NEED HELP Engine swap problems

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Hi all, 2007 TB 4.2L.

The folks from Trailvoy sent me this way, and have done some searches on here and think things are getting closer.

So here are the details:

Bought a 2007 with blown motor (guy I bought it from had started the tear down then gave up), bought an 06 engine from the wreckers, got through the remove and replace and everything is bolted up.

Went for the initial start up and turns out the PCM 15A fuse was blown, so I replaced that and now it cranks at least. Trying out the remote door locks blew it again. That seems strange, headlights on one side are dimmer than the other, but might just be bulbs.

But it is cranking and wont start. I can smell fuel in the exhaust, and pulled a couple plugs and they are wet, so its definitely getting fuel.

Pulled two coils and there is lots of spark. So not sure why it wont start. No security light is on either, and the fuel pump is running. Spark was slower than I expected at least a full second between same-coil sparks while cranking.

There is a very weak sign of almost firing once every two seconds, but nothing close to almost starting.

I have a OBDII reader, and its doesnt seem to be getting a signal from the PCM , when I hook it up to the port under the steering column. That is a bit worrysome.

I understand they changed the reluctors in the 2008 model. Mine was manufactured in march of 2007, and shows as a 2007 model when running the VIN. So not sure that is the issue, but sure seems like a timing thing.

Anyone have any idea if it was a mid year change on the reluctor? Anything I should double check before losing it? Getting fuel and spark, so not sure what else could be wrong.

Apparently Lingenfelter makes a adapter that gets a 24 tooth signal to the computer even with a 58 bit reluctor wheel, but they dont have one listed for the I6. I'll call them tomorrow and see what they say. Hoping its something simpler than that, but out of ideas.

The gremlins in the lights and the blown PCM fuse when doorlocks triggered make me wonder.

That said the wiring harness connectors on the donor engine exactly fit the stock harness with the exception of the alternator, the donor alternator is a 3 pin connector, while the original was a two pin. No biggie, I'll just put the original alternator back in. Anyone know if the on the 58 tooth reluctor if the wiring harness was significantly different? that might answer the question right there. Part numbers on the ignition coils are the same between donor and stock as well.

So many questions. I am not looking forward to pulling this engine all over again.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Make sure all the grounds are connected on the block, clean and tight. They can be the cause of some gremlins.

I'd leave the plugs out to dry it out overnight if it's that badly flooded. Might also have to change the oil if it's full of fuel. Smell the dipstick.

Blowing fuses could be indicative of either bad wiring or ground. Did you keep your wiring or the donor truck's? What about the PCM? According to this
http://www.vortec4200.com/forum1/viewtopic.php?f=7&t=783
2007 saw a different PCM so I hope you kept it. Other than that, seems to have not changed with 2006. 2008 was the year for the reluctor change.
 
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limequat

Member
Dec 8, 2011
520
^2nded on the harness question. Although the 2006 engine harness will plug into a 2007 body, it's not plug in play. You should have the 2006 engine with stock harness and stock PCM.

Beyond that, the fuse you're describing is the main power feed for the PCM, all 6 injectors and all 6 coils. If you're blowing it, bad things. Try pulling off one of the coil connectors and checking:
1) voltage on the power feed (pink wire). It should be battery voltage with key on.
2) resistance between the pink wire and the black wire (ground). It should be infinite.

It kinda sounds like there's a short between power and ground that's dragging down the voltage to the PCM. Is it smoking???
 
Last edited:

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Hey All, thanks for the thoughts. I went back through the grounds on the drivers side down below the starter, three small ones and the main engine ground. All attached well and clean. No dice.

As for the PCM and harness they are original from the truck (2007) the engine is a 2006. All the connectors off the stock harness hooked up no issues, with the exception of the alternator, which is the 2 wire on the stock harness, but the donor motor had a three pin. (I still havent swapped the alt, so that lead is unplugged, assuming it shouldnt generate a no-start scenario).

One thing that worries me is that my OBDII isnt reading anything from the connector. Its like the connector doesnt exist to the scanner. Now its no snap on scanner, but its worked on other cars fine. So I have to think something isnt getting to the connector there.

