Intake Gasket replacement, now misfire

1999 Suburban, 114,000, the usual suspect, coolant loss and for the last 2 days, 12" diameter puddle under bellhousing on the driveway.....intake gasket letting go I suspect, pick up the parts.......let's rock!

Truck ran money before this, but didn't want to take a chance of the gasket failing completely and lunching it so I decided to change it, mind you it has ran perfect up to this point....emission testing was way clean without even doing a tuneup on the girl.

The procedure went well, I thought, start her up and she is missing like CRAZY.......shut it down.

first thought, got a wire not reconnected---check
second thought, got a plug wire switched, reverified---check
third thought, vacuum leak, retrtace the vac lines, all connected correctly, gingerly spray some choke cleaner around the manifold looking for a rise in RPM-none---check
4th, today pulled the upper and thought the injector tower gasket got maybe smooshed upon reassemly, it looked like it, replaced with old one, lubed upper reinstalled and verified correctly seated----check

still same problem, could be I am off a tooth on the distributor, although I have done distributors before on BBC and know how it feels when she slides home safe.....rotor was pointed dead straight at the firewall, any missed tooth, the rotor would be facing ~10deg or so left or right. Replaced plug wires, plugs, cap, rotor, swapped the MAF and IAT intake with another 99 suburban that is parked right next to her.

At a loss now and looking for help, spent the better part of today on the justanswer site with a GM tech, conclusion, get it scanned, LOL.

It is spitting a p0300 and a p1345(when I rotated Distributor) and nothing else. I do not believe I have disconnected any O2 sensors, as I thought of that too.

Just now was under the car again to verify if I have everything correct like the CPS and such and noticed driver side exhaust collector considerably cooler than passenger......don't know if driver side is correct, or driver side is not firing, or passenger side is REAL lean......seems the later to me.

Any thoughts??????

Thanks for your time, God Bless.
-Scotty

I would put my money on the distributor. The rotor may be facing the right way, but is the cap in the right position? With the P1345 code I would put money on the distributor. I actually forgot to plug in the connector that plugs into the distributor when I did mine and it spit that code out. Did you mark the position of the distributor cap in relation to the firewall as well as the distributor rotor?

First thing is to identify which cylinder is missing. Start pulling plug wires to find which cylinder is dead. Check the plug and plug wire to that cylinder first. I have actually seen a piece of carbon get across the electrode and short the plug, could be as simple as that.

1999 Suburban, 114,000, the usual suspect, coolant loss and for the last 2 days, 12" diameter puddle under bellhousing on the driveway.....intake gasket letting go I suspect, pick up the parts.......let's rock!

Truck ran money before this, but didn't want to take a chance of the gasket failing completely and lunching it so I decided to change it, mind you it has ran perfect up to this point....emission testing was way clean without even doing a tuneup on the girl.

The procedure went well, I thought, start her up and she is missing like CRAZY.......shut it down.

first thought, got a wire not reconnected---check
second thought, got a plug wire switched, reverified---check
third thought, vacuum leak, retrtace the vac lines, all connected correctly, gingerly spray some choke cleaner around the manifold looking for a rise in RPM-none---check
4th, today pulled the upper and thought the injector tower gasket got maybe smooshed upon reassemly, it looked like it, replaced with old one, lubed upper reinstalled and verified correctly seated----check

still same problem, could be I am off a tooth on the distributor, although I have done distributors before on BBC and know how it feels when she slides home safe.....rotor was pointed dead straight at the firewall, any missed tooth, the rotor would be facing ~10deg or so left or right. Replaced plug wires, plugs, cap, rotor, swapped the MAF and IAT intake with another 99 suburban that is parked right next to her.

At a loss now and looking for help, spent the better part of today on the justanswer site with a GM tech, conclusion, get it scanned, LOL.

It is spitting a p0300 and a p1345(when I rotated Distributor) and nothing else. I do not believe I have disconnected any O2 sensors, as I thought of that too.

Just now was under the car again to verify if I have everything correct like the CPS and such and noticed driver side exhaust collector considerably cooler than passenger......don't know if driver side is correct, or driver side is not firing, or passenger side is REAL lean......seems the later to me.

Any thoughts??????

Thanks for your time, God Bless.
-Scotty
http://files.automotiveforums.com/gallery/showphoto.php?photo=51302

After that you need to get it on a engine capable scanner and read out camshaft offset readings.

