Car Dropping Revs, Feels Lumpy & Lots of Black Smoke

[Gt_Galant]

Hey all,

First off im sorry if this is already answered somewhere but couldn't get a definite answer.

I drove my car today about 20 minutes to where i need to be and when driving i noticed when i took a corner (left or right turn) sometimes the cars rev would die at 0 while car is moving and when i touch the accelerator its back but i do feel something is not right.

So i parked the car and when i left it idle (say its meant to be at 800-1000rpm idle) i can see it go's down to about 300-400rpm and car feels not right on idle like its shaking/lumpy and alot of black smoke was coming out of the exhaust, i mean alot.

So didnt wanna risk driving it anywhere i got it towed to my house to see what it could be, so i just undid the 2 clamps on the manifold elbow and one intercooler pipe but put it back not clamped just i can start it again and it started fine, no lumpy no smoke ??

So i clamped everything back and starts normal - no smoke, tested it around the bloke and fine.

Now i know its still gotta be something but what could it be ?

I thought maybe:
* spark plugs are bad ?
* AFM playing up ?
* TPS sensor maybe ?
* earthing problem ?

Had anyone kinda had this problem ? I just dont get the black smoke, fuel problem ? Fuel pump changed 2years ago.

Please any advice would be good, someone was telling me maybe a intercooler hose was loose but even if it was would it produced so much black smoke .

 

[whats_doing]

To be honest mate, you have solved your problem. Black smoke is due to over fueling. So it was running rich due to a boost leak. Which is what also caused your drop in revs and lumpy idle.

Since you undid and reclaimed any hose clamps, they would be the source of the issue.

 

[Gt_Galant]

I doubt it was the 2 clamps i undid only because they were tight and secured in the first place.

I know black smoke means fuel, even if i undo a clamp and leave it half on at the elbow (so it creates a boost leak) i know it will idle rough but no black smoke would come out because i just tested it 10 minutes ago. the black smoke im taking about is if i rev'd it for 10 seconds i cant see anything behind me that's how much there was

 

[Gt_Galant]

Also sorry i just confirm with a friend as he was here helping the car actually started idling fine before we unclamped anything and we then we going to change a part but decided not to thats why the 2 clamps were undone.

I had boost leaks in the past and never that much black smoke or any, the car holds boost fine, i know a proper boost test leak is a better answer, but besides a boost leak what else could it be so i can maybe change over parts, rather do it now then car plays up later (if it does)

At first i thought i blew my engine lol

 

[VOLK]

I'm going with huge vac leak. Inspect all piping and hoses, boost leak test and Bob's your uncle. Post MAF leaks get drowned.

 

[Gt_Galant]

Yesterday and today thought id do a few things, inspected most/all hoses looked okay, ones i thought needed changing i did, changed spark plugs, new leads, changed afm, fuel regulator, throttle body (and sensors on it) rubber on elbow from the throttle body i think that's it and still nothing, feels like its more black smoke now.

So might try and see if i take it to a mechanic and do a smoke test on all air lines and see if there's a leak.

i the a feeling it might be one of the injectors that's stuff and leaking a lot.

what a annoying job to do if it is a air leak somewhere, lets hope the problem is solved soon.

again if anyone recommends something else please let me know. cheers.

 

[VOLK]

What'd the plugs look like? They'll tell a combustion tale...

 

[Gt_Galant]

They were all black with a little black crap on it (not much black crap on them) none looked different from each other, i had a friend that looked at them and said they looked like it was 100% running to much fuel and you can really smell it when car is idling at them moment.

 

[VOLK]

Right. Probably rules out injector(s) stuck open then. So for some odd reason, your ECU is going into some form of fail-safe or receiving a value from a sensor that's making it richen extremely. I wouldn't imagine a failed temp sensor would cause it to run this rich. Pulled codes yet?

 

[Gt_Galant]

Hopefully maybe Tuesday i should get it put on a scanner so we'll see what it says.

Funny you mentioned failed temp sensor because my radiator fans don't kick in anymore only when i put aircon on because when car is warmed up and the thermo should open and fans kick in and you actually feel not much pressure in radiator hose, its not doing that for some reason, i doubt a stuck thermostat is causing the problem, i do have a new thermo which i can change but have a feeling its not that just car is playing up from original problem.

 

[VOLK]

So, at working temp, rad feels cold still?

 

[Gt_Galant]

Na, radiator is very hot.

 

[Gt_Galant]

Nothing to do with the problem but some dumb f*** hit the side/back, went to start the car to test something and noticed it. And car was meant to be towed today morning but decided for tomorrow, my luck who ever hit the car left no note or don't know who.

 

[Cameron McPherson]

I had a similar issue when I put my car back together after doing lifters.

Didn't do the clamp up that attaches the post-intercooler pipe to the throttle body tight enough, put some jandal into it and it popped off, but only on the underside so it looked like it was still on from the top. Idled low and lumpy like you mentioned, and dumped shitonnes of fuel/black smoke when I revved it - because I assume a large vac/boost/air leak like that would mean the air the engine is thinking it's getting is a different amount to what's actually going in, and it's overfuelling like a mofo.

Soon as I put it back on and re did the clamp up everything was fine

 

[Size1]

Cant Handle the Jandle. Bwahahaha.

 

[Gt_Galant]

Hmm if i get time tomorrow will triple check things but still waiting to take the car to the mechanic just don't have time. And now that it got hit from the side and dunno by who i just feel like i can't be bothered because everything is shitting me.

 

[Gt_Galant]

A friend suggested maybe the temp sensor because the radiator fans are not even kicking in when hot, changed it and nothing.

What i find strange is that when all this happened i got it towed home and started it and still idling crappy and then started it about a hour later and it works perfectly, drove it around the block and drives perfect. And then started it the next day and still crappy ever since. Anyway tomorrow i got a little time so might fiddle with it.

 

[AKKO]

A friend suggested maybe the temp sensor because the radiator fans are not even kicking in when hot, changed it and nothing.

How hot is hot though, without A/c the fans don't go on full until like 110 degrees iirc

 

[Gt_Galant]

It's hot trust me normally i know when fan is suppost to kick in and nothing, even the radiator hoses looks like it's ganna explode because there's so much pressure. Normally with my car once it's at normal temp about 10minutes max idling it kicks in, but at normal temp and car idling 20minutes while me revving it i know it's meant to kick it and nothing. But I'll see tomorrow when i fiddle with things, i wonder if a injector is stuffed or maybe inlet mainfold has a leak somewhere or crack.

 

[TME_Steve]

You're all looking at it wrong. A boost/vac leak is not going to run rich under vacuum conditions, it will run lean. So at idle a leak would cause it to run lean. Given it was smoky id be looking at that coolant temp sensor. Fans start at 99 degrees in evoscan which is actually about 92 degrees.

That all said, it could be a leak, the lean condition can make revs dip low them the ecu goes into an idle recovery mode that can run afrs of who knows, but I'd still think it unlikely. I'd think you have something like a wiring problem to your coolant temp sensor so it's intermittently going open circuit and therefore rich.

Hard to diagnose on the interwebs though. It's one step worse than doing it over the phone