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Username Post: 1998 C1500 5.7 stalls after start-up        (Topic#244461)
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-26-10 05:46 AM - Post#1936273    

Hey guys! I'm new to the forum; you guys have some great info! I have a problem with my 1998 Chevrolet 1500. It is a 5.7/auto.
Here is the problem: the heads were pulled after 326,XXX miles for a refresh. Once the heads went back on, the truck will run for about two minutes and will then die. The truck can be "nursed" with the throttle when it begins to stumble to achieve another few seconds of good idle. Eventually, the engine will die, though.
The timing chain and water pump were all replaced at the same time. When first cranked, the engine runs evenly and well; it sounds healthy. Then it seems to run on about 4 or 5 cylinders, but then it dies.
Fuel pressure is at about 63 psi at idle. It does not decrease while running. FP remains constant through the "stumbling" episodes.
I get a CMP A fault and a CKP A fault. I changed the CMP even though it tested good (12VDC +, 5VAC output, good ground), but to no avail.
The ignition module was changed, but that didn't fix it either.
I hate just throwing parts at my truck, but am having fewer ideas about what the problem is. Does anyone have an idea?
Oh, after it stalls, the truck must cool down before it will start and run again.

Thanks for the help! Sorry my first post is a trouble call, too..........

-Les
Covington, GA

 
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355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
06-26-10 07:21 AM - Post#1936304    
    In response to fastasleep

Hello and welcome to Chevytalk. Sounds like you got a good start on trouble shooting and have some good information. Right off hand, I would want to check compression on all cylinders. I say this because you said you have to wait for it too cool down to start it back up again and this is a symptom of low cylinder compression.

The next question I have is, how did you set timing on this motor? Did you mark the distributor? or did you TDC and use the factory marks? and did you ever use a scan tool to fine tune the cam retard offset to zero degrees?

Tom
98 Silverado k1500 4x4 350


 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-26-10 07:50 AM - Post#1936324    
    In response to 355Cheyenne

Tom, I did not do the head refurbish/replacement on this engine. I bought it after the previous owner got fed up with it.
I did not initially place the distributor in the hole. I did, however, advance and retard the distributor one tooth to see if it made a difference. I was thinking that the ECM could only compensate the timing difference so much.
I do not have a TechII scanner to check the cam retard offset. Is there an alternative?
I can always go back to zero and go to TDC on #1 cylinder and set the distributor to #1 spark plug wire, as I have not yet tried that.
It just seems as if once the engine goes into "closed-loop" the idle quality changes and it wants to shut off. I checked the coolant temp. sensor, but that had a good connection.........but then again, it is new. I wonder if the engine is thinking it is too hot and leaning it waaaay out in closed-loop?
I'll do a compression check and get back with you.

Thanks, Tom!

-Les


 
355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
06-26-10 08:21 AM - Post#1936350    
    In response to fastasleep

is the CMP fault the only error you are getting? The timing on these trucks is a very unique process that you only see on these 96 to 98~99 trucks. Read the FAQ as I have a write up on how to properly set timing, if you are just a little off you get some strange things happening and this could be as simple as a timing problem.

EDIT:

here is the link to the actual thread. timing 96 to 98 vortec.
98 Silverado k1500 4x4 350


Edited by 355Cheyenne on 06-26-10 08:22 AM. Reason for edit: No reason given.

 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-26-10 09:03 AM - Post#1936370    
    In response to 355Cheyenne

Thanks! I will give it a read right now. I get a CMP fault and a misfire fault now. Initially, I was getting a CMP and CKP fault.

-Les


 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-26-10 09:11 AM - Post#1936378    
    In response to fastasleep

Is it possible for the engine to start and run for two minutes and rev like it is supposed to during those two minutes and then want to putter out if the timing is off?
I am going to do my compression test and then re-set the timing according to the sticky on the FAQ. Maybe this will help.
Also, I have no scanner here. Is there an alternative?

-Les


 
355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
06-26-10 09:55 AM - Post#1936403    
    In response to fastasleep

  • fastasleep Said:
Is it possible for the engine to start and run for two minutes and rev like it is supposed to during those two minutes and then want to putter out if the timing is off?
I am going to do my compression test and then re-set the timing according to the sticky on the FAQ. Maybe this will help.
Also, I have no scanner here. Is there an alternative?

-Les




I think so, I mean it is all computer controlled so it is hard to say exactly what would happen with the distributor off. How it works exactly is this. The distributor position really has nothing to do with timing anymore. The Computer looks at the crank sensor to determine when to fire. The sensor in the distributor tells the computer where the distributor is so it knows if the alignment is out of spec, most other applications put a notch in the casing so you couldn't turn the distributor and I am not sure why GM did not do this. The problem is if you have the distributor turned too much out of spec then you have the possibility of cross fire. The rotor may not be pointing close enough to the correct pin and the ignition meant to go to one cylinder ends up going to another causing a random miss fire and other odd running problems and erroneous MIL codes.

What I would do is leave the timing. make sure you are TDC #1 and see if the rotor is pointing to the #8 in the plastic casing of the distributor. If it is then this isn't a timing issue, if it is off, correct and see what it does.

