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Discussion Starter · #1 ·
I have a 1986 grand national and it shows a 42 code and the scanner says thaat it is a misfire in the engine I am not sure if what is common I have only had the car for 3 weeks and am a little unfamiler with these cars It also will jerk a 65 mph on the highway once in a great while and just die in town at idle and start right back up and run fine also if I am full throttle just before it shifts it acts like a govener cuts it right out and comes right back to life when it shifts and it also has somewhat of a low idle I think all the problems are related but I need to know what to replace first!!! please help out if you know anything
Thank you Jan
 

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It's either the C3I module itself which is located under the coil pack, or else the connector that plugs into it with the wiring from the drivers side of the car. Try cleaning the connections with some spray cleaner if it shows up intermittantly.

Connector is held on with a small bolt.

Coil pack comes off with 6 torx screws and the module is below it.

Good luck.
 

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Discussion Starter · #3 ·
Is this a part I should buy from GM or is this a after market piece that will work just as well???

Thank you
 

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Safe to stick with GM in my opinion on these kinda things.
 

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Don't ask Steve to think only adds to the Global Warming problem.....


Hey buy a Helm's service manual for that thing it's the best $70 you will ever spend.

Don't rely on the factory boost and tachometer to tell you much of anything either. Get some real gauges.

Good luck.




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WE4, Daily Driver, PTE51, 43lb. Bosch, THDP race cat., Postons Headers, 21/2"SS Ultraflows and pipes, 16 pos. Maxeffort thumbwheel chip, Bilsteins, Airbags/snubber,snows, 307 adj.reg./ gauges,scamaster and D.S.,BSTC,small stuff too. V4 IS IN!!! Not legal for racing.
GN loaded, mostly stock, car #2. 112K miles. Accufab reg. 160stat.,Scanmaster.
 

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Discussion Starter · #7 ·
Hey thanks you guys have been a big help for a new guy I am a tech but for Fords and have no experience on these cars. But I can tell you that is the most fun car I have ever owned.


I also own a 71 Dodge Challenger R/T 440 magnum and a 1965 Mustang convert. 289 4 spd
but the Grand National is funnnnnnnnnnn!! and fast!!!
 

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What everybody is correctly suggesting is that you upgrade the stock pieces before you crank it up. The factory system was designed for factory boost / fueling / derivability and emissions. If we want to go faster we are going to have to change some of the elements of the factory system. We are also going to need more information than the factory gauge package provided.
Ok can I have further clarification on the ADJ FP reg-wastegate
ADJ FP = Adjustable Fuel pressure regulator. This allows you to manually trim the fuel pressure. Every car has a different fuel pressure sweet spot so you are going to need the pieces to adjust yours also. More air is going to need more fuel. You'll also need a good, removable, fuel pressure gauge. Fuel pressure is generally measured "static", that is with the vacuum line removed from the regulator.
ADJ - wastegate = Adjustable wastegate. This allows for the same trim adjustments for your boost settings. Poor fuel/ hot day /high timing = less boost. Good fuel / dense cold air / less timing = more boost. Rock solid boost control is critical.
160 stat = 160 degree thermostat. This will keep the engine cooler and provide better performance. No downside on derivability except your heater won't blow as hot on the cold winter days. High boost creates high heat. We need to keep things cool under the hood from both a performance and longevity standpoint.
307-340 walbro hotwired = New Walbro 307 or 340 Fuel Pump. The stock fuel pump was marginal at best so we need to make sure we can flow the higher volumes of fuel at the higher HP levels. No downsides, it's an "in-tank" pump. Hotwired means running a hot wire from the alternator so the pump never goes low on voltage. Fuel pumps are like any other electric motor, they need adequate voltage to perform as designed.
FP and Boost gauge = Removable fuel pressure gauge so you know your settings and an aftermarket boost gauge. The stock boost gauge is notoriously inaccurate. You need precise boost and fuel information at all times.
Scantool = An absolute must. The various sensors on the car are constantly gathering information and sending that data to the computer. The computer in turn is making decisions based upon that input. The sensor data and the decisions the computer is making have a massive impact on the derivability and performance of the car.
You need to know both what information is being gathered by the sensors and what the computer is doing about it. The sensor data is the common denominator or langauge of our cars, we all gather the same information, we all speak the same language.
Scanmaster II is a great start, but if you already have a laptop then look into a data logger like
either TurboLink or Direct Scan.
Now that you have the adjustable features you need, adequate fueling and good information - it's time to safely crank up the horses!!. Traction will be your first "new" problem.
Where can I get this stuff how much?
Pricing will vary but I would call Mike at Ramchargers, Joe at Precision Turbo and Engine or Jack Cotton. Drop Ken Mosher a note if looking into TurboLink. All are great guys and all have helped me immensely over the years.
The above was prepared by Mile High GN.

After this is done you can go with a non-stock chip and turn up the boost.

The trasher is a good chip and only cost $25.

PS – You will also need a open air K & N filter.
Don't see what MODS you have but the above plus the spring cleaning on www.gnttype.org are the places to start.
 

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Originally posted by salvageV6:
Don't ask Steve to think only adds to the Global Warming problem.....



When the polar cap melts, You will have me to thanks for the water lapping up against your window felts!



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Steve Wood

Growing old is mandatory; growing up is optional.


86 GN bought new, 87 T-type-81 El Camino with GN drive train-basically stock 86, 94 Caprice 9C1, 69 SS396 Camaro Convertible
 

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ES?????????????

Have you fallen and can't get up???????????
 

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Originally posted by Steve Wood:
ahS#it??????????

I Have fallen and can't get up???????????
 

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For a moment I was sure you would have added "it" to the statement! Then I realized whom the editor is and I knew there was nothing to worry about!

I would say, "Keep it up", but I know the failure to is what keeps you here hassling ol' men!
 

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Its a givin that you cant get it up"When ya go over the hill theres no getting back up!
 

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There are two sides to every equation...top and bottom (which does sound a bit oxymoronish but what the heck? Turbonics will soon displace ebonics as the number two preferred form of communication if these boards stay in existence)
 
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