Detonation at WOT

kokdezal

New Member
I have an 87 GN purchased after it's been sitting since 93. Since purchasing I've installed the following: Racetronix pump and sending unit, plugs, plug wires, coil, TT chip with 60# injectors, caspers heated O2 sensor, LT1 Maf with translator, RJC 3" downpipe , test pipe and exhaust.

Scanmaster shows all numbers are within range I get a slight detonation at WOT. The turbo surges from 12-18lbs while at WOT with 93 octane. The car did this before all the new upgraded parts and I thought the upgrades would fix the problem. Does anyone know what else I could check. The only thing I can think of is perhaps a vacuum leak but if that was the case I think the scanmaster would show it. I did notice the cross count slowed after installing the heated O2 sensor. Any help is appreciated. Thanks.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Numbers on the Scanmaster with the engine fully warmed up in Park. Max boost should be 14 lbs with 93.
 

kokdezal

New Member
Numbers on the Scanmaster with the engine fully warmed up in Park. Max boost should be 14 lbs with 93.
I'll get the numbers this evening. Boost increased after installing injectors and chip but it's stock turbo and wastegate. Is that normal? Appologies for dumb questions but even though I've learned alot about the car in the past year I'm still learning and have much more to learn. Thanks for the response.
 

TireFryer

The New Kid
I'll get the numbers this evening. Boost increased after installing injectors and chip but it's stock turbo and wastegate. Is that normal? Appologies for dumb questions but even though I've learned alot about the car in the past year I'm still learning and have much more to learn. Thanks for the response.
Boost shouldn’t have increased. Although I think Erics chip disables the boost solenoid. You should run a line right from the compressor housing to the WG actuator. And adjust boost tuner style. There’s this guy on YouTube “turbobuicks101” that has a video on this… You shouldn’t have any knock at 14 psi. If it’s real then you have a problem. Check motor mounts, see if the downpipe is rattling on the frame etc. My trans was slipping the 2-3 shift and kicking up a bunch of false knock. Rebuilt the tranny and knock went away. Never know with these cars. Maybe try backing the timing down if you can too while you’re testing.
 

kokdezal

New Member
Boost shouldn’t have increased. Although I think Erics chip disables the boost solenoid. You should run a line right from the compressor housing to the WG actuator. And adjust boost tuner style. There’s this guy on YouTube “turbobuicks101” that has a video on this… You shouldn’t have any knock at 14 psi. If it’s real then you have a problem. Check motor mounts, see if the downpipe is rattling on the frame etc. My trans was slipping the 2-3 shift and kicking up a bunch of false knock. Rebuilt the tranny and knock went away. Never know with these cars. Maybe try backing the timing down if you can too while you’re testing.
ok. Thanks for the info!
 

turbo nasty

Turbo Dojo / MNTR
Disconnect wastegate and go WOT and see if you get KR. That will help pin point a posible machanical false KR like a loose something rattling against frame or block and knock sensor picking that up.
 

TireFryer

The New Kid
Disconnect this rod. Not the wastegate line. Just to clarify. Will let most of the exhaust bypass and you won’t make much boost. If you disconnected the WG line you’ll make as much boost as the turbo could possibly make and bye bye motoro_O
image.jpg
 

kokdezal

New Member
Numbers on the Scanmaster with the engine fully warmed up in Park. Max boost should be 14 lbs with 93.
AF - 04
LV8 - 37-38
Int - 128
BLM - 133
r - 825-850
TPS - .46
IAC - 12

KR stays at zero so I tapped on the block with a wrench while it was running and it didn't pick up anything so maybe the sensor is bad? Thanks.
 

kokdezal

New Member
Numbers on the Scanmaster with the engine fully warmed up in Park. Max boost should be 14 lbs with 93.
Also, the cc number stayed the same no change. I know the TT chip might have something to do with it but it's a heated sensor but thought maybe the sensor is bad?
 

TireFryer

The New Kid
AF - 04
LV8 - 37-38
Int - 128
BLM - 133
r - 825-850
TPS - .46
IAC - 12

KR stays at zero so I tapped on the block with a wrench while it was running and it didn't pick up anything so maybe the sensor is bad? Thanks.
Blm high and tps is too high. Right where the car doesn’t know if you want to idle or take off. Get the tps down to about .40-.42 and and check for vacuum leaks or a pre turbo exhaust leak to fix high blm.

Read through this link and look at “tps adjustment” and all the other tech pages on this website and be super familiar with everything on these cars.

^^^^Link to “the basics of turbobuicks”
 

kokdezal

New Member
Blm high and tps is too high. Right where the car doesn’t know if you want to idle or take off. Get the tps down to about .40-.42 and and check for vacuum leaks or a pre turbo exhaust leak to fix high blm.

Read through this link and look at “tps adjustment” and all the other tech pages on this website and be super familiar with everything on these cars.

^^^^Link to “the basics of turbobuicks”
Ok. Will do. Thanks for your help. Also, the car has always shifted perfect as it should (fimly) but last night I took it out and noticed it reved a little between shifts (I've read on this and they call it shift flare I believe). Trans fluid looks good (flushed and replaced fluid right when I bought it) and doesn't smell burnt. Any clue what may have changed the shift? I took the TV cable off when replacing injectors but I didn't change or adjust it, just put it back like it was. Thanks again and sorry for all the questions but you guys know your stuff!!
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
BLM's are a tad high at 133. I want you to look for pre turbo exhaust leaks and vacuum leaks. Close enuf isn't good enuf with these cars. If you're in Canada I have free calling. I have free North America texting. Where are you located. Might be someone near you to help.
 

kokdezal

New Member
BLM's are a tad high at 133. I want you to look for pre turbo exhaust leaks and vacuum leaks. Close enuf isn't good enuf with these cars. If you're in Canada I have free calling. I have free North America texting. Where are you located. Might be someone near you to help.
I'm located in the U.S. in WV.
 

kokdezal

New Member
You need to verify the fuel pressure rise 1 to1 with boost.new parts dont mean everything is working
ok. i've checked the pressure at idle several times and it's 43lbs with vac off. I will have to get a different guage I can read at WOT. Thanks!
 

Chuck Leeper

Toxic old bastard
Staff member
Original cat converter?
Shorten the TV cable 1 click.
Loosen and retorque the knock sensor to 14#/ft.
Translator settings?
 
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