domsgarage

on the JDM motor I just dropped in.

Reads like this, from front back to front...


180 ----------------------------- 145-150


180 ----------------------------- 160


170 ----------------------------- 175


Intake -------- Throttle Body -------- Intake



Should I worried about the 145-150 and the 160 in comparison to the rest of the cylinders?

Ive got a miss some where. Its not injectors 5 of them read 12.5, 1 reads 12.7 and I cleaned all of the corrosion off of them and tested them both at the injector and through the wires of a harness and they all read well.

I tried checking spark with the old plug on the plenum test but none of them sparked, i dont know why. The car runs so theres obviously spark and if they were all that weak where they wouldnt spark on a piece of metal it wouldnt start right?

Same thing happened with my jeep, i saw no spark on any plug but the car runs fine.

ZLover4Life

There should not be more than a ~15 psi deviation between cylinders, so yes, you should be concerned that the 4 and 6 cylinders are low.

As for the misfire, does it always misfire or just under certain circumstances?

domsgarage

it feels like it did when i had a bad injector. fuel pressure is good too though, injectors all read good.

it feels really sluggish, sounds like a v8 kind of. back fires from time to time, not always, just once in a while.

domsgarage

i tried to take a video but the sound wasnt that great.

domsgarage

could it be a timing issue?

at first a friend told me that might be why it was running so rough so i messed with it a little bit but i positioned the sensor back to where it was before i messed with it.

i gotta find my timing light i guess.

domsgarage

sorry, but another question referring to the compression test is.

i read on twinturbo.net to have the car at normal running temperature to do the compression test.

ive tested for compression before but I decided to just look it up real quick before i got into it.

the low cylinders are the last ones that i tested, could the engine cooling down have anything to do with low numbers?

ZLover4Life

The metal in the engine doesn't cool down all that quickly. Unless you were super slow on the test, I doubt that's contributing.

Timing could cause it... yes, find a timing light.

domsgarage

I guess it took like 40 minutes or so to do the test.

The motor wasnt that hot, ill check the timing, let it run for a little bit and then check those cylinders again.

they were the last two i checked which is why i thought about it cooling down. I didnt let it get that high in temp to begin with.

ZLover4Life

if the needle was in the normal operating range of the gauge (around the middle), then it was sufficiently warmed up.

And I'm not trying to **** in your Wheaties, but rather prepare you for the disappointment - your new test will show the same problem... too much deviation between cylinders.

domsgarage

It wasnt, at all.

I let it warm up so it was maybe just about the C on the temp gauge.

Ive never heard of warming the engine before the test until i read it in the TT write up.

The worst thing is that I have to pull the motor out and drive it back to philly.

I have a 6 month warranty on it. I dont really want to do that at all but I also dont want to be stuck with a **** motor.

domsgarage

Furthermore, i dont eat Wheaties.

ZLover4Life

The reason that you're supposed to warm up the engine is because expanding metal changes the pistons' shape. When they're not at operating temperature, they're actually oval (ever so slightly). When they heat up, due to the piston skirts, the piston expands differently in different spots, ultimately resulting in a circular piston (which seals more effectively in the circular cylinder).