Sudden loss of power in 5th?

T

Turbo Smoke

Member
:
Mazdaspeed Protege
Ok guys here's a weird one.

The last few days driving home from work I have been getting a sudden but brief loss of power while cruising in 5th gear. I does not ever happen in the morning only on the way home from work. And it only has happened in 5th gear.

So I'll be driving along in 5th gear going about 80-90km/h (50-55 MPH) revving between 2100-2400 rpms, about -10-15 inHg vaccuum. And then suddenly I have no power at all and the engine just starts to vibrate. Its somewhat of a light vibration but definitely noticable. Could also be because I have 88 duro front and rear mounts. So while its just vibrating my stomach starts to drop and I'm looking around to see if I notice anything weird going on with any of the gauges. But nothing! RPMs and speed seem to stay pretty constant, temp gauge doesn't rise, vaccuum is still normal while driving and idling, battery voltage doesn't drop, no dash lights come one and no CEL ever. I can press on the gas and nothing happens at all until it breaks free of its vibration.

When it occurrs it only lasts for about 5 seconds and then goes away and never comes back for the rest of the drive. Most of the time it seems to happen while driving up a slight hill but yesterday it happened on flat road.

What could this be?! I have never experienced this in any car I have ever owned or driven. It's the weirdest thing. I'm not overly concerned about it yet since it does not seem to affect the performance of the car at all before or after it happens.

Any ideas? Coil packs and wires maybe? I think they're original, 134000km on the car (83000 miles). But I don't get any misfiring or CELs. Spark plugs are new though. Could it be the TPS? I really have no idea. Car is pretty much stock right now. Only boost gauge, TT and motor mounts.

Any ideas, put em out there. I don't really want to just throw parts at it at this point.
 
Maybe a fuel issue? Perhaps your fuel pump is starting to go out. This is a weird one.
 
You're bogging the motor in 5th at those speeds, on boosted cars it causes more harm to the car by leaving it in a gear too high, than to have it at a higher RPM.

Are you trying to accelerate at all when it happens? Also do you have any mods?
 
Check your egr valve. If it's sticking you could get symptoms like you have described. If it was a coil, you'd more then likely have thrown a cel by now (a flashing one).
 
Knox Joe said:
You're bogging the motor in 5th at those speeds, on boosted cars it causes more harm to the car by leaving it in a gear too high, than to have it at a higher RPM.

Are you trying to accelerate at all when it happens? Also do you have any mods?
Click to expand...

My mods are only boost gauge, turbo timer and motor mounts. I am not trying to accelerate when this happens. Just driving at light throttle. I should re-phrase that, it's not revving at 2100 rpms closer to the 2300-2400 range at those speeds. Like I said it seems to happen more often when going up a slight hill but it happened on flat road yesterday as well. I am still not trying to accelerate up the hill though.

I've been driving to work everyday for the past few months at that speed in 5th gear and never had this issue before. Even if it was bogging at that rpm I don't know why that would happen. It only happens for 5 seconds and then never again...

I suppose it could be a fuel issue. I just don't know why it would only happen in 5th gear and only for 5 seconds and only once during the drive if the fuel pump was on its way out.
 
BOOSTR said:
That's MSP abuse, especially asking one to go up a hill or grade at that low of an rpm and in 5th.
Click to expand...

It's hard to define a hill in writing unless I was to try and give you the percent of the grade. I'm talking an extremely slight hill, very small grade. Nothing very hard on the motor, it doesn't take any extra throttle to get up the hill while keeping the speed constant. I'm trying to make this "hill" clearer for everybody, before people thing I'm and MSP abuser lol.

I don't think the hill is the actual cause of this since it happened on level ground yesterday as well.
 
Not trying to make light of your situation, just trying to impress upon you the need to not lug your engine by being in overdrive at that engine speed and mph.
 
