I was driving home from work on Tuesday, when I noticed my FD wasn't running quite right. I didn't really notice something happening all of a sudden, but when I was out on the interstate, I noticed I didn't have near the power it should have. I first noticed it when in fifth passing another car. It just kind of bogged down. Not the usual zip it has.
After getting off the highway, I noticed the idle was lower than usual too. Then, at a stop when I put it in gear, the idle dropped to zero, and almost stalled.

So, HELP!
Here are the symptoms:
Down on power.
Low idle that will cycle from around 550 to zero at a stop when in gear.
Slight bucking at cruising speed, not smooth like it used to be.
It seems like it is boosting, per my shitty autometer gauge. I can't really tell if the second turbo is kicking in or not, I think it is, but there is no power to it.

Here are my mods and recent work:
Downpipe
Bonex cat
rebuilt engine with 15k on it
replaced check valves and PCV about a month ago
replaced throttle body gasket yesterday, the old one was shot
checked the TPS, and it was within range
no codes, I have a lingering code for O2 feedback

I have searched (and continue to do so) so just looking for someone to point me in the right direction. I am going through the fsm right now, looking for possibilities.

Thanks a ton.
Dave

 

i just had this problem fixed..

my fuel tank was full of ****!!!! the car sat at the docks in japan for half a year so the top half of the tank rusted and crap blocked the fuel filter

its all good now!!!

 

Well, mine has been daily driven for a year and a half, and got a new filter with the rebuild.
I am thinking possibly EGR valve?

 

Turbos? How old and how many miles vs new engine??

 

Turbos have 85K on them, and I suspect they are on their last leg or beyond. I have smoke on startup.
I have a spare low mileage set in the garage, because I suspected them as the cause of the smoke on startup issue.
Do you think they could be the problem?
Why would that cause a low idle?
Thanks,
Dave

 

I have very similiar issue and would like to know the answer.

 

I have been mulling this over in my mind all week, trying to get an idea of how to troubleshoot it.
Here are my thoughts so far;
In this order:
Intake hoses, possible small crack? I still think that this would raise the idle, not lower it though.
EGR
o2 sensor, although this would only account for the rough running problem, not the low idle. That would make it two problems instead of just one.
Leaky UIM
Relief charge valve

Anybody shoot holes in these theories? I am shooting in the dark here.

 

is the boost needle moving at all at idle? Down on power, and lowering idle kinda sounds almost like a chipped apex seal...I know it's a rebuilt engine, but I'd get a compression check to be sure. Other than that it might be one of the thousand vacuum lines either with a hole in it or popped off.

 

You mention you have a crappy autometer gauge but you don't mention the crappy boost pressure your getting (we should maybe guess what it is ?) You can do the 3rd gear pull to see if your turbo control system and turbo's are working correctly and possibly eliminate where you need to look, since the o2 sensor should work properly for the ECU to make the correct adjustment this might be a good place to start.

 

Ok,
The crappy autometer is telling me that I have 5lbs of boost when i do the third gear test. But, it has always read that on boost. When you turn the car off the gauge resets to 5 inches of Mercury. i.e. it doesn't reset to zero, but five inches below. So, I don't really know if it's boosting to five or ten. But, either way it's consistent.
The only thing that seems like it has really changed, is there seems to be less vacuum at idle.

 

Also, the car has a full set of brand new silicone hoses.
If it had a chipped apex seal I would expect some rough idling, hard starting, and smoke.
I can do a compression test, but I really don't think that is the problem. It starts way too easy.

 

Oh, and there are no pills in it either. The po removed them, and I haven't fixed that yet. I am using it as insurance for now.

 

yeah, you could have a turbo problem. That's a tough one, though...it's not making any other funny noises is it? And you can still hear the turbo spooling?

Also could be that sensor in the backby the firewall on the driver's side...sorry, I haven't had an FD in a while so I forgot the name. I just know that one time that vacuum line that goes to that sensor came off and it idled really rough. Open the hood and disconnect the vacuum line to that sensor and see if it makes any difference. If it doesn't the sensor might be bad. If it does, at least you know that is not the problem.

 

Yea, the turbo is working. I can't absolutely verify the second one is, but that doesn't matter. The problem is before the turbo really kicks in.
The only other symptoms are:
If you floor it, it bogs down. Not a hesitation (it does that too) but a real bog.
And, after I changed the check valves and PCV a month ago, it has a sound from the engine that I have not heard before. A low bass note. Hard to explain, but the first time I ever heard that sound was when I was a kid in my 63 chevy auto. I ran it up to about 40 mph in first (by accident), and when I let off the gas, I had that sound. The sound of compression from the engine under deceleration. If that makes sense.

 

Anyone think this could be a double throttle issue?

 

I doubt the double throttle would be the main culprit, as it wouldn't affect your idle.

It sounds to me like one of your new silicone hoses may have popped off somehow. The turbos appear to be nowhere near spooling up when you get in the throttle, judging by the bogging before anything happens. Unfortunately, it may require a painstaking process of checking many individual hoses before you find the culprit.

 

Kento,
I can definitely see it being one of the hoses. I just have not headed in that direction so far, because they are all new silicone, and all tie wrapped.
But, I did see that one of them today is torn. It must have happened when I replaced the check valve. It is a very small tear, so I don't know if that could cause all of this problem or not.

I am going to replace the turbos next week, I am going to test the EGR at the same time, and obviously double check all of the hoses.
I am contemplating disabling/blocking off the EGR and the double throttle at the same time.

 

Let see what you know.....the gauge doesn't zero. The previous owner removed the pills. New hoses. Problem didn't exist before any of these things changed ?
Possible solutions to your problems.
Try a different gauge, indication of low vacuum could be engine compression or vacuum leak, or if the gauge is bad then there's nothing wrong.
Without the pills you will only build 7 psi (wastegate spring pressure) if your gauge is correct and only making 5psi then your second turbo won't come on line (search turbo troubleshooting) if your gauge isn't correct then how do you knowwhat your boost pressure is (see item one)
Determine if you have a vacuum leak or low compression....remember your baising all this on a gauge you don't believe. Not sure how much help any of us can be until you believe in your gauges and what they are telling you. Our information is based on what you tell us.

 

Yea, I am going to replace the gauge and see what "true" numbers I get. I have a brand new 60mm gauge, but no way to mount it. (I have a pillar pod right now, 52mm)
But, as I drive it, it acts like it is boosting ok, but it bogs BEFORE the turbo really starts kicking in.
I will know more in a day or two, in the meantime, I am going to hook up a new gauge.
and BTW, the pills, hoses, and gauge were done years ago, the problem just surfaced.

 

update:

New boost gauge, reading 7/6/7 which is right for no pills.
Found the low idle problem, it was a bad clutch switch.

 

good to hear

 

have you simply checked the map sensor vacuum line? it detaches itself under high boost. it should sound like its going to explode though...lol. maybe thats not your problem? a compression test would prob be smart

 

You didn't read more than the first post, did you...