Vibrating car..

Ok so I've fixed my egr tube, replaced all lower intake gaskets, replaced all vacuum lines, replaced spark plugs and wires(cheap wires) cleaned off the spark plug adapter thingy(still learning) replaced fuel pump, replaced master cycle see do it was leaking out of the top of the brake booster line( leaked out of adapter to firewall and brake poster line that connected). I think that's about it, but CAR STILL VIBRATES:( I can't figure out what else would be the culprit, I've also sprayed starter fluid everywhere! No check engine light

Did you check all the engine/trans mounts to make sure that the engine isn't sitting against the chassis?

I'd try a good set of spark plug wires. You may want to try a little trick with the fuel injectors -

try disconnecting the electrical plug to one fuel injector at a time. Each one you disconnect should introduce a miss/vibration. Hook it back up and it should go back to normal. One of them may introduce no change. If so, you might have found a bad injector.

I'll check the motor and transmission mounts, how do I know if their bad? And I'll try the injector trick, and if these don't work, I'm going to get a good set of oem spark plug wires, any other sudjestions, like should I clean anything to help, I've already clean the maf sensor with some maf cleaner.

Just checked the injectors, I have a boost guage, would that cause it to vibrate? There's no leaks in it

bmcd9179 wrote:

Just checked the injectors, I have a boost guage, would that cause it to vibrate? There's no leaks in it

It would if it were causing a vacuum leak. How is it hooked up? Can you disconnect it and plug the opening?

Interesting. It is a cheap gauge, i will check it tomorrow and buy a new vacuum line, if that is what's going on, then I will just take the gauge out. My car struggles to start up, it will spit and sputter but once I give it throttle it's fine, it's been doing that for a week now, what the heck is that all about? I swear one problem to the next but hey it is running way better then I first got the car

Go over your entire intake connection. Is your IAT sensor hooked up right?

I have the cold air intake, and the IAT sensor is right next to it, I just unpluged it from the stock air box and took the stock one out, and I plugged it back in and set it right next to the intake, not proffesional but idk would it be ok? Could the sensor be bad?

bmcd9179 wrote:

I have the cold air intake, and the IAT sensor is right next to it, I just unpluged it from the stock air box and took the stock one out, and I plugged it back in and set it right next to the intake, not proffesional but idk would it be ok? Could the sensor be bad?

By leaving the IAT hanging next to the Intake, you're going to be measuring actual outside air temp, or engine bay temp, NOT intake air temp. That thing NEEDS to be mounted inside the intake tube, otherwise the engine isn't going to run properly at all. That little tiny sensor plays a HUGE role in engine fueling and spark advance/retard. If it's measuring too cold of an intake air temp, it will cause the engine to run way too rich.

Interesting, I thought I read that people actually unplug and call it good, alright I'll put the stock intake back on and call it good till I do something better for it, I will get back to this after I do this

So I gutted my air box while I was at it, put everything back to stock, and WOW I have much more power then before! And the vibration is nearly even noticeable, barely even there now much smoother, I'm considering ditching the cone glitter and getting a knn, one for just the stock box.

Cool stuff. That IAT sensor is more important than you think. Trust me, you didn't read ANYWHERE (on this site) about someone unplugging the IAT and calling it good. If they did, they'd get an ear-full.

May I ask what kind of Intake/filter you had on it? I know of a few companies that offer CAI's for the 3.8L, but they work worth shit and cause exactly what you were experiencing.

I have a 50$ spectra cold air intake 9 inch long?

I guess that's ok as long there isn't an Air Foil or something like that inside the duct/piping to interrupt the airflow, and the tube is the same size (or damn close) to 68mm. I'm betting that just the IAT not being inside the pipe is/was the problem.

What would an air foil be if u can describe that a little more? And how could I get the sensor in the tube??

A good example of a junk CAI is the Weapon "R" system.

Here is a LINK to a pic.

Anything inside the Intake tubes on our S/C'd 3800 will severely affect the way the engine runs. It swirls the incoming air, and most of it misses the MAF sensor, causing adverse running conditions.
The same goes for the IAT sensor. If it cannot read ACTUAL intake air temp, engine fueling and timing is affected quite a bit.

All the S/C needs is air. It doesn't need to be redirected, swirled, or anything else. That's one reason why the Throttle Body has that honeycomb thing in it. It's there to split up the incoming air to get an even flow across the MAF.

bmcd9179 wrote:

And how could I get the sensor in the tube??

You can build your own cold air intake or fwi. Drill a hole in the tube for the sensor. There is more information in the write ups if you want to go that route. The filter really should have its own shield or be in the fender to keep the heat out.

I had an elbow in my past intake made from PVC, and drilled a hole and used a file to notch so that the IAT sensor mounted back into that elbow just like the hole that used to be in the OEM airbox. Eventually I changed to a whole different setup, but that worked well when I just had a cone.

I can say that the gutted airbox works extremely well and is really all you need for a long ways. You don't get the earful of supercharger, but it actually works great. If you notice, the gutted airbox is already a "CAI" as in it draws it's air source through the holes to outside the engine bay. For a long time I had the gutted airbox and I used a bunch of insulating foam strips to seal it to the outside holes, and had excellent intake air temps. We actually might restore my (brother's) Riv to that setup in the near future.

Agreed. I've been running a gutted air box the whole time. It draws air in from the fender, and I cut a hole underneath the box (in the chassis) to draw air in that way, and also from the headlight opening. It works great. Best part is, nobody knows it's there. It all looks stock