Losing power and bogging down.

[mssVT98]

Been having the same problem

I've been going through the exact same thing with my car. Until last night it was limited to zero throttle response, but only intermittently. Then I started having it stall every time I gave it any throttle. For better or worse, I was a lot closer to a local mechanic than to my house when it became undrivable, so I dragged it there. I'll post any solution that they come up with. Hopefully it's soon and not terribly $$$.

Mark

[ColinM]

mssVT98 -- could be a malfunctoning idle control system.

The idle system is triggered into action/inaction by the Throttle Position Switch (TPS).

Diagnose the TPS and work from there.

[wookie1976]

Originally posted by ColinM
mssVT98 -- could be a malfunctoning idle control system.

The idle system is triggered into action/inaction by the Throttle Position Switch (TPS).

Diagnose the TPS and work from there.

Also a bad AFM may cause similar problems especially if the mechanical "pot" is worn out. I believe that AFM's of our types tend to wear out most in common engine loading positions. This can lead to a dead spot, sending the ECU an incorrect signal.

Try to see if another board member will let you try their AFM first. Its an easy swap and could lead to an easy (but not cheap) fix.

[mazenz]

Originally posted by wookie1976
Also a bad AFM may cause similar problems especially if the mechanical "pot" is worn out. I believe that AFM's of our types tend to wear out most in common engine loading positions. This can lead to a dead spot, sending the ECU an incorrect signal.

Try to see if another board member will let you try their AFM first. Its an easy swap and could lead to an easy (but not cheap) fix.

the problem happens so intermittently that it could be weeks before it happens again for all i know. i dont think i could borrow somones afm for that long

there are alot of suggestions here that i never would have thought about. when i get the time im going to try them all and ill post how it turns out.

i also thought it might be a defective afm. if i had any money, id say its a perfect time to get rid of it

[arvzs1]

hey! can you pls. pm or email me

when you get your car fix? im having the same exact problem too.
my car will run normal at start and when on the highway, i'll press the gas at times and end up no power at all. i'll press and play the gas pedal or downshift to lower gear to recover the power. then it will kickback again to normal like nothing happen..
to the next traffic lite, at full stop, the engine stall.
kind of weird, the car run and operates normal and no signs of abnormal until awhile of driving..
ty
arvzs1

[mssVT98]

In my case I don't think it's the TPS. At one point when I was having the problem, I disconnected it and still got the same symptoms. That was my first thought, but don't think it's the issue here.

If it's the AFM, wouldn't the problem go away as soon as you changed throttle position? Then you wouldn't be in the dead spot anymore. When this started, I could depress the gas pedal several times and get no response. Then all of a sudden it would be fine. Now it's "progressed" to where if I give it gas it stalls. At idle I'm fine.

The other thing I did before I was stranded was clean and reconnect the connector at the ECU. At first I thought that fixed it, but evidently not.

[arvzs1]

it was the oxygen sensor that's been causing the occasional power lose ive been experiencing for the past few days.what i did was disconnect the O2 sensor harness and the symtoms never comeback..
the previous owner(1st) never change it sinced he bought the car brandnew and the car has hundreds of thousand mileage on it..imagine if the car runs on timing belt.
checkout this thread, maybe it could help..

http://www.s14.net/forums/showthread.php?s=&threadid=8856&perpage=15&pagenumber=1

[mssVT98]

Solution!

Well, in my case it ended up being the AFM. Replaced it with new (alternatives just aren't feasible at the moment), and the problems appear to be gone. Plus the car is much smoother throughout the RPM range.

So it wasn't the cheapest of parts to replace, but at least it's an easy install. And the shiny new metal looks nice.

Hope this is helpful... seems to be a pretty common problem right about now.


Mark

[arvzs1]

[Chris W]

Hey mssVT98,

how long ago did you replace the AFM, and do you have the part number you used?

When I tried to order an new AFM a few months ago, the dealership told me the old part number was superceded by a new part number. When I ordered the new part, what I got was a smaller AFM that didn't fit the existing air plenum hose or air box. In fact, it was labelled as an AFM for a 318 and it looked exactly like the AFM for a 318 with an M40 engine.

The dealership ordered the part twice, and both times they got the same AFM labelled for a 318.

I'm just wondering if that's what happened to you, or whether things have been fixed now.

[mazenz]

Originally posted by wookie1976
I believe that AFM's of our types tend to wear out most in common engine loading positions. This can lead to a dead spot, sending the ECU an incorrect signal.

i just reread this line several times and that seems to make the most sence as far as the dying at engine speeds is concerned. it happened at the same speeds (aprox) at the same engine load and throttle position. if that can wear out the afm in that particular position/setting, than that may be what it is. i travel at that speed alot since that is the highway speed here.

the interesting thing is, after i made this post, the problem hasnt come back. no stalling, no hesitating, no shutting down, nothing. f***ed up.

the guibo/driveshaft issue i still need to look at, although im suspecting the rear suspension as well.

[EVOIIIM3]

Originally posted by Chris W
Hey mssVT98,

how long ago did you replace the AFM, and do you have the part number you used?

When I tried to order an new AFM a few months ago, the dealership told me the old part number was superceded by a new part number. When I ordered the new part, what I got was a smaller AFM that didn't fit the existing air plenum hose or air box. In fact, it was labelled as an AFM for a 318 and it looked exactly like the AFM for a 318 with an M40 engine.

The dealership ordered the part twice, and both times they got the same AFM labelled for a 318.

I'm just wondering if that's what happened to you, or whether things have been fixed now.

It's the wrong AFM, the Dealer doesn't know what they are talking about.

The correct part is still in the system. Get it from a reliable OE parts place, and tell the dealer to get a clue.

[mssVT98]

Chris - EVOIIIM3 is right - your dealer's an idiot. I don't have the PN, but this was just done yesterday, so it's available. I think Maximillian had it for a little over $400.

mazenz - If your car is cutting out under the same condidtions every time, I'd think that would point to dead spots in the AFM. Mine wasn't that consistent - I couldn't recreate the problem when I wanted. But I had been noticing drivability problems under certain conditions, and those seem to have cleared up with the new AFM. And yeah - mine would be just fine one time, then an hour (or a week) later it would happen again. That's why I'm still crossing my fingers a little bit until I'm sure I'm fixed.

[mazenz]

i cannot recreate the conditions, but every time its happened, it was under the same conditions, which is probably exactly what you are trying to say anyways :p

[arvzs1]

mazenz, try to disconnect your O2 sensor and run the car in the way you experienced the problem.
if the car runs good , maybe its time to change it, this tends to give wrong signal to the comp. brain and messes up the timing.
mine is still disconnected and never experienced anyproblem since then. give it a try, you have nothing to loose..
arvzs