SneakyTouchYourPlace
New Member
ya narrow it down from there, why dont they come on? is it the ecu signal ground? or lack of power supply?
Injector dilemma, me pissed!
- Thread starter Justin66
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sleeper88
My mom thinks i'm cool
i had a 88 hatch with obd0 b16 running with a pw0. One time the car was running like shit. Then check engine light came on.I go to check the pw0 and the light is solid. So i check everything under sun. To find out the O-ring on the valve cover was leaking enough oil down in where the spark plugs sit. I changed the plugs and new gasket set for the valvecover and reset the ecu. Solid red light was gone and it ran great
SneakyTouchYourPlace
New Member
The 2 wires on the injectors head in 2 different directions. One to an ecu controlled ground an the other to a power source. Have you determined which direction the fault is yet? If you unplug so much as a single injector, the red light will come on and the engine will never start untill you plug it back in, turn the key off, and back on again. The ecu has volt meters just before the ground transistors for each injector. if it doesn't sense the correct voltage during power up, the ecu will not function. The check engine light will go on solid and it will crank and crank and never fire an injector.
With the injectors unplugged, and key on, you should have 12v at each injector. if you do have 12v at each injector but the noid doesn't pulse (make sure the noid is plugged in and all injectors plugged in before you turn the key on), your next step is to find a diagram of the pcm, its usualy connector A pins 1 3 5 and 7, not sure if thats true for yours, and check if there is voltage there at all 4 pins. If even just one doesnt have 12v, the pcm will detect the fault with keyon and not allow any of the injectors to fire. These volt sensors were meant to protect the ecu from damage in the case of an open or short. It expects to see 12v at startup, and 0 volts when the transistor is on. If the transistor is on and it still sees 12v its designed to shut it off instantly to prevent the ecu from frying.
Don't use test lights with bulbs, use diode lights, low amperage. The ecu cannot protect itself from high current flow, only shorts and opens.
If you have 12v on all pins 1 3 5 and 7 at the ecu connector (unplugged) then you have a problem with the ecu not providing the grounds. The solid light on can also indicate an internal problem with the ECU, however internal problems with ecus are usualy caused by external sources. slightly shorted sensors, injectors, coils, and MOST COMMONLY, poor ecu ground. I dont know about your vehicle but usualy Honda ECUs ground to the engine block somewhere near the T-stat/throttle body area. Grounds most commonly go bad because they flow more current than any other wires on the vehicle. For example all your injectors, your coil, the ecu, many sensors and such all return that current thru that ground wire. Ive seen a lot of ground wires go bad, and a lot of poor connections to ground. This creates its own load and even though the ecu gets 12v up front, it gets starved by the ammount of volts the ground consumes. If you put 12 in, and the ground wire wants 4v, the ecu will only get 8, which in many cases isn't enough. Bad grounds can also cause fields within the ecu causing unusual voltage and current flows within the ecu causing it to malfunction.
Using an ecu diagram, locate the ground pin, leave everything plugged in, turn the key on, and backprobe the circuit with a volt meter to ground. If you have voltage on the ground wire, you have a problem. An alternative is testing ohms from that pin to the battery negative post. Anything above 40 ohms with keyon will start causing problems. With keyoff you don't want anymore than .5 ohms. If that checks out, it may just be a faulty ecu.
If its all too confusing Id recommend shipping it to a dealer, or a tech who knows electronics. I hate to see people throw expensive parts at vehicles like ecu's and distributors and such when all it is might be a loost bolt or corroded fuse. Ive unfortunatly have had customers who spend thousands of dollars trying to fix concerns and I find it to be a loose fuse or dirty relay.