So in your opinion it would be better to cruise along at light throttle revving at say around 3200 rpm in 4th gear rather then 2400 rpm in 5th? If you were going up a steep hill or were attempting to accelerate then yes 4th gear would be the obvious choice. But for light throttle cruising I wouldn't have thought it would be necessary to stay in 4th but maybe you're right. I'm not exactly new to driving a manual car and have never had an issue with my driving style in any of the cars I have had.

CrazyCaker said:
Check your egr valve. If it's sticking you could get symptoms like you have described. If it was a coil, you'd more then likely have thrown a cel by now (a flashing one).
Click to expand...

I was thinking it could be the egr as well. I took it out to clean it a few weeks ago and it was pretty dirty. I couldn't get it cleaned very well so maybe that is the problem.
 
Turbo Smoke said:
I was thinking it could be the egr as well. I took it out to clean it a few weeks ago and it was pretty dirty. I couldn't get it cleaned very well so maybe that is the problem.
Click to expand...

How did you clean it? Just spraying carb cleaner in it and letting it sit will do absolutely nothing. The best way to clean it is to use a brass brush bit on a rotorary tool (eg. Dremel). Stick the brush bit into the openings, and then press down on the spring to open the valve. This will clean the actual valve stem, which is what gets gummed up. After you finish that, DON'T add any oil to it! That will simply just gum it up again. Instead use some graphite lube (or even teflon), which is hi-temp resistant.
 
Yeah I followed the How-To and just cleaned it with intake cleaner. It was pretty useless. Your way sounds good but unfortunately I dont have a dremel. And I can't get the solenoid off of the valve because the screws are seized in there. Hmm I wish I could get those screws off, but I don't want to heat it up since the solenoid is plastic. Maybe I'll just have to replace it. *Sigh...
 
Turbo Smoke said:
Yeah I followed the How-To and just cleaned it with intake cleaner. It was pretty useless. Your way sounds good but unfortunately I dont have a dremel. And I can't get the solenoid off of the valve because the screws are seized in there. Hmm I wish I could get those screws off, but I don't want to heat it up since the solenoid is plastic. Maybe I'll just have to replace it. *Sigh...
Click to expand...

The how-to on this forum is useless. The screws are not seized in there, they have a bit of thread lock on them which makes it seem like they are. Use a proper sized philips bit (iirc, it's a #2) and press down firmly while loosening them. You can also use needle nose pliers on the head of the screws to break them loose, if you have to, but you shouldn't need to do this.
 
Turbo Smoke said:
Yeah I followed the How-To and just cleaned it with intake cleaner. It was pretty useless. Your way sounds good but unfortunately I dont have a dremel. And I can't get the solenoid off of the valve because the screws are seized in there. Hmm I wish I could get those screws off, but I don't want to heat it up since the solenoid is plastic. Maybe I'll just have to replace it. *Sigh...
Click to expand...

I used a hand held wire brush, it's just easier with a dremel tool.
 
CrazyCaker said:
The how-to on this forum is useless. The screws are not seized in there, they have a bit of thread lock on them which makes it seem like they are. Use a proper sized philips bit (iirc, it's a #2) and press down firmly while loosening them. You can also use needle nose pliers on the head of the screws to break them loose, if you have to, but you shouldn't need to do this.
Click to expand...

Tried to get them out for quite some time but no luck. I'll just have to try again. But they were pretty stuck. (I'm not a noob at this).

And I just remembered I have an air powered die grinder with a wire brush bit lying around somewhere so I could use that to clean it up.

Do you think the egr is most likely the problem? I was thinking it was a possibility but it was only my best guess. I wouldn't hurt to start by trying to clean it, that's for sure. I just wonder if that's whats causing this very strange problem. I hope I can get the screws out this time.
 
^ it's possibly the egr. As mentioned it's doesn't hurt to start there since it can be checked relatively easily, and for free.
 
CrazyCaker said:
^ it's possibly the egr. As mentioned it's doesn't hurt to start there since it can be checked relatively easily, and for free.
Click to expand...

How exactly would you check it? Just try and open and close the valve and see if it sticks? Or do you have another method?
 
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