2G No fuel in #3 or #4

[Jacob_Barnes520GST]

Heres an interesting one, I replaced my throttle body today with new gaskets, and all of a sudden I have no fuel in 3 and 4. I pulled the plugs and 1 and 2 were wet but 3 and 4 were dry. Can anyone give me an idea why the injectors aren’t pulsing? The car will try to start after the first few cranks but then won’t do anything

 

[1990TSIAWDTALON]

Yes. As suggested in post 18, the CAS sends a signal to the ECU to ground the injector, firing it. I would be checking both of those units and the wiring between them.
I always preach, check your grounds. This applies here. You would be surprised how many times that is a problem with anything electrical. injectors have to see ground to open. They are wired like a dome light to make it simpler.

 

[Jacob_Barnes520GST]

I tested ECU with another working ECU. I ordered a CAS today. Mine is old so it will be replaced anyway. If that doesn't work then I will trace the wiring back through the loom again to see if I see any breaks. Worst comes to worst I will replace the wires.

 

[Jacob_Barnes520GST]

Also I have checked every ground I could see. I really appreciate all the input here

 

[Jacob_Barnes520GST]

Tried a new CAS, no start still

 

[Jacob_Barnes520GST]

How would I go about re wiring the injectors? It must be a broken wire somewhere and I can’t find it for the life of me

 

[delta448]

Well, the short and dirty way would be a new wire between the non-hot side of injector 3 to ecu pin 2 and another between the non-hot side of injector 4 and pin 15. Assuming you're using a 95 ECU with a 2Ga (under intake cam sproket) CAS. If you are using a 1G CAS or 2Gb CAS or are using a 97+ ECU then those pins need to be switched to this and there is probably an issue with either the way the p.o. rewired it or the ECU is seeing a new misalignment of the CAS due to a timing belt issue. If I were hunting this gremlin, I'd start by checking for continuity between the injector and corresponding ECU pin.

 

[motomattx]

What codes are stored in the ecu?

 

[Jacob_Barnes520GST]

I will continue to look for broken wires. And I have no codes in the ecu, I checked them through link

 

[Jacob_Barnes520GST]

Just to make sure, the ecu wire that runs to the injector is on the passenger side of the pigtail right?

 

[Jacob_Barnes520GST]

Wired the injectors straight from the ecu, still no change. Im at a loss here. Any ideas?

 

[motomattx]

Have you tried probing the actual ecu during cranking to see if those to injector outputs are getting pulsed grounds? you could even have an ecu connector that is not making a good contact even though that would be weird, I have seen some crazy things. How SURE are you that you havent connected any connectors to the wrong plug? Your also going to need to probe the cas inputs to the ecu at this point to make sure they are inputting the proper pulses into the ecu...something is just wrong here.

 

[Jacob_Barnes520GST]

I tried probing the ecu, and not getting ground pulse. The only things I disconnected were the tps and the iac. I’m stumped. What else is there to check that I haven’t listed? Remember I have spark throughout all 4. Is there specific grounds I should be looking for? I added another battery ground as well.

 

[motomattx]

Spark will be there as long as it has the crank signal, without a cam signal it likely wouldnt have the injector pulses that it needs...

 

[jakk220]

I would be checking the CAS wiring at this point.

 

[Jacob_Barnes520GST]

I’ll once again check the wiring at the cas. It is brand new too. I have no idea at this point what else could be the culprit

 

[Jacob_Barnes520GST]

I guess what I’m trying to ask here is what all controls the injectors. Like from the ecu to the injector itself.

 

[Tyeler18]

The cam sensor controls the injectors. Regardless of how new/old/otherwise the cam sensor itself is, that doesn't rule out anything on the 30 year old wiring going to/from it. You need to be testing for a cam signal AT the ecu, because it doesn't matter if the sensor has a signal coming out of it, if it isn't making it to the ecu.

What did you use to verify a ground pulse on the injectors? A DVOM isn't near fast enough to use to diagnose a IPW.

 

[Gwaihir]

Have you tried swapping the known working injectors to the position the current bad injectors are in? If they work then your injectors are bad, if they don't then it's definitely a wire issue?

 

[motomattx]

Are you running a 2g cas or a 1g cas setup?

 

[Jacob_Barnes520GST]

To verify the injectors, I used 2 different noid lights, and 2 ECUs to make sure it that wasn’t it. I have swapped injectors to have the same affect. I will check my CAS wiring, which is a 2Ga under the intake cam sensor. I will check for CAS signal at the computer

 

[Jacob_Barnes520GST]

I checked cas wires, pulled them around and proved it to the ecu. Now I have fuel In all 4, but only spark in 1 and 4, allowing it to idle. Throwing code for camshaft position sensor circuit malfunction.

 

[Jacob_Barnes520GST]

Back to the same problem. And still throwing same code.

 

[pauleyman]

Back to the same problem. And still throwing same code.

Guessing I missed it. Code? What code?

 

[Jacob_Barnes520GST]

Code for cas circuit malfunction.

 

[luv2rallye]

The CAS determines WHEN to fire injectors and also WHICH cylinder pair to fire spark plugs on (2/3 or 1/4) when get pulse from CPS. Note it selects which cylinder pair to fire spark plugs on, NOT when to fire them (CPS determines WHEN to fire spark plugs). Sounds like you've got a CAS problem (CAS or the CAS wiring). Maybe ECU if you shorted something while working on throttle body (and didn't disconnect battery first).

Are you still using factory CAS and CPS or are you running a 1g CAS?

What year/model is this?