Stalling / Misfire #7 and Stumbles around 1800-1900 rpm

[rumblefish73]

Just replaced the distributor on my 98 Tahoe as per advice from a local dealer's shop supervisor to cure stalling / misfires / stumbling.

Found that after i've replaced it that it lit up the engine light and spit out a P1345 code.

I remember after I had the intake coolant leak fixed and they also replaced the timing chain that the camshaft reading was -3 and I thought that they might have been off a tooth when reinstalling the cam gear on the cam. Can someone let me know if this is possible to find out or if the cam retard reading is only the correlation between the crank and the cam and if negative 3 would have made the motor run rough, stall and all the crap i've been going through with this?

I used a Snap-On scanner today and was able to check the cam retard reading to remove the P1345 code. Every other time I start the truck it says 0 or -2 cam retard so i'm close.

Changed out the cap and rotor, even though I had previously ruled them out because the scanner is picking up a small misfire on cylinder #7. Not enough to create a code though. And I think that's where my stumble at idle is coming from! I swapped spark plugs, plug wires with cylinder #5 and #7 still has a misfire with new cap and rotor and different wire and different plug.

What's the chance I have a bad injector or sticky valves and does anyone know how to check?

Thanks!

Jay

[wildcatkit52]

I am looking for the same answer. My GF's 95 Tahoe just started that same type of "stumble" No code. Runs fine in higher RPM. I haven't changed the plugs or wires yet. I wanted to look to see if I could find any usual issues like this first. My first guess would be plugs on hers. I will be finding out soon enough.

[rumblefish73]

I replaced the old advance auto cap and rotor with an ac-delco cap and rotor. I still have a stumble at idle but the hesistation around 1700rpms is better now and not as noticable. The scanner still shows some misfires in cylinder #7 but not enough to set a code and i've read that you have to have more than 20 misfires in 200 revolutions of the engine to set a code and some misfires are normal?

Doesn't explain the bad idle though still but i'm happy with it and gone back to the old distributor set at 0 degrees Cam Retard.

I did a fuel injection balance test, testing cylinder #7 several times and they all start out around 58psi and go to 48psi.

I think I might have a sticky valve or some carbon buildup causing pre-ignition in some cylinders.

I might put a set of spark plugs in it next week to see if the idle is better even though they look great.

Anybody have any feedback on what plugs to use in my 98 Tahoe 5.7l ?

[TXTahoe]

my 2002 Hoe, I just replace the plugs with the AC delco Iridiums....seems fine, but I still have a slight stumble at idle. No code showing up and the rpms don't jump. This didn't start until I had some AC work done. I've cleaned the throttle body, injector cleaner, fuel filter replace....etc. and still she's not running smooth at idle. My next area will be to change the wires. One thing you'll hear is that you should only use ACDelco plugs for chevy's. When I replace the OEM's they were AC's....but NGK made them. HHMMMM.. I could've saved some money on my replacements.

Note the gaps on the the Irids came factor spec. .035 and .060 is the factor spec.