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Major help needed for 86 GN

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turbo96max

Member
Joined
Jun 6, 2007
Messages
825
Ok . I am a relatively new owner of a 86 gn. Quick breakdown, the car has what i was told is a pt54 or ta54 from precision, converter with a 3500 stall with od. rebuilt tranny by Ivan in miami Tranny tech, front mount (big one that is not sold anymore??) with 3 inch piping, dual fan setup running high only(they both turn on like around 170 or so, then shut off after temps lower, on with ac), it has what i was told to be 42 lb green injectors, a red chip that i was told was for pump gas, 3 inch down pipe, aftermarket fuel regulator, a stainless dual exhaust kit.Stock block and stock heads.

I have a small miss at idle that is recent, with about 17 inches of vaccuum, and im wasting a whole lot of gas, and the car pops after like 15 psi of boost and breaks up. I have what I think is too much fuel pressuer under boost. I have 37 psi at idle, and at 14 psi i have about 64 psi of fuel pressure, If I increase the boost to about 16 psi i get even more fuel pressure and the problem gets worse. yesterday i checked the fuel psi , bc when i turn off the car, initially it went up, upto 42 , then in a matter of 10-20 minutes it dropped to 20 psi,??? I am thinkig I may have several issues at hand.

I want to replace the plugs, but i dont know which ones would be the best to use for my set up????

what on these cars may cause the fuel pressure to increase so much under boost? 70 psi at 17-18 psi of boost??

is a 3500 stall too much for my daily driven car with this turbo? im not sure what version it is, but its a precision and its a 54 trim, could be pte ,pt, ta?? how can i tell by looking at it. The inlet is a 3 inch , not 4, and uses a rubber coupling on the intake side, not a bolt on adapter.

you guys know anyone in fl that will tune tha car for me correctly, bc i got some service done at harpers racing, but he doesnt drive the cars, so he cant tell me wats wrong. i guess hes scared of breaking something ??? first time i hear that, he just tells me to put up the boost and it should clean up, but then i also get too much fuel psi? unsure what to do at this point.
 
first time i hear that, he just tells me to put up the boost and it should clean up,

That's horrible advice. I think Hartline Perf. is in FL. Maybe a post in your regional section on this board would give you some ideas.
 
You're right to be concerned; your car is not performing correctly. Fuel pressure should only rise 1 lb per psi of boost. The initial 37 psi should be 40-42 for most chips. If it is a Red's chip it'll probably be rich anyhow.

Here are some suggestions and comments:
1. Get a new chip from a current chipmaker; lots of people swear by Eric from Turbotweak.com. If you don't know much about your current chip, get a new one that you can be confident in.
2. Street plugs are usually AC Delco R42TS. Gap them at .030.
3. Change the fuel filter under the car in front of the left rear tire. The lines can strip real easy so be cautious and use lots of penetrating oil. First relieve the fuel pressure at the left front of the fuel rail by removing the knurled cap and depressing the schraeder valve inside. Catch the fuel in a wad of paper towels. Otherwise you'll get a gasoline shower when you remove the fuel filter lines.
4. Check ohms across coil pack towers. Each pair of towers should show between 11 - 13 kiloOhms across them. Set a digital multimeter to Ohms and touch both tower ends; polarity does not matter since you are checking resistance.
5. Check spark plug wires the same way, check them for ohms. Remove one at a time and touch each end of the wire with the multimeter still set to Ohms. You should see a number around 3.5 kOhms. Install your new spark plugs at this time also.
6. Check your fuel pressure gauge against a known good one for accuracy. A mechanic might be able to do this for you or perhaps a performance shop.
7. Check all your rubber vacuum lines on the engine. Rub them between your fingers lightly. If your fingers get really black, the lines are dry rotted and need replaced. 95% of the lines are easily replaceable with off-the-shelf cut-to-length vacuum hose you can buy at a parts store. I think you should have more like 20 inches of vacuum at idle unless someone put a cam in the car. Leaky vacuum lines are a problem that is hard to trace so just replace them. They are 21 years old (1986).
8. Try to run all the gas out of your car and use Shell 93. I have always had good luck with Shell, worse with BP and discount brands. Sunoco 94 is the best though but hard to find.
9. You probably won't be able to run more than 16 psi on 93 octane without knock. You can hurt the engine if you do.
10. You are going to need some electronic monitoring equipment to go much farther. Do you have a ScanMaster? If not, get one.

This should keep you busy for a few days. Good luck. As for the converter stall, 3500 is alot for a TA54 but not extreme. You will get worse fuel economy around town versus a 3200 stall but on the highway, it is locked up in overdrive anyhow so no difference there. Here is a photo of my TA54:
 

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thanks for the advice, it all sounds great. Got one major holdback that did not allow me to sleep last night. I just got a rod nock , got louder the closer i got home, lol so now the tuning is the least of my worries. I seem to need a new engine. I was told I should go oversized pistons bc the cylinders usually loose there shape in time. sucks huh.... I didnt even run the car hard, I just got on it about 60% throttle afterwork, and the noise came in slow, not like right after a pull or anything like that. :( :mad:

oh and my turbo is a pte54, i have a scanmaster, intercooler is a v2,
 
If you have rod knock it's most likely because that popping sound was preceded by a TON of knock.
 
