GenVibe - Community for Pontiac Vibe Enthusiasts

Hello,

Not sure if this is some issue but recently changed intake gasket manifold. All seems to be ok no PCM errors, no vacuum leaks but noticed after week or two when starting car like mornings or sometimes if its standing longer period like 3 -4 hours engine when starts RPM's kicks to 3,000 then slowly drops to normal. Is there possible gas leak into cylinder or some seal that may be worn out?

Thanks

One of 2 things:

-It's cold and the car is revving higher at first to warm the engine up.
-The throttle is re-learning how much air/fuel to mix after changing out the manifold gasket. This is more likely to be the case if you had to disconnect the battery. The car will normal out soon if this is the case.

-----Both of these things are completely normal.

I understand its warming up. Its just never jump that high. The engine its 183K. I haven't got disconnected battery after I have changed the gasket. Engine was for like half hour with higher RPM's but then adjusted itself. I will try to disconnect battery and then see if that will do any better. This has been change already over two weeks now.

Just to clarify that gas hike at start feels like you are holding gas pedal down while starting engine then release it.

Did it just start after the change? Could be a sticky IAC valve on the throttle body.

Did you try cleaning you throttle body and Maf?

I think it started after manifold gasket replacement. Yes I did cleaned throttle body. I may try to spray and clean Mad again as I haven't done it that time. Just curious if the IAC valve will stick wouldn't that happen all the time even after warm up engine?

Any difference after you unplugged the battery? That would force the car to relearn the idle.

I did battery but not really difference. Its just on the initial start when the car stands longer like couple hours. I have had battery unplugged for like 5 minutes.

How did you check for a vacuum leak?

If you're desperate you could try to take apart the intake manifold again and make sure everything is hooked up correctly. There was someone on here who had a rough idle after replacing the gasket because they forgot to plug in one little hidden vacuum line near the throttle body/manifold area.

No vacuum leaks as the rpms holds steady. Not really issue so I wouldn't messed up with it. I was just wondering if that's not some kind of prediction of something going bad.
Yes I have reconnected all hoses especially the one from back so that's not an issue.

Just gonna go ahead and ask: was this vibe part of the PCM recall? It does funky things.

I'd check for a vacuum leak anyway, using the old carb cleaner spray everywhere method. It could be sucking in extra air while cold, then sealing when things warm and expand. 3k RPMs sounds waaay high, even for cold starts.

Never hear on throttle body recall for Pontiac 2005. I will check.
The vacuum leak spray everywhere method can you be more specific on what to spray on and what to look out for? There are some articles but not well described.
After last attempted MAF sensor cleaning it seems less. Haven't seen them go over 2000rpm when starting cold. What's interesting that this isn't happening all the time. Some starts are perfectly normal kick to 1500 climbs to 18000 warms up and adjusts to 750.

Just to correct PCM module has been changed yes this car was in the recall. And was working fine.

Spray where the fuel injectors meet the head, where the intake manifold meets the head and throttle body, and where hoses meet anything on the intake as well as maybe where the PCV and breather hoses attach to the valve cover.

What you're looking for is a massive drop in engine idle speed when you spray the part. I can make the Impala stall so badly it almost dies, it's loads of fun.

No CEL codes?
How long does it take to drop below 1500 rpm?
A minute or less I wouldn't worry about it.

No codes. Its instant drop its just elevated above 2000 when you started on cold or after a while. Seems not doing it anymore. Or at least not to kick into 3000 rpms. So not sure if this was some glitch and adjusted after while.

Is the throttle cable mounted on the intake manifold? If so, you might be putting a slight amount of extra tension on the throttle with the aftermarket intake which, when the cable is cold and the metal in the cable is contracted, could cause the throttle to open slightly and the engine to idle high. Then when the engine heats up and the throttle cable is warm and elongated, the throttle would be able to return to being fully closed when you take your foot off the gas. I had a problem with the exact same symptoms that I caused by over-tightening my throttle cable. Try to adjust the tension on your cable and see if that helps

I don't know if I have a throttle cable issue or something electronic with my '03 GT. When stopped at an intersection or light, etc. the engine rpm is close to 2K. If I rev the engine by tapping hard on the accelerator pedal to kick up the rpm it will drop down where you would expect normal idle to be at about 900. Acts like it is something sticking in the cable but it is so consistent I am thinking it may not be entirely mechanical.

Regards

The only thing electronic that it could be is the cruise control module, so try unplugging its electrical connector and retest. You can check the cable for the throttle for signs of corrosion as well, and then also the throttle body to see if it's really gummed up. Then there's also the possibility of an issue with the idle air control valve, but you need to be careful about it because coolant runs through the TB and I heard someone hydrolocked the engine due to misaligning parts with the IAC or TB.

My car is DBW so I am not 100% sure how it actually looks.

I had a 2003 that would idle at about 1800rpm on cold starts but after it would warm up it would go to a normal idle until the engine got cold again.Never worried about it and it wasn't the first one I seen like it.I figured it was just normal.