2005 Cadillac Cts 3.6 injector# 2 misfire [FIXED]

2005 Cadillac cts injector #2 stops working when the engine gets warm...i replaced the injector...coil pack...spark plug ..checked the wiring...cylider compression 175 psi...the ecm drops it.i used the power probe 4 injector tester..

and i get P0202.. p0302.
any help how to fix it. .please.



.thanks.

Hey bud, when the injector starts misfiring what happens if you shut off the engine and start it up again? Does the misfire continue? It's abit of a dirty test but might be worth running jumper wires from the feed circuit to the injector and from the pcm just to fully eliminate wiring. Then if symptoms do still occur you might be looking at a bad pcm driver, at this point worth checking all your inputs, although it's pretty unlikely that a bad input would cause a singles cylinder misfire (not unheard of tho!) Do you definitely still have spark when the injector drops out?

Hello rabbit as Rick suggested you can try running new wires to injector to see if that fixes it . A scope would be handy to see what the injector driver does when it acts up but without 1 I would try the wiring before condemning the ECM . Maybe you live near someone with a scope?

You could also check the resistance of the injector wiring from Injector to ECM and also for short to ground, make sure to disconnect ECM before testing a faulty injector is a possibility but unlikely since it still works cold and not warm but might be worth checking the ECM is the last thing to replace without being able to verify it is faulty

It is very possible that the engine is detecting a misfire, and intentionally shutting down this injector to prevent catalyst damage. It is also possible that the engine computer is misidentifying cylinder #6 as the misfiring cylinder, when the actual problem is on a different cylinder. This is a more common issue on Fords, but I have seen it fairly often on GM's. I would start with a cylinder contribution test with the engine cold and all injectors enabled to determine where the misfire is actually occurring.

Also, is it actually throwing the P0202 fault code, or is this resultant of testing you have performed on the vehicle? That would change my direction significantly into looking at the computer and injector circuit.

I took the ecm to Autozone to be rebuilt by cardone .i just got it back .they said there was nothing rong with the ecm.($450) .....i steel have the some problem..injector 2 no control from the ecm. ..

Ouch. you need more testing before replacing parts !do you have access to a scope ? Another thing to check is the resistance of the injector cold and hot when it starts acting up if the resistance becomes too high it could make the ECM think it has failed.

It used to work fine in a cold srtart...as it gets the engine hot .stops working ..no control from the ecm...but now it quit working.

Was that as soon as ECM was changed? The easiest thing to do is check the resistance of the injector then the wiring . Did they rebuild your ECM or exchange yours for a reman? To rebuild it would take atleast a week to send it out do a repair and send it back . The failed injector driver is Fairly common for that specific vehicle I wonder if they didn't find the problem in which case it did not get fixed... but before replacing the ECM you need to check the injector resistance and check wiring for short to ground and also resistance if you don't know how to do this I can explain what you need to do . A cheap dvom would be fine if all that is good then I would suspect a faulty ECM where do you live maybe a member near you has a scope which would make testing pretty easy

Before the misfire happen...i got P0420 Cat code. Few months ago

I got p0420 ..p0202
.p0303 before testing

Ok so let's establish a time line it started as you had a p0420 then it started misfiring and you retrieved a p0202 and a p0302? This part is important was the p0202 there before you started working on it? Or was it a p0302 and you began replacing stuff and now you have a p0202 as well?

I would swap the no2 injector with another injector on the same car. Say no1. Now if the problem moves to cyl1, you know you have a bad injector. If the problem stays on Cyl2, you know the injector is ok and you need to check wiring or another issue.

Often on these I will send the spark plug to one cylinder, the coil to a different cylinder, and the injector to a third cylinder. Than see if / where the problem moves to. As has been said previously, if the computer sees a misfire it can shut off the injector.

Normally I would agree that moving plug coil and injector would be a good place to start but since the plugs coil and injector were all replaced I don't think that is going to be relevant to are testing it's time check the resistance of the wiring to injector and the injector itself it's not a hard test if you don't have a dvom you can get a cheap 1 under $20 and you may need a roll of wire or a few jumper wires to get you from ECM wire harness to the injector wire harness . Assuming this is a key on power to all injectors and the ECM pulses ground to each to fire it you only need to check resistance to ECM on the ground wire with ECM disconnected you could then check your voltage and voltage drop with key on to the power wire at the injector . But first check the resistance of the injector if either the wiring or the injector is out of range the ECM will shut it down and throw p0202 it's very unlikely a ignition missfire would cause the computer to shut down this injector and then throw a p0202 .

Hi,
I would move the injector to a good cylinder and see if #2still has the misfire or it moved. If it moved replace the injector with a OEM injector. If the miss is still at #2 cylinder.

I would revisit the coil may be do the same move the coil to a different cylinder.

UPDATE
Cadillac is Fixed

I replaced the computer myself it worked.


Thanks.

Thanks for updating this please add fixed to your topic . This is a common failure for these vehicles it's not always the ECM but quite frequently when we see any of the p0201 through p0206 it ends up being a burnt ECM

Sent from my SM-N920P using Tapatalk

Yeah glad you got a result in the end. It just shows you can't always take it for granted when you are told the module you sent off for check/repair is OK. I have often wondered how these companies do the testing on certain components, if they bench test them and if so do they stress the circuits whilst testing, do they test them whilst getting them hot when resistance will start to increase (like in your case).