Hard to start after long trips.

[r32flow]

Thank you guys for all the suggestions. I will report back tomorrow after I scan it. Lots of good info here. Thank you again.

 

[r32flow]

Hey guys, so it looks like I have the dreaded misfire on cylinder 4 and 7. Also there is a weird high voltage at the coil code. No idea what that means.

While running the scanner and watching the misfires I noticed something odd. If I put the truck in drive all the misfires go away. But if I accelerate they come back but are very minimal. I will have like 40 misfires in park but maybe 4 WOT in drive. And if I'm just stopped in drive I have 0.

All the sensors seem to be reading correctly.

I've been hearing this could be an intake manifold gasket. I did an old school redneck test, where you spray starter fluid around the intake manifold to see if the idle changes. No change.

So I'm kind of at a loss right now. Any help would be so appreciated.

Thanks again,
Rob

 

[r32flow]

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[r32flow]

Bump

 

[r32flow]

Any tips guys? I'm at a loss with this thing.

 

[east302]

I’d start with the P1351 since it’s being reported, but it could be setting due to extended cranking times. Did you check the fuel pressure? It could be bleeding off.

The GM manuals can be downloaded at the link below.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

It will have the diagnostic procedure for each DTC. Here’s the P1351 for a 98, maybe it will help.

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[r32flow]

That helps a lot. Thank you so much.

I didn't see a reading for fuel pressure on my scanner. And I don't have a manual gauge laying around. Should I be able to see if on the scanner?

 

[east302]

No, you’d connect a gauge to the fuel supply line fitting on the driver side by the intake. Check pressure with key on, engine off. Spec is 60-66 psi. Then turn the key off and watch the gauge to see if it drops and how long it takes to do so.

A parts store will usually rent a set to you.

 

[GoToGuy]

Remember when spraying for a vacuum leak ,your only testing the external area. That does not eliminate a leak in inside manifold valley, lifter area. Checked vacuum lines for cracked, loose hoses, abrasion leaks.