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Discussion Starter #1
I have posted several posts on this issue, but have received very little response. I really need some fresh ideas here. I will mention that this issue did seem to occur about a month after my cossie manifold install, though did not happen immediately after the install and tune.

My car will accelerate fine and without problems. The problems starts when I enter a constant speed and start closed loop, usually in 4th or 5th gear. At first it started doing it every now and then, but now is happening more frequently several times a week, almost always when leaving work, but never when going into work. When I get to a constant speed, its like a complete stall/loss of power for a split second, followed by a complete recovery, then back to stall, then back to recovery. It will do this until I punch the gas and accelerate. Once the car warms up it will not happen at all, only in the first 5 or 6 minutes after sitting all day. But it doesn't happen in the morning. When this happens, the wideband goes from about 10 to 16 VERY quickly. It usually reads full lean at idle, except after warmup, in which it reads normal. I got pissed this week and started taking my computer to work and datalogging the fuel pressure, AFR, and some other data on the way home and have done this for the last 2 weeks and it has not done it once. I know the problem is still there. I will continue to datalog on the way home and will eventually catch it.


Things I am certain it is not.

O2 sensor(replaced in last 15k miles)
IACV(replaced in the last 1k miles)
TPS(replaced in the last 1k miles)
MAF(replaced in the last 10k miles)
Injectors(replaced in the last 15k miles)
Plugs(replaced in the last 15k miles)
Fuel Filter(replaced in last 10k miles)

After reading some forums I am starting to suspect the PCV valve/system. I have read that the pcv hose and valve has caused trouble after people install the cossie manifold, though I felt the hose and everything is connected securely and the hose is a high quality hose. I feel like it may be related to the Cosworth Manifold though it didn't happen till at least a month after install, so i dunno.

PLEASE HELP!
 

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Morning...not sure if this is much help....my knowledge takes a faceplant after 04 foci really...they may be the same for all i know lol.

But your exactly problem just by feel(no data measurements) happened to me when my DPFE crapped the bed. crusing....4th 5th it would feel like someone was pulsing the brakes or a surging. Then it continually got worse until it happened in pretty much every gear. My mpg was junk and the car was slow as balls.
I went through 3 of these on my 01 until ford made a revision that worked.
May be worth at least looking into but not sure.
Remember just because you replaced something, it doesn't mean that it works.
Things fail out of the box everyday.
Hopefully this isn't your case and hopefully I was some help lol.

Good luck and keep us posted.
 

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oh oh, almost forgot....sounds like you have a tune still w/ the intake? What other mods?
Give us as much data as you can plz.
Do you have the parts to swap back(may be your last resort just for testing)
 

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Discussion Starter #4
I didn't think the 2005 ST had a DPPE sensor. I remember trying to find out about that related to another issue a year ago. I had it custom tuned by Randy after installing the manifold and for about the first month and a half it ran great. Then this problem slowly developed. I took her out last night and she ran beautifully and did not stumble once. I do have the parts, but I believe its something that has messed up lately, sensor going bad or something. I had the EGR system disabled in the tune. I am starting to suspect something pcv related.
 

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If you think that it may be PCV related, can you not temporarily disable the PCV valve/system? There is no real need - other than for emissions - for the PCV to vent to the intake manifold; you can vent the crankcase to atmosphere, as was the case with most older pre-smogged cars. You would need to remove the spring and plunger from a second, back up PCV valve to do this (so vacuum is no longer required to provide ventilation) and fit and route a length of hose to the modified end. I haven't done it myself but I believe the turbo guys do this to keep oil vapour/heat out of the intake and reduce the risk of detonation. Perhaps ask on the FI forum section.
A PCV valve isn't on your list of changed parts; have you tried a new one? They are inexpensive if you think that may be the root of the problem.
 

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Discussion Starter #6
I changed the pcv valve out when I changed out the manifold, since I was there. I really dont think it is the pcv valve but have begun to suspect it due to other things being ruled out. I felt the hose and followed it with my hand all the way to the valve and it was in good shape and connected securely.

