X" RUNNING TEMP BECAUSE PEOPLE AND ENGINEERS SAID SO.
Click to expand...

First of all it is required or you can get dreaded P0128. The engine WAS designed to run at 195, fans turn on in 220-230 range.
Without retuning for cooler T-stat your just trying to mix parts in wrong way.
Now can an engine run cooler, sure. BUT listen to this, the internal combustion engine is designed to turn heat energy into motion. So learn that tuning for the stock tstat is better than putting a bandaid over an arterial bleeder.

As an engine builder/tuner I have seen so many car come to me all patched up and still not working right.
Had guy bring me a 502 Chevelle had a HUGE 5 row custom radiator, multiple fans, 160 degree tstat, and factory 8.1L harness from a truck (yep all the emissions and all.
So we decided to convert back over to carb, yanked 90% of the cooling crap off.
Dragged out a factory 3 row and 4 row radiator. Spares from my Monte Carlo days.
I finally found a tall deck HEI, phenolic intake spacers and second had Victor Jr intake. Owner brought of a nice 950HP Holley he got used.
I swapped in a wide band O2, put a 195 tstat in and actually started with the 3 row rad as it was fresh recore.
I installed the front half of an old Monte Carlo shroud. Got a decent deal on proper fan.
Dropped all the ign/induction on and got it to start and run great, wideband numbers actually were pretty close.
Did swap out some air bleeds, changed power valve.
Drivability went through the roof. Actually made great power and never ran hot. Customer came back and wanted no shroud. SO I pull all that off and swapped in the electric from the overly huge radiator. Installed a decent fan controller and car ran cool. Owner wanted it to run lower temp so we took it to dyno. Guess what, cooler made less power. We tuned about 70% back but still left power on table cause engien is LESS efficient.
IF you have to crutch something your not tuning properly.
I have actually put three drag engines out and they are built to run NORMALLY at 215DegF. We used Evan coolant and picked up a large amount of power raising the running temp.
We gained 28hp on the small engine(377 dart block) gained 48hp on 434.
I have decided to step back and come at these cars as a tuner again, while learning about the ways the current information has been used. Hoping to have some fun and expand on what to do with these cars to make them run.
I think a few things can be done different and I like experimenting.
BUT THERE ARE REASONS FOR CERTAIN OPERATING PARAMETERS.
If you run cooler tstat you really need to adjust specific parameters like fan turn on and such.
 
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