If off more than 1-2 or 1-2 + degrees you need to adjust it with the scanner readings.

Post back readings.
Did you set the dist as shown in picture?

Will crank #1 to TDC and then see where I am with the distributor. When I replaced it, the first time it dropped in, I knew I was off, then take out, turn oil pump shaft a bit with screwdriver (read FUN), then dropped it down so...The cap was dead nuts to the firewall straight back, then marked the cap to the housing in two spots....

Why would a complete bank be different temperature than the other? I have pulled a plug wire one by one yesterday, and they all seem to have some kind of effect to the performance. It kinda hard to tell, because she is missing on more than one I'm afraid....but they al effected it.

I was thinking that maybe one gasket slipped???? I highly doubt it, but at this point....

Thanks for the ideas on trying to diagnose this. Yeh, and engine scanner would be great, but I really don't want to tow it in to a dealer. I work on your suggestions and report back what I find...
-Scotty

Will crank #1 to TDC and then see where I am with the distributor. When I replaced it, the first time it dropped in, I knew I was off, then take out, turn oil pump shaft a bit with screwdriver (read FUN), then dropped it down so...The cap was dead nuts to the firewall straight back, then marked the cap to the housing in two spots....

Why would a complete bank be different temperature than the other? I have pulled a plug wire one by one yesterday, and they all seem to have some kind of effect to the performance. It kinda hard to tell, because she is missing on more than one I'm afraid....but they al effected it.

I was thinking that maybe one gasket slipped???? I highly doubt it, but at this point....

Thanks for the ideas on trying to diagnose this. Yeh, and engine scanner would be great, but I really don't want to tow it in to a dealer. I work on your suggestions and report back what I find...
-Scotty

TDC compression stroke not TDC exhaust stroke.

The degree camshaft off set readings are not tempt readings.

verified timing, check compression, they are all at 149-150 except for #4 which was 145. After I checked compression, brought #1 to TDC on compression stroke and verified distributor installation-was off a fraction, and I passed the mark back and forth while trying to see if that was the cause without the TDC on compression approach.

Borrowed a temp gauge and very interestingly, cyl #2,4,6,8,1 are all within a few degrees ~210-220 measured at the top of the exhaust manifold port. cyl #3,5, are all ~160 and #7 is ~115. Three dead holes on one bank.....Verified ignition by pulling plug wires while I was grounded----you know the rest of that, anyway got bit hard by all 3 of them. Rechecked plug wires, even swapped #5 and #7 plug wires thinking I was dyslexic. Still same results....

Any thoughts or do I yank the intake again???....maybe to verify gasket mating surface? Its holding water pressure and level when at operatiing temperature. Just odd that #1 is normal, but maybe it is just where it falls in the firing order.

Thanks for your time, God Bless.
-Scotty

UPDATE:

Ran it out of gas in the driveway (pretty steep angle)trying to get her back running and smoked the fuel pump..:biggrin:
Ordered replacement pump, but now can't even do any additional diagnositics....

To recap,

-Coolant leak leads to intake gasket replacement plan
-truck runs flawless, no hiccups, codes, rough idle, hesitation, etc.
-tear down, replace intake manifold gaskets, reassemble.
-start car and barely runs.
-check wires for crossed, check connectors on sensors, check distributor placement, coil ground.
-replace plug wires with new aftermarket NASCAR set (LOL)
-replace cap, rotor, cam sensor, Crank sensor, swapped O2 sensors from driver to passenger, swapped #6 and #8 injector poppets with #5 and #7, swapped ECM, replaced intake gaskets again after thinking gasket had improper seal. was going to check fuel pressure regulator next but before I yanked the upper, wanted to try the other ECM one more time....barely ran and died---outta fuel and now no pump noise...

-

just read your thread did u get it running? what was it?

Yeah, was a bad fuel pressure regulator, probably damaged when I blew off the excess cleaner off the manifold when I had the intake off. With the new pump, it was leaking even more severely and the truck barely ran at all, backfired once then (thankfully) died. Pulled upper to find there was a fire in the upper intake from the excess fuel, and it burned up the spider...

She's fine now, albeit with a couple lugi's on the hood, but other than that, can't complain. I deffo know the ins and outs of the intake manifold gasket replacement for a '96-'99 GM small block....