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Tahoe & Suburban The power, space, and brutal towing ability make the Tahoe and its longer sibling, the Suburban, arguably the best full size SUV's on the market today.

2013 Chevrolet Suburban
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  #1  
Old 06-02-2009, 02:32 PM
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Default 98 350 Vortec won't start after intake gasket replacement

Hi all, a new member here with his first desperate post

I did use the search and Google first (For several days).

Vehicle: Suburban, 1998, Vortec 350, not modified.

I have replaced the intake manifold gaskets due to a water leak.
I put everything back together and the engine fired up and ran great, but I got a code about the cam and crank sensor signals being out of sync.
The engine started a bit hard, as if it had too much initial advance. Once started, it ran normal.

So I thought I had the dist one tooth off, affecting initial timing. I know the computer controls actual ign timing and the distributor positioning affects mainly the cam position sensor signal.

So I put the dist back in one tooth different, and it ran worse, real weak. So I pulled the dist again. At this point I cleaned the cap and rotor, heavy corrosion buildup there. Long story short, I modified the rotor to extend the tip a little further to make up for lost metal at the point where sparks erode it.
I put the dist back in in the position where the engine ran ok (but threw the code). No start. Hasn't started since, and I have tried just about every dist position possible.

Other things I have tried or tested:

cleaned and gapped the plugs & dried them
Tested fuel pressure (65 initial when pump primes, then 60 when pump turns off, holding)
I DO get spark at #1 plug. Every time.

Plugs seem a bit wet each time I pull them after trying to start the engine.

The best I get now is low thumping sounds from the muffler, and occasional short burst as if it tried to fire up. Engine turns over great. Shooting carb claner in the intake before or during cranking doesn't make any difference.

I have lined up the TDC mark and the dist rotor with the "8" mark at compression stroke. I know of the dimple at thedriven gear lining up with the paint mark on the dist body, but that is essentially just another way to make sure the rotor will point at the "8" mark. It cannot do anything else, the shaft is solid from teh driven gear to the rotor. Driven gear was never removed. Rotor was, but it can go on only one way.

With a timing light hooked up to #1, the mark on the damper lines up close with the mark on the timing cover. TUrning the dist doesnät change timing. (As it shouldn't, right?)

Cam position sensor gets 11V input voltage and it produces 3-6V output signal (fluctuating as expected) during cranking.


I'm stumped.

Jan Andersson, Orlando FL
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Last edited by Bugfuel; 06-02-2009 at 02:47 PM.
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  #2  
Old 06-02-2009, 03:06 PM
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You must unplug the timing bypass connector and fix your timing it is probably off!
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Old 06-02-2009, 04:27 PM
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Quote:
Originally Posted by Bugfuel View Post
At this point I cleaned the cap and rotor, heavy corrosion buildup there. Long story short, I modified the rotor to extend the tip a little further to make up for lost metal at the point where sparks erode it.

Jan Andersson, Orlando FL
Welcome to the forum

I'm thinking you need to replace the cap and rotor if it required you to "modify" it
if your plugs are that wet they are not getting a spark
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Last edited by in2pro; 06-02-2009 at 04:30 PM.
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Old 06-02-2009, 06:55 PM
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Where's the bypass? I thought only older engines had it, not the Vortec. But I don't know for sure. Don't have a book for this car, I usually work on imports

I'll probably throw in new plugs, it's about time anyways.
The cap and rotor worked fine with no hiccups before I cleaned them. Therefore I have a hard time believing they could now be bad, all I did was bring the rotor contact out a hair. And thinking back, I now think I did that after it quit running.

A new complete distributor would cost me $60 so I might go that route eventually. It would give me a new cam position sensor too

I just didn't want to start throwing parts (money) at it at random.

Jan
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Old 06-02-2009, 07:02 PM
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Welcome aboard and good luck, sounds like Distributor Cap/ Rotor changes are in order and go from there.
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Old 06-02-2009, 09:07 PM
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you could try at least a new rotor if not the cap
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Old 06-02-2009, 10:08 PM
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You need to replace the "modified cap and rotor" There is no timing bypass on trucks after 1995. The timing light is useless on this truck. The only thing that can cause p1345 cam crank correlation is a improperly installed distributor or incorrect cam retard #. Once you put the distributor in you must look at cam retard on a scanner the spec must be 0 + or- 2 anything else will set p1345. You set the cam retard number by turning the distributor and looking at a scanner instead of a timing light. If you noticed you did not give me to code number I just know it becase this is the kind of stuff I deal with everyday
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Old 06-02-2009, 10:21 PM
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Quote:
Originally Posted by MDTAHOE View Post
You need to replace the "modified cap and rotor" There is no timing bypass on trucks after 1995. The timing light is useless on this truck. The only thing that can cause p1345 cam crank correlation is a improperly installed distributor or incorrect cam retard #. Once you put the distributor in you must look at cam retard on a scanner the spec must be 0 + or- 2 anything else will set p1345. You set the cam retard number by turning the distributor and looking at a scanner instead of a timing light. If you noticed you did not give me to code number I just know it becase this is the kind of stuff I deal with everyday

Thanks MDTAHOE. I'll get the cap and rotor, and I also thought this engine no longer had the bypass. I know about setting the cam retard to within +/-2 deg, but you can't do that if the engine doesn't run!
You were correct though, I did get that code initially, when the engine ran ok. Now it won't start, and therefore, no codes.
My scanner doesn't show cam retard (bummer). I know I can get it close enough with trial and error, just by clearing the code, look for the CEL to go out and not come back.
I am certain that I have the dist set within 1 tooth either way from the correct position, if not dead on. It SHOULD run like this, even if it does trigger the code. Heck, it DID already. I'd be happy to get the damn thing started and get the code. I'd be home free from there.
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  #9  
Old 01-22-2012, 10:50 AM
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HEY guys I NEED HELP !!!!!!! I have a 1995 tahoe with a 350 tbi. It has 250,000 kms and it runs like crap. It runs better in park then once you put a load on the motor the truck tries to die. It runs alot better when cold and if your driving at higher speeds (thats if it can even get to like 80 kms), and you put the pedle to the ground it sometimes dies or will down shift and try and take off but wont go anywhere. I have un plugged the o2 sensor and no change in running, i have un plugged the knock sensor and no change in running. The EGR is new i have done the distributor, cap, rotor, plugs,wires, coil, tps, map, tbi gasket, checked the fuel pressure its at 7 psi,grinded down the grounds, timed it, checked for vaccum leaks, and it doesnt throw a code. If there is anything else i could try PLEASE let me know. thanks.
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Old 01-22-2012, 10:50 AM
 
 
 
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20, 350, cam, correlation, dist, gasket, hard, intake, p1345, replace, retard, setting, start, timing, view, vortec


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