Car Runs but sounds of...


New Member
I have an '86 GN that I just dropped my rebuild 109 stroker motor in. The car runs but it sounds off.
The car has a rough start. When it's cold, I have to keep giving it gas while it cranks and cranks. After a few seconds it starts to fire then it gets better and better till it stays running on its own. When the car is running it sounds like a tractor. It lacks that distinct GN sound. It sounds like the timing is off but I have pictures of the timing chain lined up inside the motor and have set the Cam Sensor three times, so I know its in time. But when it sounds like a Hi-Lo I know something isn't right.
I need some HELP! I have changed the coil pack and module, new o2 sensor, changing computers, resetting the cam sensor, and changing mass air flows sensors. Some of the things I've tried has helped the car run better but it still has that overall Hi-Lo sounds. The headers start to really glow red when the o2 read low on the Scanmaster. Fuel pressures good and the TPS is good. I am running out of things to think of.
The thing that I don't understand is, I recently bought the car early this year and had a good running motor and trans it in. When I first brought it home I drove it around and it drove great. Pretty much a stock motor and an Art Car trans with a vigilante converter. Then I set that motor and trans aside and put in my build motor and trans. Now the car sounds like a tractor and I can't build more than 3 pounds of boost when I'm doing a brake torque.
I know something is wrong and I just want that distinct GN sound, I have used both sets of sensors from both set ups to try and see if that was the problem but nothing. I'm hoping you guys can help me!

Here's my set up:
109 '87 GN Block
Forged 3.625 Stroker Crank
Forged Rods
20 over JE Pistons
4 Steel Mains
212/206 Billet Roller Cam
Custom Made Pushrods
1.65 Scorpion Roller Rockers
Fully Ported Champion Aluminum Heads
Fully Ported Intake
70mm Hemco Plenum
70mm Throttle Body
72# High Impedance Injectors
Lt-76mm Turbo
Front mount Intercooler
Hard pipe to Cold Air by TinMan
Turbo Tweak Chip
ATR Headers
GN1 Down pipe with External Wastegate
2 1/2 Hook Exhaust with Dump
Build 200 4R Trans with a Vigilante 3600 Stall Converter

Thanks for taking the time to read my post. If you have anything please let me know. I have run out of things to think of so anything that I can try would be greatly appreciated.

- Justin


Well-Known Member
Is it misfiring? Are the injectors new or used if used how long have they been sitting? Fuel pressure is good. How is the volume?

Chuck Leeper

Toxic old bastard
Staff member
A SERIOUS vac leak will do what you are describing....
It's obviously lean when starting.
The red headers says it's lean.
The "tractor "sound says it's lean.
As mentioned, inj issues will cause what I've listed.
A compression check might show an issue, too. Like, the valves are not closing fully.
Keep running it, and trying to boost it, and it's toast.


Resident mad scientist
Staff member
did you degree the camshaft, or verify that the balancer Tdc mark was correct? Ignition timing that is very late/retarded will cause issues like that also.

or it might just be lean. Where did you get the injectors? Do you have a chip for injectors that are a bunch smaller (like 50's) you could try to see if it changes anything.



New Member
Hey guys, thanks for you replies. As an update on my progress I'll fill you guys in on whats been happening.

Since my post, I have gotten the to idle back to sounding more like a National. What I did was to take a half turn out of my roller rockers. Initially, I have set the rockers to Zero Lash on the push rods and then gave them one full turn. In most cars I have done a half turn is all you need but a lot of the times I get complaints from customers that the rockers are too loud. After taking the half turn out, the car really started to sound like a GN. Since I was there, I rechecked PushRod length, checks out. Put Machining Die on the top of the stem and rolled it over to see the wear marks of travel, also right on the money.

Unfortunately the car still have a lean issue. Once I got the car sounding like a car again I took it out and just drove like a normal car just putsing around the block and the car drove fine. Took off from lights great. BUT when you start to put your foot in it, it SERIOUSLY lacks power.

Crazy enough, after adjusting the rockers the car picked up Boost no problem. I can make as much Boost as the car will hold at a break torque and driving make 15+ Easy. I dont stay on it so I have not givin the car more then 15 but it makes it very quick and easy. The strange part about all of that is that the car make ZERO POWER. Even though the boost gauge is showing that the car is making plenty of boost it feels like the car is driving without a turbo on it. You know that feeling when your turbo goes and you feel like a Mini Van can take you! So I through new plugs and an 02 in the car but didnt seem to change anything.

Thanks for the advice Chopped39 with the injectors. It really got me thinking about the fuel delivery. So I put a fuel gauge on the car and the pump keeps up, pound for pound. When the car is idling I unplugged the cam sensor to make the car go into Batch Fire but it didnt seem to change much. The injectors got noisier and you can feel all them firing at the same time but it doesnt change the overall tone or idle of the car. Usually when you unplug that it sound really off but it this case the motor sounds the same plugged or unplugged. Then I decided the unplug an injector while the car was running but this even made a small difference and in some cylinders it was not even noticeable. So I changed the injectors to a 009 set I used to run and through a chip in there but pretty much the same response. This time when I unplugged an injector it really sounded like I had a dead hole.

Overall, the car seems to run ok at an idle but when there is a slight load on the car it drops to DEAD LEAN! The car would idle in drive fine, 02s in the 7-800s but all I have to do is turn the wheel a half turn to put a slight load on the car and the 02s just drop to 007-114, sometime 000. Just dead lean... When taking off, like I said it leaves ok, but when you would normally start to feel that GN pull it seem to choke and the 02s drop off for a second then seem to pick up again but never has that pull. 15+ pounds and nothing, just no power. So I thought my mufflers could of gotten clogged up to loose that much power so I open the dump on the exhaust but nothing changed.

Just by the was it sounds, I get the feeling that the components are not working together in some way. Like timing... But I have photos of everything from bar block to the crank and cam timing chain marks, to completely dressing the motor to running. I have photos every step of the way. If you guys wanna see anything, I'm pretty sure I got a pic of it and would be more then happy to share with you guys.

Something Generally just sounds off...

Thanks again for the comments and taking the time to read this post.

- Justin


Well-Known Member
Have you checked your fuel filter?? Is the arrow on it facing toward the front of the car? Lets see pics. of timing marks.


Gone To The Dark Side
Do you have a spare ECM you can try out? Mine did close to the same thing . Loss of power and fall on its face and back fire anything more than half throttle.


New Member
Hey guys, thanks again for the replays. I have done a few more things to it but nothing has seem to fix the main problem.

As for the fuel filter, it's going in the right direction. The car, with its original motor and trans, ran really well when I first brought the car home. I just put my built motor and trans in it so I assume I built the problem into the car.

I did use a different computer out of a good running car but still the same issues.

I checked for any vacuum leaks but I couldn't find anything. I used a can if brake clean all around the intake as well to see if the idle would change and it didn't. The gauge reads a consistent 13-15psi of vacuum.

I did do a compression test and they were all pretty consistent averaging around 100psi. I think the lowest was 90-95 and the highest was 100-105psi.

The block was not decked or shaved nor were the heads and I used .040 Cometic head gaskets.

In any case, any load on the car still makes the 02s fall dead lean and lacks power even though its showing boost.

Here are the pics of the cam and timing chain:

Thanks for your time and I hope we can figure this car out!

- Justin


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Staff member
100 is low , should be near 150

do a leak down and se what you get
if cam is in right than the valves arent sealing. possibly too much preload holding them open or they got bent