With the injectors unplugged, and key on, you should have 12v at each injector. if you do have 12v at each injector but the noid doesn't pulse (make sure the noid is plugged in and all injectors plugged in before you turn the key on), your next step is to find a diagram of the pcm, its usualy connector A pins 1 3 5 and 7, not sure if thats true for yours, and check if there is voltage there at all 4 pins. If even just one doesnt have 12v, the pcm will detect the fault with keyon and not allow any of the injectors to fire. These volt sensors were meant to protect the ecu from damage in the case of an open or short. It expects to see 12v at startup, and 0 volts when the transistor is on. If the transistor is on and it still sees 12v its designed to shut it off instantly to prevent the ecu from frying.
Don't use test lights with bulbs, use diode lights, low amperage. The ecu cannot protect itself from high current flow, only shorts and opens.
If you have 12v on all pins 1 3 5 and 7 at the ecu connector (unplugged) then you have a problem with the ecu not providing the grounds. The solid light on can also indicate an internal problem with the ECU, however internal problems with ecus are usualy caused by external sources. slightly shorted sensors, injectors, coils, and MOST COMMONLY, poor ecu ground. I dont know about your vehicle but usualy Honda ECUs ground to the engine block somewhere near the T-stat/throttle body area. Grounds most commonly go bad because they flow more current than any other wires on the vehicle. For example all your injectors, your coil, the ecu, many sensors and such all return that current thru that ground wire. Ive seen a lot of ground wires go bad, and a lot of poor connections to ground. This creates its own load and even though the ecu gets 12v up front, it gets starved by the ammount of volts the ground consumes. If you put 12 in, and the ground wire wants 4v, the ecu will only get 8, which in many cases isn't enough. Bad grounds can also cause fields within the ecu causing unusual voltage and current flows within the ecu causing it to malfunction.
Using an ecu diagram, locate the ground pin, leave everything plugged in, turn the key on, and backprobe the circuit with a volt meter to ground. If you have voltage on the ground wire, you have a problem. An alternative is testing ohms from that pin to the battery negative post. Anything above 40 ohms with keyon will start causing problems. With keyoff you don't want anymore than .5 ohms. If that checks out, it may just be a faulty ecu.
If its all too confusing Id recommend shipping it to a dealer, or a tech who knows electronics. I hate to see people throw expensive parts at vehicles like ecu's and distributors and such when all it is might be a loost bolt or corroded fuse. Ive unfortunatly have had customers who spend thousands of dollars trying to fix concerns and I find it to be a loose fuse or dirty relay.
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Justin66
The Hondaswap Canadian
Ya its a little much for me, i only know the basics especially with the electronics. It is in fact at the Honda dealer. I should mention to him about the grounds and such. I wouldnt throw out the ECU, either way i just need an ECU to plug in and see from there, cause if it were a ground problem wouldnt it also cause the new ECU not to work properly either?
SneakyTouchYourPlace
New Member
yes
Justin66
The Hondaswap Canadian
Ok ive been pondering the ECU ground thing and its making more sense. Especially since the car worked when i got there, though poorly, it still ran and started. Now it doesnt. All he did was take off the old dizzy, put the new one on and rewired the original mess, gets spark and everything. He also disconnected the crappy ignition killswitch/ immobilizer that the other owner put in. Now that at all shouldnt have any effect on the injectors and/or ECU right? Saying that, the ECU ground being near the thermostat/TB area, maybe he broke/rubbed/hit the already bad ground, now completely severing the connection resulting in ECU fault? Im hoping thats it.
Ill give him a call and see if he can find where it is and if in fact that might be it.
Ill give him a call and see if he can find where it is and if in fact that might be it.
SneakyTouchYourPlace
New Member
I think if it were severed or open, it wouldn't boot up at all. I don't think it has any other ground, not even case grounded.
SneakyTouchYourPlace
New Member
Are you paying the dealer for this? or is this like some under the table, for a friend deal?
Justin66
The Hondaswap Canadian
Half and half. So far its only been 2 hours of labor for the the 4 its actually been. I know the guy and he got me the right harnesses for the OBD1 dizzy and he has been trying to get a hold of an OBD0 ECU but everyone he knows no longer has them nor uses them much anymore.
