Engine issues, running rich with bad gas mileage, stalls, hard to start

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JamSKahler

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Hey guys,

Really appreciate your all's help with this one. I've been working at this thing for the longest time.

Got an issue where the engine will stall at stop lights. Has been gradually getting worse. Car now nearly impossible to drive, stalls at all stoplights/stop signs/stops. Car is difficult to start, usually takes multiple tries to get it started, have to pump pedal. Also have had intermittent issue that causes the car not to be able to rev past 2500 rpm, now consistent as of today.

I suspect that there's been a head gasket leak for a while now but have only recently been able to get that far on my own repair-wise.

Right now engine is running rich in both banks and my O2 sensors show high voltage in bank 1 and low voltage in bank 2. Also showing a P2311 and P2308 for secondary ignition coil circuit in C and D. Gas mileage is in the 6-7 mpg range.

Have checked the fuel injectors and power supply, all with power. Fuel injector resistance is roughly equal for all 6 injectors with no noticeable blockages in injector ports on both ends. Switched out ignition coils in cylinders 3 and 4 with no improvement. Have checked power supply to ignition coils, all with power (but didn't check the ground..)

If there were issues with head gasket / warped heads from previous overheating (with confirmed white smoke, loss of coolant, and misfires most recently treated with Blue Devil...) could this cause fuel to get dumped into cylinders without igniting? The O2 sensor codes and issues with gas mileage are recent, but the car has had issues with performance, starting, idling, etc. for a while. I think most recent issues have put car over the edge performance-wise.

Thanks for your all's help.

Also, my oil light has been on for a couple of weeks, but the dipstick shows it as full. I've had a steady oil leak for a while, although for some reason it's gone now (Blue Devil or thick oil stop leak X 2 applications) I'd say something about it not giving the typical sounds of an engine lacking oil, but the issues with cylinders not firing, inevitable stalling, and irregular engine performance make it difficult to discern if it's not getting oil. It does feel smooth for the most part, but as if there were like... one cylinder keeping it alive at idle sometimes.
 
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JamSKahler

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Update

Hey everyone, just an update - replaced spark plugs today which were fouled pretty good with carbon buildup over the past year (last replacement). Vehicle performance is significantly improved, although still issues. Car will stall on occasion now, gas mileage is back up to 15-17 mpg.

Something I've noticed though - the car responds slowly when the gas pedal is pressed, which it was doing yesterday, but is now easier to identify now that car will idle. It can take anywhere from 0.5 to 3-5 seconds to get any kind of response from the car, sometimes its like it doesn't get enough power (up hills, etc. will take longer response) but in general there is a defined delay between gas pedal press and acceleration.

Will replacing heads solve this situation? I feel confident enough to replace them after removing heads in junkyard, having a solid understanding of timing/camshaft installation, and removing the fuel rail on my own car. Honestly wouldn't take too terribly long (hardest part is removing the exhaust pipe for some reason, depending on the year)
 

Sephiroth

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I would check the throttle position sensor and make sure IAC valve, and cam crank shaft sensors are working too.

Sent from my SM-G955U1 using Tapatalk
 

tjkj2002

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Somewhere between being sane and insane!
Just get a remaned engine and be done with it.

What you poured in the oil has now trashed the entire engine and the coolant in that has been getting into the engine has trashed all the bearings anyways.

Remaned engine or fight with it for god knows how long before you get mad and sell it off for scrap and loose alot of $$$.
 

ElCheapo

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Wow, so much.
OK, first, pumping the gas pedal on a fuel injected motor to start it, does absolutely nothing. That only works for carburetors.
If a head gasket, or head issue, you will see bubbles in the radiator, and a coolant test will show exhaust gasses.
Good on changing plugs, fix cheap easy stuff first!
Check all vacuum lines and valves for leaks. Often a problem.
Check TPS, EGT, other electronics.

Right now engine is running rich in both banks and my O2 sensors show high voltage in bank 1 and low voltage in bank 2. Also showing a P2311 and P2308 for secondary ignition coil circuit in C and D
Have you done anything with that? Low voltage will cause weak spark, running rich, etc.

Hold off on replacing heads until you know that's the problem.
Get an oil analysis, motor may be junk.
 

J33Pfan

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Try cleaning the idle control valve throttle body. clean out PVC valves & passages, etc
 

JamSKahler

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Just wanted to keep this thread alive.

So I had a guy come up to my car today, and he's like "You want me to save you a whole heck of a lot of effort?" and I'm like ".... Yes."

And he looks me in the eye and says "Fuel Pressure Regulator".

ASE certified tech, the guy honestly sounded very smart, like very much on his shit.

Also mentioned crankshaft pos sensor as another primary dx

How cool is that though lol - sitting here in a random parking lot in Idaho, never been here before

In other news, my car drives fairly ok on road trips at the moment, despite stalling if it ever has to stop. 13 hours so far, no major issues.

Maybe smart idea would be to record engine performance, throw on YouTube and post on here.

Also as far as the engine goes, I'm not hearing any bearing noises or noticing any issues typical to failing engines other than misfire.

Hoping the sensor stuff works. Will try those out.

I appreciate your all's help and input, lemme know if you think anything else.

Cheers
 

JamSKahler

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I'm not sure where to start with engine running rich conditions, chicken or egg I'm not sure but misfires make me think that probably O2 sensors working properly, or at least they're showing correctly.

Voltage low/high codes for O2 sensors indicate the output, not the input correct? It'd make sense based on how the engine has been performing.
 

JamSKahler

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Also I should note that in this situation, pumping fuel pedal, for whatever reason, has 100% effect on whether car starts or not.
 

J33Pfan

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Also I should note that in this situation, pumping fuel pedal, for whatever reason, has 100% effect on whether car starts or not.

IMO: Pumping should not help starting a fuel injection car unless there is a problem with TPS.
 

Disco95

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I'd be looking at the intake air controller/ sensor and PCV valve/ sensor first.
Edit: J33Pfan is right, TPS shoild be added to that too.
 
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Michael Wolfe

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You should be able to monitor PID's with a decent OBD interface. I use a bluetooth reader with my smartphone, using the torque app. I have a CRD, but you could probably check fuel pressure values, pedal position %, etc. You are kind of really hampering your efforts to fix issues, without at least knowing what the ECU thinks is going on.
 

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