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99 'burb possible timing issue
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duncan
Novice
Dec 10, 2012, 7:37 PM
Post #1 of 9
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99 'burb possible timing issue
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Been having trouble for about a year with this; I have a 99 Chevy Suburban k1500 5.7, 170K miles that will not start. The engine was professionally rebuilt at 90k and the tranny at 95k. About a year ago it started shuddering at about 1800-2200 rpm idle at highway speed. It always runs perfect under load just would shudder at steady speeds. It also would stutter while shifting from 1st to 2nd. It eventually threw a code p1345, checked at Autozone. I replaced my plugs(autolite double plat), wires(omnispark), cap and rotor(masterpro), and crank position sensor(masterpro). The problem went away but I still had the code.
After a few months, whenever it got overly humid or was raining it would start missing again. I suspected wires or dizzy cap so I tried spraying water on the components to check for spark jump.. nothing.
About 6 months ago it completely died like I ran out of fuel. I had fuel, and it was flowing. After about an hour of tinkering with the wires and plugs I got it started. It chugged and was backfiring into the cat so I had it towed home. I looked into a service bulletin with the crank sensor and noted it needed a shim, I added a shim and it came to life purring like a kitten.
A few weeks ago it started running crappy again. The same symptoms I had when all this started, again it was humid then rainy.
The other day, after the burb sat for 3 days, I tried to start it. It just cranks. After cranking, it would kick a full cycle and die as if it had a very late spark. I checked for spark off the coil, off the dizzy on the 1 cylinder wire, and the 1 cylinder plug. I have spark and then I checked for TDC while I had the plug out. It seems to spark in time with TDC cycle also. I plugged everything back in and tried pouring a shot of fuel into the throttle body and had no luck. I checked the dizzy for lateral play and it seems fine and no rotating movement from the shaft hold-down. I can't imagine I skipped a tooth if I don't have any play. Yes, I'm avoiding pulling the whole assembly out. I then checked the crank sensor for gouges. It looked fine but I added another shim in case. No luck. I now have the cap and rotor off, don't notice any cracks, but have a small carbon track between the center and #3 point. (possibility) I did not do a pressure check on the fuel rail since I don't have the gauge but my pump is kicking on and the plug I pulled had gas on it, I would not suspect fuel anyway since it didn't fire when I poured gas into the TB.
Any ideas or anything else I can check before I start throwing more money at it. I don't have a code reader to see if I'm throwing a different code than the old p1345 but I think I can borrow one within a few days. It's close to the holidays so money and time is short.
While I have your attention, I also have the Passlock fuel shutoff problem only when it's hot and humid outside, this is not my problem now, but I have this issue. I don't know if these two relate in any way, but it's part of my headache with this vehicle. I just want to get this P.O.S. running so I can get it sold, I'm tired of getting stranded.
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 10, 2012, 7:44 PM
Post #2 of 9
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Re: 99 'burb possible timing issue
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Save your Passlock problem for a different question.
The ignition timing on that truck is not adjustable although you do have the distributor installed wrong. Turning the distributor changes the cam offset and the synch of the secondary ignition to the primary. You need a professional scan tool to adjust it correctly.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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duncan
Novice
Dec 10, 2012, 7:56 PM
Post #3 of 9
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Re: 99 'burb possible timing issue
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I've never taken out the distributor, I just replaced the cap and rotor, there's only 1 way for those to go on, and I did mark the direction anyway before I changed it. I'm leaning that something may need to have been reset when I replaced the crank sensor. I have never had the cam retard/advance set, I tried to eyeball that it was at TDC, but I never unbolted the dizzy to turn it at all anyway. I guess if it had significant wear at the gear it could be off by a degree or two, but not enough to cause a no-start IMO. I'm not a mechanic by any means and I may be way off base. I scoured other forums and many say that delco parts must be used in Vortech's since they are very picky. Anyway, I am sure the dizzy is correctly installed, unless it ran for about 2 years 180 degrees off.
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Hammer Time
Ultimate Carjunky
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Dec 10, 2012, 7:59 PM
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Re: 99 'burb possible timing issue
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Nobody said it was 180 out. The P1345 indicates the offset is off in excess of the acceptable 2 degrees.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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duncan
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Dec 10, 2012, 8:05 PM
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Re: 99 'burb possible timing issue
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If it's off enough to throw the code, what would have caused it? is it a sensor issue since I've never had the dizzy out? I'm just very short on $ and want to be accurate in diagnosing the issue without having to tow it into the stealership.
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Hammer Time
Ultimate Carjunky
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Dec 10, 2012, 8:07 PM
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Re: 99 'burb possible timing issue
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The distributor being in the wrong position is the only thing that can set that code.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
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Dec 10, 2012, 8:08 PM
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Re: 99 'burb possible timing issue
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I find it a bit odd that the P1345 came on by itself......usually that will pop on as soon as you start it up after a repair...
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duncan
Novice
Dec 10, 2012, 8:24 PM
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Re: 99 'burb possible timing issue
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When I got the code I was driving on the highway then it acted like I was out of gas, it started sputtering then it backfired and ran okay enough to get it to Autozone to scan the code. Changing the crank sensor fixed the symptoms but did not reset the code. The symptoms were intermittent but acted worse during wet or humid weather. Makes me think it's the cap getting moisture inside. It's been raining and humid the last few days and I have no start at all now. I'm just confused since I've never had the dizzy out, how it is out of position now? Could it be a sensor picking up moisture? Or should I just bear it and pull the dizzy and check the gear? OR could it be the timing chain? Sorry, I'm just putting down any thought I have.. A.D.D. is horrible when I'm angry at my burb!
(This post was edited by duncan on Dec 10, 2012, 8:26 PM)
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duncan
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Dec 10, 2012, 9:07 PM
Post #9 of 9
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Re: 99 'burb possible timing issue
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Thank you for your input Hammer, I'm going to change out my cap and rotor, plugs, and wires with delco (might as well do it right!) and hope for a start so I can drive it into the shop to have the retard/advance set. If not I think I still have a tow left on my insurance. I'll post back with my results, likely after next week. Thanks again, and Happy Holiday's!!
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