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is my ecu bad?

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93 gsx skidz

10+ Year Contributor
43
0
Sep 15, 2012
masontown, Pennsylvania
i have a 93 eclipse gsx which had a 1 1/2 gen 7 bolt so i rebuilt a 1990 6 bolt and installed it in my car then i put a new 16g turbo on which was already on the car and it started fine no problems ran great just drove around the block scared to break something then pulling into my driveway and the car stald then it wouldnt crank i would just hear a loud ticking noise then waited and the car finally cranked now it cranks every time but it wont stay running not even long enough to give it gas it sounds like bad plugs and wires or a bad injector. i was told by an expert on these cars that it was an ecu but i dont have the money to buy another one so i have to make sure its bad i checked for spark and its good i check for fuel all the way up to the fuel rail and its good however i didnt check the injectors ### i dont know how. i think it could be the knock sensor or the cam sensor but the guy that said its the ecu is a lot better at this than me so i just need more people to confirm it let me know what you think
 
Believe it or not but the ecu can take somewhat of a beating. Check for compression and make sure your okay mechanically. You can get a noid set to check your injectors. Or remove the rail and carefully crank the engine and check the spray on the injectors. check that the t-belt hasnt slipped. Check that sensors are connected and not loose such as the maf, tps, temp, etc. And as stated before you can visually check the ecu for damage such as lifted tracks, you can also test for continuity within the ecu.
 
i am going to plug my ecu back in and check the injectors by pulling off the fuel rail thanks for that and i opened the ecu and i dont really know what im looking at but this is what i did notice the hole board inside is shiny and some areas are daul almost as if something leaked on it and dried and in that daul area seems to be signs of what i believe to be corossion its really hard to explain im going to have a couple people look at it within the next few days. ill let you all know what i find out thanks everyone for the help

also monday i have to replace my water pump so i will make sure its in time i never seen a timing belt slip but i have a busted axel boot and the tbelt doesnt have the bottom cover so i wouldnt doubt if thats what happeded thanks for that i overlooked that bar a far
 
Be careful when doing the fuel check. Make sure no fuel goes into the chambers and accidently turning the car on. Tends to freak you out LOL so put a rag over the holes where the injectors go. Just a heads up. :)
 
i did the compression test and it doesnt make any sense i have 90 psi in the 1,3,and 4 cylinders and 0 psi in 2
 
Possibly the timing jumped and now your valves are bent. Take the head off and inspect the vales and the tops of the pistons. If they all check out, replaced head gasket and studs. If the valves are bent you can install new ones (I would probably replace the lifters with the revised lifters while you're at it, they might be damaged as well) and grind down the piston crowns at the point of collision to make them smooth reducing the chance for heat pooling up around the area.

Work on the pistons one at a time, bringing the one you are working on to top dead center, then place a thick layer of grease around the piston where it seats into the cylinder, this will catch the metal shaving that you will produce by smoothing the piston out. Wad up some paper towels and block off each antifreeze and oil jacket.
 
there is no sign of impact on the pistons and it has an even burn on the head from what i am seeing and i dont see any cracks. how do i know if the valves are seated. is there a pressure test that i can perform or can i just pour over the valves and see if it leaks out and if it does i need to replace what? and how do i compress the springs because i dont think a universal tool will do.
 
With the head off the engine, tilt it at an angle and poor kerosene down the exhaust/intake side of the engine, depending which side you're doing. If it is leaking, you will find that the kerosene leaks out of the valve. Make sure the cam isnt coming to to contact with the valve on the respective cylinder you're testing. The only other way to check is by doing a valve lap job and inspecting the smear pattern of the lapping compound.

If there is no visible damage to the piston crowns I suspect you just need a new head gasket and studs. Before isntalling the new head gasket I would check the wear on the cylinder walls that might point you in the direction of having a problem with your piston rings. Also, take a look at the oil to make sure no antifreeze made its way into the sump.
 
If you still have the head on, try adding a lil big of oil to each cylinder and see if the numbers get better, If they do, your problem could very well be the piston rings. If you have the head off, you can spray the cylinder wall with some lube and rotate the engine by hand, checking to see if the oil scraping off the excess oil in a uniform pattern.