One other thing, a couple times while cranking it, it has cranked pretty much as soon as I put the key in, without turning it more or less. Just twice so far over probably 40 start attempts. I hear the ignition switch can get pooched in these, but still getting fuel and spark so have ruled that out for now, possibly in error.

Ill run and check the voltage on the coils now.
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Ok, checked the coils, all getting battery voltage to pink. Black is basically reading as a open circut on the ohms, same as if I have the leads not touching each other. I'm a multimeter rookie, is that an infinite resistance? if have to think that if a switch is open the resistance is infinite?

The other thing I should mention is that the passenger window regulator must be pooched as it looks like the previous owner had started to take the interior panel off. Right now window switches dont work and the cigarette lighter fuse is blown. I am assuming they are on the same fuse as dont see another for the windows. Who knows what I will find when I get the door panel working, maybe he gibbled the wires, but I am thinking whatever wiring harness is running through the door shouldnt impact engine. Hoping to hold off on window until running as can sink dollars into that when it is moving under its own power.

Other than that, Im drawing blanks
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Oh and right. The PCM is not smoking near as I can tell. The battery is brand new has been in it hooked up three days and is reading 11.84 volts which I think is OK with about 3 minutes of total cranking on it. So battery isnt draining to ground with ignition off.
 
Apr 26, 2014
53
Did you swap over fuel rail and injectors? How old is the fuel in both the donor and the 07? Maybe old fuel wouldn't light and just got the plugs wet.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Replace the lighter fuse. It also powers the OBD port.
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Thanks guys. Fuel is probably old. I would guess truck has been sitting for a year and a half. But doesn't smell like old gas, there is a half tank in the vehicle, so its should have preserved fairly well. I'll pull some off the fuel rail and see if any high ends are left and if I can ignite vapors in a dish.

Thinking more today that it could be a ignition switch. Anybody think the symptoms match that? blown PCM fuze, cranking when key inserted, but with fuel and spark, although long gaps between sparks? Assuming it is cranking at 200 RPM, that 100 ignitions per cylinder per minute or 2 per second. Id say the sparks are occurring closer to one per second. Not sure if a ignition switch could fail and get spark half of the time.
 

limequat

Member
Dec 8, 2011
520
Doesn't sound right to me. I could see it being another problem in addition to the problem that's blowing the fuse. I say, fix the cigarette lighter fuse so you can check for codes and go from there.
Let's back up. You bought it with a bad engine? How do you know the original engine was bad?
Is the MAF hooked up when you're trying to start?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Gas goes bad really fast, within 6 months nowadays, because of the crap ethanol. I would drain it and refill with fresh fuel and then purge the fuel rail through the shrader valve. It might light with an open flame but it doesn't mean it will light in an engine, especially one as sensitive as these computer controlled fuel injected ones.

Another thing you should do is check the fuel pressure to be sure the in-tank pressure regulator is still working properly and not over pressurizing the system. Who knows after being parked over a year and a half?
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
I really appreciate the help guys.

limequat, I replaced fuses and am now getting codes. I got three, all air conditioner related re:low pressure. The guy who i bought it from basically tore it down to having the radiator out, and he decided he would disconnect all the ac hoses too. so its empty and I will need to buy a new dryer before it is over. But those are the only codes. I did pull the fuel pump relay tonight to try and dry the engine out a bit, and that showed up on the reader, so its talking at least.

The guy I bought it from, bought it from a fleet, and said all he knew was that the engine was blown. He quit on it as the front halfshafts through the oil pan scared him. Sure enough when I was doing the R&R, a valve stem fell out of the intake side, so it was toasted.

AFM is connected, but I have alternated between having the resonator connected to the piping and disconnected, and cranked it both ways. No difference.

Tonight i pulled the plugs on all six, pulled the fuel pump relay, and spun it 5 or so cranks with the plugs out. Put new plugs in, old ones looked tired but were still functional. Set the coils and plugs on the valve cover, cranked it, nice spark to all 6. Did notice the coils in the donor had a diffferent number stamped on them, vs the originals. I put the original coils in. No difference.

