Engine Ticking

[Dmod81]

Thanks, good to know that it has happened before.

Yes, the limiter is now set at 7200.

On a side note, the throttle sticks slightly coming down to idle now. A slight tap will bring it back down from 900 to 750. So I think I'll go ahead and have the throttle body rebuilt after all (and ported to 63 mm).

[Dmod81]

Looks like I have spoken too soon about it running great.

Symptoms (other than the slightly high idle that will go back down after a small tap on the throttle):

Miss every few seconds at idle (rpms will drop about 20 on tech 1)
Every once in a while it will stumble and almost die at idle
After coasting, when I get back on the gas, it will stumble and buck until it clear out and runs normally again
Smooth operation in normal driving and heavy throttle

KOEO pressure is 0 psi, slightly over 40 at idle
Both pumps run when tested
Car starts normally

It looks like the book points me to the hoses in the tank (entire new pump assembly was installed in April 2013) or the fuel filter (new installed April 2013), but I wonder if I might have a bad injector (s) too? They're accells that were installed at the same time as my failed coil (Sometime in late 2008 I believe)

[lfalzarano]

Save time and call Mark Hailbbeck at 630-458-8427 with your symptoms. Don't take it to a Chevy dealer...

[FU]

Dmod81 where are you located ?

[Dmod81]

Currently Central Coast California, near Santa Maria

[Dmod81]

Just a little update:

I ran through the fuel pressure test procedure and was getting almost instant leakdown, so I replaced both pumps. Now I get 52 psi when the pumps are running, which drops to about 43 when the pumps stop and holds there with very slight leakdown. Pressure at idle is about 42. I also replaced the fuel filter. Rough running/miss at idle still there.

Finally I replaced the injectors. There was some crud in the rails that I cleaned out. I also checked my plug wire routing/reseated the wires, replaced plugs, O2s, and checked all other connections/vacuum lines. All seemed good. Rough/miss at idle is still there, but it might be very slightly better. However, the stumble with throttle after coasting is MUCH better. Almost non-existent.

As a kicker- I now have a very large screw in a rear tire. Must be a gift for driving the car only 40 miles over the last 4 months trying to fix it. I think something is trying to tell me it's time to throw in the towel.

[XfireZ51]

You're sure you don't have a vacuum leak like at the PCV valves?

[Dmod81]

All of the pcv parts are new and attached snugly, but there could be a leak somewhere. I'll see if I can find a leak with a homebuilt smoke machine or something.

[LGAFF]

Will apologize if its been discussed as I did not read the thread, but sounds like a MAP sensor issue;either a rotten hose on the primary or under the ECM

[Dmod81]

No worries - I don't believe it has been discussed, although the map and the hose (plastic) are relatively new. The MAP seems to be reacting correctly on the tech 1. The sensor under the ecm is open to atmosphere, as I've eliminated the secondaries (That is correct, right?)