help

**** I hope this works...
This reply interests me as I seems you know a LOT about an issue I am having. I have a 2007 Prius, basic model I believe. I am the second owner, purchased it in Jan of this year-about 45000 miles.
The problem I am having sounds similar - bumping or pulsing like a misfire. BUT it only happens during the first ICE run after turning on the car. I can go into a store, come out and restart, if it starts the ICE I almost always get these bumps. I have taken it to the dealers three times now. First they changed the spark plugs, next they cleaned the throttle body, this last time they did all the computer tests they could think of (?) but no misfires, no codes, nada... I think they believe me a bit off my rocker and am too, way too picky.

I recently talked to an '06 owner and he said he NEVER had anything like that at all. His was always smooth as silk.

Today, I did notice that I could not repeat it for the tech ***until I had the headlights on*** (I had just turned them off as I arrived at the shop but always leave the switch in the ON position) ***and seat belts fastened.*** Twice I tried it when the lights were off and no seat belts in use -- it was quite smooth. But I remembered I normally had the lights on and seat belts used and doing that it repeated for the tech. Unfortunately it was weaker than I normally feel and I go this 'you got to be kidding' look form the tech which seems to be their final answer to me...normal for this high tech car - NOT!

Do you have any ideas what is going on during that first run after turning the car on which might cause a bumping (stumble/misfire-like pulse, etc.)? I don't think this is going to hurt my Prius but it still is abnormal behavior, IMO.

Help???
Steve K
2007 Green Prius (47752 miles, about 45 mpg, lovely car!)

 

I did run the MX internal check using the MFD and my results were spot on for a good battery. Since I just bought this one in Jan/Feb I am not sure if it's new or original. It does look very new... I guess I should see if I can find a date on it and also double check the connections.

I'm going to look into the gas treatments, PCV replacement, cleaning the MAF and IAT - each a step at I time as I can get to it. Hopefully one of these will help.

I am also lucky that these are fairly gentle bumps, more like the very first hint that the engine is shutting off, just that it can't make up it's mind...

 

I think I may have fixed my problem. I will know in a day or two at most.

So, why do I think that I have found the problem? While under the hood, after checking my oil level, I noticed the RELAY box that sits up by the windshield right in the center of the car. In mine I have 4 relays, 1 large gray one (I think it's the CHS W/P relay) and 3 smaller and light blue in color. I was touching them to see if I could help the contacts and noticed the large gray relay was not seated, just resting on it's contacts. As I touched it the relay tilted just a bit and some of the connector 'blades' lost contact and I heard a fast buzzing sound like the relay (some relay) was going on and off fast. I firmly seated this relay, it really was not seated at all. I then got in the car and put it into start mode. I waited for the engine to run, it did, and WOW, not a bump.

Plus, the relay 'blades' looked dirty (what I remember seeing) as if they have been out for a long time. I can only guess that the relay box cover kept it in place just enough for the car to operate as well as it did - and that was pretty wonderful save this bumping.

I surely hope this does the trick.

Anybody have a good diag of these relays and what each is for?

Thanks,
Steve K.

 

I be hoping it's gone. I did run it once right after seating the CHS WP and it seemed fixed. But it has been smooth when at the dealership - so....

I have my fingers crossed. Will try again in AM when it has normally shown its bumping.

I will update later.

Oh, thanks so much for the info on the relays. I can't believe I didn't find out anything in the Owner's Manual or with searches on the Web. Very odd.

Thanks,
Steve K.

 

I just went out and started my 07 up, let it run the ICE from a good time in Park - no bumps at all and normally I'd have them at that time. I then put it into R the D for just a bit in each - probably not enough time to see if bumps happened, then put it into N (which I rarely do) and the engine noise changed a bit - seemed to quiet a tiny bit with a minor increase in RPM then I got a few bumps, then very shortly the engine cycled off. More time needed...

 

Well, bummer. I went out just before dinner and tested my 07, it is not fixed. I guess it is what it is for now. It isn't a show-stopper by any means, just a funny quirk. I may figure it out. I will try for a while, but I will just love my 07 nonetheless! It is a GREAT car!