96 Monte Carlo Z34 turns over but won't start

[DFresh]

I have a 96 Monte Carlo Z34 with 129K miles that hasn't been giving me any trouble besides the occasional P0410 code. The last time it was driven was Monday this week. It always sits outside and it wasn't driven at all on Tuesday. It's been very cold this week, single digits, but it's started in weather as cold as 10 below zero with no trouble before and I've never had trouble starting it in cold weather. I started it up on Wednesday to move it out of the way and it started like normal. Thursday I go to start it and it won't start at all. I can hear the fuel pump fine and it turns over fine, some cylinders are hitting, but not all at the same time. It sounds like it's close to starting sometimes, but just can't. I tried scanning for DTCs but there's none in the computer. I've checked everything I can think of, spark plugs, wires, fuel pressure, haven't looked at the injectors (but to have all six to go out suddenly?) and I know they're getting fuel to the cylinders because the plugs are wet when I pull them out and there's vapor coming from the cylinder. Can anyone give me some suggestions? I'm totally lost to this one and really don't wanna take it to a dealer. I'm to the point where I think the timing belt may have jumped and the cam's outta position. Thanks

[pocket-rocket]

Have you ever had the timing belt changed on the car? When was the last time? 60k is the OEM recommended mileage, but personally, I wouldn't go that long. If the plugs were wet when you pulled them out, it sounds like they might not be getting a spark. Hope this helps some.

[DFresh]

I pulled the cover off the timing belt earlier today and it's in really good shape. I cranked it over a few times to look at more parts of it and I couldn't find any cracks or worn or broken teeth. The belt's never been changed as far as I know, I bought it when it had 34K miles so I doubt the previous owner changed it. As far as the plugs go, I tried putting in new ones in the front 3 only since the back 3 are a bit of a pain to get to. That didn't make any difference, I should at least get some firing with 3 plugs sparking right?

[jmgtp]

I pulled the cover off the timing belt earlier today and it's in really good shape. I cranked it over a few times to look at more parts of it and I couldn't find any cracks or worn or broken teeth. The belt's never been changed as far as I know, I bought it when it had 34K miles so I doubt the previous owner changed it. As far as the plugs go, I tried putting in new ones in the front 3 only since the back 3 are a bit of a pain to get to. That didn't make any difference, I should at least get some firing with 3 plugs sparking right?

Are you sure that they are recieving the spark though? Pull the front 3 spark plug wires and snap old plugs into them and ground them on the engine. Have someone crank and watch if they spark. Don't be touching any part of the wire or plug when they crank or it will zap you, tape them down to make the connection if you have to. The reason to test all 3 is because that way you could see if each coil pack is working or not, if none are working I'd suspect the Ignition Control Module or possibly Crank Position Sensor. To change the rear spark plugs the Plenum has to come off on 96+ engines.

On another note, change the Tbelt. The 96+ engines are supposed to be intereference. When that belt breaks, and it will, you could potentially ruin the valves because they may strike the pistons.

[pocket-rocket]

On another note, change the Tbelt. The 96+ engines are supposed to be intereference. When that belt breaks, and it will, you could potentially ruin the valves because they may strike the pistons.

I second that one! If that belt isn't bad right now (mine went bad one time, the belt had tention and looked like it was still good when we pulled the cover off, but had shredded where it goes around the intermediate shaft, and wouldn't turn the cams), you have been really, really, REALLY lucky.

[DFresh]

I already tested the front 3 for spark with both the old and new ones. The front 3 are all getting spark with no trouble. I guess the next thing to do is tear it apart and check the position of the cams.

[DFresh]

Yea, I had my dad turn it over several times and I watched the belt move fine. That's why I'm so reluctant to do it.

[SappySE107]

You can check the front cams easily compared to the timing mark on the crank pulley. The front intake cam is the one your fuel is based on for SFI operation. I thought startup was batch fire but maybe its SFI...i dunno.

It could be your crank position sensor is getting messed up, or the wiring isn't too good.

That belt needs to be changed so regardless of what you wanna do with the belt, its your best interest to change it and the idler pullies, tensioner, and tensioner pulley. im not 100% on your engine being interference but its possible given the close tolerance the older DOHC engines are for your valves to bend either way. Its possible they wont, but I wouldn't take that chance.

Have you checked your fuel pressure? Maybe your pump or FPR are causing your current problem.

[pocket-rocket]

http://www.60degreev6.com/index.php?p=pages&pid=3 and
http://www.60degreev6.com/index.php?p=pages&pid=62 will help for sure. I deleted my last post because I forgot about the mileage on the belt and pretty much contradicted what I had said before, lol. Those two links (first one tells how to make cam hold down tools, and the second one is the timing procedure) will help you out alot. If you can, I would suggest getting the DOHC special toolkit if you can find it on ebay (they pop up on there from time to time) if you plan on keeping the car a while longer.

[SappySE107]

No point in the whole tool kit for a 96. The cam hold down is easy to make, don't need the cam gear puller, and the cam gear holder to loosen/tighten the bolts is less than 50 bucks online. The rest of the kit isn't used most of the time, if ever.

[DFresh]

Anybody know a place that I can get all the parts from? I checked partsamerica.com (advance auto) and o'reilly's websites, but they can't get them. They do show an idler pulley under heating & cooling, but that's not the same right? Thanks for all the help too.

[SappySE107]

https://www.gmpartsdirect.com

timing belt - 24502982

tensioner pulley - 24503561 bolt - 10162013

idler pullies - 24503859 bolt- 11514441

tensioner actuator - 24503860

May want to cross reference them to your 96...but I think those are all the same.

[DFresh]

Ok, I replaced all the spark plugs & wires and put it back together. After I tried to start it, it fired and turned like normal for a second then died. I tried cranking it over again and was getting some firing again. Next I tried playing with the throttle and after putting the petal to the floor it started up. The idle was fluctuating a little bit and it would dip a little sometimes, but no rough running or misfiring. After a couple minutes I turned it off then tried starting it again and had to give it throttle to start. After shutting it off again and trying to start it a third time it started normally. I hooked up my OBDII code reader to it and it's giving me a P1406 error code with is "EGR Valve Pintle Position Circuit". I believe this rules out the timing belt now. Anyone have any ideas on this. I don't wanna buy a $160 EGR valve for nothing.

[pocket-rocket]

Take the EGR off and clean it out as best as you can with a tooth brush (I hope one will get in there, but I have no clue because both of my cars have the digital egrs, not the linear one) and some carb spray. Spray some in it and let it soak for a while before trying to clean it, so it has time to break up the crap. If that doesn't work, your EGR passage in the plenum might be clogged up if the EGR is ok.

[DFresh]

I just took it for a quick 8 mile test drive and it ran great. Gonna leave it parked outside to see if the cold will mess with it tonight. My car has a digital EGR too so I'll take a look at it when I get a little more time this weekend. I did come across a blown fuse for the Air Injection Reactor pump. Could that have been the root of the problem? It didn't start right after I replaced the fuse but I was wondering if it may have someting to do with the EGR valve or could've affected some other sensors.