Disconnected fuel line, and its doing the 2 second pump at key on, and then I filled a pint or so while cranking. Gas was flat-ish, but nothing as bad as lawnmower gas after sitting for the winter. Did a non scientific flash test vs new gas. No real noticable difference, but Mooseman, its down to the short and curllies on this one, so agree it cant hurt to suck it out and try fresh. Not looking forward to trying to pull a half a tank out of the thing. I dont have a fuel pressure tester, but will see what I can find.

Since cleaning the connectors yesterday, I cant get the PCM fuse to blow again so maybe that is for the better. The wrecker I bought the donor engine from had a decent reputation, said it ran well, rated it a A, and had a 60 day warranty, which I am now well past after chipping away on it, but I have no reason to believe this is a bad donor. I suppose I could put the compression tester to it, but even with crappy compression i should get a rough start.
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Yep, checked the carproof. The last registration was April 2013. The registration would last a year so it blew the motor somewhere in 2013 or before April 2014. So best case the fuel is more than 2 years old, worst case, its 3 years old. So a fuel drain it is.

And double checked the vin on the donor, and it is a 06. Im starting to get paranoid and worried they shipped me an 08.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
It would have been very noticeable if you got an '08 motor as there were changes to the coils and the crank sensor. I'm pretty sure the engine is not the problem. Don't forget to check for gas in the oil. Apart from causing issues with vapours through the PCM, it could destroy the engine if the oil has been diluted.

Another thing you could try is pull the fuel pump fuse and try starting it with starting fluid. This would confirm it works and that the fuel is the problem.

For the drain, I don't think you'll be able to use a siphon hose in the tank filler as there is a rollover valve in the way. Maybe disconnect the hose to the fuel rail, find a way to connect another hose to a gas can and jump the pump relay.

Half an tank is a lot of skunky gas!
 
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limequat

Member
Dec 8, 2011
520
^Yep. The connectors wouldn't even fit on an 08 engine. So you're in the clear there.

2nded on starting fluid too. If it runs on that, drain the tank. If not...keep looking. I would say compression is the next check after starting fluid.
 

mrrsm

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Alowther

Original poster
Member
Jul 11, 2016
10
Canada
So bad news. Pulled out the ether bunny, no dice.

Compression test, #2 cylinder had 120. Rest were below 40. Engine is toast. Will see what I can do with the wrecker tomorrow.

No chance that 5 of six lifters are stuck open after sitting for a while or something stupid is there?

Lesson learned "yard tested runs good" doesnt equal a decent engine.

Now that I am this far, probably just find another donor and swap it. Should take 10 less hours second time around. Im all in right now $1800 and its otherwise in pretty good shape. another $1K for a decent engine, and still come out ok.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Why not try talking to the yard IN PERSON where you bought it from, even though it's beyond warranty, depending on how long after the warranty. They may still exchange it if you explain what happened. Either way, still sucks. Sucks even more if you have to fork over even more for another motor :frown:

With so many cylinders with low compression, I wonder if something else is at play here, like if it was sitting so long that the cylinders were rusty or completely dry.
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Phoned wrecker Abe's Auto in Bowmanville Ont. Basically told me tough nuts. Wanted to give me a "discount" on another one, but I when asked for compression test numbers said, "we dont do compression tests" when asked to do one, he said "we dont have a compression tester".

Shady outfit. Owner is back on Monday, I'll try again, but not sure I want to go any further with these jokers.

I'll update to provide closure to the thread once I get things figured out. Thanks for all the help through this.

Adam
 

Alowther

Original poster
Member
Jul 11, 2016
10
Canada
Thanks all. Got another engine being shipped today. Should be able to get it in over the next few weeks.

As soon as it arrives, I plan on spinning it on slow speed on a big drill, and test compression while still on the pallet. The VVT wont screw with my readings on this will it, I assume it isn't THAT variable.

I will say removing the front clip, halfshafts, and unbolting bellhousing to get ready for the new, new, engine took me 3 hours compared to the 10 first go around. I'll have to do a few more of these now that I can make time on them.
 

gmcman

Member
Dec 12, 2011
4,656
Sorry about all your frustration....with water under the bridge, I would absolutely pull the fuel line and use the pump to drain all the gas. What's bad is that you turned the key with the bad fuel so no going back there.

Get some fresh gas in there before you try to crank the new motor. One spark per second is about right if you are only watching one plug.
 

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