HELP: Why am I having a hard time passing emissions

[1Byounkin]

I was reading on here that if I was to go to a junk yard to find a 91 with a BAP sensor

 

[1Byounkin]

I do know that all wiring is away for the exhaust and has never touched it. I've been reading different pages about it. But still nothing has helped much :/ Just a weird problem somewhere in the system

 

[1Byounkin]

Would it be worth trying a computer from a junk yard to try it? The right one

 

[1Byounkin]

What about timing??

I know before I had this truck the bottom end was rebuilt and bored. I've been told the timing has been off maybe to cause a slight miss and hard start. What about the adjustment to be wrong on the CMP sensor?

But runs strong and never a power problem just idle and high HC.

 

[1Byounkin]

Bump?

 

[Tony H]

Thermostat running a bit cold. that was my problem No code shown

 

[1Byounkin]

That's all been replaced

 

[4x4junkie]

It missing is a direct cause for hydrocarbons to go up (HCs are unburnt fuel). So you'll need to fix whatever is causing it to miss at idle.

Like Tbars said, there's no good way for us to know what is wrong, especially with all the basics having already been covered. Only way to figure it out is with hands-on diagnostics. Maybe a friend knows a trusted mechanic you can take it to if you're having a hard time with it yourself.

FWIW, My Ranger (4.0L) for years had been right on the very limit for HC, though never actually failing (new plugs & wires, new O2, MAF cleaned, fresh oil change, etc.). Last time around I ran a bottle of Techron fuel additive through it and this time it passed about 20% or so under the limit. YMMV.

 

[1Byounkin]

What I think I've narrowed it down to is the facted that I'm using the Duralast wireset. What I've read is that cause problems with a miss and stuff. I know other night in the dark a could see green arcs coming from the wires. Wires look good and a few years old. They are what I've ran ever since I've had it. And its always had a slight miss. Replaced them once for warrenty. same set.

I've ordered Motorcraft wireset. Tomorrow ill know if it runs better. Would a slight miss becausing other troubles?

 

[4x4junkie]

I know other night in the dark a could see green arcs coming from the wires.

Looks like you found your problem then.

I use nothing but Bosch wires on these trucks (Bosch make the Ford (Motorcraft) ones as well, so either way you should be good)

As for other issues... hard to say. It missing bad enough would certainly trigger the CEL, but I couldn't say for sure if it would affect the tranny shifting like that (I wouldn't think so though).

 

[1Byounkin]

I think so. Smoother idle. The only thing is I went out to drive it down the road and it would miss under the load, first time it's ever done that. Engine stopped as i was driving and than it ran better. Now it sounds better. I guess the computer had to relearn. I still have problem with it firing SOMETIME when hot/warm. Very random. It would hit once kick the starter back like if the motor was running. Than I would have to crank it again a little long for it to hit. Than would run fine.

I've been told the fuel pump can be getting weak. Cold it has 30 psi and running at 30psi. Hot prime to 37psi and run at 30psi. Starting at 37psi hot. Never would show bleed down. I was told the average is 35-45psi for cold. I'm going to replace the fuel filter soon

 

[1Byounkin]

UPDATE: Did the test again for the 3rd time still failed.

First test: 273 HC
Second: 234 HC < using Guarantee to Pass
Third: 257 HC .77 CO

Limit in TN is 220 HC

4x4Junkie - I talked to a mechanic today. He said that I can pull the spout connecter to advance the timing and idle it up to 1,200 rpms.
I know you can't change the timing like in a 350 or something like that. But you can some. But for me to advance the timing means its too low. I read on here ( http://www.explorerforum.com/forums/showthread.php?t=361167 ) That this guy talked about the chain being loose which would retard the timing. So if I have to advance it would mean its too low now. The only thing this motor has is a miss at idle, you can feel it. I don't have performance problems. It can rev to redline and pull strong. But like what I read in that thread the torque curve is changed. Thus this makes me wonder if the timing is off that would cause a miss and would be the reason why the transmission don't kick into over. BTW 5-6 years go is when all this started the OD quick working, the engine would run rich (not so bad now) and started having a miss.

The motor has been into, as to what I can see is it has been bored. So pinions and maybe rods and crank. I know it had the original heads (because those cracked) and the rockers are really worn. So that makes me wonder about the timing set (chain, gears, tensioner) if they are worn too. I have 290,000 on this truck. And those parts might be original with those miles.

Any ideas??

 

[1Byounkin]

Bump?

 

[1Byounkin]

UPDATE: I replaced the crank sensor. Still has the mis. I unhooked the battery all day. Hooked it back up last night. Started and let it run for a few mins. No driving. But within those few mins the mis was back. Without a driving cycle to learn. I'm going to a junk yard today to find a computer to try that.

I've had this truck for about 8-9 years. Never have had a code thrown ever even when I've had problems before. I have a code reader that shows a digital read out for the numbers. No flashing light.

 

[1Byounkin]

UPDATE Replaced the computer. Runs a lot better. Got the crazy mis gone. But the bad thing is it still failed Emissions again :/ HC this time was up to 320.

What else can I do???? Nothing is working

 

[Iron Weasel]

UPDATE Replaced the computer. Runs a lot better. Got the crazy mis gone. But the bad thing is it still failed Emissions again :/ HC this time was up to 320.

What else can I do???? Nothing is working

I didn't read the entire thread, so forgive me if this has already been asked:

How's your catalytic convertor? Has it already been replaced in your quest to pass emissions?

 

[1Byounkin]

Ok I'm still on the quest of why this thing will not pass. I have now until OCT to do it again.

Problem now with a new computer the truck will idle 2200 rpms. If I unplug the IAC it will idle back to 500 rpms. Now I've replaced the IAC 3 times. When it's unplugg running the engine speed is right, but as soon as I plugged it in it will rev up high. I can un plugg the MAF abd it will slow down some. And ivd replaced that. If you in gear with the brake on it will hold at 1,000 rpms. But you can tell the engine is wanting to run higher. The weird thing is I'm getting tons better fuel mileage. Was getting 15 mpg, now get 20+ mpg. But I still have high HC.

Also when I run codes I get a code for idle set too low. Set to low but runs high???

 

[1Byounkin]

Well after replacing everything. Sensors and computer I still can't pass!!! HC too high still. 375 HC. I have ran out of things to look for!!

 

[1Byounkin]

Seafoamed it. Seems better. Maybe that will work

 

[awood]

I read through the thread, and I think I got everything. It sounds like you already replaced both the ECT (engine coolant temp) sensor and the ACT (air charge temp) sensor. These both act together to perform the similar function of a choke on a carburetor. Since you are running rich, and you've already replaced both these components, I would try this test...
Both sensors are "negative coefficient" sensors - meaning that as the temperature goes up, the resistance goes down. Here are some values:
50 degrees F....58,750 ohms
86 degrees F....24,270 ohms
158 degrees F...5.370 ohms
248 degrees F...1,180 ohms
But here's what I'd do. Measure these values directly at the sensors. Then at the same temperature, measure the pins where the wires plug into the PCM (refer to a wiring diagram to determine which pins to measure). There should be very little, if any, difference in the resistance readings. If there's a big difference, say more than 1 or 2 ohms, then you have a wiring problem.