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2005 Cadillac SRX 3.6 V6
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31 Posts
Discussion Starter #1
The owner buys vehicles at auctions and this is one of them. He checked the oil in it one day and thought it was low, poured 5 quarts of oil in it and it slung a rod through the block. He later discovered the dipstick was cut and be way over filled it. After that tidbit that could be useful, so he brought it to me to change the engine out and he bought an engine from lkq and it turned out to have a bad bottom end so he warrantied the engine out for one that we heard run. I dropped the second engine in and it ran but I got a p0300, p0302 and p0306 and it idles like crap but smooths out around 2400 rpm. Upon first start up it blew chunks of the drivers side catalytic converter out the exhaust. Cylinder 2 and 6 plugs are wet (gas) when I pull them, they are both getting spark, obviously getting fuel and I'm stumped. I sprayed starting fluid all around and can't find a vacuum leak in the new intake gaskets. If the coil packs are unplugged on those cylinders the idle doesn't change, I haven't tried unpluging the injectors yet since they aren't accessible under the new gaskets. Compression is a hair under 180psi on the 2 cylinders, I've cleaned the throttle body, replaced it with a known working one that is fine on another 3.6, swapped out coil packs even though there's spark, cleaned sensors, cleaned the oil out of the intakes, swapped out injectors, used an ecm that I ended up having to jump the starter relay due to a "starting disabled remove key" message and it idled the same. I've cleaned all grounds very good, battery is good, I put new oil/filter in it but read oil changes have cured this so I tried that, new properly gapped plugs, picked through wires for quite a while and I'm at a loss. I've been doing a lot of searching and all of the post die or their success stories don't work for me. Will that junk cat cause this? I've pulled the exhaust off right behind the cats and it's hollow. Sorry for the whole book but I'm just trying to give all of the details. I figured I would get some kind of bad converter code but nothing other than the misfire codes show.
 

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06 v6 SRX
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491 Posts
Gone are the days when you take a 350 4-bolt main and drop it in . Just too many things to make work . The only way I'd try an engine swap is if it was a brother - sister SRX a few serial no. away .
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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3,177 Posts
Sounds like injectors 2 & 6 are leaking too much fuel and at low RPM flooding the cyls., preventing firing. Flow test or replace them.
 

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2005 Cadillac SRX 3.6 V6
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31 Posts
Discussion Starter #4
I've changed the injectors around from cylinder to cylinder and no matter what cylinder I change them over to or from the issue remains on numbers 2 and 6. I've swapped fuel rails as well, the engine is out of a 2006 SRX. I wanted to lean towards a timing issue but cylinder 4 is running fine.
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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3,177 Posts
The problem is likely in the wiring then. Look for shorts to ground or voltage in coil and injector circuits.
 

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2005 Cadillac SRX 3.6 V6
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31 Posts
Discussion Starter #6
I've been picking through the wiring and haven't found damage and I can't find a short yet. I haven't been able to find what the correct voltage should be to the coils and injectors, would you happen to know what they should be at?
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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3,177 Posts
12V to injectors. My thinking is a short to ground in control circuit. ECM fires injectors by grounding control circuit, so if it's shorted, the injector is continually firing (wet plugs) and when RPM increases enough it no longer matters and engine smooths out. I'd guess your fuel trims are way off and mileage has fallen. Check for short with ignition off. Voltage is at pk/bk wires, other is control circuit.
 

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2005 Cadillac SRX 3.6 V6
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31 Posts
Discussion Starter #8
I assume check at the plug that goes to the injector harness? Checking at a body ground it from pk/bk I get .001-.000 volts and going to the positive battery post the meter starts at .157 volts and it creeps down to nothing slowly with the key off. Key on I get a steady 8.60 volts on all wires except for the 2 white wires that are at .010 volts, battery voltage is 12.60
 

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2006 SRX4
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3 Posts
My experience is that the cats will do this. The identical thing happened to me 30 days ago. I bought an 06 with 121K miles. Changed the oil, and took it on a road trip. The engine left my family on the side of the road 2000 miles into the trip. The guy who swapped the engine out told me it was 4 quarts low. Nice. The fact that this car burns more oil than gas would have been a useful consumer tip.

After the engine was replaced, we went to Florida. Apart from a small problem with a sensor (which the dealer said could have been broken during the engine swap), the car ran fine. As soon as we pulled out of the dealer, I started to get some coughing on quick acceleration, some engine hesitation. I did the whole top end cleaning, injectors, etc. Didn't seem to fix anything. From my point of view the engine had less power. I figured I'd live with it until I got the car back to my mechanic.

We then drove 60 miles to daytona beach and the car was absolutely struggling to get up small hills, etc. Always downshifting to keep the speed up. The car sounded far too loud, too. Like it was working too hard. Dropped the kids and the wife at the beach, and took the car to a local Firestone (only place open on Sunday). I gotta hand it to their tech, who did a very thorough diagnostic.

The conclusion was that the passenger cat (in my case) was bad. They wanted $900 to replace it, and I told him forget it, ram a rod through it instead. You can guess their answer. I asked him to take the o2 sensor out, and he said sure. Problem solved.