I think after he does this and nothing, im gonna get it towed home. I cant stand it being there sitting in the snow. Id rather it be at home, sitting in the snow lol. It sucks thought because this is all at the worst timing. All i wanted was a new dizzy in, oil change and to put it away for winter. Now its sitting with dirty oil, doesnt start and the snow (and soon salt) will be piling up.
I think after the grounds are check ill assume its the ECU. Id like it to be a simple ground or something but hell after these 2 weeks id rather it be ECu just so its an easy fix, but more expensive.
I think after he does this and nothing, im gonna get it towed home. I cant stand it being there sitting in the snow. Id rather it be at home, sitting in the snow lol. It sucks thought because this is all at the worst timing. All i wanted was a new dizzy in, oil change and to put it away for winter. Now its sitting with dirty oil, doesnt start and the snow (and soon salt) will be piling up.
I think after the grounds are check ill assume its the ECU. Id like it to be a simple ground or something but hell after these 2 weeks id rather it be ECu just so its an easy fix, but more expensive.
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Justin66
The Hondaswap Canadian
Ok i know its been a while so here is an update. TorontoJDM came through and apparently they have lots of PR3 ECUs considering they have lots of OBD0 B16a swaps. He took a look at my old comp and it looks like its got some water damage and got fried, makes sense. My dad will be bringing me the new ECU on friday and hopefully she works, wish me luck and ill keep you posted.
SneakyTouchYourPlace
New Member
How did water get inside? Do you have a leaking windshield? or weather strip?
SneakyTouchYourPlace
New Member
Test for power supply to each injector with the key on using the ECU connector. Unplug it, turn the key on, and put a light bulb type test light in each pin of the ecu connector with the alagator clip attached to ground. 12 volts doesnt nessesarily mean you have good current flow, if the light bulb is dim you may have excessive resistance on your power supply. If all 4 circuits light up strong then inspect the ecu connector for damaged, pushed out or corroded pins (water).
If all is ok with the power side, then you have a problem with the ecu controlling the ground. The ecu wont fire injectors if it detects and open circuits or lack of voltage on all 4 pins at the ecu. Beyond this point I beleive the only other reason it wouldn't fire that probably wont throw a code is a lack of camshaft sensor signal, a sensor located inside the distributor. A faulty sensor or broken/corroded wire can cause lack of signal.If you had water in your ecu, then there was probably water in your connectors, causing high resistance or lack of signal.
If all is ok with the power side, then you have a problem with the ecu controlling the ground. The ecu wont fire injectors if it detects and open circuits or lack of voltage on all 4 pins at the ecu. Beyond this point I beleive the only other reason it wouldn't fire that probably wont throw a code is a lack of camshaft sensor signal, a sensor located inside the distributor. A faulty sensor or broken/corroded wire can cause lack of signal.If you had water in your ecu, then there was probably water in your connectors, causing high resistance or lack of signal.
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YBLEGAL
Regular Member w/ Cheese
My SiR2 is still OBD1 (P30), although, my mechanic who did my engine swap had issues with my injectors working as well. He had to reverse the 2 wires going to each injector. I rewired my engine harness and put it the way honda has the harness from the factory on other OBD1 cars, but have yet to crank it. But just throwing that out there.
Maybe sneakytouch knows about that. Does "polarity" matter with the injectors?
You should be using a multimeter, not a testlight these days.
Maybe sneakytouch knows about that. Does "polarity" matter with the injectors?
You should be using a multimeter, not a testlight these days.
SneakyTouchYourPlace
New Member
yes polarity matters, hook it up backwards and they will never open.
Justin66
The Hondaswap Canadian
Ok i guess ill have to do some testing on the connectors, the dizzy is a brand new OBD1 one, ECU is new OBD0 PR3. I hear the ECU fire up. It usually blinks a LED flash when i first turn the ignition on whether that has anything to do with it. Now the only thing im not sure of is which are the injector wires/connectors out of the ECU, it has 3 harnesses?
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