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Discussion Starter · #1 ·
Hey guys, new to the community so sorry if this is in the wrong place or has already been answered. I've searched this forum and several others, but nothing is quite matching the issues I seem to be having.

Here's the full story. I'll put a Tl;dr at the end too

I have an 08 Focus coupe with a 5 speed manual & 2L engine. No powertrain modifications other than Shortly after I bought it 3 years ago I put a cold air intake on it. Didn't gain much power mostly just a bit more sound, but no issues.

About 2 months ago, my engine light came on and the car kept acting as though it was about to stall out sometimes during breaking or hard turns. Took me about a week to realize the intake and filter had separated. reconnected them and had no further issues. About 2 weeks ago I noticed my car seemed down on power and the intake noise had increased. A few days later the light came on again so I checked and the intake/filter had come apart again. I fixed it again, but the light didn't go off and it still seemed down on power. This continued to get worse so on my dads recommendation I put seafoam into the gas tank and because I'm almost due for an oil change I placed the recommended amount into the crank case as well. Since then the power has steadily declined and now my car takes about 40 seconds to reach 60mph at full throttle and will not rev above about 4k rpm in any gear. I ran it to check the codes and it gave the message "catalyst system efficiency below threshold".

I have since removed and cleaned the mass airflow sensor, and tried removing the exhaust in front of the Catalytic convertor to see if that was clogged up. Neither had any serious effect on the issue. I also tried cleaning the error code from the ECU (in case it was in limp mode), but that didn't solve the issue either although the check engine light has not come back on.


I'm nearly our of ideas at this point... going to try checking the O2 sensors and spark plugs after midterms this week, but other than that I dont know what to do.

Tl;dr
Engine is severely down on power. does not appear to be a dirty Mass airflow sensor, clogged Cat, or limp mode on ECU.


Any suggestions would be fantastic. thanks in advance!
 

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It runs smooth, but you have power loss like it's in limp mode? I would pull the negative battery cable and make sure that PCM is clear. Might also pull the spark plugs and make sure you're okay there. Before I get ahead of myself, does it run smoothly?

Toby
 

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Yes, do what Toby said. Check spark plugs and reset the PCM.

Your cat converter may be on its' way out. Hope not, but that's what I smell.

Here is a good Cat Converter video that shows testing of O2 sensors and doing temperature testing of the cat.
https://www.youtube.com/watch?v=9VZ5K8n5jj0

Another test to consider is checking exhaust backpressure using a low pressure gauge.
http://www.autozone.com/autozone/ac...25ll?itemIdentifier=347232&_requestid=2100619

Edit: I just bought a backpressure tester and will be doing the test in the next week or so.
http://www.amazon.com/gp/product/B0002SQW9S/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
 

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Try cleaning the MAF sensor, it may have got coated in gunk with the filter detached.
 

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'08 model has a CAT in the exh. manifold, so you only can detach exh. before the SECOND CAT.

Has the CAT code returned?

I worry about how much "Seafoam" was put in the oil, any use there should be VERY short term before a change. Dilute the oil & run it long can kill an engine, change that out ASAP IMHO.

Any "cleaner" in the oil is typically used no longer than it takes to warm up the engine and then drain it, unless there's an unusual amount of crud built up causing an issue that requires such an expedient to try to 'save' an engine you'd be better off just changing oil more often than usual for cleaning.
 

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Discussion Starter · #6 ·
It runs smooth, but you have power loss like it's in limp mode? I would pull the negative battery cable and make sure that PCM is clear. Might also pull the spark plugs and make sure you're okay there.
I did this... the spark plugs all looked fine on inspection, but I realized one of the cylinders is not firing. Going to see if its the coil or something else causing the cylinder to not fire. also disconnected the battery overnight with no changes to performance.

Before I get ahead of myself, does it run smoothly?
it idles smoothly and it accelerates smoothly (albeit very slowly) other than at specific combinations of throttle and rpm. For instance around 3k rpm in 2nd and 3rd gear it drops revs then snaps back over and over if I give it less than about 50% throttle


Try cleaning the MAF sensor, it may have got coated in gunk with the filter detached.
done. no effect

'08 model has a CAT in the exh. manifold, so you only can detach exh. before the SECOND CAT.
ahhh... so the first cat might be clogged?

Has the CAT code returned?
no. but I have only driven it maybe 20 miles since clearing the codes. trying to avoid using it when possible


I worry about how much "Seafoam" was put in the oil, any use there should be VERY short term before a change. Dilute the oil & run it long can kill an engine, change that out ASAP IMHO.

