Rough Idle... High Hydrocarbons

[sicknickclassics33]

So, rebuilt a friends 92 V6 XLT... 127k mi. Sat garaged for 8yrs.

Drives good. Its had a rough irregular idle, and I notice the misfire situation at all RPMs. Checked for all possible vacuume leaks, replaced plugs, wires and coil packs. Replaced fuel pump, PCV valve, fresh gas with Seafoam injector cleaner. Aside from swapping out the fuel filter next, im at a loss. Would this be the cause? Was considering the capacitor at the coil pack as well, but read it only prevents radio interference and has no other function.

I took it to see if it might pass smog anyways, the guy did a pre-reading at idle and said the hydrocarbons were high and to address this issue first before an official test... so no additional emissions reading to go off at this time. When I swapped the plugs which had run recently for about 80 miles, they were clean with a yellow tinge.

Im looking to rule out full injectors or exhaust valve seating issues. Being all the plugs are the same, it doesn't seen to be an individual cylinder issue. Any ideas guys?

Thank you in advance!

 

[~X~]

Have you scanned it? I would do KOEO & KOER.

Running rich could be the temp sensor, a scan can at least point you in the right direction.

 

[DaSovietPotato]

One thing which could contribute to a rough idle is a vacuum leak within the intake hose. The intake hoses are prone to springing vacuum leaks at the accordion sections, especially after 30 years. I would also consider reading the output of the MAF or O2 sensors if they have not been looked at for a long time.

 

[sicknickclassics33]

Have you scanned it? I would do KOEO & KOER.

Running rich could be the temp sensor, a scan can at least point you in the right direction.

ECT sensor? I do have it on the list of possible issues. I dont have an obd1 scanner. I took it to O'Reilly Auto Parts for a free scan and they couldn't get theirs to read it at all. So no codes available to work with at this time. But, no CEL either.

 

[donalds]

ECT sensor

Engine coolant temperature sensor

There is a way to check your codes with a paper clip in the OBD port use a search function above

 

[sicknickclassics33]

Engine coolant temperature sensor

There is a way to check your codes with a paper clip in the OBD port use a search function above

Thank you for the tip!!

Ok. I figured out the paper clip deal.

KOEO I got a 33 (EGR)

KOER I got a 116 (ECT)

I believe these are the right meanings of the codes. Can you help me to confirm? And is it definately both to be replaced, or might one affect the other?

I also ran it 3 times as it took me a bit to figure out how it works. The first time I also got a 138... which I looked up as Cold Start Injector Flow insufficient. Would that be related to the first 2? Or maybe the fuel filter needing replacement?

 

[sicknickclassics33]

Thank you for the tip!!

Ok. I figured out the paper clip deal.

KOEO I got a 33 (EGR)

KOER I got a 116 (ECT)

I believe these are the right meanings of the codes. Can you help me to confirm? And is it definately both to be replaced, or might one affect the other?

I also ran it 3 times as it took me a bit to figure out how it works. The first time I also got a 138... which I looked up as Cold Start Injector Flow insufficient. Would that be related to the first 2? Or maybe the fuel filter needing replacement?

Looking into things a bit further, 8m reading a 92 XLT doesn't have an EGR Valve. So, confused about code 33

 

[sicknickclassics33]

Looking into things a bit further, 8m reading a 92 XLT doesn't have an EGR Valve. So, confused about code 33

Answering my own question, since it seems to be a bit of confusion for others throughout forums, 333 is 1,1,1 repeat 1,1,1 pass codes.

So it looks like it is the ECT sensor that is the big issue here

I will follow up with the results of replacement.

 

[~X~]

You're tracking it down . Listen to guys in this thread.

I have an Innova scanner that was gifted to me, cost $29 & I bought an extension cable on Amazon for $15. I wouldn't go anywhere without it.

KOER will give you a balance test, might pertain to your lack of goodness....I don't know, I'm not a pro just my 2cents. I've learned alot on here though. My current 94 ran rich & it was the coolant temp sensor....easy fix. I went on from there.

 

[donalds]

I think he is on the right track toO

 

[Nadams01]

Coolant temp. sensor is a good track, I posted the testing graph on a forum, I will link it for you. If its a 92 with California emissions im pretty sure it has an EGR, can you take a picture of the intake manifold from the driverside of the engine bay facing the passanger side? if the EGR is stuck open, or not opening when the computer wants it too it can jack up your AFR.

 

[Nadams01]

Failed Smog: HC, NO OK - but CO is high

I have a 1993 Explorer w/4.0 - and I am having a hard time passing smog. I have changed the Oil, Filter, Air Filter, Plugs and pulled codes - everything passed, no indications of any problem. The plug were platinum and had been in there 50k plus. That said, they looked like the motor had been...

www.explorerforum.com

 

[sicknickclassics33]

Coolant temp. sensor is a good track, I posted the testing graph on a forum, I will link it for you. If its a 92 with California emissions im pretty sure it has an EGR, can you take a picture of the intake manifold from the driverside of the engine bay facing the passanger side? if the EGR is stuck open, or not opening when the computer wants it too it can jack up your AFR.

I'll check it out tomorrow. It is a Cali car originally if I recall. I was pretty sure I was looking for an EGR at one point and thought it can't be this hard to find it... and gave up I'll report back with verification or a photo tomorrow. Pouring down rain at the moment.

 

[~X~]

As Da Soviet Potato said, the intake tube from the MAF to the throttle body is known to crack & let in unmetered air, a very common problem. This should be checked out while you're chasing things down. Usually happens in the pleats near the air box.

Good luck

 

[sicknickclassics33]

Have you scanned it? I would do KOEO & KOER.

Running rich could be the temp sensor, a scan can at least point you in the right direction.

Scanned the codes. Only got that 116. Replaced the ECT and still running the same. Re-scanned... same 116 code. Any ideas?

 

[sicknickclassics33]

As Da Soviet Potato said, the intake tube from the MAF to the throttle body is known to crack & let in unmetered air, a very common problem. This should be checked out while you're chasing things down. Usually happens in the pleats near the air box.

Good luck

I checked and rechecked ALL vacuume lines... and, then I checked again ive even tried ether around all the critical areas to see if I could get a rise... nothin.

 

[sicknickclassics33]

UPDATE: Replaced ECT due to 116 code. Still persisted after re-test. Did some more research and realized I hadn't brought truck up to operating temp and tested again.. all 111's now and experiencing no change of symptoms.

Now I'm really confused how to proceed.

 

[Nadams01]

Reset your KAM (keep alive memory) which stores all the temporary data for AFR and other stuff by disconnecting the battery for 30 mins or so. do check that intake boot, Mine had holes in it where it goes over the fan shroud.

 

[sicknickclassics33]

Coolant temp. sensor is a good track, I posted the testing graph on a forum, I will link it for you. If its a 92 with California emissions im pretty sure it has an EGR, can you take a picture of the intake manifold from the driverside of the engine bay facing the passanger side? if the EGR is stuck open, or not opening when the computer wants it too it can jack up your AFR.

No EGR

 

[sicknickclassics33]

UPDATE: Inspected the intake pipe (airbox to throttle body)... no leaks. Also swapped out the fuel filter... no difference. Left battery unplugged for an hr to reset as well.

Any more ideas?