Ok, first of all I didn't want to have to ask for help here but running out of options. I'll explain as best I can what happened.

I was driving the other day, pootling along in 3rd at around 40mph when the engine decided to completely misfire, no warnings, nothing. It lost all power. I pulled it over hoping it was something simple like a vac line but saw nothing of the sort.

I managed to limp it home in 2nd gear (4 miles) and all I can say is it literally feels like it is running on one rotor.

Today I received a new ignition pack - leads, coils, plugs which I have fitted to no avail, although the rear rotor plugs were a little black.

I do have a video of the issue which I will link in this thread.

I have always kept on top of maintenance, oil changes, checking it each week and never run low.

So, things I have done are:
Changed plugs
Changed leads
Changed coils
Cleaned MAF
Run without MAF to rule that out
Checked all vac lines.
Deflooded
Replaced SSV (etc) solenoids earlier in the year

Car is an 04 with 105k on the clock.

Basically I wanted to know what else I could try before having to buy a compression tester. Could apex seals cause P0171?

Also please note that there were two other codes when it first happened which I cleared and they have not come back. - P0302 and P2097 I believe.

https://www.youtube.com/watch?v=Z0Z9...67501349896122

 

Oh and all this with NO CEL if that helps at all

 

Judging by the way it starts up, you might be down on compression, but that's not really a solution. Get a compression test to know what you're investing into, but I don't think that's the root cause here.

P0171 is system running too lean, like you have a big vacuum leak that the computer isn't able to compensate for. I know you said you checked the vacuum lines, but check them again. If you have an OBD reader (with which I assume you read the codes?) see what the short term and long term fuel trims are on a warm idle.

 

Loki... Did you used to be on the MX3 forum? Name rings a bell.

Just checked again, had the intake manifold off to check under there too and theres no leak from what I can see but it does sound like there is one at the end of the video. Constant chuff chuff.. As for starting that was before I changed the plugs and I had just deflooded it so that's why it took a while to crank over. It used to fire up on the button hot or cold.

 

Oh the weird thing is that on overrun, letting the revs off it sounds perfect. Only when it's under any load (idle or revving) does it sound like a bag of spanners.

 

Get that fuel trim data read. Vacuum leaks can happen in hidden places (vacuum tanks, nipples under the manifold, etc).

 

 

I've uploaded some pics from the scanner for you but it says it needs a mod to approve.

 

If they don't show up LTFT 0% - STFT 25%. Now I have no idea what any of that means lol

 

Whoa I think you have a big vac leak like Loki said. That stft is high.

 

You have a large open hose somewhere. Keep searching. I suppose, given the sudden onset, it popped off or failed while driving. Sometimes the vacuum tank for the 3 intake solenoids behind the intake manifold cracks.

What was the airflow g/sec when you measured that 25% stft? Remeasure if you can. Must be on a warm idle.

 

Hmm. I did the carb cleaner test but I guess I will have to be a little more thorough then. It's so strange that it came out of nowhere while driving. Thanks for the help guys. I'll get all the vac pipes removed. That "chuff" noise in the video seems to be coming from behind the intake manifold so I'll have to have a proper look down there.

 

Air flow from MAF was 6.34g/sec which seems pretty normal. This was at idle btw and yes was warm

 

Check the vacuum caps on the LIM. Also, the vacuum line from the drivers rear of the UIM, through the check valve, into the accumulator, and through the three solenoids on the back of the UIM.

 

I've stripped it down again and removed all vac lines for an inspection but they all look fine, removed and checked the thick lines (oil breather?) to the air box, no splits and all seated properly. Removed and checked that plastic part that the solenoids go in/oil filler and can't see any cracks, no cracks in the intake manifold (top part), I can't get the bottom part off as my sockets won't reach that far. I managed to sheer a bolt on the intake manifold so that will definitely cause a leak now :/ Honestly I am stumped. Running out of daylight now but will carry on tomorrow. If you guys have any other ideas where the leak could be coming from drop a message on here and I will check it tomorrow. Thank you for the help guys

 

Notapreppie could you point me to where the LIM caps would sit please. Thank you

 

if standing at passenger side fender look down where the black plastic uim meets the metal lim. theres two "nipples" that are metal sticking out of the lim they should be capped. i had one of the caps split on me years ago

 

Sweet thank you. Drivers side for me but it's all good lol. I'll check those out tomorrow. Surely something so small wouldn't cause such a big issue but I guess you never know. Will keep you guys posted.

 

what year is your car btw? i think they did away with the service ports on 2006+ but i may be wrong about that

 

Mine is an 04. Had a ganders on google and saw where you're talking about. Half way down ish. I'll check that tomorrow. Would make sense for it to be something like that as it was sudden so hopefully a cap just fell off.

 

6.34 g/sec on warm 800 rpm idle? That seems high.. its like you're sucking in too much metered air. Shouldn't be possible :/

 

I'll put that down to it struggling to idle at the moment. I have to ease the throttle down otherwise it just stalls out.

 

Yay my pictures showed up.

OK so been out, checked everything again, checked the nipples on the lower intake manifold and they're all fine, stripped out and rerouted all vac lines, all connected, reseated spark plugs, leads and made sure the coils working. Tightened everything that could cause a leak. I'm at a loss here.

I am pretty sure she's still running on one rotor so I am going to have to chalk this up to apex or side seals gone. Engine is covered in WD40 trying to find any change in idle to no avail.

 

Get a comp test if that's what you believe, but the symptoms don't fit. Assuming its compression and rebuilding is an expensive way to find out that wasn't the problem.

 

Is there anything else you guys could recommend trying? Thank you all again for the help. Going to triple check the plugs are in the right spot in a sec. When I removed the rears earlier they were already blacking with oil