Just got a Scanmaster, need help sorting out my car.

[rob j]

I own a stock, pristine 87GN with 16k miles on it. I've had the car a few years now (bought from original owner), and have rarely driven it since ownership. While the car is in immaculate condition, it has not run right since I acquired it. Now I'm finally getting around to dedicating some time to it, and sort it out. While I have a lot of car experience, have owned many cars, and worked on many cars, I have to admit I have very little knowledge of these 3.8 SFI Turbo motors, so pardon my ignorance.

The issue my car has had since day one, is not running properly. She does not idle smoothly, she sputters and surges when cruising at a constant speed. Go heavy on the throttle, and the motor seems to run ok however.

Today I just installed the Scanmaster 2.1, so hopefully it will help determine the issues I'm having.

First a bit about the car, and what I've done, checked so far. As far as I can tell, and from what the previous owner told me, the car is 100% stock with the exception that it has a Hypertech 41372 chip installed. Today for the first time, I did verify that it does indeed have this chip installed. Everything else appears to be stock, and untouched.
1. Fresh Amsoil synthetic oil and Filter installed.
2. Fresh set of AC Delco R44TS plugs gaped and installed.
3. Fresh set of AC Delco plug wires installed
4. New Coil Pack installed
5. New AC Delco Air Filter
6. Scanmaster installed today

Changing all of this stuff did not help the running rough issues I have been having.

All of the readings I got off the scanmaster today seem to be normal (I referenced the instruction manual of the scanmaster) with the exception of the timing retard. During several full throttle acceleration runs, I witnessed the timing retard jumped way above the manuals recommended 2-3. It jumped up to double digits range. 11 or so. I'm no expert, but this can't be good.

My intention is to keep this car mostly stock, I may consider doing some slight mod's to it in the future, but right now, my focus is on getting it sorted and running well before I do so.

Please advise.

Thanks, Rob.

 

[TurboTdr3.8]

I would install a Turbo Tweak chip and this may fix your double digit retards on WOT as your chip may be too aggressive . If you can post some SM readings and see if we see anything out of the ordinary .

 

[TurboTdr3.8]

X2

 

[salvageV6]

X3 on a TurboTweak street chip for the octane available in your area.

Also you need to check and verify fuel delivery at WOT with a gauge (temporary is ok).

Adjustable fuel reg., filter, and a good fuel pump are a must if not new/recently installed on the car.

 

[earlbrown]

I really need to make a post I can just link to....


chip, injectors, hotwire, fuel pump, timing set, cam button, breather bypass, spring cleaning, valve springs, check valves, vacuum hoses, etc, etc, etc....

 

[rob j]

Thanks for the replies so far. Yes, A Turbo Tweak chip is on my to do list. Before I go there, I'd like to address why the motor is not running smoothly. Why does it hesitate, stumble? Could this be related to the dated Hypertech chip? Could I have a clogged, bad, or tired injector?

Remember car only has 16k miles.

 

[TurboTdr3.8]

Like Earlbrown said it could be any of the things he posted and more , I worked on one the other day that was hesitating and slow to rev it was a tps reading was way off and this car was all stock and unmolested .

 

[rob j]

Like Earlbrown said it could be any of the things he posted and more , I worked on one the other day that was hesitating and slow to rev it was a tps reading was way off and this car was all stock and unmolested .

I checked the TPS readings on the Scanmaster today.

With engine off, key on, not touching the throttle it read .42
Floored it read 4.6
According to the Scan manual this is within normal range, correct?

 

[87-WE2]

Thanks for the replies so far. Yes, A Turbo Tweak chip is on my to do list. Before I go there, I'd like to address why the motor is not running smoothly. Why does it hesitate, stumble? Could this be related to the dated Hypertech chip? Could I have a clogged, bad, or tired injector?

Remember car only has 16k miles.

Your hesitation and stumble may very well be related to the chip. I speak from experience. My Gn was relatively stock when I first bought it and had terrible idle quality and a horrible stumble around 45 mph. New injectors and chip solved both issues immediately.

