No power to injector 3 and 4

[Leo_99]

I want to start off by saying this is my first post. I have been able to solve many issues with your great posts but I am completely stumped on this one and really use some help!

I have a 1999 Eclipse GST FWD turbo. I have installed a complete motor that I picked up that was built up on a 96 2nd gen engine. I used the existing ECU and wiring harness (99) and used the cams from the 99 as well so I could hook up the cam angle sensor.

The engine starts but only runs on two cylinders (1 & 2). I have spark on all four cylinders. I do not have injector pulse on cylinder 3 & 4. I checked the one side of the injector plug for resistance (which goes to the transistor/resistor) and it reads 0.02 ohms. So I have concluded on that side that there is no broken wire. I then tested the opposite side of the plug for resistance (which goes to ECU) and it reads 0.02 ohms so I am sure the other side of the injector plug has no broken wire.

I swapped out the transistor/resistor from a working car, no difference no injector pulse.

I swapped injectors

I swapped the ECU for one that works (from a 96 same as the motor) and no difference in injector pulse.

Are there any other differences between the 96 and 99 motors, ECU’s or wiring harness? What could cause me to lose power to just the 2 injectors??

Thank you all in advance

 

[1995gsx20g]

.02 ohms sounds a little to low to me. when you put your test leads from your meter together what do they read? Also what do they read when they are not touching anything in mid air?

iirc the 96 ecu expects to see an inverted cam angle sensor signal so im not so sure i would count that 96 ecu as a known good part.

injectors are ground-side switched. they all share the same power so i would also check to make sure each injector is getting the same voltage.(wiggle the wires while doing this test) but don't expect 12v because the ecu steps it down to prevent normal fluctuations in voltage from the alternator from affecting the injector firing.

how is the rubber seal that sits inside the injector connector? i have seen the rubber squished from someone pushing down on it so much and it actually caused a misfire.

do you have all the metal clips in place?

are the injector pins clean from oil or anything else?

 

[Leo_99]

Hey 1995gsx20g,

Thanks for the quick response!

When I touch the multi meter wires they read 0.02 and mid air is 0.00.

OK so maybe the 96 ecu won't work for the cam sensor but I don't believe they changed the pins for the injectors from 95-99 did they? If there ground side switched and share the same power then wouldn't all of the injectors fail?

I disconnected the injectors and tested right to the plugs to try to eliminate the injectors as the issue. I even swapped injectors.

Is there something im missing?

 

[1995gsx20g]

no problem that's what we are here for

hmm...

im not exactly sure if they changed pins but when hooking that 96 ecu up to a 99 harness and 99 cas im not sure if it would even trigger any injector to open.

one power wire goes into the injector resistor box then the injector resistor box splits it to 4 injectors.
check the wires from the resistor box to the injectors.

 

[Leo_99]

Hey, thanks for the info. Sent it into a shop and they are telling me its the ECU but im not so sure. I read that the CAS is different in the 96 than the 99. Apparently it is off by 180 degrees. I did swap the CAS from the 99 so im really stumped. I dont want to spend the money on another ecu for nothing. ALso having a real hard time finding one. Can i use the ecu from the awd? I think the diff is in the rev limiter but im not 100 % sure

 

[kilo4]

I ran into a similar problem, but mine was spark issues. I was ready to throw down the hammer. Until one day after a few beers. My freind and I started the car, and let it run on 2 cylinders while my buddy wiggled wires on the ECU. "Wallla" It was a loose pin on the ECU that the previous owner tampered with.....grrrrr. Then I bought more beers to celebrate. Good Luck and dont give up

 

[1995gsx20g]

Hey, thanks for the info. Sent it into a shop and they are telling me its the ECU but im not so sure. I read that the CAS is different in the 96 than the 99. Apparently it is off by 180 degrees. I did swap the CAS from the 99 so im really stumped. I dont want to spend the money on another ecu for nothing. ALso having a real hard time finding one. Can i use the ecu from the awd? I think the diff is in the rev limiter but im not 100 % sure

The cas is different from 96 to 99. personally i don't like rewiring sensors so they can work most of the time. and possibly have a random misfire code that never goes away.

if i were in your shoes and have some time, i would use the 96 cas, 96 ecu(if your 99 ecu is bad). you will have to use one cam gear from the 96 also.

awd or fwd does not matter and the rev limiter is the same on 90-99 turbo ecu's (atleast in the us).