Last week I begun to suspect the fuel pressure sensor/pump due to the complete drop off in power I was experiencing, though I haven't been able to catch it on the datalog yet, of course it runs tip top when you hook up the datalog.
 

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Discussion Starter #8
I may have stumbled onto something here. I went and took off the "power by cosworth" plate to see what the inside of the intake manifold looked like. It was cleaner than the virgin mary's vagina. However I discovered that the vacuum line that goes from the fuel rail pressure sensor to the manifold was lose as crap on the manifold fitting. Like really really lose. There is no way it formed a seal. I sealed it and will see in the next week if that was it.
 

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DTC P0606
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A loose fuel pressure sensor hose is a very good candidate for both a vacuum leak and for providing incorrect fuel pressure readings to the ECU. That'll likely be it.
 

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Discussion Starter #10
So I tighten the vacuum hose going form the fuel rail pressure sensor to the intake manifold and the car runs perfect for the past week. It has not messed up a single time in the past week, until today. I intended to report this issue resolved. This time the car started losing power/stumbling after warming up, which seemed to be a break from recent trends. When I got home I decided to take out the spark plugs in hopes of finding anything at all. I found heavy oil inside cylinders 2 and 3 from the threads down. I am about to do a search. Any thoughts?
 

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NO need to search, that's an obvious valve cover leak. It should not screw up anything else, so that might not be your problem.

Where does Cosworth route the PCV vacuum to? Lack of a PCV can cause oil to be forced up through the rings, and usually a lot of oil in the air intake too.

Did you reset the ECU after repairing the vacuum leak to the fuel sensor? BTW, it's not a FPR, it's a fuel sensor because it doesn't regulate pressure, it sends a signal to the ECU about how much pressure is present and fuel temp, then the ECU regulates fuel pressure by changing the pump flow. That's why there's no return line coming out of the fuel sensor.
 

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Discussion Starter #13
The cylinders are dry. The oil dropped down as the plug was coming out. Still dont know what is causing the problem.
 

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Discussion Starter #14
NO need to search, that's an obvious valve cover leak. It should not screw up anything else, so that might not be your problem.

Where does Cosworth route the PCV vacuum to? Lack of a PCV can cause oil to be forced up through the rings, and usually a lot of oil in the air intake too.

Did you reset the ECU after repairing the vacuum leak to the fuel sensor? BTW, it's not a FPR, it's a fuel sensor because it doesn't regulate pressure, it sends a signal to the ECU about how much pressure is present and fuel temp, then the ECU regulates fuel pressure by changing the pump flow. That's why there's no return line coming out of the fuel sensor.
How would the oil end up in the intake? It would seem the only way for it to get there would be through the manifold? I took the "power by cosworth" plate off last week and it was as clean in there as the day I put it on. No oil has ever been in there. My pcv valve is new, I changed it when I installed the manifold. I had to use a longer hose. I can feel the hose and where it connects to the valve and manifold, and everything feels solid. I can't understand why the car ran so perfect for a week and then bam right back to crap. I did not reset the ECU after repairing the vacuum leak. It ran so perfect aftwerward. I will try that, definitely need to try everything I can.
 

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Discussion Starter #15
So after tightening that vacuum hose, the car did not seem to want to mess up, until one Saturday, right after I happened to fill the car up with gas. Then for the next two weeks it did not mess up a single time. I drove around tonight for 20-30 miles of city driving without it messing up once, until I filled it up with gas again. When I fill the car up with gas, it immediately starts running like hell until i burn a half a gallon or so out, then it runs beautifully until the next fill up. The only thing I can possibly thing it could be would be the fuel pump.

ANY ideas would be appreciated.
 

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What if u throw just a half tank in there see what happens. If it still does it toss some water remover in there too. Do you buy the same fuel from the same place?
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