As far as the scanner. My method should get you close enough that if that was the problem it would run fine. But no real way around it, in the past I paid the dealer to do it. I have been trying very hard to find a cheap enough scan tool that has this function although it is an advanced GM code set and all cheap scanners I can find require you pay a larger fee for the GM set that has it. So far the cheapest I have seen was in a autoxray scan tool I think. Once I do find a sub $100 tool I will be sure to report it in the faq.

To sum it all up, the distributor position does nothing to affect timing at all. by setting the distributor position or Cam Retard Offset, all you accomplish is preventing crossfire. The spec is +- 0 degrees, if you set it to -2 degrees and then compare it to setting to +4 degrees the truck will run identically and you have not affected the timing curve at all, as would have been the case in the pre 96 TBI and as well older HEI stuff.

EDIT: off my head I didn't know the acronym CMP fault, I can tell you with 100% certainty that this is a cam position fault error. So your timing is very likely the problem. I need a more specific error then CMP fault though, there should be a number error.
98 Silverado k1500 4x4 350


 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-26-10 11:11 AM - Post#1936421    
    In response to 355Cheyenne

I am now able to go out and look at it (have been tied up this morning). I will get the exact code for you and report as soon as I get it.
Thank you so much for the help and I hope we can find the issue!

-Les


 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-26-10 03:01 PM - Post#1936531    
    In response to fastasleep

It gives me a P0345 and a P1341 hard code. I get a P0339 as a pending code.

I have good compression. The rotor button is now directly facing the 8 on the distributor housing; I had to move it one tooth to get it in the middle of the mobility range (rotation of the distributor housing).
I am still having the same issue. BTW, after I start it and run it and it stumbles and shuts off and I try to restart, the plugs are wet with fuel.
Anything?

-Les


 
355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
06-26-10 08:57 PM - Post#1936670    
    In response to fastasleep

O.K. so P1341 is a multiple miss fire and the ECU cut the fuel. So this is why it shuts off, looks like the ecu shut it down...

If you clear the codes does P0339 regenerate? If so you may still have a crank sensor issue.

With P0345 error I would check the wire harness on the distributor. I bet you that it is either damaged or disconnected. Else this may be an indication that the sensor it bad.
98 Silverado k1500 4x4 350


 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-27-10 04:21 AM - Post#1936717    
    In response to 355Cheyenne

Yes, the P0339 will come back. I did change the cam position sensor, but will inspect the harness. With the heads being removed, it wouldn't be too hard to pinch those little wires back there.
I will change the crank sensor as well.

-Les


 
355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
06-27-10 07:17 AM - Post#1936767    
    In response to fastasleep

also check your grounds. off my head I believe there are 3, one at the passenger side fire wall body. and then one on the thermostat stud and one on the driver side head. Then the one going from the battery to body. If any of these are bad it could cause this issue.
98 Silverado k1500 4x4 350


 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-27-10 07:24 AM - Post#1936771    
    In response to 355Cheyenne

It turns out that it was the crank sensor. I replaced it this morning and cleaned the spark plugs. Also, only one of the grounds were connected. I reconnected the two that were omitted and added another for good measure. Could the inadequate grounding cause a crank sensor to fail?
Thanks SO MUCH for helping me with this issue! This truck runs very well and I estimate another 300,000 miles of service!

-Les


 
355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
06-27-10 07:29 AM - Post#1936773    
    In response to fastasleep

Hey no problem. Likely the grounds were your problem. Think of it like this, if the sensors were light bulbs and to get them to light you need to complete the circuit. Two wires, one wire goes to the ecu and the other goes to a common ground. Well the sensor or "lightbulb" wont work if the common ground is bad. I would be willing to bet that the ecu thought that both cam and crank sensors were bad because they shared a common ground that was disconnected.

From my understanding the ECU can start the motor on a guessed pulse but once it gets to a certain point, if it doesn't see an actual pulse it shuts it down because it has no idea what is going on.

I would recommend that you take it some place to get the Cam offset done. Honestly from all that I have read, if it runs fine and you don't get an SES light, you should be close enough that you likely won't have issues. I just rebuilt my 98 here this winter and I still cannot find anyone other than the dealer that wants $80 just to check it, but it has been running like a champ for about 4~5 months now and have kind of let it go...

at the end of the day, all setting the distributor position accomplishes is to prevent crossfire.
98 Silverado k1500 4x4 350


Edited by 355Cheyenne on 06-27-10 07:33 AM. Reason for edit: No reason given.

 
fastasleep 
Forum Newbie
Posts: 9

Reg: 06-26-10
06-27-10 08:52 AM - Post#1936791    
    In response to 355Cheyenne

Thanks again! I have driven it for about 50 miles now and the thing drives like new. It is hard to believe that it has so many miles on it!

-Les


 
808 
Forum Newbie
Posts: 1

Reg: 08-18-11
08-18-11 03:54 PM - Post#2127433    
    In response to 355Cheyenne

I have an AutoXray 5000 tool. When I try to check the timing on my 1998 C-1500 (5.7), I get about 24* at 1000 rpm. Is there a wire that needs to be disconnected from the distributor? I remember my old truck having a brown wire that needed to be unhooked prior to timing. I don't see a wire like that on my 1998.

 
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