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Discussion Starter · #1 ·
I posted"help cyl. E misfire" and got a few replies(thank you) BUT nothing ive done has fixed the cyl. 3 misfire. Ive.... Replaced plug wire, moved coil around, checked spark plug, checked wiring to injector, reman injector in hole, using correct resistor for injectors. Replaced head gasket reflashed ecu with larger injector info,checked timing belt alingment..... Wtf am i missing im about ready to send it to the crusher. Ijust rebuilt eng. And itdif not do this before rebuild is correct so what the hell am i not checking or doing please help i truly at my wits end
 

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Discussion Starter · #11 ·
I had a miss fire issue while I was on the stock ecu, changed out everything to try and fix it and nothing did, I’ve spend more money than the car is worth by huge margin. The instant I changed out my ecu to a stand-alone and got it running and tuned it ran like a dream no miss fire and I beat the piss out of it.

This is one reason I went with a stand-alone ECU the stock ecu on a tactix cable I felt wasn’t reliable enough for data logging especially if you don’t know what you’re looking at. And having to shut the car off while making adjustments to reflash is such a pain in the ass.

if you haven’t already I would noid check your ecu at the injectors. I’ve know lots of people that have had issues with ecu injector drivers being wonk.
Cool is thete a stand aline that works the best with the 4g64? And a t25 out of a 97 gst only planing on pushing no more then 8-9 lbs boost
 

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Discussion Starter · #14 ·
you could prob use any stand alone, it’ll all depend on what features you want, link ecu, haltech, AEM, mega squirt. There’s a lot of ecus out there just going to have to research what could work for you.
FYI it isn’t cheap and takes a lot of work with wiring if your not familiar with stand-alone I would research about them.
Copy and thank you
 

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Discussion Starter · #16 ·
You did a leak down, checked cranking compression, or both? Is the plug wetting with fuel? Does a noid light flash on that injector connector?

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Just a leak down have to order noid light. Plug not wet with fuel but blackened from being too rich
 

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Discussion Starter · #19 ·
Are you using blow through with the MAF? Or is it on the intake side of the turbo, also is your BOV going to the atmosphere or is it recirculating? Are you using the DSM injectors if so did you use a resister pack for them? Could possibly need a transient throttle tune along with a full tune.
My mass air flow is on the intake side of the turbo and i have the resistor that goes with the 450 low impedance injectors that were on the 97 gst i also used the fuel pump and fuel rail from the gst. I turned the turbo 180 deg from how it was mounted in the 97 and ran it through the intercooler that also came on the 97. I reflashed the ecu with the injector scaling changed to 432 from the 238 that it had at stock setting. The 275 i took out and replaced with the 450s i guessed the 432 should be close. Other then that i havent changed any other settings.
 

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Discussion Starter · #20 ·
My mass air flow is on the intake side of the turbo and i have the resistor that goes with the 450 low impedance injectors that were on the 97 gst i also used the fuel pump and fuel rail from the gst. I turned the turbo 180 deg from how it was mounted in the 97 and ran it through the intercooler that also came on the 97. I reflashed the ecu with the injector scaling changed to 432 from the 238 that it had at stock setting. The 275 i took out and replaced with the 450s i guessed the 432 should be close. Other then that i havent changed any other settings.
Im ordering a noid light set today i also need to get a wide band o2 sensor im using the sensor from the 97 at this point.
 

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Discussion Starter · #21 ·
The too rich plug reading is probably from the misfire. Not a fuel issue. Check the injector out with the noid light when you get it, but I would keep looking at ignition or ECU. ...J.D.
Thanks ill run down the injector and coil.wiring today to make sure its not the cause...thank you for your help
 

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Discussion Starter · #23 ·
Are you using blow through with the MAF? Or is it on the intake side of the turbo, also is your BOV going to the atmosphere or is it recirculating? Are you using the DSM injectors if so did you use a resister pack for them? Could possibly need a transient throttle tune along with a full tune.
My bov vents to atmosphere not back into the intake side of turbo does it need to go to the up or down wind side of the mass air flow?
 

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Discussion Starter · #24 ·
you could prob use any stand alone, it’ll all depend on what features you want, link ecu, haltech, AEM, mega squirt. There’s a lot of ecus out there just going to have to research what could work for you.
FYI it isn’t cheap and takes a lot of work with wiring if your not familiar with stand-alone I would research about them.
Wiring dosnt scare me in the least and ill research stand alones as well thank you for your help
 

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Discussion Starter · #27 ·
That makes me think it's a compression issue, you can burn a little and make soot but not contribute to the engine running. I would check cranking compression just to cover all the bases. If you disable fuel and crank the engine does it sound like it's skipping over a cylinder or does it crank normally?

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Normal but ill fo a direct comp test just to cover all the bases.
Question do i need to try and run the 2g ecu or is my 3g ecu ok to continue using
 

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Discussion Starter · #28 ·
Normal but ill fo a direct comp test just to cover all the bases.
Question do i need to try and run the 2g ecu or is my 3g ecu ok to continue using
I reslise the 3g dosnt have theextra wire on the mass air that to 2g does but i have all of the 2g if i need to modify my 3g.
No i have mot swapped any intetnals from 2 to 3 g engines just the turbo equip. And asdociated parts its a fresh rebuild has less thad 30 min run time since rebuild. This all devopped after rebuild yes it's assembled correctly I used the mits service man. As a referance
 

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Discussion Starter · #31 ·
Wait are you using the 2g MAF, you should be using your 3g MAF along with recirculating the BOV back into the intake, other wise it’ll run rich.
No im running the 3g maf and should the bov be returned before or after the maf?
Recirc or not shouldn't make cyl 3 misfire especially when not in boost, it sounds like this is an all the time misfire and not just an on boost misfire. Nor should a different MAF make one cylinder misfire.

