Compression results...talk to me guys

[vickyvp]

180,170,160,162

We just dropped this 99 engine in. The seller said they 'didn't get a chance' to test compression before we went out the door with it.

have we just spent the last 4 days for nothing? Is this an ok compression or no?
This is a 99 SL1 SOHC 1.9L with 74,000 miles

[VUEmaniac]

Originally Posted by vickyvp

180,170,160,162

We just dropped this 99 engine in. The seller said they 'didn't get a chance' to test compression before we went out the door with it.

have we just spent the last 4 days for nothing? Is this an ok compression or no?
This is a 99 SL1 SOHC 1.9L with 74,000 miles

180 is about what I'd expect in a used engine. 170 is on the ragged edge of what I'd accept. 160/162 are unacceptable.

[saturn94v]

Originally Posted by vickyvp

180,170,160,162

We just dropped this 99 engine in. The seller said they 'didn't get a chance' to test compression before we went out the door with it.

have we just spent the last 4 days for nothing? Is this an ok compression or no?
This is a 99 SL1 SOHC 1.9L with 74,000 miles

Factory spec is 190 psi
185 is also considered good.
160 & 162 is more than a little low.

When running the test, did you: ??

Run engine to full operating temp? (a warm engine is needed for proper results)
disable the fuel system?
Remove all spark plugs?
Make sure your battery was fully charged?
Depress the accelerator to wide open throttle for every cylinder tested?
Crank the engine a whole revolution? [4 cranks]

P.S; During a compression test, the first and second bump should exhibit the most psi. Meaning: on the first crank the reading should bump well over 100 psi on a good cylinder.
ALSO: On the two cylinders that read 160 & 162 respectively, add 2-3 tsp of engine oil. Then complete compression test on those two cylinders again.
If the psi rises: the piston rings are your issue.
If the psi stays close to the same 160 psi reading: You have a valve train issue.
If the valves prove to be the issue: next complete cylinder leak down test to determine if its the intake or exhaust valves.[you will need shop air and a special compression/leak-down gauge]

My '94 SC-1 SOHC reads 185, 185, 180, 155
been like that for a couple years now. It has 274, 000 miles on it.

[vickyvp]

HOW do we disable the fuel system?

We re-ran the compression test with WARM engine and dry tested
178 170 175 170

added a bit of oil to each cylinder (1 tsp?)
195 185 190 185

BUT did not disable fuel system (HOW??)
did not open throttle...

will re-run test when somebody explains how to disable fuel system...

Tkx guys!...

[fetchitfido]

Pull fuel pump relay or
Pull fuel pump fuse or
Pull wiring to injectors or
Pull one of the PCM fuses (I know "B" is PCM memory...dunno if it turns off PCM as well...)



Lots of options. There might be a better one I'm not thinking of or don't know of though.

[vickyvp]

where is the fuel pump relay or fuse?

[fetchitfido]

Bottom right corner of the in cabin fuse box. It's below the radio on the passenger side, pull the panel off and it should have a fuse diagram on it....if not then the owners manual does and the good Chilton's' might.

[madpogue]

PCM I (may be PCM 1 in your case) fuse is probably the easiset. Should disable both spark and fuel.

Those numbers could easily be explained by the fact that you didn't have the throttle open.

[vickyvp]

ok, with the fuse pulled for fuel pump
engine warm, all plugs pulled, all cyl wet (1 tsp oil in cyl) throttle open
185 185 185 180

dry and cold it was 180 170 160 162

here's the thing...on the other thread I posted the you tube of the idle:
w w w .youtube.com/watch?v=porMCMlwAL0
and comment is that it is definitely missing...
this is our last $800 to get this car going (my way to get my grandkids to school) and I wondering if we have spent this money well.. The guy at the recycle yard said because they didn't do compression test, they would let us return it. (Forget the 4 days wasted getting it in, right?)

Honest opinion...do we keep this as is? Live with it missing? Is the compression good enough? Not looking for mind readers - just HONEST opinions

[bigalpha]

Did you test it warm and dry?

[vickyvp]

The last test that we did, we did not add more oil. I don't know how long you wait between wet and dry. The test prior to that was the wet test. We let the car run another 5 minutes prior to doing the last test, then did the test that came up with the 185 185 185 180 I'm assuming all the oil was outta there, or at least for the most part.

[madpogue]

Those numbers look better. Not great, but a good-running engine.

Having run the engine, that oil was burned off within milliseconds.

[VUEmaniac]

Originally Posted by madpogue

Those numbers look better. Not great, but a good-running engine.

Having run the engine, that oil was burned off within milliseconds.

