Well here is a little history first (since haven't posted on this board much - use to a lot on cnet (celica.net) back in the day though....

I had done a 3sgte engine swap and had a buddy do all the wiring for me (about 3 years ago). After finishing the mechanical stuff and putting th engine in, I found out the wiring was hosed. I took it to a shop to get it looked at and they put a microtech standalone ecu in it.

I finally got it running and it ran great for about 2 hours of usage and then just died on me. I haven't been able to restart it since then (but haven't been working on it too much)...

The pistons all seem to have really low compression (all around 90-100 psi). I am wondering if
1. what the compression should be.
2. if it is low, why is it low on all of the cylinders - does this mean the head gasket may have been put on wrong?? What could this imply?

Thanks for any assistance.
Ben

well, as for the compression #'s, if the motor is cold when you do it, the #'s will be lower overall.
did you hold the pedal to the floor when you did it?

>

I wasn't flooring it all the way, but I probably had aprox 75% open throttle...


This post has been edited by Celica_At_GT: Dec 16, 2005 - 8:20 AM

Check for vacume leaks, check your fuses, double check everything. make sure everything is tight. its most likely something small causeing your problems

So I shouldn't worry about those compression numbers at all. What values are normal for a cold 3sgte engine (JDM)?

Thanks - I'll double check the everything and have the stand-alone do another self check w/ it's sensors... hopefully it's something small like you said...

Check the sensors yourself, dont trust the standalone. its better to know for sure

>


Good Call...should I do the same process/resistance chart for the jdm engine as the us version. I only have the table for the us versions...

compression should be around 164 or more. try doing the test again, and follow these directions.
http://www.celicatech.com/93rmsour/1993/93...em/compress.pdf

did you or anyone take the head off during your swap? why did you do the swap 3 yrs ago, and not work on the car since?

is the car cranking? are you gretting fuel or spark ?

why didnt you take the car back to the place that installed the stand alone as soon as you noticed that the car didnt want to run after 2 hrs.

>

The head was taking off during the swap - new head gasket and ARP head studs put in. I haven't really been working on it much because I just started a new job and lived in an APT and couldn't have a spot to do massives amount of work.

Now I bought my house I can.

The shop went out of business so i'm hosed there. I was fighting with them for a while, but they where saying since they didn't do the entire swap - it must be other components. They weren't a very big help...

The starter is turning, and there's both fuel and spark... - running out of ideas...

Should the compression be 164 when it hasn't run, or after it warmed up? If it is after running, do you know what it should be when cold?

EDIT: as a side not - I don't think I put the head gasket on wrong - I've changed head gaskets/timing belts/etc... before but anything is possible I suppose...

This post has been edited by Celica_At_GT: Dec 16, 2005 - 3:44 PM

well... if you are getting spark and fuel, then chances are its not the ecu or harness...but you never know for sure with these things.

seeing as how you took the head off, there is a very good chance you might have done something wrong. you might not be getting a good seal. thats why its really a good idea not to mess with the head gasket unless you know its bad. you can never get as good of a seal as they did in the factory.

them min spec for compression is 128psi, so hot or cold, i think you need to get at least that in order for the car to start. google "compression test", there are a lot of tips and tricks to help you diagnose why the compression is that low.

when i bought my 3s, the guy who sold it did a cold test at my numbers were around 175 all accross. ... make sure you floor the gas pedal, pull out all the spark plugs, and watch the gauge as you are cranking it, every time you see the needle jump, thats 1 compression stroke. you should crank it for about 5 comression strokes.

>

Yeah, that's what I figured also. I don't think it's piston seals etc, due to the the compressoin being low on all of the cylinders...

Thanks for all the info - I'll do the recommendations and see what I find out.

>

I've never heard this. How could you never get as good of a seal? What if I replace my headgasket with a metal one? I've been debating plaining the head and putting in a metal head gasket. Sorry for the thread highjack Celica at GT. Wish I could help you, but I don't know enough.

>

No worries - no that you mention that - I'm curious of it too...

>
if the mating surfaces are not PERFECTLY flat, and SUPER clean, especially with a MHG, its will prolly leak at some point.
when your motor was at the factory being built, everything was brand new, and perfectly smooth and clean.
i wouldnt say "never" get a good seal, but without the proper prep work (IE: machine work ect.) things are bound to go wrong at some point.

This post has been edited by presure2: Dec 16, 2005 - 9:26 PM

>

Thats why you test it for flatness and get it machined if need be.

ok...i got a new saying then ....if it aint broke, dont fix it! lol

>

Yeah, that was my mistake (just like taking it to a shop that went under shortly after having my car - I can write a book about the pains w/ the CC company to get my money back...)

I was always told to do a new head gasket/timing belt/etc... with the JDM engines though - just becuase they are put through such abuse...

So back to the issue, do you think it's a faulty job putting on the head gasket...?

did u redo the compression test? what were your numbers this time around?

just gonna throw this out there but i was always told that if all the numbers are relativly close on the test then everything is more than likely ok. people do test differently. compression test dont tell you a lot, it would be different if you had one way low or two way different from the others.
-Aaron-

why didnt you go back to the shop that installed the standalone ECU and let them fix it. sounds to me llike something is not right there

>

Zipstrips,
They went out of business...so they aren't really returning calls. I've gotten most of my money back, besides the dealer cost of some of the parts (like stand alone...)



I redid the test and i was 90 on all of the pistons except number 4 had 60. These seem WAY to low to me. I then put a cap full of oil in each piston and waited a couple of minutes and the readings jumped up to 120....Guess that means the piston rings or bore is causing the problems, right?

i still dont fully trust your standalone. find another dealer local or call the company directly.

yeah thats not enough compression for the engine to start and like zip said, who knows what the stand alone is programed to do. ... but like it or not, looks like you have to take it apart again .

at least you are getting fuel and spark, so that gives some good sign that the ecu is trying to do its job.

It's time to install JE piston and do a oversize