Losing power and bogging down.

[mazenz]

alright guys, i have a weird problem im having trouble diagnosing since it happens very intermittently. its actually a couple of things but i beleive they are related.

first off, and this has happend about 3 or 4 times in the last month and a half, ill be driving at about 2400-3500rpm in fifth gear just cruizing on a freeway or whatever. im not accelerating or decellerating, just maintaining speed with fairly minimal pedal effort. suddenly, the rpms will just drop to 500 or so rpm and the car will be coasting as if the car was in neutral or with the clutch pedal pressed. my foot is still on the gas and not on the clutch, and the stereo is still on, so it seems very weird. after a couple of seconds, if i play with the pedals, the car comes back to life as if nothing ever happened. once i decided to let it ride since the roads were clear, and after about 5 or 6 seconds, the car actually shut off.

the next problem happens occasionally while accelerating, usually but not always when im starting at a fairly low rmp. ill step on the accellerator hard, and the car just bogs for a half a second and doesnt do anything. being used to instant throttle responce over the last 4 years of owning this car, it comes at quite a shock when i step on the gas and nothing happens. this happens maybe once every 2 or 3 days. and on both brands of fuel that i use (chevron 94 octane and petro canada 94 octane)

the third problem is i believe comming from the drivetrain somewhere between the tranny and the dif. it is a sorta creaking sound when i accellerate from a stop at a slow rate (traffic, stop go yadda yadda).

any help in diagnosing any of these problems would be greatly appreaciated

[UNHCLL]

#2 - TPS sensor

[la folie verte]

guibo need replacing?

[Magnus]

Yeah. Either it's the sensor or a intermitten connection problem. First and second are 1 in the same. It does not know what posistion your throttle is in (intermittenly). If it were another problem, then it would sputter or shutdown.

Problem 3, I think you need to visually inspect your guibo and driveshft area. If you don't see anything it may be throw-out bearing/pilot bearing? Do you feel any noticeable change in vibration when shifting? While in a gear? Do you hear the sound with the clutch in? As soon as you hear it push your clutch in and check to hear if it's gone. Play with it. Is the sound getting louder, any grinding, etc? WHen a throw-out bearing really fails, you are not given a lot of time to fix it before it completely dies and rips on your flywheel sensors... This is why I'd start wit a good visual inspection of the area. My guibo went ninja-star and took out my reverse light wires.

You will have a natural transmission yada yadda sound when your foot is off the clutch in neutral...

[mazenz]

i was pretty sure it was the quibo in number 3. number one and two are the same problem you say?

as far as number 3 is concerned, i noticed also that there was alot more forward and back movement (pitch) than their should be as well when accelerating and decelerating. would this be related?

[Magnus]

No I don't think that play would relate with pitch play.

I do suspect that the easier the clutch is to engage/ foot removal the more worn your clutch is. I mean to say that a brand new clutch will engage very high. So a worn clutch engages 3 inches up from floor, were a new would engage more like 6" high.

[mazenz]

i dont think the problem is in the clutch, but ill inspect it based on what you said. thanks again magnus.

[Magnus]

I don't suspect clutch either. I was simply just adding a theory about clutch pedal height since we were discussing driveline. SOrry to mix you up.

[wookie1976]

I dont think the TP switch is the problem since it only really does anything at idle and WOT. You have problems all over the board. Id be more inclined to say fuel pump or clogged filter or line. You could have a corroded ground or power wire there as well.

[Mmark]

The shutting off/cutting out/stalling at speed.
Look for:
1, broken ground wire near the ECU possibly.
Are you getting alternator and spark noise thru the stereo?
2, broken solder connections in the ECU.
specifically , you open the case, remove the PCB and you'll see a big transistor with 3 connections to the PCB that is on a heatsink. this transistor is the ignition driver. sometimes the solder cracks at the connections, ie the thin circle around each connection. You may need a magnifier to see the break(s).
3, The OBC box... driver side, green, 5"x8" can interrupt power from the main relay causing power loss and or no-start.
If you use the OBC(code), it may need replacement. Otherwise you could pull the OBC plug and securely short the terminals in the plug together.

RPM drop.
Clogged fuel filter?
fuel pump(s) problem?
Bad wire causing a drop of one cylinder?

Rear End

This is in the suspension or the tranny mounts maybe.

m

[ADA///M]

TPS for 1 and 2

Also check the motor and tranny mounts along with the guibo.

Might as well check the diff bushing too.

[mazenz]

Originally posted by Mmark
The shutting off/cutting out/stalling at speed.
Look for:
1, broken ground wire near the ECU possibly.
Are you getting alternator and spark noise thru the stereo?
2, broken solder connections in the ECU.
specifically , you open the case, remove the PCB and you'll see a big transistor with 3 connections to the PCB that is on a heatsink. this transistor is the ignition driver. sometimes the solder cracks at the connections, ie the thin circle around each connection. You may need a magnifier to see the break(s).
3, The OBC box... driver side, green, 5"x8" can interrupt power from the main relay causing power loss and or no-start.
If you use the OBC(code), it may need replacement. Otherwise you could pull the OBC plug and securely short the terminals in the plug together.

RPM drop.
Clogged fuel filter?
fuel pump(s) problem?
Bad wire causing a drop of one cylinder?

Rear End

This is in the suspension or the tranny mounts maybe.

m

1) no alternator noise
2) and 3) never thought about that.
rmp drop) i thought it might be the pump as well. it seemed strange that the problem was so intermittent, unrepeatable, and when the car was working normally, which is most of the time, it felt just as good as ever. ill have to check that out along with the filter. anyone suggest a possible fuel pump upgrade while im thinking of replacing it?

is it possible to inspect the suspension mounts without disassembling the suspension?

[EVOIIIM3]

1. Change the fuel pump relay. it may shut off and cause this.
2. check the 2 flywheel sensors, it's in the Bentley manual.
3. Pull the plugs and make sure they all look the same. (sticking/leaking injector)
4.Remove, clean & reinstall all the engine ground straps.

[mazenz]

thanks for all the suggestions. its a crappy problem with many possibilities. again, thanks for the help.

[OnrailsM3]

At the back of the top of the motor behind and under the fuel rail is an aluminium elbow with a vapor return hose running into the intake. The elbow came loose and leaned the car out on me in the past. It caused symptoms similar to what you felt.

It is under the hose that goes to the valve cover. Make sure it's tight cause it can lean out your motor and as our favorite house decorating convict would say "That's not a good thing"