[prismatic]

Here's the situation. I had a bad head gasket and a cracked head giving me a rough idle when cold started and leaking coolant. I got a new head, new gaskets and fixed that. The engine is running fantastic now. No stuttering at all when starting cold.

However, it's got a new or maybe old but now exposed issue. When I start it cold, the engine runs fine, idles great. The second I put it into gear it goes vroom vroom vroom vroom as the RPM needle bounces up and down 150-200rpm for a few seconds then stops. It will also do this sitting at red lights sometimes.

Any ideas? I thought it could be the transmission so I'm gonna drain the fluid and put a new filter in sometime next week.

 

[jw89sho]

CEL? Any codes? Sounds like maybe a vacuum leak causing a lean condition.

 

[prismatic]

CEL? Any codes? Sounds like maybe a vacuum leak causing a lean condition.

There is a CEL yes. I'm going down to get some food so I'll stop by PepBoys on the way and get it pulled. I'll let you know in a little while.

edit - PepBoys was unable to pull the code for me today, they're swamped. I'll try again tomorrow.

 

[sadistic]

check timeing. does the same thing on my pontiac fiero when timing is off a tad.

 

[Jeff K]

The timing is not adjustable without a PCM reprogram.

 

[shoz123]

IAC regulates idle speed. Sounds like yours is slow to respond.

 

[sadistic]

The timing is not adjustable without a PCM reprogram.

if it the one in his avatar yes it is not adjustable but if it's a 3.8l which i was not sure of. but any ways good point.

 

[prismatic]

if it the one in his avatar yes it is not adjustable but if it's a 3.8l which i was not sure of. but any ways good point.

That info is accurate. It's a 3l Vulcan

 

[austex04]

How long ago did you get the head done? Was it done at a shop? If so, why not take it back to them, as a vac line or something didn't get put back. It could also be the iac valve or throttle body is dirty.

 

[prismatic]

How long ago did you get the head done? Was it done at a shop? If so, why not take it back to them, as a vac line or something didn't get put back. It could also be the iac valve or throttle body is dirty.

Did the work myself. Throttle body is clean. I meticulously cleaned it and the intakes.

When I unplug the IAC the engine idles very slowly, around 500rpm. With it plugged in the idle is normal in park.

 

[shoz123]

The engine should die immediately if the IAC is unplugged at idle.

 

[prismatic]

The engine should die immediately if the IAC is unplugged at idle.

I started it unplugged.

 

[jw89sho]

Actually, you are running at base idle with IAC disconnected, around 450-500 RPM. I could only get mine to run that way after cleaning the TB and removing major amounts of gunk. There is a (sealed) screw to adjust base idle before the PCM takes over.

 

[sadistic]

Engine lopes or idling roughly

Number one cause is vacuum leaks so check the intake manifold mounting bolts for tightness make sure vacuum hose are connected and in good condition. then go over all the other possible causes because it was a head gasket just done . plus I do not know the exact mileage or how the car was taken care of like weather stuff that should have been replace was. So take a look at the following.

2 leaking egr valve plugged pcv valve= posible
3air filter clogged but do not think so
4 fuel pump not supplying enough fuel =possible
5 leaking head gasket check compression = possible
6 timming chain worn = possible
7 cam shaft lobes worn = possible
8 valves burned or leaking on new or the old head depending on if you installed new valve seals etc.. = possible
9 ignition system not function right =possible
10fuel injection or engine control system malfunction =possible

 

[prismatic]

Engine lopes or idling roughly

Number one cause is vacuum leaks so check the intake manifold mounting bolts for tightness make sure vacuum hose are connected and in good condition. then go over all the other possible causes because it was a head gasket just done . plus I do not know the exact mileage or how the car was taken care of like weather stuff that should have been replace was. So take a look at the following.

2 leaking egr valve plugged pcv valve= posible
3air filter clogged but do not think so
4 fuel pump not supplying enough fuel =possible
5 leaking head gasket check compression = possible
6 timming chain worn = possible
7 cam shaft lobes worn = possible
8 valves burned or leaking on new or the old head depending on if you installed new valve seals etc.. = possible
9 ignition system not function right =possible
10fuel injection or engine control system malfunction =possible

Thank you, I'll start checking those.

 

[prismatic]

just got back from PepBoys

The code is P1309 - Misfire Monitor Fault

Google suggests the cause is probably the Camshaft sensor out of alignment.

I used the special tool to insert it and align the sensor the way it came out, what the heck.

No chirping noises and no oil pressure warning lights. Is it possible I managed to, using the special tool and the manual, install it out of time and thats causing the issues?

 

[Monsoon]

I have a couple of questions because I have seen this before.

Does the engine pull 18 to 22 inches of vacuum? If not fix this problem. Adjust for altitude if necessary.

Does the engine stumble when it is under a load but idles great? If yes check the coil, coil pack and or ignition cables.

Rationale when the engine is idling it is not under a load condition and requires very little spark to keep it running. When the engine is under a load condition it requires greater spark for power, but if the coil can not generate enough spark for the added air/fuel mixture the engine will stumble.

Let me know what you think.

Monsoon

 

[jw89sho]

I have a couple of questions because I have seen this before.

Does the engine pull 18 to 22 inches of vacuum? If not fix this problem. Adjust for altitude if necessary.

Does the engine stumble when it is under a load but idles great? If yes check the coil, coil pack and or ignition cables.

Rationale when the engine is idling it is not under a load condition and requires very little spark to keep it running. When the engine is under a load condition it requires greater spark for power, but if the coil can not generate enough spark for the added air/fuel mixture the engine will stumble.

Let me know what you think.

Monsoon

I agree with bad plug wires, coil pack, and possibly bad plugs (worn or excessive gap).