New problem: fumes in the car. Okay, so I take it right back, tell him I'm an idiot, and would he please take all my money.
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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Disconnect the wires at the injector. Key off, check for ohms between the not pk/bk wire and a good ground. If not '0', you found the problem. Pk/bk wires should be 12V with key in run.

edit. correction, meter should read '1' if there is no short, a '0' would indicate a dead short.
 

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2005 Cadillac SRX 3.6 V6
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Discussion Starter #13
My experience is that the cats will do this. The identical thing happened to me 30 days ago. I bought an 06 with 121K miles. Changed the oil, and took it on a road trip. The engine left my family on the side of the road 2000 miles into the trip. The guy who swapped the engine out told me it was 4 quarts low. Nice. The fact that this car burns more oil than gas would have been a useful consumer tip.

After the engine was replaced, we went to Florida. Apart from a small problem with a sensor (which the dealer said could have been broken during the engine swap), the car ran fine. As soon as we pulled out of the dealer, I started to get some coughing on quick acceleration, some engine hesitation. I did the whole top end cleaning, injectors, etc. Didn't seem to fix anything. From my point of view the engine had less power. I figured I'd live with it until I got the car back to my mechanic.

We then drove 60 miles to daytona beach and the car was absolutely struggling to get up small hills, etc. Always downshifting to keep the speed up. The car sounded far too loud, too. Like it was working too hard. Dropped the kids and the wife at the beach, and took the car to a local Firestone (only place open on Sunday). I gotta hand it to their tech, who did a very thorough diagnostic.

The conclusion was that the passenger cat (in my case) was bad. They wanted $900 to replace it, and I told him forget it, ram a rod through it instead. You can guess their answer. I asked him to take the o2 sensor out, and he said sure. Problem solved.

New problem: fumes in the car. Okay, so I take it right back, tell him I'm an idiot, and would he please take all my money.
That was my first thought cylinders 2 and 6 are missing but #4 is burning just fine, the plug looks right and everything. I'm 99.9% sure the cat failure is a down stream effect of another issue. It'll be replaced but I don't want to put it on and destroy another new converter. The bad one is disconnected and it hollowed itself out so it's not plugged and causing the issue.

Disconnect the wires at the injector. Key off, check for ohms between the not pk/bk wire and a good ground. If not '0', you found the problem. Pk/bk wires should be 12V with key in run.

edit. correction, meter should read '1' if there is no short, a '0' would indicate a dead short.
Ohms on the not pk/bk wire, the 2 cylinders that are missing and all of the other white injector wires are at 5.20 ohms.
 

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2005 Cadillac SRX 3.6 V6
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31 Posts
Discussion Starter #14
I'm not confident in my meter but the injector and ignition part of the lkq engines wiring harness wasn't molested so I probed from the ecm plug to the injector plugs on the junk harness and did the same on the Cadillac and got the same readings... I mentioned in the first post I swapped out another ecm but it locked me out so I jumped the starter relay to start it and it ran the same. Could the ecm be the issue?
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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My wiring schematic does not show any white wires in the injector harness. The control wires are all various colors. Anyway, sounds like you are measuring resistance of wire from injector to ECM. That's not what you're looking for. Test your meter by setting on ohms and touching the 2 probes together. Your reading should be '0'. Then attach 1 probe to a good engine ground and the other to the control wire at the injector with the wires disconnected from the injector. What do you get?
 

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2005 Cadillac SRX 3.6 V6
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Discussion Starter #16
My reading are from ground to control with the meter, I get 2.8 on the meter when I put the leads together then it creeps down to 1.8 and I know that's not right, I didn't think about that before... The harness off the original 2005 engine has a white wire going to each injector and 2 white wires in the plug. The spare/junk harness has 2 pink and black wires but both injector harnesses (the ones attached to the rail) have 2 white wires. My first readings I told you I took were from the white wire at the injector plugs to body ground. I'm trying to upload pictures of the harnesses to show you what's going on with the colors but it keeps giving me an error message.
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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For your pics, you need to go to edit function in album and reduce size. 640x480 will post.
Sounds like something is wrong with the meter.
 

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2005 Cadillac SRX 3.6 V6
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Discussion Starter #18
I slid the pics under the 2 white wires so it's easier to tell what's going on. In the second picture the 2 stray pink and blacks turn to solid white then go to the injectors. I'm working on getting another meter now.
 

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2005 Cadillac SRX 3.6 V6
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Discussion Starter #19
I just bought a new meter, on ohms it zeros out as it should and it's reading various voltages right on stuff I have sitting around. I'm getting 1.1-1.3 ohms from the end of the injector plug to ground on the engine block. When I tried using a body ground it bounced from 12-14 ohms.
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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OK, went to a different section of the SM and it does show white as the voltage wire to the injectors. Inj.2 has L-GN as control wire, #6 has YE/BK. Those are the ones you want to check for shorts. I would expect a variance between body and engine grounds but that sounds like a lot. What do you get when you short the 2 meter probes together?

As to the voltage wires you should get 12 when running or cranking. ECM shuts off voltage when ignition is off.

Since this problem has existed from the get-go, don't dismiss the possibility of a physical/mechanical cause.

After running, check fuel pressure to see if it stays up or drains down.

The pics you posted looks like the multiway connector for the injector & coil harnesses.
 
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