Compression 60, 60, 100, 100 (1,3,2,4) Whats wrong?

[Subarutex]

Both check out just fine with a volt meter.

 

Another problem the car has: When holding the throttle at 2500 it will drop, to about 1300, then rev back up, then immediately drop back to 1300. However its done this ever since I swapped to the spider intake and its TPS. I've rewired it several times too...

 

I am concerned about the MAF voltage being thrown out of whack by the SAFC when it exceeds 5v. I'm trying to determine if the SAFC caps voltage at 5v on output, or just won't modify anything over 5v.

 

Oi.

[Cougar]

I don't think any of the things mentioned will create the low compression like you have. You really need to check the valve timing.

[JWX]

I really think its the safc interupting voltage to the ecu, making it confused. the low comp numbers are prolly all the fuel washing out the ring sealing, or the CUHGs.

[Mark Humble]

First check cam timing. A cam that is timed too late will leave the intake valve open as the piston is on the up stroke so there won't be as much air to compress in the first place. If the cam timing is correct, then do a leak down test. Be sure to follow the instructions in the leak down tester or the engine might bite you. Opening the throttle for compression test should be done, but the reason this should be done is to get to the highest reading with the least amount of cranking, and on engines with carbs, to keep from sucking in to much fuel into the engine. As for engine break in, the cam is the first thing that needs to be broken in. This is done by running the engine at 2000 to 2500 rpm for at least 15 min. right after first start up. As soon as the engine first starts, run the rpms up, don't wait, run it up. After that, check all the other stuff, ing. timing ect. Then its time to drive it, (sensibly). Given time the rest of the parts will break in. If the cams where used in another engine, well, there is no way to break them in again and they may or may not live.

[nipper]

have you done a wets compression test. I know alot of sites say it cant be done, but it can on a sooby. If the numbers come up you have tired rings, if they dont you have tired valves

 

 

nipper

[oddcomp]

keep in mind i never read any further than page one so....

 

my.00000000002 cents on the issue

it will certainly allow it to run but not very well especially on these motors it seems with the dual timing belts

all it takes is for half the motor to run sorta well and that half will most likely be the drivers side with the disty

 

and yes it will in fact affect compression

[Danbob99]

Hey, just a thought, i'm suprised that we havn't done this yet, but we really aughta do a running compresion test on your car to see what it does then...

[fbh]

Any neat method to check if a piston is at TDC? I spose just a good penlight shining down in there would do decent...

 

I'm jumping in a bit late here, I know, but this is a nice trick methinks. Works for inline-4's anyway.

 

Tape two kebab sticks together and stick that down the spark plug hole. Turn the engine (by hand) until the stick "peaks"

[4x4_Welder]

IIRC, #1 and 3 TDC is established with the numbered lines on the flywheel, and the others are established with a dot on the flywheel. I'm probably wrong, I'm a lot better with 300-6 engines and FE series Fords.