My 07 H3 w/ I-5 drops in RPMs down to the 200-300 range and feels like it's going to stall when I am almost stopped. It will also do this when I'm in park and rev it up. When the RPMs are on the way down, it drops to the 200-300 range, feels like it's going to stall, and then pulls up into the normal idle range. What seems to be the problem??

 

Will a PCMforless upgrade help this?

 

That does not sound normal. I would get that diagnosed and fixed before getting the tune. You wouldn't want to get a tune and still have some underlying problem. I got the PCMforless tune and it made a world of difference in drivability. Good luck.

 

Funny thing, this is now happening on my 06' H3. The last thing I remember doing to the truck prior to me having the same issues was, change out the Air filter to a K&N filter, and also change out all the spark plugs.

Does anyone know why the RPM's drop like this, and also make it seem like it's going to stall?

Thanks.

 

failed spark plugs? Pulse Plugs anyone?

 

I installed the Spark Plugs myself, they were brand new out of the box. I don't think they are misfiring or anything because I don't think it would cause that kind of problem even if they were...

Anyone else?

 

only a guess but my ford probe did this when the rubber boot feeding the air intake(mass air sensor)?

i had to hit the gas, mainly till it got hot.

strange but i think an air leak AFTER that point speeds it up, like opening the throttle. some guys spray water on those areas to see if it seals up and changes rpm

just a guess
tom

ps the probe was a turbo, but at idle i dont think the turbo had any effect,,,???

 

What actually matters is......ta da....... the truck does not actually stall, you just assume it feels that way. You know what happens when you assume something.

The PCM in the 3s has fuel consumption management strategies programmed in to lower your rpm as low as possible, and shut off the alternator output, when it senses you halting the vehicle, and there is no need for additional electrical output. The process reins in the rpms very low until it senses that the timing needs advancement and throttle needs to bring the rpms back up to normal idle. There is a slight lag, this is normal, but is some vehicles you may notice it more than others.

It will NOT allow the engine to stall and has NOTHING to do with intakes or filters. It is trying to save fuel when you are coming to a stop, and it will do it in forward and reverse. There are several other aspects of this same fuel consumption management, but they do not relate to this question.

 

Well, all that is fine and dandy, but at the same time my lights in the car will dim with the decrease in RPM's. The vehicles headlights also dim as well. The RPM's drop dramatically, and then jump back up. Sometimes, the engine will also fluctuate in RPM's by dropping and rising, and doing that a couple times before settling at it's normal mark.

Ultimately, if your first answer wasn't the right answer to this problem.. Could there possibly be another issue we might be overlooking?

Thanks for your time, Doc.

-Stavros

 

my 07 h3, 47k is smooth, apx 500 rpm min , nothing like you describe,,,there is something out of order,,,???

tom