rebuilt engine low compression no start. PLEASE HELP

[dsmcurse]

okay i put a hx40 on a internally stock motor and busted to ring lands on number 1 and 3 piston. took car apart and put all the sensors and bolt on parts on the shelf in garage. took me a year to save and buy all the parts for rebuild. so fast forward a year later and i have my dsm rebuilt and ready to go but she wont start. 6bolt block was decked and done .20 by a reputable machinest. i have ross pistons and rings in there, a never been shaved 6bolt head with excellent headgasket surface and 16 new oem valves in it. car just cranks and cranks and cranks. wont fire. i have 40 psi right at the rail. new 780s that i used last year i know they work. i have excellent spark. i use a stock coilpack with 8mm wires and ngkbpr6es plugs. i turn engine over untill the timing marks all line up timing belts is on correctly. my cam marks line up straight across, the dowel pins in cam sprockets are up, my crank mark is dead on. it wont start! i hear little puffs out the muffler like it wants to do it but it just wont. then i end up with fuel soaked sparkplugs. i do a compression test it has 75psi all 4 cylinders. WHAT THE HECK ONLY 75PSI! there all consistant but low. i can only explain this by the fact that its pure cold metal, no heat expansion. Plus the fact that my new rings arent seated into the fresh hone job. Is this correct? to my understanding once i get it started i let it run for like 30min straight at like 1800-2200RPM that seats my rings into the new hone right? after this my compression will double right? like 150psi when i do this test on my "warmed up to normal operating temp" motor right? should i be scared that its only 75psi right now? im a mechanic by trade, i hold a wrench for a living so i got a pretty good understanding of what im doin but dang it wont start! ive been told that my big fuel system is washing down the cylinders making my compression worse, put stock 450s in there for initial start up. is that what i should do? ive been told that since my starter only spins engine at 350-450rpm its not enough engine speed to create enough compression to have compustion and that i should tow start it in 2nd gear at about 20mph, force on the rpm and itll start. is that right? my cam sensor is not 180 out the speacial mark is correct. if that thing took a dump on me from just sittin my shelf spark plug wires wouldnt work but they do. is it possible that my ecu went out? im totally stressed on this you guys. all i wanna do is drive the thing and enjoy it. please help. any advice would be super helpfull. thanks in advance. Tristen.

 

[92AWDHX40]

Well compression that low, sounds like valves are bent, these engines are picky, have you done a timing belt job before? Is your battery charged?, i have valves that just nicked the pistons and it didnt start. So i was at the shop with my head again.

 

[kenamond]

How are you compensating for the larger injectors? SAFC? ECM/DSMlink? If you don't have anything on the car to compensate for those injectors, you might be *way* rich, and the car won't start. In that case, put the 450s back in and try. I'm not sure what compression you should expect for a freshly rebuilt motor, though.

 

[rstchris]

Most of the time when you fuel soak a plug and soot it it won't come back. Replace the plugs, stock injectors, stock fuel pressure, no fuel compensation. 350-450 rpm is acually more than most people see during crank. check the firing order again cause if there's spark and fuel (within reason) it should run. I never checked compression on a fresh build before cause it's usually a waste of time til the rings get filed.

 

[bnr32_coupe]

are you sure your valves are seating properly?
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[dsmcurse]

16 new valves, timing belt is on correctly, have changed the timing belt somany times in the past i could do it blind folded. its deffinatley on right. the valves are new. the correction is a chiped eprom ecu. i used this fuel set up last year when i was runnin a 60trim. a guy i know socketed my ecu and burned me a chip so my 780's run like stock. i have afc but dont have to pull correction. i just use it for knock sensor gauge. if for some reason some of my valves wernt seated my compression would flucuate from cylinder to cylinder. i poor a cap full of oil down the spark plug holes and do another compression test and it bumps up a few psi. which totally tells me rings. im not a expert but i think my compression will get normall after it runs for 20-30min. has any one rebuilt one of these thing and just had a SUPER HARD time with the initial start up? whats the deal? i dont know what to do. and whats the deal with ECU's having "leaky capaciters" that they can just magically fail? i have ecu power tho or my afc wouldnt turn on with the key.