 

[Leo_99]

I stopped into Mitsubishi for some ideas and they said that the crank gear might be a diff size or off by a tooth that is throwing off the timing.

If the timing was off could it run on 2 pistons? I know that i had to switch to my old cam gears cause the aem ones i had were off by 1 degree. I guess its possible the crank gear could be as well?

 

[1995gsx20g]

aren't those aem gears adjustable??

i had the timing off by one tooth on the crank and it started up and ran but lets just say i knew it wasn't right once i started driving it.

the car would not run at all if it doesn't get the crank and cam signal both syncronized.

to be honest i have never even heard a 2.4t having a different size crank gear let alone a 2.0

 

[Leo_99]

Thanks, i called the dealer to verify and yes the crank gears the same. The aem are adjustable but when the car wouldnt run i tried to go back to the old gears as the aem were off by a bit. I will install those and adjust them once i have the car running properly. So am i to assume timing would not cause me to run on just 2 cylinders?

I was thinking if the timing was off the computer would not get the signal to fire the next set of injectors due to the crank or CAS sensor.

 

[1995gsx20g]

Thanks, i called the dealer to verify and yes the crank gears the same. The aem are adjustable but when the car wouldnt run i tried to go back to the old gears as the aem were off by a bit. I will install those and adjust them once i have the car running properly. So am i to assume timing would not cause me to run on just 2 cylinders?

I was thinking if the timing was off the computer would not get the signal to fire the next set of injectors due to the crank or CAS sensor.

if the gears are adjustable then i can't see how they can be off..

yea, the ecu either does it all or nothing when it comes to running.

 

[delta448]

Stop going to that dealer, it sounds like they know very litle about DSMs.

The 96 CAS and 99 ECU are not compatible. The CAS signal isn't just off by 180 degrees, the problem is the signal is completely different. The 95-96 CAS voltage signal is inverted -think upside down (when viewed on an oscilloscope)- compared to all the other cam angle sensors that came on DSMs. The CAS and CPS signals are compared by the ECU to determine which injector fires at which time, or at all. Messing with the injection offset time on any engine can cause problems with drivability and misfiring. Properly timed sequential injection is always better than random mishapen batch fire.

You may need to rewire the CAS's connection to the ECU as well.

 

[Leo_99]

Thanks Delta448, i put in the CAS and crank sensor from the 99 eclipse so that it would match the cpu. I found out the hard way that the 96 wouldnt work when i installed them and the car didnt fire up at all. I got a code that pointed to them so swapped them out. Now i dont get any codes but i only run on 2 cylinders. ;(

 

[delta448]

So the engine does fire up and run somewhat on 2 cylinders?

Have you verified the Crankshaft Position Sensor is good? This engine doesn't have any crankshaft endplay does it? It's a 2Ga block after all, they're the most prone to it from what I've read. Sometimes CW completely takes out the CPS and sometimes it only causes it to misread.

A rarer problem would be that the CPS pickup plate is bent or damaged and not able to create the 4 pulses per rev the ECU needs to see. If the ECU doesn't see a spike from the CPS at the right offset from the CAS, it won't open the corresponding injector(s). The CAS and CPS harness plugs and wires could also be checked, if the sensors both check out good.

Have you ruled out the two injectors themselves?

 

[Leo_99]

Great info Zack, i didnt even take CW into consideration. Considering i bought the motor already built that is def a possibility.

We were testing the injectors with a node light so the injectors are unplugged at the time so that should rule them out.

I am giong to try buying a new crank sensor as a last resort a bit of a pricey test but cheaper then doing more diags!

 

[Leo_99]

OK i bought a brand new crank sensor and will try that this weekend. I will also try to get a new sensor pick up. (Not sure what its called). There is a brand new crank in the motor along with race bearings so im hoping they are not off by a bit.

 

[Leo_99]

OK i was able to fix this on the weekend. I bought a black top 93 CAS and bypassed and removed the crank sensor similar to when doing the 1 gen short block swap and it poured like a kitten

 

[delta448]

Glad to hear it's fixed.

I like the 1G CAS swap better too, since that means there's one less sensor to check for any problems in the future and it also eliminates the extra work involved with getting access to the CPS to check it.