Agreed. Those numbers are acceptable. I'd look at traditional sources of missing now...plugs/wires/coils/vacuum leaks/etc. I'd also change the fuel and air filters.

[saturn94v]

Originally Posted by VUEmaniac

Agreed. Those numbers are acceptable. I'd look at traditional sources of missing now...plugs/wires/coils/vacuum leaks/etc. I'd also change the fuel and air filters.

I ALSO AGREE...Those compression numbers are what I would expect from a used engine. Safe to say that Engine compression is NOT your source of the rough running/misfire.
Check traditional means: plugs/wires/firing order.
Also check your fuel injectors on the fuel rail. The "O" rings could be leaking.
I all ways use new 'O' rings and seals on fuel components. It is also easy to clog an injector during removal & installation.
Confirm Ignition System is operating to spec; then if problem still exists, move on to Fuel System.
You must locate and repair the source of the rough running! Or your $800 will be wasted!
Also check all your Vacuum Lines, PCV, MAP Sensor.
Perform an Engine Vacuum Test: your reading should be between
18 - 20 in hg if it is much less, you have a major vac leak.
I'd be looking for a vac leak- it would explain the high idle you are having.
It should idle around 750 RPM

Good-Luck!

[magtec]

i've been sort of following your various threads. just a suggestion: it would be easier to keep track of what's going on if you kept it all to a single thread. that said...

iirc, you stated in a previous thread that you "swapped injectors" when you installed the '99 motor in the '95 car. did you mean that you used the '99 injectors? from what i've read, and someone please correct me if i'm wrong, you need to use the '95 injectors because the '99s are higher resistance and won't work properly with the '95 computer.

[madpogue]

Originally Posted by magtec

i've been sort of following your various threads. just a suggestion: it would be easier to keep track of what's going on if you kept it all to a single thread. that said...

Already mentioned, but it's in another thread....

iirc, you stated in a previous thread that you "swapped injectors" when you installed the '99 motor in the '95 car. did you mean that you used the '99 injectors? from what i've read, and someone please correct me if i'm wrong, you need to use the '95 injectors because the '99s are higher resistance and won't work properly with the '95 computer.

She's using the '95 rail/injectors, but swapped one injector in from the '99 donor, but that's in another thread as well...

[Mechanized]

What is the Saturn factory differential between cyls in that motor?
Those readings look good for a used engine. You don't want the same # across the board, but rather a certain range. A Haynes manual should tell you the maximum allowable differential. You may be near the limit with 160 and a 180 right next to it; but I doubt very much. Its usually 20-25psi, iirc.
Turbo motors I work on are much stricter (10-15psi max)

For insurance throw some steel seal in there. That will patch up any leaks in your HG between cylinders.

[vickyvp]

Sorry about the multiple threads...thought I had to create new for ea topic. We will stick to this one.

We don't have an Engine Vacuum Tester. I guess we need to buy? as I can't find a rental
Husband is going to buy new o-rings/seals for the fuel injectors. Yes, we used the 95 injectors but have some concern as one looked burnt. Possibly pick up a spare at pull-a-part yard ($4.00)

We are putting the wheels back on tonight...

Is it possible this will even out after driving for a bit? Don't the computers have to 'sync up'?

[madpogue]

Originally Posted by vickyvp

Sorry about the multiple threads...thought I had to create new for ea topic. We will stick to this one.

If they were unrelated, yeah, it would be best to start separate threads. But since this is one of those "one thing leads to another" processes, keeping it together seems to work better.

Or at least, when moving on from one issue to another, you can reply to the one thread saying "okay, I've figured this out; on to ....., new thread, meet ya there..." before starting the new one.

We don't have an Engine Vacuum Tester. I guess we need to buy? as I can't find a rental
Husband is going to buy new o-rings/seals for the fuel injectors. Yes, we used the 95 injectors but have some concern as one looked burnt. Possibly pick up a spare at pull-a-part yard ($4.00)

We are putting the wheels back on tonight...

Is it possible this will even out after driving for a bit? Don't the computers have to 'sync up'?

One bad injector could make it run unevenly. For four bucks (make sure it's the right one, not for a later year car), it's def worth a try. There is only one PCM, so no multiple computers to sync up. An engine swap is a replacement of mechanical devices (moving parts); the car retains its electronics, so there's no relearning or resyncing or reprogramming necessary.

Shoot, for four bucks a pop, you might want to grab a whole set of injectors from one car, just so you know they all have a uniform history.

[magtec]

just for clarification, if this hasn't been gone over already in another thread: you NEED to use '95 injectors. based on what i've read, the '99 injectors will make the engine run lean, which can physically damage the engine (e.g. burned exhaust valves).