To check if the compression is being bleed off to its neighbor cylinder try a test with the spark plug in and the spark plug out of the neighbor. If your numbers get better with the spark plug installed it could point to compression leaking between cylinders through a blown head gasket.
 
More likely then not, you have bent valves. Take the head to a machine shop and have them check it. Theyll let you know if it needs to rebuilt. Ive already had this exact situation happen to me and sure enough it was bent valves. While your at it.. upgrade :D
 
okay ill have it checked out i litterally poured 3400 dollars into this car i just rebuilt it i did everything right to a T. i even had a shop go over the whole thing since it was my first build. the only thing that is reused is the crank which was polished and the rods. everything else is new and the the head gasket along with the rest of the parts dont even have 20 miles on them yet it ran for one night and now this but when it ran. No leaks and no noises ran smooth as hell and out of nowhere just shut off thats why im so confused. BUT come to think of it i replaced the pistons with new because i broke valves in the original head and i put the 1 and a half gen 7 bolt head which was rebuilt by previous owner now in doing that i reused the head bolts but i didnt think it would hurt anything being that the motor only started once with the 6 bolt head on so the head bolts had zero miles. but could they be over stretched since i already torqued them once.
 
As a rule of thumb you are never suppose to reuse headstuds, torque to yield or not. I highly doubt its a problem with the head studs, but with one cylinder at zero and other at half compression there is something seriously wrong. Best thing to do is take it apart and go over it with a fine tooth comb.

What kind of headgasket are you using, and did you have your head milled flush? Where the pistons you had installed present when the machine shop was checking clearences? My machine shop will not bore or hone a cylinder unless you have the corresponding piston and rings. Do you remember what your ring gaps were and how did you break the car in? I personally use dino oil instead of synthetic to break in a new engine.

Some people go as far as using used engine oil for a new rebuild. This helps the rings seat better. They will never seat if you didn't break it in right.

Having zero on one cylinder is probably not going to be your piston rings, it might have a huge crack in the head, but you will never know tell you get down there

My first rebuild bit the dust because I asked for a hottank and didn't specifically ask that my oil gallys be flushed. Everything else was perfect. Rebuilding modern engines is no walk the the park and the builder should be obsessive, triple checking every clearance and inspecting every square inch of the block, head and parts that are contained in these, while keeping everything spotless and free of contamination.
 
i was in the process of breaking it in i was driving it and letting it hit boost for a couple seconds and easing out of it i went 17 miles with a bad turbo and 2 miles maybe with the new turbo. i honestly dont know what or how it happened it ran fine till i cam to a complete stop with the wheel turned to the left to pull in my parking spot. i dont know what the gap of the rings were ### i let a shop install them because i dont have a press and they doublechecked my work and fine some minor mistakes and took me through it and they said it was ready to go so i took it home and the turbo wasnt building boost and they said i need a new turbo so i bought the same exact one that was on the car to replace it and ran it for one night and now this.
 
Well anything can happen when youre rebuilding an engine. I drove a rebuilt one two miles and blew a hg. Turns out i shouldve gotten the head resurfaced ### it was 0.020" out. And by the way, it does help those of us reading when you dont let your sentences run together. Use periods, thats what theyre there for :)
 
If the head is off.. then get it checked for compression, cracks, warp etc. Dont always rely on other peoples work. Believe me i would kno. I would also recommend using a 1g head, arp studs and their recommended torque spec (dont forget the lubricant/grease they recommend). Dont reuse head bolts but i believe arp are reusable. Make sure to clean mating faces of the head and block. Now unto the pistons, check the gap of the rings for proper spec. But id personally Start with the head and work my way down.
 
well i found the problem. i have 2 bent exhaust valves in the number 2 and all the others seat proplerly and there is no marks on any of the pistons.
 
Ah I see now. Those valves could have possibly bent themselves on a different bottom end? Valves are pretty heavy duty, when you hold one for the first time it's surprising how heavy such a little part is. It would be near impossible to bend the valves and not dent the piston crown.

A valve lapping job is in order since the valve seats are probably scuffed up. What a great time for a head rebuild with revised lifters. :D
 
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