2000 C3500 truck dies when put in park

[pigpin]

So here is what I have and an odd problem nobody has been able to figure out.
2000 C3500 5.7 4L80E 200K on the truck when I did the following:
New GM L31 crate engine
Fuel injector conversion
Fuel pump and filter
Radiator, water pump, heater core, and all hoses
AC compressor, condenser, evaporator, hoses, HVAC controls, all hoses and lines
Distributor (Crappy factory plastic style), cap (first two were defective), rotor, plugs and wires
Coil, IACV, TPS, crank position sensor
Along with this drive train work new springs front and rear, steering box, bushings, ball joints, shocks, tie rod ends, sway bars and links, u joints, wheels and tires (factory steel wheels and correct size tires), front rotors, pads, calipers and hardware, rear drums, wheel cylinders and shoes, and all brake lines ( hard and rubber).
After all this work I just could not get the timing set. I took it to a local shop and it turned out that the cap that came with the new distributor was shorted across two of the plug wire connections. It took the guy about an hour to figure out. It ran great after this but started weird, sort of like the timing was too advanced. I drove it trouble free for about 4k miles and then it started intermittently dyeing when put into park. Never while stopped at a light and doesn’t die when stopped until put into park. At first it was very intermittent and has gotten worse as time goes on and is now about 50/50. No check engine light is on, no codes. I’ve had it to two shops and neither can find a thing wrong with it, one of them had it for 2 months. It has even been on a chassis dyno at a transmission shop and they could find anything wrong with it but I don’t think it did it while they had it. I’ve talked to two of my local Chevy dealers but neither work on anything older than 2001. The problem has slowly gotten wore and it will now idle rough at stop lights, sometimes, and seems to lag when accelerating from 30mph idle.
Anybody have any ideas? Thanks.

[Rod_Lei]

The only thing I can think of is that the timing is off. The timing on a vortec engine can't be set like an old school sbc, it requires a specific computer to force it into cam offset mode. It's not something you can do with a timing light.

[pigpin]

Thanks for responding Rod_lie. Timing was set by a reputable local shop and has been checked by another and my local GM dealer, the only thing the GM shop was willing to do. GM service writer claiming they are not trained to work on "old" Vortec trucks.

The problem seems to be getting worse, a good thing I guess. It was idling bad this morning so I knew it would die when I put it in park. Here is a video of it.
https://youtu.be/HiaQvq3dxUI

[sntrym95]

What kind of fuel pump did you put in? Have you checked fuel pressure at the engine yet?

[pigpin]

sntrym95 The fuel pump put in was:
http://www.rockauto.com/en/moreinfo....1358502&jsn=38
the shop that had it for two months tells me they checked the fuel pressure and that it was good but I don't have a way to know how they checked it or even confirm that they did.

[sntrym95]

You should always use a Delco or Delphi pump.

Here are a couple posts on Vortec motor fuel pressure:
http://67-72chevytrucks.com/vboard/s...d.php?t=359063
Sticky on lots of things: http://67-72chevytrucks.com/vboard/s...d.php?t=445487

[pigpin]

With a fuel pressure gauge, key on engine off 57.
Engine idling 48.

looks like the spec for key on engine off is 60-66.
So it is low, now to figure out if its pump or regulator.

[clinebarger]

Originally Posted by pigpin

With a fuel pressure gauge, key on engine off 57.
Engine idling 48.

looks like the spec for key on engine off is 60-66.
So it is low, now to figure out if its pump or regulator.

With a MPI Conversion Spider, The original fuel pressure specs no longer apply. MPI Injectors do not require as much FP as the Poppet Style Injectors.

Did you check all the grounds? Rear Passenger side Cylinder Head, Thermostat Housing Bolt, Driver side of the Block behind the PS Pump.

[68C15]

Disconnect trans range sensor and retest.

But I'd be real curious what the IAC counts are in gear and park along with trim numbers

[pigpin]

I've checked the grounds and connectors but might give that another go around just to be sure.

68C15, when I Disconnect the trans range sensor any thing weird I should be ready for?

And what's your suggestion for reading IAC counts and fuel trim numbers? I've got the free version of the Torque app on a tablet, good enough?
Thanks
Joe

And not that it matters but here is what I'm working on. Camping season will be here soon and I'm really wanting to get this fixed before then.

[pigpin]

68c15, with the range selector switch unglugged I get a no crank. A trick I should try to jumper it?

[pigpin]

68c15, with the range selector switch unglugged I get a no crank. So I plugged it back in, started it and drove it. Seemed to drive fine and didn't die when put in park, but I only went around the block and normally have to drive farther than that for it to die. I questioned this switch when the mechanic had it. I was told that the switch can't kill the truck, the fact that it being unplugged gives a no crank tells me otherwise. And the little blue safety clip on the connector was undone so he must have messed with it. So I need to do some more testing.

As for fuel trim numbers it looks like they run anywhere from 0 to -5.5

[clinebarger]

Jump Purple wire to Purple & White wire, This will bypass the Neutral Safety portion. Be CAREFULL!

