What could be keeping my 7mgte from getting injector pulse and spark?

N

nextproject

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Jun 4, 2010
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TN
I've gotten to the part in my swapping a 7mgte into my '87 volvo 740 where its time to get her to at least IDLE.

Well she cranks over just fine, ecu has power at 4 places with the key on (the places its supposed to have power) and good grounds.

The injectors have power, just no ground pulse.

There is no spark although there is power at the igniter and coil harness connector.

I am leaning towards the CPS. Although i did the resistance checks and it turned out ok.

The CPS connector on the harness side looks suspect. While probing the connector i seem to get an intermittent ground on 3 of the prongs, and the 4th i get a solid ground. I did a resistance check between the CPS connector and the terminals at the ecu and i get continuity. I checked for shorts to ground and im getting none.

Is there supposed to be POWER at the cps connector? Because i KNOW i dont have that.

The only thing i KNOW i didnt have (didnt realize it til after i got home) is that the Igniter's bracket was painted and NOT bolted down, so im pretty sure the igniter didnt have a suitable ground (i also took it apart and installed a ground wire and hadnt gotten around to hooking that up to the engine block).

I guess im wondering if an ungrounded igniter or a poorly grounded igniter will affect injector pulse, since it seems it would only have to do with ignition and lack of spark. And is the CPS supposed to get any sort of voltage? If so any thoughts on why mine isnt?

The engine idled fine before the swap. I have 2 ecus and i still get the same results.

I plan on running more tests tomorrow if i have time, i just threw this up there in case some experts might toss something up here that i'd never think to check, i've looked over both mitchell on demand and TSRM's wiring diagrams to no avail.

Im still in the beginning stages of diagnosing this.
 
Nick M

Nick M

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nextproject;1595589 said:
The CPS connector on the harness side looks suspect. While probing the connector i seem to get an intermittent ground on 3 of the prongs, and the 4th i get a solid ground. I did a resistance check between the CPS connector and the terminals at the ecu and i get continuity. I checked for shorts to ground and im getting none.
Click to expand...

You should be suspect. The pickup creates its own voltage signal. You don't check for voltage going in. If you don't get that signal, you will not get the command for spark or fuel. The ECU grounds the injectors, which I think you have already noticed.
 
8

89supra7mgte

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Sep 20, 2009
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Did you ever remove the cps? may have installed in wrong position? also i believe there is a test for the air gaps inside the cps. If you suspect your harness repair or replace it. My car ran fine with the igniter jsut hanging, had no bracket for awhile so i am not sure if that can create an issue or not but never rule it out. grounds are good:) Have you checked for codes?
 
N

nextproject

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Jun 4, 2010
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i have to rig up a test light to check for codes although im certain that missing cam/crank signal codes will be there. ok so the cps generates its own signal. didnt know that. i figured that there must be some kind of voltage going TO the cps.

yes i removed the cps to replace the seal and i aligned it per the instructions on the TSRM before installation. and like i said it DID run before i pulled the engine from the supra. wish i had some kinda tool to "see" the signal from the cps. you'd think if it was installed WRONG that since it would still be spinning it would still generate spark or injector pulse, only at the wrong time.

i am getting no spark or pulse whatsoever.
 
Nick M

Nick M

Black Rifles Matter
Sep 9, 2005
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U.S.
www.ebay.com
nextproject;1595667 said:
i have to rig up a test light to check for codes although im certain that missing cam/crank signal codes will be there. ok so the cps generates its own signal. didnt know that. i figured that there must be some kind of voltage going TO the cps.
Click to expand...

It is a magnetic pickup that generates a signal that varies from variance in the reluctor wheel.

you'd think if it was installed WRONG that since it would still be spinning it would still generate spark or injector pulse, only at the wrong time.
Click to expand...

It does. You have either lost your pickup signal or the CPS isn't making one.
 
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89supra7mgte

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Sep 20, 2009
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If by chance the air gap got screwed up wouldnt that do the same? Kinda like points in an old vehicle? And dont they sell the cps internals at the dealer? I think if you can find the wire that pulse the voltage you can back probe with an analog meter and see whats up. You may also have a good cps and broken wire(s) somewhere else in the harness, you did put into a volvo right anything is possible.
 
N

nextproject

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Jun 4, 2010
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lol yeah, anything's possible. i think i'll check the air gaps today and then i'll just snip the connector completely off and run a jumper harness from the cps outside the car to the ecu and see if i don't get some sort of signal that way. just boggles the mind because it worked alright beforehand, just had lots of boost leaks and a stuck open diverter valve.
 
N

nextproject

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Jun 4, 2010
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well because it wasnt as simple as it is when the engine's in the car it came out of. So i looked at the wiring diagram, found the wire i needed to hook up to the test light, found the terminals i needed to jumper in the diagnostic connector, and then i realized that it wouldnt have any codes because i had the battery disconnected until i got around to looking at it today.

so i figure hey, why not just make sure all the wires are securely attached and run that additional ground wire from inside the igniter box. so i hooked it all back up, attached the ground, and voila, i had a weak injector pulse signal through the noid light i had attached to injector 6. so i decided to check spark again. and there it was. we sprayed some ether in the TB and she fired right up and the noid light flashed nice and strong.

so all SEEMS to be good right now. i am not getting fuel because the brand new fuel pump i installed 5 months ago before the car sat without power until now seems to be dead, going to pull that back out tomorrow, then finalize all my wiring and hard-wire the CPS to the other side of the connector because i THINK the cps connector was the issue, i had my "helper" wiggle/fiddle with the cps wiring while was cranking and he checked the noid light.

thanks for the help, i'll probably pull codes anyway just to make sure there arent any extras, but the project is still a ways away from driving due to fabrication of cooling hoses and intercooler piping.
 
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