Ca18 issues

[Crozier]

Hey I'm pretty new here but anyways here's my problem, back in July I decided to replace my head gasket because it was leaking. While I had my head off I sold my motorcycle and decided to upgrade to a t28. I installed the new head gasket to torque specs put the t28 on upgraded to 550cc injectors, a walboro fuel pump, Megan fpr and nistune installed on my ecu. Made sure my timing was right and cranked it over and nothing. So I put a stock ecu in and same problem except it backfired once. Ran a compression test and the numbers were pretty low in order they were 1-90 2-90 3-55 4-95. I know I'm getting spark fuel and air, but any ideas on why compression is so low now would help a lot

[Croustibat]

Your engine is worn. It needs a rebuild.

Or ... you made your compression test with a weak battery, and/or were not holding the throttle wide open.

Do another compression test and add a spoon of oil in every cylinder . If comps go up, your rings are done for (at least).

BTW you might want to bin the megan FPR, it wont do any good.

You may also want to get an SR20DET MAF, because the CA MAF will be maxed out at around 0.6/0.7bar on a T28. Also, change the 2 bolts holding the T28 actuator for 5mm longer ones, and stack 5mm shims between turbo and actuator, otherwise it will boost to 0.4bar (which is slower than the oem T25), and you wont be able to get a stable boost regulation when going up to 1bar and more.

Did you use the "resize injector" feature in the nistune software ? If not, do it. Stock ECU wont work because of that. Does the nistune give you any error code ?

[Crozier]

I did do the resize injectors. Set it up for the ca maf (about to put in z32 one) and yeah that was a dry test with throttle closed. Car ran fine before I broke it down. I took the head off and everything looked fine. And no error codes appear on nistune

[Crozier]

Any help would be great

[boyou2]

there's no link between code errors and weak compressions

do what croustibat said, and tell us if the compressions goes up.

Did the head been tested??

It may be damaged to.

[Croustibat]

throttle closed = readings are off . Try again with throttle wide open, and then with a wet test.

Maybe your head needed a skim and is not sealing right.

No error codes mean your sensors are in GWO.

Are you sure you set the timing belt correctly ? If cams are not set properly, they can have more overlap, leading to less compression.

[boyou2]

another thing, backfires : CAS correctly set?

[Crozier]

Ill be taking the head to the machine shop tomorrow. As far as the timing goes, set number one cylinder to tdc and set the cams to the proper marks. I did run into one problem with the cas, the key on the cam gear(half moon shaped piece and cas has half moon shaped key) broke but I'm a hundred percent it's lined up right. I'm also using new oem head gaskets and the stock head studs, may go with arp though.

[Crozier]

But how can I know for certain cas is properly lined. Another thing, compression was good before removing the head, why would compression go down after putting it back together except for maybe the head needing a resurface

[Crozier]

Update, took the head to the machine shop and it needed 9 one thousandths machined from it which is quite a lot. Had 4 bent intake valves so had new ones put in along with all new valve seals. Installed another new head gasket and put it all back together tried starting it and still won't start at this point I'm ready to throw the towel in and call it quits with this engine.

[humilde_s13]

NOOO fix it so we can roll ca18 together lol if you need any ca parts lmk

[Crozier]

Ill be doing a compression test tomorrow and hopefully that turns out all good. If it doesn't ill just build the bottom end. Only other thing I can think of is wether or not my nistune is programmed correctly

[humilde_s13]

are you still looking for a ca head? cuz I haz one.

[Crozier]

No. I actually have an extra one now lol

[humilde_s13]

alright kool

[omgRWDgoodness!]

If you had 4 bent valves, that's where all your compression was going...little/no compression = no start. That also means you probably reinstalled your camshafts incorrectly. You'd better hope you didn't just bend more valves. Re-read the FSM!!

[Crozier]

I'm a hundred percent sure timing is set right. I did another compression test and it was 125 on all four cylinders. Added a spoon full of oil to each cylinder and it bumped it up to 150 in each so I'm thinking rings. On the plus side it was turning over and sputtered a couple times and backfired twice

[Clarke240]

Its also going to read low with a cold motor. The wet test isnt looking great, but reas up on Nico what the average cold compression test numbers are.

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