[pigpin]

What I have been doing the last few days is plugging the switch in, I got all the glue off of it, starting the truck, and then unplugging it. It seems to run and idle better with the switch unplugged. It hasn't died going into park since I've been doing this. I was raining this this morning and it stumbled a little in park but didn't die. Acceleration also seemed sluggish this morning. So I've got a new PRNDL switch on the way but I'm still thinking something else is wrong.

[pigpin]

New PRNDL switch didn't help. So I took the truck to another shop with a good reputation for trouble shooting. They found the timing was 11 degrees off and that the harness under the dash that I was charged for wasn't replaced.....that's a conversation for another day and explains why I try and do everything myself.
This shop had the truck for a couple days and checked it over pretty good. They even had the harness out of the truck and wire loom off checking the connectors and condition of the wiring. All checked out good. The shop tech said it was the best looking C/K truck he has worked on in about ten years. Since they couldn't find anything wrong they are thinking it is a PCM issue. So I have a used one that has been reflashed with my VIN on its way to see if that helps.

[pigpin]

For anyone following along the new PCM didn't change anything. Still dies intermittently when put into park. But with the timing set correctly it runs and drives amazing.

[68C15]

ask shop to reset minimum air rate. It's kind of like adjusting idle speed with a carburetor but you need to watch the TPS voltage when doing so. If that gets out of normal range you will have erratic idle. Also have them scope the TPS for drop-outs

[speedygonzales]

In early April this

Originally Posted by pigpin

Timing was set by a reputable local shop and has been checked by another and my local GM dealer,

Now this

Originally Posted by pigpin

For anyone following along the new PCM didn't change anything. Still dies intermittently when put into park. But with the timing set correctly it runs and drives amazing.

Got to think something is changing over time to effect timing. Got to think there is another issue if you didn't get a code for being that far off. Although I have personally witnessed it being further in a negative direction and not throw a code. Went 1 degree positive and it threw it right away. IDK.

During an episode of the problem occurring. Try disconnecting the IAC while it's idling good and see if the problem goes away.

[pigpin]

Originally Posted by 68C15

ask shop to reset minimum air rate. It's kind of like adjusting idle speed with a carburetor but you need to watch the TPS voltage when doing so. If that gets out of normal range you will have erratic idle. Also have them scope the TPS for drop-outs

68C10 I've talked to a couple shops about your suggestion and I'm being told that idle speed isn't adjustable. Also being told that they don't have the ability to scope the TPS. I'm thinking they are all just tired of working on it. Pretty sure I'm on my own at this point.

I did some investigating last Thursday. Looking for damaged wires bad connections etc. I decided to take the throttle body off and check out the seat for IAC. It was all a little dirty but not too bad. I took the TPS and IAC off and removed the butterfly and cleaned it all with throttle body cleaner and reassembled with a new gasket between the throttle body and intake manifold. I noticed that the seal in the bottom of the plastic air box that seals to the top of the throttle body is shot. After some looking around it doesn't look like this seal is available. I did a temporary fix with some grease. And it ran amazing, smooth idle, good power. just like it should. The last couple days it has been cranking longer start again and at lunch today it started and died. Set code P1351. First time I've seen it give a code.

[pigpin]

Originally Posted by speedygonzales

In early April this



Now this


Got to think something is changing over time to effect timing. Got to think there is another issue if you didn't get a code for being that far off. Although I have personally witnessed it being further in a negative direction and not throw a code. Went 1 degree positive and it threw it right away. IDK.

During an episode of the problem occurring. Try disconnecting the IAC while it's idling good and see if the problem goes away.

Speedy after putting a lot of my own time into it and reaching out for help I'd say that the first shop wasn't familiar with Vortec trucks and didn't a number of things they said they did, and charged me for, but that's a conversation for another day.

The last shop that worked on it seems to be a little batter but they don't have room in the schedule to do anymore with it for 4-5 weeks.

[speedygonzales]

1351 is IC signal from the PCM to the ICM. It's the solid white wire going to the ICM. Disconnect the harness at the ICM and probe the white wire to ground. Set your meter to AC and while someone cranks it, you want to see no more than 4 volts AC. Reconnect it turn KOEO and back probe the same pin set to DC and confirm the voltage is less than 1 volt DC.

If all those pass, see if you can tighten up the same pin in the harness and reconnect it. Give it a try.

[pigpin]

Thanks Speedy. I'll check all that out.
What ever it is, it is intermittent. After it did it at lunch yesterday it started and ran fine the rest of the day and the check engine light is out.

[speedygonzales]

Contact issue probably at the ICM. Incidentally, the ICM is mounted to the plate with heat sink compound between them. Over time the heat sink compound goes away and dries up. Clean it with a solvent and reapply new heat sink compound. Don't confuse dielectric grease with heat sink compound. One is clear and the other is white.

[pigpin]

just in case anyone ever runs across this thread in future trying figure out the same problem Cleaning the throttle body and butterfly made a big difference as well as replacing the orange seal where the intake tube meets the throttle body. So in the end I spent about $6k chasing a $10 fix that four independent shops and three Chevy dealers couldn't figure out. My lesson here is to not keep trucks past about 150k, off them and move on. I'd of been about $12k ahead if I'd of done that.

[speedygonzales]

Where did you get the orange TB seal?