 

[Afroclipse]

I had a similar problem with my baby she wouldn't start for shit, check you cam sensor, they usually fail and that would cause a serious no start problem, if you have access to a 1g cas upgrade to that and all your starting issues should be fixed. By the way did you pull your fuel rail and make sure the injectors are firing.

 

[dsmcurse]

its a 6bolt in a 2g. the cam sensor has a lil center punch mark like a dot when you install it the dot is soppossed to be near the line in the body of the camsensor like where the o-ring is. its installed right. its not 180 out. the thing is from a 92. someone told me that theres somethin speacial about a 94 cas and they cut back on the random misfire issue that comes with a 6bolt in a 95-96 car. i dont know. is it possible the cam sensor could still make my spark plugs work just not comunicate the cylinder position part to the ecu? cause my plugs do indeed make fire. and my injectors do indeed squirt fuel. son of a b#!&* jus wont start. should i do a tow start and force it to?

 

[dsmcurse]

okay i found a stock non chiped 2g ecu. its from a auto but i dont think it matters. i rounded up some stocker 450's. you guys just think i should try switchin to this and give it another try? should i tow start it with the help of a buddy? maybe 20mph, 2nd gear let the clutch out nice and easy. does the tow start sound like a bad idea? this initial start up is MUCH harder than what i thought it was gonna be!

 

[1bad95tsi]

If your car is a 5-spd i dont believe an auto ecu will work - my buddy thought his was bad in his 97 gst brought it to my house to borrow one of mine and the plugs on my 5spd ecu,s were different - it wouldnt even plug in

 

[92AWDHX40]

Hey i hope you figure it out, i sware i have had my dsm tore apart for this and that, i trouble shoot, my car it just takes time before i figure out my problems.

 

[Afroclipse]

If your car is a 5-spd i dont believe an auto ecu will work - my buddy thought his was bad in his 97 gst brought it to my house to borrow one of mine and the plugs on my 5spd ecu,s were different - it wouldnt even plug in

It will work, both the auto's and manuals run the same ecu, only difference is that auto's have no clutch switch.

 

[dsmcurse]

no the ecu from a auto does indeed fit. the auto crs come with 2 ecu's. a brain box for engine and a seperate brain box for tranny. i know this cause my car was a auto. i did the 5speed swap like 3 years ago at the same time i did the 6bolt swap. i totally ditched the autowire harness for a 5speed and used the 5speed ecu just for good measure. that 5spd ecu was indeed EProm. so like i said that thing is chiped for 780s. i kinda think that the 780's are washin down my cylinders makin such low compression that it wont create combustion. i have to think that fuel is a detergant, its a solvent that cleans away all my oil in there makin just metal to metal and air easily escapes past the new rings because there not seated. well thats my beleife any how. tomorrow im gonna try the 450cc injectors with a non chiped ecu. the auto ecu has 2 large plastic plug ins one medeium sized plug in and one small plastic plugin(where harness goes in of course) im just not sure if its maped differant. i know unlike 1g cars that are auto and come with 390cc all 2g's auto or not use 450. like i said tomorrow im gonna try 450s just kinda unsure about the ecu. and if that dont work my last option is a push start. well tow start. unless thats a really baad idea for some crazy reason tha im forgetting. please tell me if u think a tow start is a bad idea. my plan is to pour a cap full of oil down each plug hole put thing back together have key on, tow at 20mph and let clutch out very easy in 2ndgear. like i said if thats a dumb idea please stop me

 

[BogusSVO]

it still sounds like you have internal sealing issues. rings or valves.

pull your spark plugs out and inject shop air into each cylinder, then listen at the TB and the exahust.

since you said you have 16 new oe valves in the head it would be safe to assue you had a V-job done.

the valve tip height should be checked, they may be too tall and cracking the valve off the seat.

75 psi is low new or not.

your about half of what the book says you need for an engine.

I would not try to tow start it. you stand to make a bad issue worse.