While earl's recommendations are valid, the most likely culprit of your wot retard issue is the chip and possibly fuel delivery (fuel pump hotwire and/or fuel pump itself).

 

[TurboTdr3.8]

I checked the TPS readings on the Scanmanster today.

With engine off, key on, not touching the throttle it read .42
Floored it read 4.6
According to the Scan manual this is within normal range, correct?

That's sounds OK

 

[87-WE2]

I really need to make a post I can just link to....


chip, injectors, hotwire, fuel pump, timing set, cam button, breather bypass, spring cleaning, valve springs, check valves, vacuum hoses, etc, etc, etc....

I'm glad you're still around and so willing to help with the same sh!t over and over and over.

 

[dynoman]

It may only have 16k miles but all the hoses , connectors ,& chip technology is 25 years old . You need to check everything Earl suggested. One bad connection or cracked vacuum hose can give you those problems. Good luck, Sam

 

[rob j]

I'm thinking my next course of action should be a new chip, injectors, and hotwire kit.

Should I bother replacing the fuel pump, or just do the hotwire kit first?

I did check all the hoses and vac lines today, all looks good.

This car has been kept in a climate controlled garage all of it's life. Things under the hood look brand new. It's amazing how well preserved this car is. It still has the factory delivered Eagle GT's on it. I checked the date codes to be sure.

I will also most likely put new tires on the car, to preserve the original ones.

 

[TurboTdr3.8]

Another thing check that DS header for a crack , my brothers stock GN had 24,000 mile and his was cracked

 

[Bescurred]

Pump and hotwire go hand and hand do them both at the same time.

 

[dynoman]

Don't change to many things at one time...Start with the chip to bring it up to current technology, and it's easy to do !!

 

[GNONYX]

X2 on changing one thing at a time
That's what I did and eventually as you can see my sig. I did what I wanted to replace.
The only thing I might need to do is to replace the valve spring; in due time

 

[earlbrown]

That chip was junk back when it was new and 'current' and your injectors have had fuel sitting in them for over 1/4 of a century. The fuel pump is undersized for a stocker and the power wire to feed it is substandard. The valve springs are too week to maintain proper valvetrain action. For those hard parts mileage isn't a factor, it's time.

I understand you only want to fix what it will take to fix the one running condition, and 99.9% of the time that makes perfect sense. I rarely recommend throwing parts at a problem.

...in this instance it's the wrong path. EVERY weak link these cars have HAS to be addressed. Any of them will ruin your day. And by 'day' I mean your wallet.

There is a long list of parts that I mentioned earlier. Omit one thing off that list and you have a car that is waiting until the worst possible time to puke it's guts out.

Right now chip technology has came so far the gas mileage gains alone necessitate getting a new chip and injectors. All the preventative maintenance has to be done before beating on the car.

 

[HighMileage]

I had the stumble problem you described. It occurred especially on the hiway at a steady speed. Smooth idle.

I checked all of the inexpensive,easy-to-check things first. (vac hoses) Changed ECM's and factory chips,fiddled with adjustments,spark plugs...

Replacing the stock injectors solved the problem.

Install the chip/60lb injector combo from TurboTweak,and notice how drivability will improve 100%.

Keep those old injectors in a box somewhere for originality purposes. ...but nobody is ever gonna install 'em again!

 

[rob j]

Yes, Earl, I agree. When I first got this car several years ago I was dead set on not touching it, and leaving it stock as to not affect it's value. The more that I've read, the more I believe certain upgrades are a must. I won't do anything to butcher the car, but I certainly want to improve on it's drivability and longevity.

Thanks for all the replies so far. Seems this forum is full of great knowledge and helpful folks.

Will order a chip and injector set Monday. How difficult it is changing the injectors on this car? Seems fairly tight in there. I need to also complete the rest of the spring cleaning items, and think I'll change plugs over to the 43's.