HELP: Why am I having a hard time passing emissions

[1Byounkin]

I've replaced it once. Never had any codes for it.

On a GMC van with a 350 EFI we had the O2 die. Now that was enough to make you pass out in the truck. replace it everything was fine. But it had a code.

 

[Tbars4]

..I would ask what year van but instead, if you had a loose 02 sensor in a 96 or newer it would have given you a code..

...I forgot to ask about the rich smelling fuel you mentioned...Where was that emanating from?

 

[1Byounkin]

The van is a 90 so OBD I also.

I just checked mine. Its tight.

The smell was just enough to notice barely. Just at the tail pipe. No where else. Everything is sealed down stream.

 

[1Byounkin]

I did run another code check today. Found no codes. Passed on that.

 

[Roadrunner777]

I didn't read all the posts in detail, so maybe this is covered...

I can see three components doing this that you have not replaced. I really hate to replace parts without definitive proof. That said....

I might replace the temp sensor for the computer. There is one for the gauge, and one for the computer. I forget which is which, but it is in many other threads. If the computer thinks the engine is colder than it is, it seems to me like it would run rich and the computer would never know to throw a code. It's a cheap part and easy job.

I might... I would not like it, but I might replace the O2 sensors.

I'm not the best guy to explain this, but here goes... the computer uses, among other things, the O2 sensors to determine fuel injection duration. You might think, where is the CEL? That's a great question, but I am not sure the CEL threshold is less than the smog test.

I might replace the computer or at least open it up and check for blown capacitors.

Unless I missed something, the coilpack is still on the table too.

How is your oil consumption?

I'm just throwing thoughts in the air...

 

[1Byounkin]

I've always wondered about the temp senor for the computer. I do know there are two. Can you check the omhs of it?

I might look in to that about the computer. Does the cover just unscrew to see or do you have to remove the whole thing to see if so?

I know I can unplug every plug wire at the coil pack and they all make a difference when the engine is running. I have check the coil before with an ohm meter. Might have to check it again. Don't remember the numbers.

Burns none, drops very little out the back of the pan. Might add a half qu every month. Use to until I change the valve seals and now better since the heads. Replace the heads because the that famous crack problem they have. Before the seals it would eat 2 quarts a week. Thats all good now.

I can tell you this. I've always had trouble of it shifting into overdrive right. 65 mph run almost 3,000 rpms. 55mph is alittle above 2,100rpms. You don't feel the OD kick and if you shift from OD to D no change no matter what. Maybe this is all part of the problem. Ive read If the computer thinks the engine is langing it won't shift into OD.

So it might be something on the senor end or computer making other things be effected. Now showing up.

 

[Champcar_Fan]

What about the sparkplugs, when was the last time they were changed?

PCV valve and it's grommet? How old are they?

 

[1Byounkin]

The spark plug and few months old. Double platinum plugs. All clean everytime. No build put of carbon.

New PCV valve yes in the grommet, tightly

 

[1Byounkin]

Roadrunner- I opened the computer. Looks brand new on the inside. Nothing blowen. Also the connections on the plug look great too.

 

[1Byounkin]

Also another thing that comes to mind. Few time after a hot restart, like traveling to town going to a store and caming back out. Start it up. The truck would feel like a little of a miss to it. After revving it up a little it would smooth out. Sometimes it would take awhile to smooth out. Once it did it would run normal all strong again.

Maybe another clue.

 

[1Byounkin]

Does anyone think that the ECT could be the whole problem??

 

[1Byounkin]

Replaced the ECT. Checked the old vs the new ohms. Both at room temp. The new one read 18 ohm and the old one read 21 ohm.

The truck is running better. All I know the ECT has been replaced. Haven't done the test yet

 

[1Byounkin]

I haven't done the test yet. But I remembered that any time the engine is warm I would have a hard time starting. Even if I changed the wires and plugs. So I got to thinking about checking the coil.

I did the primary test. Got 0.7ohms, 1.4ohm, 1.3ohms

And the secondary test. > all 13.46 ohms.

STD readings should be 0.3-1.0 ohms for pri and 6.5 to 11.5 ohms for the secondary.

Maybe a problem too??

 

[clintexas]

Re: Help:Why am I having a hard time passing emissions?

Hello,
I also have a 1991 Ford Explorer XL and I bought it back in 2006 and after driving it about a year, I parked it. When it was parked, it only needed brakes, but after 5 years sitting, when I tried to resserect it last Oct. I took MUCH more to get it running right. I tried 3 times to get it to pass inspection (emissions) and it wouldn't even come close. So this is what I did to recently get it inspected and IT PASSED!
1) Ran the higher priced gas in it for a couple of tanks (Shell gas)
2) Poured "Guaranteed to Pass" liquid in the gas tank and ran it thru with a half of a tank.
3) Got a can of Sea Foam spray and took off my intake and adjusted the little straw and put it all back on and sprayed the can into the intake while also raising the idle. (Get the spray can of SeaFoam and the instructions are on the label on the can.)
4) Also checked all my hose clamps on the intake and tightened them up.
5) Found that there were a couple of bolts missing on the air filter housing that was allowing air and dirt to enter, so I replaced the bolts and closed the system.
6) Poured a can of seafoam into the gas tank and ran about half a can thru half a tank.
I then drove it about 50 miles or so, and then took it in early in the morning to be inspected and it passed.