May also be worth while to try swapping the resistors between injectors, double checking they're all the same resistance, and swapping the injector between cylinder positions. I like to swap parts over more than one cylinder, like if Cyl3 is the issue I'd swap it to cyl 1 not to cyl 2 or 4. That way it's further away from the possible problem and you can more solidly know if the problem went with the part or the problem stayed with the cylinder. One more thing to consider would be the possibility of Cyl 3 being lean due to a vaccum leak at the injector or the intake manifold port on the head.

So if this were in my bay at the shop I'd do things in this order to diagnose a misfire.
0. drive vehicle to ascertain exact conditions of misfire, all the time, only at idle or only under load, hot/cold, etc.
0.a verify which cylinder is misfiring by pulling plug wire or injector connector while engine is running if it's an idle misfire, have seen engines with multiple weak cylinders throw misfire code for wrong cylinder due to slowing and speeding crank shaft speeds. Usually the actual misfire is the cylinder before the indicated misfire in the firing order when this happens, seems to most commonly be a Ford issue.
1. check spark with plug out of cylinder and grounded to head to verify plug works and coil works.
2. check compression on cyl 3 and cyl 1 for a comparison, if needed follow up with compression check on cylinders adjacent to problem cylinder to check for compression bleeding across to another cylinder (unlikely with a single cylinder misfire), if low possibly leak down test to determine where loss is happening but at that point mechanical issue means engine needs to come apart anyway so who cares it'll get seen when apart so a bit of a time and money waster. Maybe pull valve cover to visually inspect for busted valve spring or something.
3. swap ignition coil from 3 to another cylinder, waste spark setup means you only get 2 coils so swap from cyl 1/4 to cyl 2/3 but leave the wires in place.
3.a swap wires/plug boots around if possible (not possible with cyl 1 and 3 sadly) and inspect closely for burn through and arcing.
4. swap spark plugs from 3 to 1 and vice versa, inspect closely for arc over on the ceramic insulator and other visible issues.
5. smoke test intake system to check for vacuum leaks, possible for idle misfire which improves as vacuum decreases when accelerating.
6. check injector signal with noid light for good bright quick flash that gets faster with engine speed and remains bright.
7. swap injectors between cyl 1 and 3, compare resistance values of all injectors to look for borderline values or out of spec values. Inspect sealing o-rings for damage closely.

One more thing to check since you did engine work would be the valve clearances but this isn't part of my normal checks since it's uncommon on a previously normal running engine. If something went wrong and the intake or exhaust valves are not opening enough on that cylinder you can have pretty good compression, no leak down, but poor combustion and misfire due to a low amount of air entering or (or leaving, exhaust won't burn again) vs the amount of fuel being added. That could look like a rich cylinder but not be a fueling or spark issue. It should show up as a bouncing vacuum gauge when cranking the engine with closed throttle or with the engine running but vaccum is funky on a 4 cylinder with a dead cylinder.
Ive done all those things exept for noid light(ordered today) and rechecking valve lash, lapped valves when installing guide seals or direct comp test. didn't use smoke but starting fluid as it ran and got no rpm increase.
Question on the crank between the pulleys is the crank sensor trigger would it make any difference if installed one side out as opossed to the other(flipped around) it fell on the floor and i didnt mark wich side was facing outward when i disassembled the eng.? Its keyed so rotationally it right bit is there a difference in its profile that would affect crank timing?
 

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Discussion Starter · #32 ·
I realize the bov wouldnt affect no3 only some one said by not returning itback the car woul run rich but i would think that air volume going in before the maf coul chang the mix if that air has been allready factored in by the maf or does it matter up stream or down so long as its returned to the low press. Side of the turbo?
 

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Discussion Starter · #35 ·
This is true it wouldn’t matter at a idle or in your situation. it’s usually on decel or between shifts so you can rule that out. I’m sure you will prob find something during the noid check. Have you swapped injectors from one cylinder to another? It really seems like it could be a injector driver from the ecu.
Yes ive switch injectors around with no results.
Question...between the crank pulleys is the crank sending units trigger disk i didnt mark wich gace was facing outwards and of course dropped it and lost its ordination wold it make any difference wich way it faced it's keyed so rotationally
CKP ring flipped over, haven't seen that in a while! I recall it causing no crank or running really badly, spark/fuel timing didn't coincide to cylinders at TDC. I don't remember it causing one cylinder to misfire.

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[/QUOTE
is the profile the trigger picks up the same either way its facing? Or does it matter wich wy it faces? I know it's slim but im running out of other causes
 

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Discussion Starter · #36 ·
Yes ive switch injectors around with no results.
Question...between the crank pulleys is the crank sending units trigger disk i didnt mark wich gace was facing outwards and of course dropped it and lost its ordination wold it make any difference wich way it faced it's keyed so rotationally
Its in the same spot but is the profile diff. I get its thin that it would affect only one cyl. But im running out of causes
 
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