If you have rod knock it's most likely because that popping sound was preceded by a TON of knock.


could be, but i didnt really run the car hard at all. maybe it was from the constant not running right from this past month finally took its toll. Do these cars not handle abuse well? my old vq30 det nissan engine took abuse like crazy, i pinged the crap out of that car a few times that the methanol ran out during a run or something, but the bearings never gave me any issues, and it had over 150k miles.
??
what do you recommend as far as getting back on the road?
 
Is the noise upper engine or lower engine? Before I started rebuilding I would check the condition of the oil, look for metal in it, pull the valve covers, check the push rods and cam first. Then if only metal in oil, oil pan will need to come off and start checking bearings. Not fun.
 
Depends. I mean, the obvious answer is to fix it. If you know cars then I'd jerk the engine and freshen the bottom end. If not I'd take it to a reputable engine builder. As far as the abuse thing goes that's kinda relative. If you're not pushing an engine and it detonates it's probably less likely to hurt it vs pushing an engine and detonating. Plus, you don't know what the last owner did.

Turbomonte2, he said he had a PTE54.

Edit: Johnlarkni is right. Make sure it's a rod before you fix it! :)
 
Is the noise upper engine or lower engine? Before I started rebuilding I would check the condition of the oil, look for metal in it, pull the valve covers, check the push rods and cam first. Then if only metal in oil, oil pan will need to come off and start checking bearings. Not fun.

wow this sucks. not fun at all. looks like i will need to purchase tools again (were stolen). I hear the noise coming from the lower part of the motor, i hear it coming from the oil pan. but i will check the valvetrain first, maybe i get lucky. its so loud that the car takes out aout 20 degrees of timing just fron the nocking.

Question: I called a local shop just to get a feel for what i am going to need to get this my daily driver back on the road.This is what i got. for a street car, that im looking for a good low 11 second car, perhaps high tens in the future. I was told to use je pistons (.20), stock rods, new bearings, oil pump, good valves and springs,balancing and build labor and parts, about 3500 dollars, how does this sound? I was hoping to get this thing back on the road with about 2000-2500 bucks, is it possible?
 
I might have good news for you. Check first to make sure your header gaskets are good. If you have after market headers it is common to blow out the gasket. It starts with a ticking noise.
 
I was hoping to get this thing back on the road with about 2000-2500 bucks, is it possible?

Not likely--unless most of labor yourself. Block flushed, etc. I would think you'd also do a valve job (hds to machinist?), seals, guides if heads removed...
 
well i did my research and yes , a very basic rebuilt with freshing up the heads is feasible with 2000.00 , but i will be pulling the motor out myself and dropping it back in. but for now, I had a friend that has been a mechanic for years come over to look at the car for me. well it started rainging so nothing really could be done, but he did hear the noise and his pretty sure that its not a rod nock. his willing to bet the engine rebuild that its not. he says it sounds like a flesplate or loose converter issue. but we will look at the valvetrain and tranny this thursday. i appreciate all the help, i will keep this post informed after findings on thursday.
 
When my flexplate cracked, it sounded like a rod/ main brg--but a little more metallic. Pull your inspection plate, get a good light & you should be able to see if a cracked flexplate. I had the same noise earlier & found 2 (of 3) tq conv'r bolts loose. I tightened them up--eliminated noise, but noise reappeared a month or so later with the broken flxplte.

I'll never know if conv'r bolts coming loose initially caused flexplate damage or not.:confused:
 
well lets see what you guys on the forum think about this. I asked the local guy and he said that the engine is basically done.!!!! I checked on the converter and the flexplate yesterday. Nothing, it all looked good, but then I was curious and I grabbed a wrench and torqued the flexplate, and it has front and rear play, kida like the shaft play on a turbo. According to the local guy when that happends its the engines thrust bearing fails, and if its sufficient that the crank and block are no good.??????? any thoughts????
 
All I have to say is make sure "your guy" knows specifically how to work on turbo buick motors. There are lots of people who think they know and they dont.

I know you dont want to spend a bunch of money, but if you pay $1000 more at a shop that really knows their sh!t, vs. your guy who doesnt really know these cars and then you get the engine back in your car and its a real TURD , you are gonna wish you spent the $1000 extra.

Just my 2 cents...

MAKE SURE you get the right guy to take care of this. Post what city you live in and maybe someone can tell you of a guy who really knows turbo regals in your area.
 
All I have to say is make sure "your guy" knows specifically how to work on turbo buick motors. There are lots of people who think they know and they dont.

I know you dont want to spend a bunch of money, but if you pay $1000 more at a shop that really knows their sh!t, vs. your guy who doesnt really know these cars and then you get the engine back in your car and its a real TURD , you are gonna wish you spent the $1000 extra.

Just my 2 cents...

MAKE SURE you get the right guy to take care of this. Post what city you live in and maybe someone can tell you of a guy who really knows turbo regals in your area.


well , does the play mean that the engine is done? thats really my question. According to my local guy its should only have something like .001 of play, and i have almost a .20 of an inch. This is guy only works on gn's.

Our engines have been around forever, you dont think a schooled tech and good engine builder should be able to handle a rebuild? specs are specs, dont think so???
 
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