need a good tuning solution with timing control

[Mellon]

a friend of mine brought over his GN. He's an older guy and isn't interesting in learning new things so he's asked me to take a look at it for him. He really can't even tell me what mods it has but at a glance I see an adjustable fuel pressure regulator(no gauge) and large garret turbo. I can't tell what size it is yet since it has a chrome shroud around the housing.

I took it for a drive and noticed it was holding ~ 18psi but pinging it's ass off. I put a scanner on it and it's "rich" and timing is getting yanked down when it's pinging so I believe it's real knock.

I'm proficient with the Apexi S-AFC, MAF-T, ARC-2 and Greddy E-Manage on my TT Stealth but I don't know what kind of piggy back/chip would be ideal on a GN.

Please give me some advice. Also I can't see any kind of boost controller.. is there a stock solenoid or something?

 

[Mellon]

btw this is for a 87ish car.. it's intercooled.

 

[TurboBob]

hey dude......!

Get an idea of his goals and we can build from there.

Find out what chip is in the ECM, injectors and turbo. Find out if he has an upgraded fuel pump and hot wire kit. Were you reading the stock boost gauge or aftermarket? 18 psi is possible on high octane pump gas as long as the chip has proper spark advance. A race chip will detonate severely.

detonation = death. These engines have very strong pistons, but nothing will survive excessive (audible) detonation.

A scantool reading "rich" is not enough, watch the O2 reading and see how rich. (make note of what kind of scantool, there is some variance in how they read)

Bob

 

[Mellon]

hey bob.. thanks for saving me, I felt like I was drowning over here in GN land without a life jacket heh. I'm really out of my element so I really appreciate the advice.

his goal right now is to get a safe tune for his car. I think it is plenty fast for him.

I have a bad feeling someone set him up with a chip that's for race gas. It's 18psi on an aftermarket VDO gauge so I feel like that's accurate. You can really fell the car lay down when it starts pinging but up until that point it rolls on pretty good. I'll put a bung and LM-1 in it soon to see what's really going on with the 02's.

a few pics I took last week:

I'll see if I can get some answers to those questions you had Bob.. thanks again.

-Chris

 

[Ormand]

First: On a GN, the chip DOES NOT control boost. There is no feedback of manifold pressure to the chip, so the chip "doesn't know" what boost the engine is running. The chip may have too much timing for the gas/boost he's running. There is a wastegate actuator under the turbo which actually controls boost. Should be a line connecting it to the turbo discharge, and maybe to the solenoid on the passenger's side valve cover. If the little rod which connects the actuator the little arm on the turbo housing has an adjustment, it should be lenthened to lower boost. That would be the place to start. You might solve the problem with another chip, and the car may be better off with a "modern" chip, like a Turbotweak, or a Commander, but if lowering the boost makes the knock go away, that is certainly an improvement.

 

[Jerryl]

a friend of mine brought over his GN. He's an older guy and isn't interesting in learning new things ...........

Define "Older" .............. (joke)
As stated by Ormand, do not drive the car or get into boost untill you either fill it up with 116 or get another chip and scan tool data. Look at my profile pic and you'll understand why I am saying that ........

 

[TurboBob]

looking at the pics, that may be a stock turbo. Which would lead me to think the injectors, fuel pump (fuel filter), and other stuff is stock original......

Let us know what you find out, 'we' will then happily offer 15 or 20 differing opinions on the best solution.....

Considering what I know of your background and tuning ability, I think you will only need a few tidbits about the GN's specific systems...

Bob
(You need to get yourself a GN....)

 

[TurboBob]

take a couple close-up pics of the engine compartment, so we can identify some of the components.

Bob

 

[broke1]

First: On a GN, the chip DOES NOT control boost. There is no feedback of manifold pressure to the chip, so the chip "doesn't know" what boost the engine is running. The chip may have too much timing for the gas/boost he's running. There is a wastegate actuator under the turbo which actually controls boost. Should be a line connecting it to the turbo discharge, and maybe to the solenoid on the passenger's side valve cover. If the little rod which connects the actuator the little arm on the turbo housing has an adjustment, it should be lenthened to lower boost. That would be the place to start. You might solve the problem with another chip, and the car may be better off with a "modern" chip, like a Turbotweak, or a Commander, but if lowering the boost makes the knock go away, that is certainly an improvement.

I REALLY wish youd stop talking out of your ass and find out more about a subject before you post.CHIP DOES CONTROL BOOST!!!!!!!!!!!!!!Why do you think that WG solenoid is there???Because if you think its there to look pretty youre wrong as usual.

You can bypass the solenoid and the chip wont control boost.....

Check WOT FP and change the fuel filter...

 

[Ormand]

I REALLY wish youd stop talking out of your ass

Does Broke refer to your BRAIN? The stock chip has NO feedback for manifold pressure. The wastegate solenoid, commanded by the chip, can INCREASE boost above the level set by the wastegate actuator. But the actual base level is set by the preload on the spring in the wastegate actuator. You can bypass the solenoid and the chip won't INCREASE boost. It sure won't control it, since it never did, nor does it have the necessary sensors to do so. Broke 1, maybe you should get somebody to explain things to you, before you start typing out junk and more junk.

 

[bruce]

The ecm controls boost, but not in a feedback manner.
You can change the WG settings, and change the boost.
You can scale back the boost in 3rd and 4th gear varing amounts as a function of WG settings, but it's not closed loop.

FWIW, there's at least one appliccation using a GM ecm that does used closed loop boost control (The Turbo Lotus).

 

[Jerryl]

Good therad on the WG solenoid.
http://www.turbobuick.com/forums/showthread.php?t=169930&highlight=solenoid

I am NO expert, but think that most chips have a timing control/tuning feature? Bruce would know. I am looking into this as well.

 

[Mellon]

Define "Older" .............. (joke)
As stated by Ormand, do not drive the car or get into boost untill you either fill it up with 116 or get another chip and scan tool data. Look at my profile pic and you'll understand why I am saying that ........

he's under 100 .. that's all I know (see how I dodged that bullet?)

I went out there this weekend for a little bit and after getting the bung welded in I connected the LM-1 and calibrated it to 02 and fired it up.

Idle initially was ~ 13.2 during warm up but once it warmed up it was ~ 16.0:1 on average.

cruise was ~ 15.0

WOT was ~ 12.0 at the richest but mostly 12.5 -13.0 so I shut it down.

I came back to the garage and with the car idling and a careful eye on the WB began to increase the FP via the AFPR but it made absolutely no difference. I ran out of time but I have to assume that the fuel pump either has a relay in the way or simply doesn't have enough voltage going to it at idle. I'm going to connect a fuel pressure gauge to get the base setting back to where it should be and go from there.

 

[TurboBob]

his stock O2 could be on the lean side, which would explain the closed loop AF mixture being like that. There could be a small leak in the exhaust which could do that too.

WOT is your issue, and that is definately on the lean side. The stock fuel pumps barely sufficient for the car when it was new....

Find out the chip data, and the fuel delivery setup.

(I'm under 100 also)

Bob

 

[Lee_Burough]

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