Compresion test results:

Cyl # - Results
1 - 180
2 - 180
3 - 180
4 - 178
5 - 182
6 - 170

All in all, I'm happy with it.

I've been running SC'ed and "driving it like I stole it" for 1.5 years now....about 25k miles.

 

good info and congrats on having a solid motor

 

you boys are up late. congrats to the solid motor.

 

We also did a compression test on maximase86's 86 Maxima Engine with 210k on it.

195 across each and every cylinder!!!

I was like:

 

now thats impressive!

 

Good to hear, makes me feel more confident on my turbo future.

 

I put new plugs in today (BKR6E-11 - 1 step colder)

Gapped to .035.

Anyway - while I was in there I did another test just for the heck of it.

Keep in mind this is a different gauge.

1 - 180
2 - 180
3 - 180
4 - 174
5 - 184
6 - 170

The difference in 5&6 has me a little worried. I'll have to keep my eye on that. It's right on the line of what's "spec" according to the FSM.

 

This is what I got from Matts 6k mile VQ30 last week.

1. 204
2. 197
3. 198
4. 188
5. 195
6. 190


And from the 65k VQ30 that we had to remove

1. 151
2. 168
3. 176
4. 176
5. 6
6. 50


I did a compression test on a VQ35 a couple of weeks ago and got 216-204 across the board.

I hope you guys are pulling the ECU and fuel pump fuses before you spin your engine. It's very bad for the ECU to attempt to fire a coil that isn't there. You can easily fry a BMW DME by doing that.

 

Whats the proper way to do a compression test ?? Do you guys take out all the Plugs and go cyl to cyl and do it that way...or do it cyl by cyl taking out and replacing the pluf as you go along ??

-matt

 

I believe you take one out at a time.

 

I usually remove all of the plugs at once and go down each bank. I keep the starter spinning with the TB wide open untill the digital meter stops climbing.

 

most pull all the plugs and spin the engine for 4 or 5 seconds

 

According to the FSM, you pull all plugs then crank 5-7 times.

Interesting you ask however - because test #1 was pulling 1 plug at a time with all the coil packs disconnected, and #2 was with all plugs pulled.

As you can see, it doesn't make much difference.

 

And it also calls out the fuel pump fuse being removed and the TB being held open.

I'd do it the same way every time, that way the results are not skewed.

 

Yes - I did both of those things both times of course.

If you don't open the throttle you get readings 30-40 below what they really are.

If you don't pull the fuse, either your car tries to start (if you have any plugs and coil packs plugged in) or you spew fuel out of your open cylinders.

Yesterday I hadn't read the FSM - today I had.

Of course, my tank fuel pump is blown anyway (2nd Walbro in 2 months ).

Running fine off the T-Rex Aux pump.

Need to re-re-replace the Walbro ASAP however.

 

Where you buyin your walbro's from ??

I think mine is shot because at idle when put boost pressure (10psi with Midyvac) on the Cartech I dont get any fuel pressure past 55...witch it very strange to me..I cant understand...When I drive the car, it goes up to 80-90psi at full boost, so at full boost its fine.... ??? Dont know ???

-matt

 

Don't know where your problem lies....

But I bought both walbros brand new.

The 1st one may not be actually bad - I have to do some tests with it. I think maybe it was just installed at the wrong angle and wasn't catching the last 1/8th of a tank.

The 2nd one was from playing with the FMU on the Dyno and pushing my Fuel up to 120PSI on accident. (can you say 7:1 A/F and flames out of your exhaust?) Ran fine on the Dyno, but as soon as I left the shop it was doing 30PSI at idle and wouldn't go over 40 under boost. Car misfired and stuttered.

Thank god i left the T-Rex in and just had to pull over and hook it up.

 

There are some old threads about Walbro issues. You can't just slap those things in without trimming the two small barbs on the outlet side.

 

Did you mean to say "can't"?

 

 

ive done a few test on the vg30 Thats in my 3rd gen.

Before boost I had 180to 178 on each cylender

Now after running very lean and driving the **** out of it for almost 2 months
now I still have 180to 178 on each cylender.

 

I had 215 in each cylinder before I started boosting.

Seems the boost has kicked a lot of carbon out of the cylinders.

I also am running very lean up top. However, the new JWT Chip will be here tomorrow and fix that with the Z32 MAF running.

 

On the two cars I've tested I've gotten all 200+ PSI. Is that due to my method or just carbon buildup? One was mine with 135K and the other was VQuick with 85K. Is this alright? Is there any way to get the carbon out? Why is it bad to leave it in there? If you want a bit more power that would increase the CR right? Or does the carbon hold heat and cause pre-detonation?

 

seafoam or some other detergent that you feed through the vacuum lines