Now, this vehicle has 409542 on the speedometer, and isn't getting any younger. It caused problems for it because it sat for 5 years, but it's now running better than I ever remembered it running previously. It still has alittle but of a tap to it, but not at all as loud as it was before I cleaned the fuel injection system from bumper to bumper!

That's what I did to pass my emissions test here in north Texas. I only had about another week or so to get it passed or the State of Texas was going to pull my registration. (THEY HAVE A DATABASE WHERE THEY CROSS REFERENCE ALL VEHICLES REGISTERED TO THE VEHICLES THAT PASS OR DON'T PASS INSPECTION.) I got a letter from them giving me 45 days to pass or they'd pull my registration. And after 3 attempts, It passed!
I hope this information helps someone else out there.....I was about to pull my hair out and trust me, I have alot of it!

I was afraid that I'd have to buy catalytic converters (there's 2 on these 1991 models) at about a $300.00 total cost, but with the bottle of "guaranteed to pass" and a couple of cans of seafoam it did the trick!
I hope this also works for you. Try it!
~Cindy Lou' in north Texas

 

[1Byounkin]

I've ran high octane gas and still failed. Even with chemicals. I think it's something within e computer system like a sensor or replay or something I that area. I have a hard time starting it when the engine is warm. Not as in turning over but as in the firing up. Than when it does there is a small miss than it will smooth right out. I've replaced plugs (and gapped them to 0.054), the ECT. Adjusted the tps. Also checked the voltage in the maf sensor when it ran. All numbers match.

Another problem in this area is it will not shift in to OD (no tCC lockup) Is there something related in this problem to be causing that problem too?????

Thanks for any help

 

[1Byounkin]

UPDATE:

Finally did the test after doing everything listed up above. Even using the Guaranteed to pass and still failed. My HC was at 273 before now at 234. The limit here is 220.

I'm running out of things to check. It's always had a hard time to start hot and misses when it does. But rev it up than it is fine. And it has alway has had a slight miss. Even replacing the wires, plugs multiple times. Check the coil. Checked everything sensor based. Even when new heads it ran the same. I'm getting to the point that I think the computer is doing something wrong or bad. Never any codes. All sensors ohm out in the right specs. And have always had trouble with OD TCC stuff.

Anybody know anything???? Bad EMC?? This is in a 91

 

[Tbars4]

...I have a 91 which I maintain which has done some interesting things when it comes to acting weird but I usually find something is not working properly even if it is new and ohms out...

..With you being so sure it is none of the before mentioned items and all sensors are operating properly, you have us at a disadvantage as we can not physically check all the items for you or even hear it run for that faint miss.

...Have you by chance chatted with a local mechanic to pick his brain and let him take a peek?

Yes, it could be your computer has issues (not uncommon) and has gone south but your no OD lockup is not related to your high HC's..

 

[1Byounkin]

I understand the no OD is not causing HC. Just two problems. OD wil not work until the engine is right. So I'm thinking whatever that is making the engine run high HC is making it not run right. I've gotten sensors from pull a parts to put in mine and still the same problem. I've always have had high HC. Every year is getting worse. Harder to cover up to pass.

I've talked to a few and said maybe the timing? I've wondered about the crank sensor. The truck runs powerful. You can gun it and it will instently pick up and go. Idle slight miss. Tail pipe smells rich. I've checked the fuel pressure. 30 psi cold 35psi warm. 45 FPR unplugged. Rev up psi goes up. To 40.

You can feel the small miss while sitting in the truck at a light.

That's way I think maybe computer, just something not processing right. Mine is one of the first 91 with the BAP/MAP on the firewall.

 

[1Byounkin]

I hooked up a volt meter to the MAF and watched the voltage changed as a rev the engine. Numbers matched the right rpms to voltage output. Same for the TPS. And the Air temp sensor and ECT (replaced)

 

[Tbars4]

..:scratch:...I'm not sure why you brought up th MAP sensor but for others who may stumble upon this, it would give a code 22 if it itself had issues..

http://www.explorerforum.com/forums/showthread.php?t=241541&highlight=map

..and from what you have posted, you could have had your tranny harness hit the exhaust which took out the possibility for the computer and tranny to communicate to shift into OD which also may have zapped your computer...

..There are a number of threads on here about multiple issues with a bad computer in the first gens..