Compression across all 4 cyls=engine's timed correctly?

[Camsauce]

Been chasing down ECU code 21 for the ignition primary circuit and I want to rule out lower and upper chain timing on my ka24de.

I did a compression test and got perfect compression on all four cylinders, is that enough to rule out timing?

The marks on my cam sprockets and idler sprocket seem to be facing the right direction as per FSM, but my chain seems to be off one too. Not sure if PO is a dummy or it skipped a tooth

[Kingtal0n]

See how both lobes are pointing away from each other (cyl1) almost perfectly horizontal?

That is traditional for 4-cylinder engines, such as the sr20det. It does look like the chain is installed incorrectly, yet if the engine has perfect compression and you have that nice horizontal lobes while piston 1 is TDC (piston 1 is TDC in this picture right? That is 100% important) then I would say its timed right, regardless of how the chain is installed.

alternatively you could always check the FSM for more answers.

[Camsauce]

I know about the cam lobes, I've checked FSM. That's how I know the chain looks incorrectly installed although sprockets point in the right direction.

My question is if a solid compression test is enough to validate the engine timing being correct

[iJDM]

A good compression test isn't enough to verify the car is timed correctly. Timing could easily be off, while still having good compression. You need both of these things (obviously) for the engine to run properly.

Example: you could have lost compression in a cylinder due to a failed internal, yet the timing could be correct and unaffected. Likewise the timing could be off (jumped a tooth) but you could test compression and it still come back acceptable within specs

Engine compression and engine timing are not necessarily in direct relation to each other.

From looking at the picture I think that you should redo the timing. While you already have the engine semi-disassembled it would probably be a good idea to triple check it. Engine timing isn't something that you want to guess with. Do that and you could have some real problems once you put it back together and try to run it. Bent valves, I've seen that all too many times.

The solid compression test is good news. The code 21 you are talking about (primary ignition circuit) can be thrown by timing being off. I can't tell you over the Internet that is 100% your problem but after reading this thread and viewing the picture that's the direction I'd point you in....

Good luck to you sir

[Kingtal0n]

It depends on how many degrees each tooth is worth, whether an engine will still give good compression result or not. I tend to feel that no, if the timing were off a single tooth on either cam, it would systemically cause a low compression reading. It might be within spec still (service limit for example) but it should be lower than you would expect.

[specialk2003]

I wouldn't be too concerned with the chain marks lining up with the marks on the gears, if that's what you're concerned about. Once you crank the engine over, the marks aren't going to be lined up again for quite a few rotations of the engine. The marks on the chain appear to be the same distance from the marks on the gears. Another part of the mechanical timing that you want to be sure of is the crank. Make sure that the crank is in the correct position as well. If all three of these line up, then your problem is not with the mechanical timing.

My personal opinion would be to start checking all of the electrical in the ignition. Step one, make sure you have spark. If not, figure out why. If you do, make sure that your distributor is timed correctly.

[iJDM]

Originally Posted by Kingtal0n

It depends on how many degrees each tooth is worth, whether an engine will still give good compression result or not. I tend to feel that no, if the timing were off a single tooth on either cam, it would systemically cause a low compression reading. It might be within spec still (service limit for example) but it should be lower than you would expect.

Yes, that is also a good point. I was just trying to explain that I've seen cars come in my shop with compression within service limit and the timing been off. Seen it in plenty of Subaru and nissans.

In his case since timing is not off much, he could still get acceptable compression results which could be why he's confused and started this thread

OP before you put that engine back together I'd highly recommend that you make sure you 110% know the timing is correct before trying to push any further

[Camsauce]

Thanks for the help guys. Just some more info, I only pulled the engine to paint the bay. It ran before I pulled it, but when I removed the engine I pulled the distributor without marking it nor having it at TDC. Now it just cranks no start, before it would start and bog without holding idle. Other times it would smoothly rev itself to redline.

I've cranked it many times without bending valves or messing with the timing so I'm hoping timing is good. I haven't checked for fuel pressure, but I pulled out the rail with the harness hooked up and cranked it and saw fuel coming out of the injectors. I'm also getting spark on all four

[iJDM]

No problem man!

With what you just described I would certainly check the fuel pressure that's actually being given from your fuel system to the engine. You can rent a tester from auto zone or advance auto if you don't have one. Make sure the psi is within acceptable OEM specs

With the info provided your base engine timing sounds like it is correct. The distributor timing is likely off since it wasn't marked and at TDC. That also makes sense with your primary ignition circuit issue

Like I said it's tough to diagnose over the internet, but hopefully we can at least point you in the right direction.

[Camsauce]

iJDM I have a gauge coming in the mail later this week. For now I'm getting low voltage to the coil at 11.77 volts, but I'm getting both spark and fuel. Dizzy is pointing directly at the core support at cyl #1 position at TDC on comp stroke! I'm trying to follow the FSM directions for diagnosing code 21 but the electrical procedure is kinda tough for someone that's never messed with wiring and such