Any "cleaner" in the oil is typically used no longer than it takes to warm up the engine and then drain it, unless there's an unusual amount of crud built up causing an issue that requires such an expedient to try to 'save' an engine you'd be better off just changing oil more often than usual for cleaning.
ah the instructions I read inferred it could be left in until "oil looked dirty". I was planning on using up the rest of the gas (with seafoam) in my tank then changing the oil. that would have been about 200 miles total, and I drove around 120 miles since adding it, the first bit was somewhat hard driving cause I thought there was crap in the injector or something and that might clean it out... guess I was very wrong.



Thanks again for all the suggestions. A few other things... I discovered there also seems to be a significant amount of pressure in the crankcase when the engine is running, however cylinder compression is fine and there is no oil in the radiator or coolant leaking into the crankcase, so I don't think its a headgasket or rings. I'm pretty much out of my depth at this point in terms of engine knowledge... someone at the auto store suggested the PCV line might have come loose or there could be valves sticking. Any of that seem plausible?
 

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Thanks again for all the suggestions. A few other things... I discovered there also seems to be a significant amount of pressure in the crankcase when the engine is running, however cylinder compression is fine and there is no oil in the radiator or coolant leaking into the crankcase, so I don't think its a headgasket or rings. I'm pretty much out of my depth at this point in terms of engine knowledge... someone at the auto store suggested the PCV line might have come loose or there could be valves sticking. Any of that seem plausible?
PCV valve comes to my mind. How many miles are on your car? Ford recommends replacing it at 100k.
 

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it has just under 50k miles
Dang it shouldn't be the PCV valve or the cat then but who knows. That's a bit too early for stuff like that to be going.
 

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Discussion Starter · #10 ·
Dang it shouldn't be the PCV valve or the cat then but who knows. That's a bit too early for stuff like that to be going.
Thats what I was thinking (same for the timing chain which someone else reccomended)

I'm thinking it may be a number of issues combined and one of them might be causing the other issues. We'll see though
 

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Do you have a code reader to check if there's any pending codes? You might want to consider checking the throttle body as well to see if the valve is sticking. I seem to remember that being a common problem on Fords although I can't remember if our 08-11's are affected.
 

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Discussion Starter · #12 ·
Do you have a code reader to check if there's any pending codes? You might want to consider checking the throttle body as well to see if the valve is sticking. I seem to remember that being a common problem on Fords.
I have an OBD reader that links with the "Torque" app on my android phone. I assume that could find pending codes?

I checked the coil and plugs and they definitely aren't the reason my one cylinder isn't firing... thinking maybe the injector or something? Like I said I really am getting past my knowledge of engines at this point so I'm not certain what all the reasons there might be for a cylinder not firing.

I'll look into the throttle body and TPS this weekend after midterms... also might take it to a local shop that a friend recommended that is good with Diagnostics. If I cant find anything by this weekend I almost definitely will be taking it somewhere.
 

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Discussion Starter · #15 ·
How did you determine one cyl is not firing?
accidentally did not plug it back in when I checked all the plugs and cylinder compression and the engine ran exactly the same with the coil plugged in/unplugged. then I unplugged another coil and the engine ran significantly worse. after that I switched the plug and coil from that cylinder with another and still only that same cylinder is not firing, so I'm thinking something else is causing it but I have no idea what except maybe clogged injectors
 

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It could be either a power or ground issue with the fuel injector on that cylinder, or a power issue with the coil. If you have a multimeter, you can use this schematic to test for continuity between the terminals of the PCM plug and the coil and fuel injector plugs on the dead cylinder. The fuel injectors go to a common ground, so you only have to follow the ground wire on the dead cylinder to the point that it splices into the others. You know the ground wire is good between the splice and the frame because the other cylinders fire. You might find the PCM is not talking to that cylinder. At that point you'll have to find the broken wire.

Here's an easier proposition. Unplug the fuel injector on the dead cylinder and test continuity across the two terminals on the injector. If you don't get continuity across those, it means the coil is open and you've found your culprit.

Toby

 

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Discussion Starter · #20 ·
Quick update. Pulled the fuel rail and injectors today and cleaned them all out, filled the tank with fresh gas, replaced the fuel filter, and changed my oil just because.

It appeared that there may have been some water in the fuel rail when I emptied it out but I'm not sure. Regardless...

All cylinders are definitely firing now and the engine runs smoother and quieter... but the problem is still there. So... what do I try next? Could it be something with the valves or cams? Not sure if it helps but it seems to run a little better at start and then get worse as it warms up which I notice is happening more quickly than normal.


Thoughts?
 
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